Exploitation of Heterosis for Yield and Quality Enhancement in Pumpkin (Cucurbita moschata Duch. Ex Poir.) Hybrids

Abstract

The hybrid development of pumpkins, utilizing local genetic material, has recently garnered attention in India. This study aimed to evaluate the combining ability, heterosis, and per se performance of pumpkin hybrids for yield-related and biochemical traits. In the present investigation, eight parental lines of pumpkins were hybridized using a half-diallel mating design, resulting in 28 F₁ hybrids (reciprocals not included). The produced F₁ hybrids, parental lines, and a commercial check were assessed in a randomized complete block design with three replications during the summers of 2023 and 2024. The results obtained in the study show that the best performers with the most desirable characteristics were P-7 for total soluble solid, dry matter content, and average fruit weight; P-3 for total carotenoids, number of seeds per fruit, and antioxidant activity; P-2 for yield per plant and flesh thickness; and P-8 for number of fruits per plant. The parent P-5 for fruit number, average fruit weight, and yield per plant; P-2 for flesh thickness and antioxidant activity; P-7 for TSS and dry matter content; P-1 for fruit number; and P-3 for total carotenoids were noted as the best general combiners in terms of the effects of the parental lines on general combining ability. Conversely, the crosses P-2 × P-5 for yield per plant and flesh thickness and P-1 × P-2 for DPPH activity were found to outperform better-parent heterosis and standard heterosis in terms of heterosis and the specific combining ability magnitude of the F₁ hybrids. Thus, the findings of this study reveal that these hybrids possess strong potential for commercial cultivation, contributing to the development of high-yielding and nutritionally superior pumpkin hybrids after being tested in various seasons and locations.

1. Introduction

India ranks as the world’s second-largest vegetable producer, with an annual output of 204.6 million tons from 11.28 million hectares, achieving a productivity rate of 18.1 tons per hectare [1], being fortunate to possess diverse agro-climatic zones with distinct seasons, enabling the cultivation of a wide range of vegetables [2]. This has led to a significant increase in vegetable production over time, accompanied by a gradual expansion of cultivable areas and increased productivity.

Pumpkin (Cucurbita moschata Duch. ex Poir) is one of India’s most crucial Cucurbitaceous vegetable crops. It has attracted increasing attention from scientists due to its high nutritional profile [3,4] and has a higher commercial value, primarily attributed to shifts in consumer patterns. Moreover, it requires fewer inputs for production [5]. Pumpkin’s fruits are rich in antioxidants such as ascorbic acid and β-carotene, which make it a highly nutritious vegetable [6]. In addition to several fruit-related nutrients, the seeds have high concentrations of simple proteins, calcium, iron, potassium, phosphorus, magnesium, zinc, and beta-carotene. Furthermore, seeds contain unsaturated fatty acids and dietary fiber, both of which promote heart health [7].

Both the immature and mature fruits are used in cooking [8]. However, immature fruits are generally preferred over mature ones. Despite being a widespread crop, most hybrids released in India have large fruits (4–5 kg), which an ideal family comprising up to four members may not find appealing [9]. Furthermore, consumers prefer to purchase only medium-sized pumpkin fruits rather than cut pieces due to the rising trend of nuclear families. Also, it is much easier to pack and transport small-sized fruits without any bruising. Focused crop improvement work is required to create a hybrid of medium-sized fruits (1–2 kg) that would be ideal for a nuclear family, minimizing waste.

The proven way to increase productivity and quality in the shortest time is through heterosis breeding, which is feasible with this crop and crucial to crop improvement [10,11]. In breeding, heterosis refers to the phenomenon in which a hybrid possesses a stronger genetic makeup than its parents despite having a homogeneous genetic background [12]. Pumpkin is a cross-pollinated, monoecious crop that produces large amounts of seeds per pollination. Its cultivation offers an excellent opportunity to harness its genetic diversity and enhance overall quality by developing high-quality hybrids. In practical crop breeding, knowing the general combining ability (GCA) and specific combining ability (SCA) is helpful in choosing the parents and makes the mode of gene action clear in a hybridization program [6]. Furthermore, minimal effort has been invested in improving the genetic makeup of this crop, particularly in terms of quality traits. This could result from a lack of genetically distant genotype collections [13]. Therefore, the breeder must understand the type and extent of variability in the genetic stocks. A significant limitation to its production is the absence of high-yielding F₁ hybrids with desirable agronomic traits. This crop exhibits considerable genetic variability among its cultivated landraces, which can be leveraged to its advantage. Thus, the goal of a breeder is to use selection to create high-yielding varieties, either from the segregates of a cross or existing genotypes. Furthermore, the growing demand for higher crop productivity underscores the need to develop improved cultivars with superior agronomic traits. This can be accomplished by leveraging heterosis and combining ability analysis of the best-yielding pumpkin genotypes that have been optimized in agroecology [14]. Therefore, the current study aimed to identify potential parental pairings for the development of superior hybrid pumpkin varieties.

2. Materials and Methods

2.1. Experiment Materials, Design, and Location

In this study, eight inbred parental lines of pumpkin were used (PPU-20220/1 (P-1), PPU-2022/2 (P-2), PPU-2022/3 (P-3), PPU-2022/4 (P-4), PPU-2022/5 (P-5), PPU-2022/6 (P-6), PPU-2022/7 (P-7) and PPU-2022/8 (P-8)) collected from Pantnagar (Uttarakhand), Lucknow (Uttar Pradesh), Kichha (Uttarakhand), Almora (Uttarakhand), Ludhiana (Punjab), Varanasi (Uttar Pradesh), Bareilly (Uttar Pradesh), and Sabour (Bihar), respectively. The 28 F₁ hybrids were produced by crossing these inbred lines in every conceivable way, excluding reciprocals, using a half diallel mating design. The eight parental lines, 28 F₁ hybrids, and one commercial check (‘Narendra Agrim’) were evaluated throughout two growing seasons (March to July) at the Vegetable Research Centre, Govind Ballabh Pant, University of Agriculture and Technology, Uttarakhand, India. Weather data for both growing seasons were obtained from a weather station situated adjacent to the experimental plot and are provided in Supplementary Table S1. The commercial check, i.e., Narendra Agrim, is an inbred line developed by the Department of Vegetable Science, Narendra Deva University of Agriculture and Technology, Kumarganj, Faizabad, Uttar Pradesh. It is an inbred line that can be grown during spring/summer and rainy seasons, with a total duration of 75 to 180 days (Supplementary Table S2). The experimental site is located at an elevation of 243.4 m above mean sea level at 29°05′ N latitude and 79°03′ E longitude (Supplementary Figure S1). Each of the five plants was spaced out 3 m × 0.6 m in the experiments, which were set up using a randomized complete block design (RCBD) with three replications.

2.2. Hybridization to Generate Hybrids and Inbred Parental Lines

The standard hybridization procedure was used for the crossing (Figure 1). The male and female flowers with yellow tips on their petals were selected for pollination the day before anthesis. To prevent unintentional cross-pollination, butter paper was placed around the selected male and female flowers that were expected to open the following morning. After dusting the chosen female flower with pollen from the male flower of the desired plant, the female flowers were kept covered with butter paper until the fruit was set. The pollination date and the parents’ names were marked on a label. The selfing of each of the eight parental lines was carried out to obtain inbred parental lines and maintain genetic purity. For the subsequent investigation, F₁ hybrid and inbred seeds were extracted from the physiologically mature fruits.

2.3. Agronomic Practices and Plant Protection

After fine-tuning the main field’s tilth with harrowing and plowing, fifteen-centimeter-deep, one-meter-wide channels were created, and hills were prepared on the north side of these channels. Seeds were sown in all plots and replications on 16 March 2023 and 22 March 2024. Seeds were placed in the center of the pit in each replication, keeping a 3 m × 0.6 m spacing between and within rows. The plot’s borders were evenly spaced 30 cm apart. Three seeds were planted per pit. Watering was performed immediately following sowing with a rose can. Throughout the cropping season, standard recommended cultural practices were followed. The prescribed nitrogen (N), phosphorus (P₂O₅), and potassium (K₂O) doses (100:50:50 kg/ha) were applied with urea, single superphosphate, and muriate of potash, respectively. During the pit-filling stage, the entire quantity of phosphorus, potassium, and one-third of the nitrogen was used as a base dose. The other two-thirds of the nitrogen was applied in two split doses, first at 30 days and then at 60 days after sowing, to ensure an adequate supply of nutrients throughout the growth cycle. Regular manual weeding keeps the experimental area free of weeds. Depending on the soil’s moisture content and environmental conditions, irrigation was given every two to three days.

2.4. Measured Traits

2.4.1. Yield and Yield Contributing Traits

In every replication, data were gathered from five plants of each genotype. Measurements and observations of morphology for different parameters were gathered. At each of the four pickings, the fruit count per plant (FCP) was calculated individually for five plants per treatment. The average was calculated for the number of fruits per plant by adding the number of fruits of each of the four pickings from all five plants in each treatment. The average fruit weight (AFW, kg) was calculated by averaging the weights of five fruits randomly selected from each genotype at edible maturity following four harvests. Fruit yield per plant (YPP, kg) was calculated by summing the weights of fruits from five plants across all four pickings, and the average was calculated in kilograms per plant. Fruit flesh thickness (FT, cm) was measured from both opposite sides using measuring scales. Observations were recorded from five fruits, and then the average was calculated. The seed count per fruit (SCPF) was determined in fully matured and dried fruits. The seeds of each fruit were extracted and counted, and then the average number of seeds of five fruits was calculated for each treatment.

2.4.2. Fruit Quality Traits

• Total Soluble Solids (°Brix)

The juice of five randomly selected fruits per genotype was extracted and strained through a muslin cloth to determine total soluble solids. The strained juice was correctly stirred. A drop of the juice was placed on the prism of the Erma hand refractometer, and the percent of total soluble solids was obtained from direct reading [15]. The average reading of five fruits was recorded, and their concentration was designated as Brix at 25 °C.

• Total carotenoids

Total carotenoids were extracted and quantified using the protocol by Boardman and Anderson [16]. A 100 mg sample of fresh fruit was taken and crushed in a mortar and pestle with 3.0 mL of 80% acetone. The crushed sample was transferred to the centrifuge tubes. These tubes were then centrifuged at 3000 rpm for 10 min. The supernatant was carefully transferred into the test tubes. The pellet was again extracted with 2.0 mL of 80% acetone and re-centrifuged. The two supernatants were mixed in the same test tubes, and the final volume was 10 mL with 80% acetone. The absorbance of the extract was then read at 645, 665, and 480 nm. As a blank, 80% acetone was used. The carotenoid content was determined using the following formula and expressed as μg/g:

Total carotenoids (μg/g) = (A480 + 0.114 A6665 − 0.638 A645 × V)/1000 × W

• Antioxidant activity

As per the method described by Addai et al. [17], the DPPH radical scavenging ability of pulp was assessed following a 45 min incubation period, and 3.0 g of fresh pulp tissue from each treatment was combined with 30 mL of ethanol (SD Fine Chemicals Ltd., India) and centrifuged at 4 °C for 20 min at an 18,000 rpm speed in a refrigerated centrifuge (Remi, India). The supernatant (0.1 mL) was combined with 2.9 mL of methanol-dissolved 0.1 mM DPPH (Sigma Aldrich, St. Louis, MO, USA). The reaction mixture was incubated in the dark at 25 °C for 30 min. As a blank, the control contained all the reagents except the sample. At 517 nm, the absorbance was determined using a spectrophotometer (Shimadzu UV–VIS, model 04834, Shimadzu Analytical (India) Pvt. Ltd., Mumbai, India).

The sample’s DPPH radical scavenging activity (%) was computed as (1 − absorbance of sample/absorbance of control) × 100.

• Dry matter content (%)

A 100 g fresh pumpkin sample was cut into small pieces and then dried in a hot air oven at 60 °C until a constant weight was achieved [18]. Dry matter content (%) was determined by following the formula given below:

Dry matter (%) = (Dry weight of fruit (g))/(Fresh weight of fruit (g)) × 100

2.5. Statistical Analysis

Data processing was performed using Excel. Data were tested for normality and log-transformed, if necessary, to satisfy the assumptions of the statistical methods. Heterosis and combining ability were analyzed using the software R 4.1 using the ‘Agricolae’ package and Windostat 9.3. Analysis of variance (ANOVA) was performed to determine the effects of different treatments, and significance was tested at a 5% level. Post hoc comparisons were conducted using Duncan’s Multiple Range Test (DMRT) to identify significant differences among treatment groups.

2.5.1. Magnitude of Heterosis

The magnitude of heterosis for all the hybrids was estimated in comparison to the better-parent and commercial hybrids, as given below. All the types of heterosis were expressed as percentages [19].

Heterobeltiosis or Better-Parent Heterosis [BPH (%)]

The deviation of F₁ over the better parent was estimated as follows:

BPH = (F₁ − BP)/BP × 100

where F₁ = the mean value of the hybrid and BP = the mean value of the better parent.

Standard Heterosis [SH (%)]

The deviation of F₁ over the commercial hybrid was estimated as follows:

SH = (F₁ − CH)/CH × 100

where F₁ = the mean value of the hybrid and CH = the mean value of the commercial check hybrid.

2.5.2. Combining Ability Estimation

Combining ability analysis was conducted according to Griffing’s method II [19], utilizing Method II (parents and one set of F1s were included but not reciprocal F1s) and Model I (a fixed-effect model). The data on the parents and one set of F₁ individuals, given by [n(n + 1)/2], were analyzed, where n represents the number of parental lines. The analysis of variance for combining ability was based on the following mathematical model:

X_ij = g_i + g_j+ s_ij + e_ijk

where

µ = the general mean;

g_i = the GCA effect of the ith line;

i = 1, 2…i;

g_j = the GCA effect of the jth line;

j = 1, 2…j;

s_ij = the SCA effect of the ijth line;

e_ijk = the error associated with the observation;

k = 1, 2…r.

The GCA effects were computed as the mean performance of a parent across all hybrids minus the grand mean. The SCA effects were calculated as the deviation of a specific hybrid’s mean from the expected mean based on the GCA effects of its parents. The significance of effects was tested using ANOVA, followed by critical difference (CD) or t-tests.

The general and specific combining effects were subsequently computed:

$$\mathrm{G}\mathrm{C}\mathrm{A} \mathrm{e}\mathrm{f}\mathrm{f}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{s} \mathrm{o}\mathrm{f}\mathrm{p}\mathrm{a}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{s}\left(g_i\right)={\displaystyle \frac{1}{p+2}}[\left(Yi+Yii\right)-{\displaystyle \frac{2}{p}}Y\dots ]$$

$$\mathrm{S}\mathrm{C}\mathrm{A} \mathrm{e}\mathrm{f}\mathrm{f}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{s} \mathrm{o}\mathrm{f} \mathrm{h}\mathrm{y}\mathrm{b}\mathrm{r}\mathrm{i}\mathrm{d}\mathrm{s}\left(S_{ij}\right)=Yij-{\displaystyle \frac{1}{p+2}}-\left(Yi+Yii+Yj+Yjj\right)+{\displaystyle \frac{2}{\left(p+1\right)\left(p+2\right)}}Y$$

where

p = the number of parents;

Y_ii = the mean value of the ith parent;

Y_jj = the mean value of the jth parent.

3. Results

3.1. Mean Performance of Parents and Hybrids

Table 1. Mean performances of 8 parents, 28 F₁ hybrids, and 1 commercial check hybrid variety for the evaluated traits.

Genotypes	FCP	AFW	YPP	FFT	SCPF	TSS	TC	AA	DMC
P-1	3.29 o ± 0.51	1.15 p ± 0.01	3.81 p ± 0.19	3.37 efg ± 0.05	197.05 m ± 6.545	6.02 e ± 0.35	0.48 mn ± 0.00	25.06 rs ± 0.21	8.72 op ± 0.17
P-2	5.14 d ± 0.28	2.08 efg ± 0.08	10.54 c ± 0.19	4.30 c ± 0.13	209.71 ± 3.49	4.21 klm ± 0.05	0.61 i ± 0.03	27.77 ijklmn ± 0.56	13.22 bc ± 0.95
P-3	2.80 r ± 0.01	1.80 j ± 0.06	5.01 n ± 0.04	2.56 qr ± 0.06	253.86 fgh ± 11.11	4.09 lmn ± 0.14	1.22 d ± 0.00	41.33 b ± 1.71	9.22 mno ± 0.33
P-4	4.00 hij ± 0.25	2.18 c ± 0.13	8.68 ef ± 0.26	3.00 mn ± 0.13	178.09 n ± 3.09	4.64 hi ± 0.17	0.95 g ± 0.06	24.08 st ± 1.74	12.52 de ± 0.25
P-5	4.97 de ± 0.22	2.10 defg ± 0.01	10.24 c ± 0.19	2.64 pq ± 0.15	238.17 j ± 12.03	4.50 ij ± 0.03	0.57 jk ± 0.01	28.59 hij ± 1.55	13.07 cd ± 0.07
P-6	3.00 pq ± 0.13	1.43 l ± 0.06	4.29 o ± 0.18	3.48 e ± 0.04	125.87 r ± 2.21	5.22 g ± 0.09	0.43 op ± 0.02	28.50 hij ± 0.19	8.11 qrs ± 0.10
P-7	4.49 g ± 0.01	2.31 b ± 0.04	10.41 c ± 0.37	3.44 ef ± 0.03	228.66 k ± 16.32	7.56 a ± 0.18	0.43 op ± 0.00	23.42 t ± 1.30	13.64 b ± 1.23
P-8	5.04 de ± 0.27	1.23 o ± 0.07	6.30 jk ± 0.24	2.82 o ± 0.20	129.25 r ± 3.55	4.84 h ± 0.20	0.58 j ± 0.05	20.78 v ± 0.54	9.33 mn ± 0.34
F1 Hybrids
P-1 × P-2	4.11 h ± 0.25	2.17 cd ± 0.06	8.88 e ± 0.04	3.46 ef ± 0.04	251.71 gh ± 13.48	2.74 r ± 0.04	0.34 tu ± 0.01	47.50 a ± 2.87	11.24 hi ± 0.33
P-1 × P-3	4.61 fg ± 0.16	1.65 k ± 0.04	7.61 hi ± 0.14	3.37 efg ± 0.03	280.24 c ± 0.34	6.00 e ± 0.03	1.45 a ± 0.01	29.75 gh ± 0.07	11.00 ij ± 0.65
P-1 × P-4	3.82 kl ± 0.03	2.01 h ± 0.01	7.72 ghi ± 0.30	3.19 ijkl ± 0.04	315.36 a ± 10.93	2.61 r ± 0.13	1.27 c ± 0.07	27.92 ijklm ± 0.23	8.56 pq ± 0.12
P-1 × P-5	4.68 f ± 0.33	2.05 fgh ± 0.12	9.66 d ± 0.63	3.33 fgh ± 0.03	276.24 cd ± 0.09	4.31 jkl ± 0.28	0.55 kl ± 0.01	23.60 t ± 1.81	10.82 ij ± 0.19
P-1 × P-6	3.44 no ± 0.12	1.43 l ± 0.01	4.92 n ± 0.07	2.77 op ± 0.04	276.77 cd ± 6.76	3.23 q ± 0.16	0.43 p ± 0.01	26.22 opqr ± 0.76	10.89 ij ± 0.18
P-1 × P-7	3.36 o ± 0.19	2.27 b ± 0.03	7.61 hi ± 0.18	3.08 klmn ± 0.06	295.18 b ± 1.53	4.90 h ± 0.28	0.41 pqr ± 0.00	31.70 ef ± 2.33	12.26 ef ± 0.04
P-1 × P-8	4.03 hi ± 0.01	2.14 cde ± 0.07	8.56 ef ± 0.22	2.69 opq ± 0.14	157.21 q ± 11.96	3.63 op ± 0.08	0.46 no ± 0.03	28.38 hijk ± 0.48	7.66 s ± 0.30
P-2 × P-3	4.56 fg ± 0.13	1.36 m ± 0.08	6.23 kl ± 0.44	2.80 o ± 0.11	261.40 ef ± 2.27	4.32 jkl ± 0.20	1.20 de ± 0.03	30.80 fg ± 0.68	10.70 ij ± 1.00
P-2 × P-4	3.44 no ± 0.04	2.56 a ± 0.01	8.79 ef ± 0.09	3.33 fgh ± 0.26	162.84 pq ± 6.81	4.39 ijk ± 0.38	0.66 h ± 0.03	26.93 lmnop ± 0.91	7.80 rs ± 0.39
P-2 × P-5	6.06 a ± 0.24	2.20 c ± 0.07	13.35 a ± 0.50	5.47 a ± 0.08	259.89 efg ± 12.77	3.38 pq ± 0.22	0.99 f ± 0.03	34.76 c ± 0.49	5.69 t ± 0.09
P-2 × P-6	2.80 r ± 0.20	2.19 c ± 0.19	6.19 kl ± 0.04	4.29 c ± 0.07	221.67 k ± 10.57	5.38 fg ± 0.28	0.41 pq ± 0.03	27.79 ijklm ± 1.84	9.15 no ± 0.07
P-2 × P-7	3.85 kl ± 0.14	2.28 b ± 0.07	8.76 ef ± 0.17	3.20 hij ± 0.21	249.71 hi ± 3.05	3.83 no ± 0.15	1.40 b ± 0.06	29.15 hi ± 0.41	13.76 b ± 0.18
P-2 × P-8	3.69 lm ± 0.24	2.11 def ± 0.00	7.85 gh ± 0.43	3.34 fgh ± 0.13	225.79 k ± 1.23	6.99 b ± 0.23	0.48 mn ± 0.01	26.52 nopq ± 0.02	11.86 fg ± 0.11
P-3 × P-4	3.54 mn ± 0.10	1.86 j ± 0.08	6.62 j ± 0.14	3.20 ijk ± 0.14	268.35 de ± 17.51	4.09 lmn ± 0.14	0.42 p ± 0.01	26.735 mnop ± 0.65	7.810 rs ± 0.41
P-3 × P-5	4.13 h ± 0.11	1.93 i ± 0.03	7.99 g ± 0.26	3.12 jklm ± 0.10	242.48 ij ± 12.18	3.57 op ± 0.06	0.38 rs ± 0.00	28.887 hi ± 2.11	9.782 lm ± 0.59
P-3 × P-6	3.99 hij ± 0.17	2.16 cd ± 0.12	8.63 ef ± 0.21	2.82 o ± 0.02	166.65 op ± 0.78	6.46 d ± 0.29	0.41 pqr ± 0.02	21.21 v ± 1.80	8.55 pq ± 0.62
P-3 × P-7	3.00 pq ± 0.01	2.08 efg ± 0.08	6.25 jkl ± 0.41	3.05 mn ± 0.21	180.01 n ± 4.15	6.50 cd ± 0.09	0.53 l ± 0.03	32.92 de ± 0.27	11.67 gh ± 0.34
P-3 × P-8	3.91 ijk ± 0.04	1.26 no ± 0.06	5.10 n ± 0.01	3.38 efg ± 0.04	297.79 b ± 15.36	7.44 a ± 0.00	0.59 ij ± 0.01	25.29 qrs ± 0.03	9.92 kl ± 0.36
P-4 × P-5	3.81 kl ± 0.22	2.16 cd ± 0.04	8.45 f ± 0.00	2.34 s ± 0.07	175.35 no ± 11.65	2.54 r ± 0.17	0.57 jk ± 0.00	27.10 klmnop ± 0.95	12.70 cde ± 0.31
P-4 × P-6	3.84 jkl ± 0.15	1.32 mn ± 0.10	4.93 n ± 0.09	3.81 d ± 0.14	197.32 m ± 2.15	2.48 r ± 0.06	1.18 e ± 0.04	32.45 de ± 0.57	8.01 qrs ± 0.18
P-4 × P-7	3.46 no ± 0.20	1.62 k ± 0.06	5.80 m ± 0.54	2.98 n ± 0.04	242.76 ij ± 2.94	5.59 f ± 0.50	0.50 m ± 0.02	27.32 jklmno ± 0.17	9.18 no ± 0.58
P-4 × P-8	5.34 c ± 0.14	1.10 p ± 0.01	5.89 lm ± 0.34	2.58 qr ± 0.04	263.55 e ± 18.70	4.51 ij ± 0.11	0.36 st ± 0.11	28.32 ijkl ± 1.36	8.23 pqr ± 0.24
P-5 × P-6	2.88 qr ± 0.22	2.52 a ± 0.06	7.35 i ± 0.52	3.06 lmn ± 0.03	112.07 s ± 3.91	5.32 fg ± 0.30	1.29 c ± 0.00	26.37 opqr ± 0.20	14.70 a ± 0.05
P-5 × P-7	5.58 b ± 0.01	2.19 c ± 0.11	11.96 b ± 0.06	4.65 b ± 0.23	240.36 j ± 0.21	4.30 jkl ± 0.09	0.65 h ± 0.02	33.84 cd ± 2.00	10.46 jk ± 0.39
P-5 × P-8	4.48 g ± 0.15	2.20 c ± 0.03	9.59 d ± 0.93	3.68 d ± 0.30	210.59 l ± 2.30	7.04 b ± 0.04	0.67 h ± 0.00	28.11 ijklm ± 1.39	10.96 ij ± 0.67
P-6 × P-7	4.95 e ± 0.17	2.05 fgh ± 0.16	10.26 c ± 0.33	2.96 n ± 0.01	193.36 m ± 4.69	6.77 bc ± 0.15	0.32 u ± 0.00	21.89 uv ± 1.26	14.44 a ± 0.18
P-6 × P-8	3.86 jk ± 0.34	2.04 gh ± 0.01	7.91 gh ± 0.56	3.31 ghi ± 0.06	110.83 s ± 1.41	4.04 lmn ± 0.27	0.38 qrs ± 0.01	25.71 pqr ± 0.60	9.34 mn ± 0.19
P-7 × P-8	3.10 p ± 0.02	2.00 hi ± 0.10	6.13 klm ± 0.06	2.45 rs ± 0.18	224.81 k ± 8.94	3.95 mn ± 0.09	0.29 v ± 0.05	23.24 tu ± 1.52	11.22 hi ± 0.32
Narendra Agrim (Check)	3.99 ijk ± 0.23	1.90 i ± 0.10	7.54 hi ± 0.62	3.50 ef ± 0.20	154.09 q ± 14.03	5.00 g ± 0.09	0.42 pqr ± 0.00	23.27 tu ± 0.40	14.22 a ± 0.17

The values presented are the average of observations recorded over the two growing seasons. FCP—fruit count per plant, AFW—average fruit weight (kg), YPP—yield per plant (kg), FFT—fruit flesh thickness (cm), SCPF—seed count per fruit, TSS—total soluble solid (°Brix), DMC—dry matter content (%), TC—total carotenoids (μg/g), AA—antioxidant activity–DPPH (%), DMC (%)—dry matter content. The mean values followed by the same letter are not significantly different at p ≤ 0.05 according to DMRT.

presents a comprehensive comparison of the 28 F₁ hybrids, their parental lines, and the commercial check hybrid, highlighting their performance across key traits in both seasons.

Fruit Count per Plant: The parental lines exhibited a fruit count ranging from 2.80 (P-3) to 5.14 (P-2). Among the hybrids, the fruit count varied from 2.80 (P-2 × P-6) to 6.06 (P-2 × P-5).

Average Fruit Weight: The parental lines displayed weights ranging from 1.15 kg (P-1) to 2.31 kg (P-7), while the hybrids varied from 1.09 kg (P-4 × P-8) to 2.55 kg (P-2 × P-4), highlighting the superior yield potential of the hybrids.

Yield per Plant: The parents yielded between 3.81 kg (P-1) and 10.54 kg (P-2), whereas the hybrids outperformed them, ranging from 4.92 kg (P-1 × P-6) to 13.35 kg (P-2 × P-5), thereby boosting hybrid vigor in pumpkin breeding. The superior-yielding hybrids (P-2 × P-5) and (P-5 × P-7) are presented in Figure 2.

Fruit Flesh Thickness: The thickness ranged from 2.56 cm (P-3) to 4.30 cm (P-2) in the parents and from 2.34 cm (P-4 × P-5) to 5.47 cm (P-2 × P-5) in the hybrids, highlighting the potential of specific crosses for improved yield and fruit quality.

Seed Count per Fruit: The parental genotypes varied widely, ranging from 125.87 (P-6) to 253.86 (P-3), while the F₁ hybrids showed even greater diversity, with counts reaching from 110.83 (P-6 × P-8) to 315.36 (P-1 × P-4), marking significant improvements.

Total Soluble Solids (TSSs): The total soluble solids (TSSs), an indicator of overall soluble content contributing to flavor quality, ranged from 4.09 °Brix (P-3) to 7.56 °Brix (P-7) among the parents, while in the hybrids, it varied from 2.48 °Brix (P-4 × P-6) to 7.44 °Brix (P-3 × P-8).

Total Carotenoids: The parents showed total carotenoid levels between 0.43 mg/100 g (P-6 & P-7) and 1.22 mg/100 g (P-3), while the hybrids demonstrated improvements, with values of 0.32 mg/100 g (P-6 × P-7) to 1.40 mg/100 g (P-2 × P-7), making them excellent sources of pro-vitamin A.

Antioxidant Activity (DPPH): The antioxidant capacity varied from 20.78% (P-8) to 41.33% (P-3) in the parents, whereas the F₁ hybrids showed values ranging from 21.21% (P-3 × P-6) to 47.50% (P-1 × P-2).

Dry Matter Content: The parental lines ranged from 8.11% (P-6) to 13.64% (P-7), whereas the hybrids exhibited a broad spectrum from 5.69% (P-2 × P-5) to 14.70% (P-5 × P-6), respectively.

Overall, the study confirms that hybrid pumpkins outperformed both the parental and commercial check varieties across multiple desirable traits, reinforcing their potential for large-scale cultivation and commercial success.

3.2. Magnitude of Heterosis over Better-Parent and Commercial Hybrids

The hybrid performance for various traits, expressed as heterosis percentages over commercial check hybrids (standard heterosis) and better-parent hybrids (heterobeltiosis), is summarized in

Table 2. Better-parent and standard heterosis of the 28 hybrids for fruit count per plant, average fruit weight, and yield per plant.

	Fruit Count per Plant				Average Fruit Weight				Yield per Plant
F1 Hybrids	Better-Parent Heterosis (%)		Standard Heterosis (%)		Better-Parent Heterosis (%)		Standard Heterosis (%)		Better-Parent Heterosis (%)		Standard Heterosis (%)
	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024
P-1 ×P-2	−21.65 **	−18.18 **	−4.28	11.95 **	0.77	19.38 **	17.75 **	14.20 **	2.51	1.25	21.87 **	8.70 *
P-1 × P-3	55.07 **	25.73 **	13.08 **	18.82 **	−18.95 **	−3.11	−2.92	−1.58	37.01 **	34.51 **	23.48 **	9.78 *
P-1 × P-4	4.74	−13.63 **	−4.37	−3.82	15.82 **	30.67 **	23.37 **	19.33 **	3.59	9.84 *	19.40 **	7.47
P-1 × P-5	−9.20 **	−2.44	0.43	38.10 **	23.83 **	−6.52 *	24.94 **	−15.19 **	3.79	6.59	22.68 **	11.59 **
P-1 × P-6	8.82 *	−2.28	−18.46 **	−7.64 *	3.88	−11.05 **	−3.82	−11.05 **	1.2	−0.13	−12.86 **	−22.55 **
P-1 × P-7	−30.27 **	−20.52 **	−30.11 **	1.57	2.2	24.37 **	25.17 **	6.71 *	−7.24 **	2.29	17.68 **	5.61
P-1 × P-8	−16.82 **	−22.93 **	−7.81 *	12.15 **	32.08 **	30.12 **	18.43 **	3.94	22.23 **	36.37 **	21.53 **	11.02 **
P-2 × P-3	−18.42 **	−3.32	−0.33	32.28 **	−3.19	−7.38 *	15.96 **	−5.92 *	−4.14	−3.62	15.56 **	4.22
P-2 × P-4	−31.86 **	−34.08 **	−16.76 **	−9.80 **	27.36 **	29.63 **	48.54 **	24.26 **	13.67 **	10.19 **	37.03 **	19.16 **
P-2 × P-5	18.52 **	13.71 **	44.80 **	60.95 **	14.45 **	10.08 **	33.48 **	5.52	44.62 **	38.57 **	74.34 **	49.85 **
P-2 × P-6	−50.23 **	−40.10 **	−39.19 **	−18.04 **	18.69 **	15.78 **	38.43 **	15.78 **	8.29 **	2.48	30.54 **	10.81 **
P-2 × P-7	−31.58 **	−17.73 **	−16.41 **	12.56 **	−10.09 **	−1.03	10.11 **	−5.13	−10.81 **	−4.62	13.15 **	3.14
P-2 × P-8	−37.08 **	−23.35 **	−23.13 **	11.54 **	22.93 **	16.46 **	43.37 **	11.64 **	0.29	−1.1	20.90 **	6.95
P-3 × P-4	−15.72 **	−7.38 *	−23.05 **	3.14	8.99 **	8.53 **	30.79 **	10.45 **	1.2	4.74	16.65 **	2.47
P-3 × P-5	−18.01 **	−15.59 **	−9.31 **	19.48 **	10.67 **	0.39	32.81 **	2.17	11.80 **	10.28 **	32.15 **	15.45 **
P-3 × P-6	10.94 *	59.59 **	−16.87 **	20.87 **	8.05 **	5.04	29.66 **	6.90 *	61.67 **	58.57 **	39.21 **	22.97 **
P-3 × P-7	−31.68 **	−34.68 **	−31.53 **	−16.53 **	11.93 **	9.11 **	37.08 **	11.05 **	−18.01 **	−6.98	4.02	−3.96
P-3 × P-8	−21.97 **	−23.03 **	−13.51 **	12.00 **	−31.65 **	−28.88 **	−17.98 **	−27.61 **	−16.45 **	−7.84	−16.93 **	−24.97 **
P-4 × P-5	−10.84 **	−34.83 **	−1.37	−7.76 *	22.15 **	44.81 **	30.11 **	31.95 **	7.90 **	12.25 **	30.08 **	17.51 **
P-4 × P-6	−7.69 *	−0.41	−15.73 **	10.90 **	−20.68 **	−32.15 **	−15.51 **	−32.15 **	−42.10 **	−30.33 **	−30.20 **	−35.43 **
P-4 × P-7	−30.24 **	−15.90 **	−30.08 **	7.48 *	−17.80 **	−17.32 **	0.67	−24.65 **	−35.20 **	−32.57 **	−17.80 **	−30.38 **
P-4 × P-8	21.14 **	−8.12 **	34.27 **	33.70 **	−16.03 **	−5.63	−10.56 **	−14.00 **	−5.48 *	10.06 *	13.95 **	2.01
P-5 × P-6	−35.33 **	−48.14 **	−28.47 **	−26.59 **	20.67 **	22.88 **	22.02 **	22.88 **	−5.67 *	6.76	13.72 **	15.45 **
P-5 × P-7	11.73 **	12.98 **	23.59 **	59.93 **	7.89 **	18.30 **	32.13 **	7.10 *	26.97 **	27.00 **	61.08 **	37.33 **
P-5 × P-8	−3.86	−17.89 **	6.56 *	19.48 **	18.00 **	8.50 **	19.33 **	−1.78	10.10 **	−0.38	32.72 **	7.72
P-6 × P-7	8.15 *	12.21 **	8.40 *	43.40 **	−19.27 **	−6.11 *	−1.12	−6.11 *	−11.45 **	5.54	12.34 **	8.96 *
P-6 × P-8	−18.18 **	−28.36 **	−9.31 **	4.25	35.77 **	5.72	25.39 **	5.72	32.91 **	26.57 **	32.15 **	3.04
P-7 × P-8	−31.82 **	−44.73 **	−24.43 **	−19.58 **	6.59 **	35.17 **	30.79 **	15.98 **	−7.52 **	−13.05 **	11.48 **	−5.97

* Significant at 0.05 level of probability, ** significant at 0.01 level of probability. Better-parent and standard heterosis values were calculated for each hybrid using the means of all experimental plants across replications.

,

Table 3. Better-parent and standard heterosis of the 28 hybrids for fruit flesh thickness, seed count per fruit, and total soluble solids.

	Fruit Flesh Thickness				Seed Count per Fruit				Total Soluble Solids
F1 Hybrids	Better-Parent Heterosis (%)		Standard Heterosis (%)		Better-Parent Heterosis (%)		Standard Heterosis (%)		Better-Parent Heterosis (%)		Standard Heterosis (%)
	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024
P-1 ×P-2	−20.39 **	−18.90 **	8.70 **	11.95 **	23.51 **	15.10 **	47.79 **	14.88 **	−58.73 **	−49.83 **	−58.73 **	−45.91 **
P-1 × P-3	0.26	−0.05	18.82 **	18.82 **	35.13 **	−8.72 **	66.72 **	26.02 **	−6.83	6.90 *	−6.83	15.26 **
P-1 × P-4	−8.56 **	−1.60	8.37 **	−3.82	78.28 **	43.57 **	85.90 **	43.30 **	−59.58 **	−53.28 **	−59.58 **	−49.63 **
P-1 × P-5	−14.46 **	14.24 **	1.37	38.10 **	31.60 **	1.15	70.19 **	19.16 **	−38.33 **	−17.43 **	−38.33 **	−10.98 **
P-1 × P-6	−16.30 **	−31.71 **	−0.81	−7.64 *	43.70 **	37.54 **	49.84 **	37.28 **	−44.21 **	−48.50 **	−44.21 **	−44.48 **
P-1 × P-7	−13.07 **	−18.03 **	3.02	1.57	29.10 **	29.08 **	71.49 **	36.30 **	−36.78 **	−33.66 **	−36.78 **	−1.92
P-1 × P-8	−24.09 **	−15.50 **	−10.04 **	12.15 **	−36.96 **	−5.09 *	−34.26 **	−5.27 *	−47.46 **	−31.36 **	−47.46 **	−25.99 **
P-2 × P-3	−31.59 **	−37.84 **	−6.58 **	32.28 **	29.39 **	−17.46 **	59.65 **	13.97 **	−15.66 **	20.46 **	−15.66 **	−9.43 **
P-2 × P-4	−27.82 **	−17.46 **	−1.44	−9.80 **	−21.30 **	−23.45 **	−5.84	−24.43 **	9.21	−20.10 **	9.21	−25.37 **
P-2 × P-5	24.33 **	29.95 **	69.77 **	60.95 **	−0.83	18.56 **	28.25 **	39.66 **	−35.93 **	−11.23 **	−35.93 **	−32.88 **
P-2 × P-6	8.36 **	−8.08 **	47.96 **	−18.04 **	6.47 *	4.90 *	27.39 **	3.56	−5.88	12.85 **	−5.88	6.20
P-2 × P-7	−15.45 **	−33.64 **	15.46 **	12.56 **	7.11 *	11.48 **	42.28 **	17.72 **	−45.92 **	−52.33 **	−45.92 **	−29.53 **
P-2 × P-8	−26.05 **	−18.84 **	0.98	11.54 **	12.34 **	2.77	34.41 **	1.46	66.21 **	25.08 **	66.21 **	18.49 **
P-3 × P-4	−2.39	15.91 **	−2.51	3.14	25.23 **	−9.38 **	54.51 **	25.12 **	−4.19	−22.56 **	−4.19	−27.67 **
P-3 × P-5	4.96 *	23.85 **	−6.57 **	19.48 **	−8.38 **	−4.88 **	18.49 **	31.33 **	−36.53 **	−1.35	−36.53 **	−25.41 **
P-3 × P-6	−15.81 **	−21.69 **	−10.12 **	20.87 **	−20.56 **	−45.02 **	−1.98	−24.09 **	15.73 **	32.37 **	15.73 **	24.57 **
P-3 × P-7	−10.03 **	−12.38 **	−5.58 **	−16.53 **	−29.69 **	−32.80 **	−6.60	−7.22 **	−16.23 **	−12.09 **	−16.23 **	29.96 **
P-3 × P-8	3.35	39.70 **	6.08 **	12.00 **	32.00 **	5.94 **	62.86 **	46.27 **	64.40 **	44.40 **	64.40 **	36.78 **
P-4 × P-5	−11.54 **	−32.26 **	−11.65 **	−7.76 *	−31.63 **	−21.39 **	−11.59 **	−7.39 **	−59.00 **	−38.92 **	−59.00 **	−42.95 **
P-4 × P-6	6.19 **	11.80 **	13.36 **	10.90 **	23.34 **	−0.61	16.68 **	−10.66 **	−55.83 **	−48.89 **	−55.83 **	−51.90 **
P-4 × P-7	−15.40 **	−11.46 **	−11.22 **	7.48 *	33.66 **	−23.74 **	77.55 **	−19.48 **	−29.22 **	−23.10 **	−29.22 **	13.69 **
P-4 × P-8	−10.18 **	−20.34 **	−7.82 **	33.70 **	82.16 **	16.88 **	72.33 **	5.08 *	3.66	−16.15 **	3.66	−20.57 **
P-5 × P-6	0.12	−22.31 **	6.88 **	−26.59 **	−54.43 **	−51.54 **	−41.07 **	−42.91 **	6.50	−2.82	6.50	−8.55 **
P-5 × P-7	41.11 **	29.97 **	48.08 **	59.93 **	−3.13	2.26	28.68 **	20.46 **	−42.75 **	−43.54 **	−42.75 **	−16.53 **
P-5 × P-8	12.73 **	39.99 **	15.70 **	19.48 **	−13.70 **	−9.56 **	11.60 **	6.54 **	43.36 **	37.56 **	43.36 **	30.31 **
P-6 × P-7	−10.77 **	−18.78 **	−4.74 *	43.40 **	−18.73 **	−11.86 **	7.95 *	−6.92 **	−1.21	−18.76 **	−1.21	20.10 **
P-6 × P-8	−5.96 **	−4.52	0.40	4.25	−12.51 *	−24.55 **	−37.94 **	−46.80 **	−21.16 **	−24.43 **	−21.16 **	−28.41 **
P-7 × P-8	−23.13 **	−33.70 **	−19.33 **	−19.58 **	−6.19 *	3.21	24.61 **	8.99 **	−47.96 **	−47.50 **	−47.96 **	−22.39 **

* Significant at 0.05 level of probability, ** significant at 0.01 level of probability. Better-parent and standard heterosis values were calculated for each hybrid using the means of all experimental plants across replications.

and

Table 4. Better-parent and standard heterosis effects were observed in the 28 hybrids for total carotenoids, antioxidant activity (DPPH), and dry matter content.

Total Carotenoids					Antioxidant Activity–DPPH				Dry Matter Content
F1 Hybrids	Better-Parent Heterosis (%)		Standard Heterosis (%)		Better-Parent Heterosis (%)		Standard Heterosis (%)		Better-Parent Heterosis (%)		Standard Heterosis (%)
	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024
P-1 ×P-2	−36.11 **	−49.94 **	−31.70 **	−28.34 **	69.37 **	72.90 **	120.73 **	88.86 **	−19.92 **	−9.84 **	−32.64 **	−5.60
P-1 × P-3	7.48 **	32.62 **	158.60 **	233.53 **	−28.55 **	−27.48 **	32.89 **	23.25 **	15.76 **	22.14 **	−34.02 **	−7.71 **
P-1 × P-4	32.36 **	36.33 **	125.58 **	193.66 **	8.77 **	5.20	27.32 **	13.25 **	−35.54 **	−27.66 **	−50.15 **	−26.11 **
P-1 × P-5	−14.84 **	5.20	−9.21 **	33.97 **	−26.19 **	−8.33 **	−3.30	5.80	−19.55 **	−14.64 **	−30.92 **	−14.64 **
P-1 × P-6	−3.91	−25.68 **	−13.81 **	−14.60 **	−7.84 **	−8.18 **	19.79 **	6.16	37.81 **	13.69 **	−30.45 **	−14.09 **
P-1 × P-7	−15.40 **	−16.09 **	−29.18 **	−3.58	24.78 **	28.35 **	46.07 **	27.23 **	−16.39 **	−4.42	−32.03 **	10.13 **
P-1 × P-8	−29.29 **	−13.29 **	−20.29 **	6.12	6.04	21.05 **	24.13 **	20.00 **	−28.25 **	−23.23 **	−49.23 **	−41.99 **
P-2 × P-3	−5.42 **	2.31	127.56 **	157.30 **	−23.32 **	−27.68 **	42.64 **	22.91 **	−14.44 **	−23.90 **	−28.03 **	−20.32 **
P-2 × P-4	−33.20 **	−26.89 **	13.85 **	57.49 **	−9.28 **	3.91	18.24 **	13.50 **	−54.58 **	−26.71 **	−61.79 **	−23.26 **
P-2 × P-5	77.27 **	48.83 **	89.52 **	113.02 **	22.23 **	20.86 **	60.16 **	39.48 **	−67.56 **	−46.55 **	−72.14 **	−44.03 **
P-2 × P-6	−27.49 **	−37.71 **	−22.48 **	−10.84 *	−2.75	−2.49	26.74 **	12.74 **	−27.64 **	−34.05 **	−39.13 **	−30.95 **
P-2 × P-7	139.80 **	119.51 **	156.36 **	214.18 **	−3.79	14.60 **	25.38 **	25.18 **	2.80	−4.19	−13.52 **	10.41 **
P-2 × P-8	−20.97 **	−25.96 **	−10.91 **	5.97	−10.19 **	1.82	17.04 **	11.21 **	−14.19 **	−6.29 *	−27.81 **	−1.88
P-3 × P-4	−63.65 **	−68.52 **	−12.55 **	−20.84 **	−38.67 **	−31.94 **	14.08 **	15.66 **	−41.46 **	−33.84 **	−54.73 **	−32.43 **
P-3 × P-5	−69.61 **	−67.43 **	−26.87 **	−18.08 **	−31.65 **	−28.58 **	27.14 **	21.37 **	−21.11 **	−29.82 **	−32.26 **	−29.81 **
P-3 × P-6	−70.00 **	−61.98 **	−27.81 **	−4.38	−48.35 **	−49.00 **	−3.94	−13.32 **	−17.60 **	3.09	−53.04 **	−22.55 **
P-3 × P-7	−59.00 **	−54.11 **	−1.36	15.41 **	−23.36 **	−17.29 **	42.56 **	40.56 **	−11.71 **	−17.03 **	−28.22 **	−4.39
P-3 × P-8	−48.23 **	−56.11 **	24.57 **	10.38	−34.43 **	−43.21 **	21.97 **	−3.49	−16.11 **	11.16 **	−40.64 **	−16.49 **
P-4 × P-5	−45.78 **	−35.30 **	−7.59 **	39.37 **	−10.34 **	0.16	17.47 **	15.59 **	−17.93 **	11.69 **	−29.53 **	14.08 **
P-4 × P-6	36.13 **	12.60 **	132.00 **	142.55 **	6.81 *	21.14 **	38.83 **	40.06 **	−43.94 **	−28.21 **	−56.64 **	−26.67 **
P-4 × P-7	−47.85 **	−47.31 **	−11.12 **	13.49 *	9.95 **	7.67 *	19.12 **	15.91 **	−12.16 **	−51.66 **	−28.59 **	−44.30 **
P-4 × P-8	−56.67 **	−66.51 **	−26.16 **	−27.86 **	33.90 **	3.80	32.60 **	11.74 **	−32.28 **	−36.17 **	−47.63 **	−34.80 **
P-5 × P-6	114.84 **	132.15 **	129.05 **	195.63 **	−10.13 **	−5.49	17.75 **	9.27 **	−1.50	28.06 **	−15.42 **	28.06 **
P-5 × P-7	21.93 **	5.45	29.99 **	34.28 **	11.49 **	25.50 **	46.08 **	44.84 **	−35.18 **	−15.76 **	−44.34 **	−2.93
P-5 × P-8	−2.71	31.43 **	9.67 **	67.36 **	−9.80 **	6.83 *	18.19 **	23.29 **	−20.22 **	−11.58 **	−31.50 **	−11.58 **
P-6 × P-7	−34.46 **	−32.85 **	−41.21 **	−31.34 **	−24.90 **	−21.46 **	−2.39	−9.19 **	6.73 *	4.94	−13.23 **	20.92 **
P-6 × P-8	−43.01 **	−24.39 **	−35.76 **	−7.46	−7.15 *	−12.53 **	20.68 **	1.13	−25.26 **	12.34 **	−47.12 **	−17.51 **
P-7 × P-8	−50.54 **	−51.83 **	−44.24 **	−41.04 **	0.12	−1.63	2.21	−7.98 *	−9.92 **	−25.06 **	−26.77 **	−13.64 **

* Significant at 0.05 level of probability, ** significant at 0.01 level of probability. Better-parent and standard heterosis values were calculated for each hybrid using the means of all experimental plants across replications.

.

• Fruit Count Per Plant

Better-parent heterosis ranged from −50.23% (P-2 × P-6) to 55.07% (P-1 × P-3) in 2023 and from −48.14% (P-5 × P-6) to 59.59% (P-3 × P-6) in 2024, while standard heterosis varied from −39.19% (P-2 × P-6) to 44.80% (P-2 × P-5) in 2023 and from −26.59% (P-5 × P-6) to 60.95% (P-2 × P-5) in 2024. The hybrids P-2 × P-5, P-5 × P-7, and P-4 × P-8 performed best in terms of fruit count per plant across both seasons.

• Average Fruit Weight

For both seasons, the better-parent heterosis ranged from −31.65% (P-3 × P-8) to 35.77% (P-6 × P-8) in 2023 and from −32.15% (P-4 × P-6) to 44.81% (P-4 × P-5) in 2024. Similarly, standard heterosis varied between −17.98% (P-3 × P-8) and 48.54% (P-2 × P-4) in 2023 and from −32.15% (P-4 × P-5) to 31.95% (P-4 × P-5) in 2024. The best-performing hybrids across both years were P-2 × P-4 and P-4 × P-5.

• Fruit Yield Per Plant

Better-parent heterosis ranged from −42.10% (P-4 × P-6) to 61.67% (P-3 × P-6) in 2023 and from −32.57% (P-4 × P-7) to 58.57% (P-3 × P-6) in 2024. Similarly, standard heterosis varied between −30.20% (P-4 × P-6) and 74.34% (P-2 × P-5) in 2023 and from −30.38% (P-4 × P-7) to 49.85% (P-2 × P-5) in 2024. Notably, the hybrids P-2 × P-5 (13.35 kg) and P-5 × P-7 (11.96 kg) displayed the highest yield per plant across both years.

• Fruit Flesh Thickness

In 2023, heterobeltiosis ranged from −31.59% (P-2 × P-3) to 41.11% (P-5 × P-7), while in 2024, it varied from −37.84% (P-2 × P-3) to 39.99% (P-5 × P-8). Standard heterosis extended from −11.22% (P-4 × P-7) to 69.77% (P-2 × P-5) in 2023 and from −49.21% (P-4 × P-5) to 46.26% (P-2 × P-5) in 2024. Among the hybrids, P-2 × P-5, P-5 × P-7, and P-2 × P-6 exhibited remarkable heterosis flesh thickness.

• Seed Count Per Fruit

Heterosis over the better parent ranged from −54.43% (P-5 × P-6) to 82.16% (P-4 × P-8) in 2023 and from −51.54% (P-5 × P-6) to 43.57% (P-1 × P-4) in 2024. Similarly, standard heterosis varied from −41.07% (P-5 × P-6) to 85.19% (P-1 × P-4) in 2023 and from −46.80% (P-6 × P-8) to 46.27% (P-3 × P-8) in 2024. The hybrids P-1 × P-4, P-3 × P-8, and P-1 × P-7 recorded the highest seed count per fruit.

• Total Soluble Solid (TSS) Content

Standard heterosis varied from −56.19% (P-4 × P-5) to 64.77% (P-2 × P-8) in 2023 and from −51.90% (P-4 × P-6) to 36.78% (P-3 × P-8) in 2024. Similarly, better-parent heterosis ranged from −59.58% (P-1 × P-4) to 66.21% (P-2 × P-8) in 2023 and from −53.28% (P-1 × P-4) to 44.40% (P-3 × P-8) in 2024. The hybrids P-3 × P-8, P-5 × P-8, and P-2 × P-8 performed exceptionally well in terms of their TSS content.

• Total Carotenoids Content

Better-parent heterosis ranged from −70.00% (P-3 × P-6) to 139.80% (P-2 × P-7) in 2023 and from −68.52% (P-3 × P-4) to 132.15% (P-5 × P-6) in 2024. Similarly, standard heterosis varied from −44.24% (P-7 × P-8) to 158.60% (P-1 × P-3) in 2023 and from −41.04% (P-7 × P-8) to 233.53% (P-1 × P-3) in 2024. The hybrids P-1 × P-3 and P-2 × P-7 had the highest total carotenoid content.

• Antioxidant Activity DPPH

Heterosis over the better parent ranged from −48.35% (P-3 × P-6) to 69.37% (P-1 × P-2) in 2023 and from −49.00% (P-3 × P-6) to 72.90% (P-1 × P-2) in 2024. Standard heterosis varied between −3.94% (P-3 × P-6) and 120.73% (P-1 × P-2) in 2023 and from −13.32% (P-3 × P-6) to 88.86% (P-1 × P-2) in 2024. Among the hybrids evaluated, P-1 × P-2 showed the best performance in terms of antioxidant activity.

• Dry Matter Content

In 2023, better-parent heterosis ranged from −67.56% (P-2 × P-5) to 37.81% (P-1 × P-6), while in 2024, it varied from −51.66% (P-4 × P-7) to 28.06% (P-5 × P-6). Standard heterosis spanned from −72.14% (P-2 × P-5) to −13.23% (P-6 × P-7) in 2023 and from −44.30% (P-4 × P-7) to 28.06% (P-5 × P-6) in 2024. Among all hybrids, P-1 × P-6 exhibited the highest dry matter content.

Across all measured traits, several hybrid combinations stood out as top performers, particularly P-2 × P-5, P-5 × P-7, P-1 × P-3, and P-1 × P-2. These hybrids demonstrated significant improvements in fruit yield, size, and quality, making them promising candidates for future commercial production.

3.3. General Combining Ability (GCA) Effect of Parents and Specific Combining Ability (SCA) Effect of F₁ Hybrids

The general combining ability (GCA) and specific combining ability (SCA) effects for F₁ hybrids across various traits are presented in

Table 5. General combining ability effect of parents and specific combining ability effect of 28 F₁ hybrids for the recorded parameters.

Genotypes	FCP		AFW		YPP		FFT		SCPF		TSS		TC		AA		DMC
GCA effects on parents
	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024	2023	2024
P-1	−0.15 **	−0.17 **	−0.09 **	−0.15 **	−0.61 **	−0.78 **	0.04 **	−0.18 **	27.24 **	26.07 **	−0.37 **	−0.30 **	−0.03 **	0.01 *	1.30 **	0.73 **	−0.54 **	−0.29 **
P-2	0.25 **	0.24 **	0.13 **	0.20 **	1.02 **	1.29 **	0.46 **	0.56 **	10.56 **	3.87 **	−0.26 **	−0.40 **	0.07 **	0.07 **	2.86 **	1.93 **	0.29 **	0.22 **
P-3	−0.31 **	−0.26 **	−0.14 **	−0.13 **	−1.17 **	−1.05 **	−0.24 **	−0.25 **	15.43 **	29.44 **	0.34 **	0.39 **	0.17 **	0.11 **	2.37 **	2.28 **	−0.51 **	−0.72 **
P-4	−0.01	−0.18 **	−0.021	−0.03 **	−0.27 **	−0.52 **	−0.19 **	−0.18 **	11.54 **	−11.25 **	−0.79 **	−0.67 **	0.08 **	0.09 **	−1.72 **	−0.27	−0.79 **	−0.54 **
P-5	0.55 **	0.50 **	0.22 **	0.20 **	2.08 **	1.76 **	0.11 **	0.20 **	−9.18 **	11.79 **	−0.33 **	−0.34 **	0.01 **	0.04 **	0.05	0.91 **	0.65 **	0.78 **
P-6	−0.43 **	−0.46 **	−0.08 **	−0.05 **	−1.07 **	−1.07 **	0.04 **	0.08 **	−45.14 **	−44.82 **	0.26 **	−0.01	−0.05 **	−0.08 **	−1.46 **	−1.80 **	−0.65 **	0.10
P-7	−0.13 **	0.13 **	0.18 **	0.15 **	0.61 **	0.99 **	−0.05 **	0.03	17.44 **	3.20 **	0.65 **	0.97 **	−0.10 **	−0.09 **	−0.91 **	−0.69 **	1.62 **	1.61 **
P-8	0.23 **	0.20 **	−0.19 **	−0.19 **	−0.58 **	−0.61 **	−0.18 **	−0.27 **	−27.91 **	−18.32 **	0.51 **	0.37 **	−0.15 **	−0.16 **	−2.48 **	−3.08 **	−0.06	−1.17 **
SCA effects of hybrids
P-1 × P-2	0.05	−0.07	0.22 **	0.17 **	0.96 **	0.41 *	−0.42 **	−0.07	5.19	−9.58 **	−1.48 **	−1.20 **	−0.34 **	−0.42 **	16.75 **	14.73 **	0.80 **	1.08 **
P-1 × P-3	1.38 **	0.68 **	−0.03	0.007	2.25 **	1.13 **	0.59 **	0.26 **	34.28 **	−12.04 **	1.14 **	1.27 **	0.60 **	0.70 **	−2.36 **	−1.48 **	1.39 **	1.77 **
P-1 × P-4	0.32 **	−0.21 *	0.233 **	0.25 **	1.65 **	0.51 **	0.23 **	0.15 *	72.58 **	64.48 **	−1.00 **	−1.14 **	0.51 **	0.55 **	0.49	−1.34 *	−0.92 **	−0.66 **
P-1 × P-5	−0.04	0.61 **	−0.01	0.08 *	−0.18	1.59 **	−0.29 **	0.26 **	65.13 **	−8.63 **	−0.14	0.60 **	−0.15 **	−0.11 **	−8.13 **	−4.34 **	0.72 **	−0.58 *
P-1 × P-6	0.12	−0.07	−0.30 **	−0.28 **	−0.95 **	−1.10 **	−0.28 **	−0.67 **	64.58 **	85.56 **	−1.11 **	−1.52 **	−0.11 **	−0.20 **	−1.45 *	−1.54 **	2.11 **	0.16
P-1 × P-7	−0.68 **	−0.33 **	0.40 **	0.21 **	−0.43 *	−0.02	−0.08	−0.13	40.83 **	35.51 **	−0.43 **	−0.22 *	−0.14 **	−0.14 **	3.86 **	2.45 **	−0.43	1.63 **
P-1 × P-8	−0.08	−0.02	0.54 **	0.54 **	2.06 **	2.18 **	−0.33 **	−0.20 **	−103.5 **	−29.19 **	−1.55 **	−0.92 **	−0.05 **	−0.03 *	0.53	3.08 **	−1.50 **	−1.99 **
P-2 × P-3	0.38 **	0.75 **	−0.59 **	−0.60 **	−1.84 **	−1.24 **	−0.59 **	−0.86 **	38.28 **	−14.85 **	−0.99 **	0.05	0.32 **	0.30 **	−1.75 **	−2.77 **	1.52 **	−0.30
P-2 × P-4	−0.63 **	−0.84 **	0.42 **	0.56 **	0.43 *	0.16	−0.49 **	−0.01	−75.31 **	−53.79 **	1.14 **	0.27 *	−0.20 **	−0.12 **	−3.10 **	−2.48 **	−3.63 **	−0.83 **
P-2 × P-5	1.48 **	1.02 **	−0.09 **	−0.13 **	3.06 **	2.01 **	1.34 **	1.72 **	6.57	56.09 **	−0.93 **	−0.46 **	0.28 **	0.17 **	4.48 **	2.60 **	−6.75 **	−4.73 **
P-2 × P-6	−1.19 **	−0.86 **	0.17 **	0.16 **	−1.90 **	−1.32 **	0.75 **	0.13	40.99 **	37.82 **	0.36 *	1.30 **	−0.26 **	−0.25 **	−1.46 *	−1.14 *	−0.12	−2.44 **
P-2 × P-7	−0.50 **	−0.35 **	0.05	−0.02	−0.91 **	−0.93 **	−0.12 **	−0.96 **	5.11	19.16 **	−1.20 **	−1.60 **	0.77 **	0.76 **	−2.31 **	0.76	1.72 **	1.14 **
P-2 × P-8	−1.16 **	−0.46 **	0.21 **	0.20 **	−1.15 **	0.27	−0.43 **	0.01	36.35 **	6.96 *	2.67 **	1.57 **	−0.10 **	−0.09 **	−2.61 **	−0.23	1.11 **	2.42 **
P-3 × P-4	−0.32 **	0.13	0.20 **	0.01	0.45 *	0.34 *	0.18 **	0.56 **	28.06 **	23.40 **	0.05	−0.65 **	−0.45 **	−0.50 **	−3.53 **	−2.31 **	−1.69 **	−1.01 **
P-3 × P-5	−0.30 **	0.03	−0.03	−0.09 *	−0.84 **	−0.25	−0.24 **	0.14 *	−15.81 **	13.23 **	−1.58 **	−0.86 **	−0.46 **	−0.44 **	−2.39 **	−2.12 **	0.48	−2.02 **
P-3 × P-6	0.35 **	1.05 **	0.46 **	0.42 **	2.45 **	3.72 **	−0.27 **	−0.23 **	−16.58 **	−45.09 **	0.91 **	1.48 **	−0.39 **	−0.26 **	−7.81 **	−7.80 **	−1.55 **	−0.45
P-3 × P-7	−0.58 **	−0.89 **	0.07 *	0.19 **	−1.11 **	−1.21 **	−0.05	0.14 *	−87.45 **	−58.12 **	0.31 *	0.79 **	−0.20 **	−0.15 **	2.01 **	4.13 **	0.16	0.27
P-3 × P-8	−0.17	0.06	−0.35 **	−0.29 **	−1.22 **	−0.62 **	0.43 **	0.75 **	82.52 **	74.35 **	1.97 **	1.75 **	−0.01	−0.11 **	−1.01	−4.14 **	−0.15	1.57 **
P-4 × P-5	−0.25 **	−1.03 **	−0.02	0.12 **	−0.26	−1.34 **	−0.44 **	−1.33 **	−65.88 **	−26.38 **	−1.54 **	−0.74 **	−0.26 **	−0.17 **	−0.46	−0.96	1.20 **	3.20 **
P-4 × P-6	0.11	0.61 **	−0.59 **	−0.41 **	−2.05 **	−0.57 **	0.38 **	0.96 **	20.79 **	23.46 **	−1.79 **	−1.55 **	0.57 **	0.41 **	5.83 **	7.67 **	−1.85 **	−1.13 **
P-4 × P-7	−0.82 **	−0.11	−0.52 **	−0.36 **	−3.26 **	−1.40 **	−0.26 **	0.10	67.38 **	−42.86 **	0.52 **	0.98 **	−0.16 **	−0.14 **	0.89	0.72	0.38	−4.82 **
P-4 × P-8	1.61 **	0.76 **	−0.56 **	−0.62 **	−0.17	−1.51 **	−0.03	−0.49 **	103.38 **	29.59 **	0.33 *	−0.25 *	−0.19 **	−0.26 **	5.46 **	2.09 **	−0.99 **	−0.85 **
P-5 × P-6	−1.02 **	−1.42 **	0.46 **	0.44 **	−0.78 **	−1.66 **	−0.12 **	−0.71 **	−62.08 **	−66.48 **	1.09 **	0.44 **	0.62 **	0.70 **	−0.66	−0.97	3.33 **	4.26 **
P-5 × P-7	0.94 **	1.09 **	−0.08 *	−0.15 **	1.52 **	1.47 **	1.20 **	1.26 **	0.45	16.94 **	−0.90 **	−0.96 **	0.13 **	−0.004	5.12 **	6.53 **	−3.60 **	−1.05 **
P-5 × P-8	−0.17	−0.43 **	0.26 **	0.25 **	0.94 **	0.10	0.36 **	0.60 **	15.17 **	9.57 **	2.20 **	2.14 **	0.07 **	0.21 **	0.46	3.69 **	0.16	0.66 **
P-6 × P-7	1.27 **	1.46 **	0.093 *	−0.02	2.81 **	2.80 **	−0.31 **	−0.41 **	−0.77	16.74 **	1.47 **	0.66 **	−0.18 **	−0.17 **	−4.18 **	−3.82 **	2.72 **	2.55 **
P-6 × P-8	0.13	−0.01	0.38 **	0.39 **	2.22 **	1.47 **	−0.02	0.436 **	−37.73 **	−44.44 **	−1.23 **	−1.33 **	−0.11 **	0.002	2.54 **	1.05 *	−1.04 **	0.61 *
P-7 × P-8	−0.83 **	−1.47 **	0.10 **	0.11 **	−1.25 **	−2.36 **	−0.52 **	−0.633 **	11.89 *	23.25 **	−2.12 **	−2.00 **	−0.10 **	−0.13 **	−0.74	−2.25 **	−0.05	−0.41

FCP—fruit count per plant, FFT—fruit flesh thickness (cm), AFW—average fruit weight (kg), YPP—yield per plant (kg), SCPF—seed count per fruit, TSS—total soluble solid (°Brix), DMC—dry matter content (%), TC—total carotenoids (mg/100 g), AA: antioxidant activity–DPPH (%). * Significant at 0.05 level of probability, ** significant at 0.01 level of probability. Note: Parents and hybrids were compared separately.

. For the fruit count per plant, the parental lines P-5 (0.55 and 0.50), P-2 (0.25 and 0.24), and P-8 (0.23 and 0.20) exhibited significantly positive GCA estimates, indicating strong genetic potential in 2023 and 2024, respectively. In contrast, P-6 (−0.43 and −0.46), P-3 (-0.31 and −0.26), and P-1 (−0.15 and −0.17) consistently showed adverse GCA effects in 2023 and 2024, respectively. The SCA effects for this trait ranged from −1.19 (P-2 × P-6) to 1.61 (P-4 × P-8) in 2023 and from −1.47 (P-7 × P-8) to 1.46 (P-6 × P-7) in 2024, respectively. Notably, eight crosses in 2023 and nine in 2024 exhibited highly significant positive SCA effects.

For the average fruit weight, P-2 (0.15 and 0.09) and P-5 (0.08 and 0.07) consistently exhibited the highest significant GCA values in 2023 and 2024, respectively. In contrast, P-8 (−0.11) and P-1 (−0.09 and −0.03) displayed negative GCA effects in 2023 and 2024, respectively. The SCA effects ranged from −0.43 (P-3 × P-8) to 0.37 (P-2 × P-4 & P-2 × P-8) in 2023 and from −0.55 (P-4 × P-6) to 0.48 (P-4 × P-5) in 2024. Notably, eighteen crosses in 2023 and fifteen in 2024 exhibited significantly positive SCA values.

For fruit yield per plant, P-5 (2.08 and 1.76), P-2 (1.02 and 1.29), and P-7 (0.61 and 0.99) exhibited strong positive GCA effects in 2023 and 2024, respectively. Meanwhile, P-3 (−1.17 and −1.05), P-6 (−1.07 each), P-1 (−0.61 and −0.78), P-8 (−0.58 and −0.61), and P-4 (−0.27 and −0.52) showed negative GCA values. The SCA effects ranged from −1.84 (P-4 × P-6) to 1.34 (P-2 × P-5) in 2023 and from −1.86 (P-4 × P-6) to 1.72 (P-2 × P-5) in 2024. Notably, fifteen crosses in 2023 and seventeen in 2024 exhibited positive SCA values.

For fruit flesh thickness, P-2 (0.46) recorded the highest significant positive GCA in 2023, followed closely by P-5 (0.11) and P-1 and P-6 (0.04 each). Conversely, negative GCA effects were observed in P-3 (−0.24), P-4 (−0.19), P-8 (−0.18), and P-7 (−0.05). In 2024, P-2 (0.56), P-5 (0.20), and P-6 (0.08) maintained strong GCA effects, whereas P-8 (−0.27), P-3 (−0.25), P-1, and P-4 (−0.18 each) exhibited negative values. The SCA effects varied from −0.59 (P-2 × P-3) to 1.34 (P-2 × P-5) in 2023 and from −1.33 (P-4 × P-5) to 1.72 (P-2 × P-5) in 2024. Notably, nine crosses in 2023 and twelve in 2024 exhibited favorable SCA effects.

The GCA impact for the seed count per fruit ranged from −45.14 (P-6) to 27.24 (P-1) in 2023. In contrast, in 2024, the range varied from −44.82 (P-6) to 29.44 (P-3). Notably, fifteen crosses in 2023 and sixteen in 2024 showed significant and positive estimates for this trait. The SCA impact ranged from −103.52 (P-1 × P-8) to 103.38 (P-4 × P-8) in 2023 and from −66.48 (P-5 × P-6) to 85.56 (P-1 × P-6) in 2024.

Estimates of the GCA effects for the TSS content ranged from −0.79 (P-4) to 0.65 (P-7) in 2023 and from −0.67 (P-4) to 0.97 (P-7) in 2024. The SCA effect for this trait showed highly significant positive values for twelve crosses in both years. The estimated SCA impact ranged from −2.12 (P-7 × P-8) to 2.67 (P-2 × P-8) in 2023 and from −2.00 (P-7 × P-8) to 2.14 (P-5× P-8) in 2024.

For the total carotenoid content, P-3 (0.17 and 0.11), P-4 (0.08 and 0.09), and P-5 (0.01 and 0.04) recorded positive GCA effects, while P-8 (−0.15 and −0.16), P-7 (−0.10 and −0.09), and P-6 (−0.05 and −0.08) exhibited negative values. The estimated SCA effects ranged from −0.46 (P-3 × P-5) to 0.77 (P-2 × P-7) in 2023 and from −0.50 (P-3 × P-4) to 0.76 (P-2 × P-7) in 2024. Nine crosses in the first year and eight in the second displayed positive SCA effects.

For antioxidant activity, P-2 (2.86 and 1.93), P-3 (2.37 and 2.28), and P-1 (1.30 and 0.73) exhibited positive GCA effects, while P-8 (−2.48 and −3.08), P-6 (−1.46 and −1.80), and P-7 (−0.91 and −0.69) displayed negative effects. The SCA values ranged from −8.13 (P-1 × P-5) to 16.75 (P-1 × P-2) in 2023 and from −7.80 (P-3 × P-6) to 14.73 (P-1 × P-2) in 2024. Eight crosses in the first year and ten in the second showed highly significant positive SCA effects (Table 5).

Among the eight parents of pumpkin, the GCA effect for dry matter content ranged from −0.79 (P-4) to 1.62 (P-7) in the first year. In contrast, during the second year, the GCA ranged from −1.17 (P-8) to 1.61 (P-7). The SCA impact varied from −6.75 (P-2 × P-5) to 3.33 (P-5 × P-6) and −4.82 (P-4 × P-7) to 4.26 (P-5 × P-6) during both seasons correspondingly. However, in both years, the cross-combinations showed desirable and significant SCA impacts for this particular trait.

4. Discussion

4.1. Mean Performance of the Studied Traits

Significant differences were observed between the parental lines and their hybrids for key agronomic and quality traits in this study. Notably, the hybrid P-2 × P-5 exhibited superior performance, producing a significantly higher number of fruits per plant (6.06) compared to its respective parents (5.14 and 4.97). These findings align with those of Hosen et al. [20] and Nisha and Veeraragavathatham [21], who also reported that F₁ hybrids outperformed their parental lines in terms of fruit number per plant, with observed ranges of 1.94 to 5.22 and 3.97 to 6.03, respectively. The variation in values across studies may be attributed to differences in the genetic makeup of the genotypes and the growing environments. In addition to fruit number, the hybrid P-2 × P-5 also demonstrated significantly greater flesh thickness (5.47 cm) compared to its parents (4.30 cm and 2.64 cm). This trait contributes not only to fruit quality but also to better postharvest handling and storage, as supported by Abdein et al. [22], who reported a flesh thickness range of 2.70 to 5.35 cm. Thicker flesh can enhance the marketability of fruits by improving shelf life and transportability. In terms of fruit weight, the hybrids P-2 × P-4, P-2 × P-5, and P-2 × P-6 exhibited significantly higher average fruit weights of 2.56, 2.20, and 2.19 kg, respectively. However, the hybrid P-2 × P-5 achieved the highest total fruit yield per plant (13.35 kg), showcasing its superior overall performance. These findings align with those of Tamilselvi et al. [23], who reported fruit weights ranging from 2.09 to 4.45 kg and yields per plant between 4.70 and 13.44 kg among various pumpkin hybrids. Such differences are likely due to the specific varietals and hybrid combinations used.

Improving fruit yield remains a primary goal in most pumpkin breeding programs. Yield is a complex trait influenced by multiple factors, including genetic potential, sex expression, resistance to diseases, and agronomic practices [24]. Direct selection for yield based solely on phenotypic performance can be unreliable, as yield is a complex trait influenced by both genetic and environmental factors. Therefore, it is more effective to consider yield-contributing traits such as fruit number and fruit size, which have a more direct and measurable genetic basis. Additionally, increasing marketable yield is of paramount importance to growers. As such, the fruit number per plant provides a more reliable estimate of potential yield, and modifying this trait can lead to direct yield improvement [23]. Hence, selection should emphasize fruit quantity over fruit size to achieve enhanced productivity.

Seed yield is another critical trait, particularly in the context of hybrid seed production. The hybrids that produced the highest seed numbers in this study were P-1 × P-4 (315.36 seeds per fruit) and P-3 × P-8 (297.79 seeds per fruit), significantly surpassing their respective parental lines. These values fall within the range reported by Hosen et al. [20] (311.80 to 702.13 seeds per fruit in hybrids) and Tamilselvi et al. [25] (145.12 to 390.75 seeds per fruit in genotypes), suggesting that our results are consistent with those reported in earlier studies.

Biochemical traits are also vital for determining fruit quality. For instance, the hybrids P-3 × P-8 (7.44 °Brix) and P-5 × P-8 (7.04 °Brix) recorded significantly higher total soluble solids (TSSs) compared to their parents. These results are consistent with the TSS values reported by Javaherashti et al. [26], which ranged from 6.83 to 8.47 °Brix. In terms of nutritional quality, the total carotenoid content is a key factor, and the hybrid P-2 × P-7 demonstrated significantly higher content (1.40 mg 100 g⁻¹) than its parents. Hatwal et al. [8] reported a carotenoid content range of 0.85 to 4.85 mg 100 g⁻¹, placing our findings within the reported variability.

Similarly, antioxidant activity, as measured by DPPH (%) scavenging, was higher in the cross P-1 × P-2 (47.50%) than in the parental lines. This is comparable to the range of 48.41% to 83.91% previously reported by Kulczyński et al. [27] and Kar et al. [28]. These biochemical traits can be influenced by environmental factors, genotype, and the stage of fruit maturity at harvest [29].

Overall, this study demonstrates that hybrid combinations consistently outperformed both their parental lines and commercial checks across key agronomic and quality traits. This superior performance is likely due to heterosis, which results from the accumulation of favorable dominant alleles from both parents. As Kumar et al. [30] emphasized, heterosis manifests in F₁ hybrids as superior performance over parental means, better parents, or standard checks, depending on the trait involved and the genetic divergence between parents. These findings suggest that the evaluated hybrids are promising genetic resources for the improvement of pumpkin. Further testing under diverse environments is recommended for their commercial exploitation.

4.2. Heterosis

One of the most significant advancements in plant breeding has been the commercial application of heterosis. The level of heterotic response in F₁ hybrids is largely determined by the genetic divergence and breeding value of the parental lines, as well as the environmental conditions in which the hybrids are cultivated. Heterosis, or hybrid vigor, is typically evaluated based on the performance of the F₁ population in comparison to the better parent, the mid-parent value, or a standard commercial check hybrid [31].

In this study, the analysis of heterosis reveals several promising hybrid combinations. For fruit number per plant, the crosses P-1 × P-3 and P-3 × P-6 showed significant better-parent heterosis, while P-2 × P-5 exhibited higher standard heterosis values of 44.80% and 60.95% compared to the commercial check. These results highlight the potential of these hybrids for increasing fruit productivity. For average fruit weight, P-4 × P-5 exhibited significant better-parent and standard heterosis. Regarding fruit flesh thickness, hybrids P-5 × P-7 and P-5 × P-8 outperformed their respective better parents, and the cross P-2 × P-5 demonstrated superior performance over the commercial check, with standard heterosis values of 69.77% and 46.26%, respectively. This suggests that these hybrids can contribute to improved postharvest handling and consumer appeal due to thicker fruit flesh. Yield per plant also showed significant heterotic responses. P-3 × P-6 exhibited 61.67% better-parent and 58.57% standard heterosis, while P-2 × P-5 recorded 74.34% better-parent and 49.85% standard heterosis. These values indicate that these hybrids possess strong genetic potential for commercial yield improvement.

In terms of quality traits, the hybrids P-2 × P-8 and P-3 × P-8 recorded the highest heterosis for total soluble solids (TSSs), with values of 64.77% and 66.21% over the better parent, and 36.78% and 44.40% over the commercial check, respectively. These increases in TSSs are associated with improved taste and market quality. Similarly, crosses such as P-2 × P-7 and P-1 × P-3 exhibited significantly higher heterosis for carotenoid content, enhancing the nutritional quality of the hybrids.

These findings are in agreement with previous studies. Yadav et al. [32] reported significant heterosis in pumpkins relative to standard and superior parents for yield per plant, dry matter content, average fruit weight, flesh thickness, and fruit number. Likewise, Pradeepika et al. [9] demonstrated that heterosis for fruit yield and the number of fruits per plant is often positively correlated, reinforcing the conclusion that fruit weight, size, and number are major contributors to overall yield. The extent of heterosis observed is strongly influenced by both the genetic composition of the parental lines and environmental interactions [25]. Pandey et al. [6] also observed significant heterotic responses in traits such as fruit flesh thickness, yield per plant, and carotene content, supporting the present findings.

The observed hybrid superiority can be attributed to the dominance hypothesis, which suggests that favorable dominant alleles from both parents suppress deleterious recessive alleles in the F₁ generation [29]. This masking effect enhances hybrid performance, making the exploitation of heterosis a reliable strategy for genetic improvement in pumpkin breeding. In summary, the study identifies several hybrids with significant heterotic advantages for both yield and quality traits, making them valuable candidates for commercial cultivation and further genetic enhancement programs.

4.3. Combining Ability

In modern plant breeding, it is uncommon to find all economically desirable traits in a single genotype. Therefore, the selection of appropriate parents and cross-combinations is crucial for developing high-yielding cultivars. A parent exhibiting significantly positive general combining ability (GCA) effects is considered a good general combiner [30], typically reflecting additive genetic variance, which influences trait inheritance.

In the present study, parental line P-2 exhibited the highest significantly positive GCA values for fruit flesh thickness (0.46 and 0.56), indicating its potential for improving this trait. Parent P-5 demonstrated the highest GCA for the number of fruits per plant (0.55 and 0.50), suggesting its usefulness in enhancing the fruit set. P-2 also showed strong GCA values for average fruit weight (0.15 and 0.09), while P-5 was superior in fruit yield per plant (2.08 and 1.76). Moreover, P-1 (27.24) and P-3 (29.44) had the highest GCA values for the number of seeds per fruit, pointing to their potential for seed yield improvement.

Regarding quality traits, P-7 exhibited the highest GCA values for total soluble solids (0.65 and 0.97), indicating its usefulness for improving sweetness. P-2 (2.86 and 1.93) and P-7 (1.62 and 1.61) also showed strong GCA values for antioxidant activity (DPPH%) and dry matter content, respectively. P-3 (0.17 and 0.11) was notable for its GCA effect on total carotenoid content. Overall, P-5, P-2, and P-7 emerged as the most promising general combiners for multiple traits. However, no single parent exhibited superior GCA across all evaluated traits, confirming that each possesses strengths in specific attributes only. Similar findings were reported by Hosen et al. [20] and Mohsin et al. [33], who noted that no parent in their pumpkin studies was a universal good combiner for yield and its components.

The specific combining ability (SCA) effects revealed several cross-combinations with significant positive impacts. For the number of fruits per plant, P-4 × P-8 (1.61) and P-7 × P-8 (1.46), both low × high GCA combinations, displayed strong SCA effects. For average fruit weight, high × low and low × high combinations such as P-2 × P-4, P-2 × P-8, and P-4 × P-5 were superior. In terms of dry matter content, combinations like P-4 × P-8, P-2 × P-8, and P-5 × P-6 showed strong performance. The cross P-2 × P-7 (high × low) exhibited significant SCA for the total carotenoid content.

Notably, the P-2 × P-5 cross showed significant SCA effects for both fruit flesh thickness and yield per plant, while P-1 × P-2 was superior for antioxidant activity (DPPH). These combinations, particularly those involving high × high general combiners, suggest additive × additive gene action. The observed SCA in various combinations, whether high × high, high × low, or low × low, points to a mix of additive, dominant, and epistatic genetic interactions. This genetic complexity is also influenced by the degree of heterozygosity in parental lines, as noted by Ene et al. [14].

Comparable observations were made by Hosen et al. [20] for traits like fruit number, dry matter, carotenoids, and DPPH activity. Mohsin et al. [33] found similar results for fruit flesh thickness and total soluble solids, while Tamilselvi et al. [25] noted corresponding outcomes for fruit weight and yield per plant. Singh et al. [34] and Gharib et al. [35] emphasized that combinations with high GCA are suitable for varietal development through pedigree breeding, while high × low combinations are better suited for heterosis breeding.

Based on these findings, the most promising hybrid combinations with strong potential for yield and quality enhancement are P-2 × P-5 for yield per plant, P-2 × P-7 for total carotenoid content, P-2 × P-8 for total soluble solids, and P-1 × P-2 for antioxidant activity. These crosses should be prioritized for future hybrid development and commercial exploitation in pumpkin breeding programs.

5. Conclusions

This study presents a comprehensive assessment of trait performance, heterosis, and combining ability in pumpkin, offering valuable insights for the development of superior F₁ hybrids. P-5 was identified as a promising parental line for general combining ability, while hybrids such as P-2 × P-5 and P-5 × P-7 exhibited strong heterotic potential, showing 77% and 58.62% higher yields, respectively, over the commercial check variety. Overall, the integration of genetic analysis with trait-based selection supports the development of high-yielding, quality-enhanced pumpkin hybrids with strong potential to advance future breeding programs and commercial cultivation.