Assessment of Moringa Accessions Performance for Adaptability, Growth and Leaf Yield Under the Subtropical Climate of Pretoria, South Africa

Abstract

Despite the extensive cultivation of Moringa trees in tropical regions, understanding of accession-specific performance across diverse agroecological zones remains inadequate. Thus, this study evaluated the growth, adaptability, and leaf yield performance of 12 Moringa accessions (11 M. oleifera and 1 M. stenopetala) over three years in a subtropical climate (Pretoria, South Africa). Seeds were planted in seedling trays in the glasshouse at the University of Pretoria’s experimental farm. Vigorous seedlings were transplanted to the field at the Roodeplaat experimental site of the Agricultural Research Council two months after establishment, following a randomized complete block design (RCBD). Data were measured on establishment (emergence, survival), growth and yield parameters, and monitored plant health via leaf greenness, vigour, chlorosis, and pest and disease incidence. Accessions exhibited substantial variation for most traits, except for stem diameter. Moringa stenopetala showed the highest initial emergence rate but later displayed lower survival rates than most M. oleifera accessions. Survival rates, morphological features (plant height, canopy diameter, and branching), visual scores for leaf greenness and plant vigour, and leaf yield (fresh and dry) varied considerably among the accessions. Moringa oleifera A2 consistently performed well, exhibiting vigorous growth, the maximum survival rate (78%), and fresh leaf production (6206 kg ha⁻¹). Accessions A3 and A8 showed intermediate yield and longevity, indicating potential for cultivation or breeding. Conversely, M. oleifera A10 and M. stenopetala markedly underperformed in most traits, limiting their cultivation potential. Based on multi-year performance, A2 is suggested for large-scale cultivation due to its vigour, yield, and stress tolerance, while A3 and A8 hold breeding potential. The study emphasizes the critical role of genetic variation and selection in enhancing Moringa productivity under subtropical environments. Future work should focus on genetic characterization and agronomic practices optimization of superior accessions.

1. Introduction

Moringa oleifera is the most extensively studied and cultivated species among the 13 species in the Moringaceae family, which includes M. arborea, M. borziana, M. hildebrandtii, M. ruspoliana, M. rivae, M. drouhardi, M. concanensis, M. longituba, M. peregrina, M. ovalifolia, M. pygmaea, M. oleifera, and M. stenopetala [1]. Its prominence is largely attributed to its multiple uses, including nutritional, medicinal, biofuel and antimicrobial applications, as well as its role in climate change mitigation, farming systems resilience, and rural livelihoods [2,3,4]. It is native to parts of northern India, Pakistan, and Nepal [5,6,7]. Moringa stenopetala is another important species in the Moringaceae family, native to northeast tropical Africa (Ethiopia, Kenya and Somalia) [7,8]. However, its distribution, cultivation and utilization are far less widespread than M. oleifera and it remains markedly underutilized in comparison [9,10,11]. The plant’s potential lies in its specific adaptations and value within its native range, which deserves more dedicated research and development.

Moringa oleifera is an evergreen, deciduous, softwood and fast-growing tree capable of reaching heights of up to 12 m in its lifetime [12,13], 3 m in 90 days [7], and 2 m in 116 days [14]. Dwarf variants also exist; however, they mature at only about 2 m tall [15]. This species prefers annual precipitation of 760 to 2500 mm, mean daily temperature of 25 °C to 35 °C, well-drained sandy loam or loamy soils with neutral to slightly acidic soils of pH 5.0 to 9.0 and altitudes of below 600 m above sea level (m.a.s.l.) [16,17]. Nevertheless, it demonstrates considerable adaptability, tolerating a wider range of conditions: annual precipitation from 250 to 3000 mm [18,19], short period of temperatures from −1 to 48 °C [20,21], and heavier clay soils if drainage is adequate [19,22]. Consequently, it is widely cultivated across dry to semi-arid tropical regions, including much of the Middle East and Africa [19,21]. Its productivity is, however, highly constrained by prolonged exposure to cold temperatures, low sunlight, waterlogged clay soils, and excessive rainy conditions [21,23]. This disparity highlights the critical need for rigorous and site-specific evaluation of diverse Moringa genetic resources to unlock their full potential under varying agro-climatic conditions.

This need is substantiated by compelling evidence of genotype-by-environment interactions. For instance, recent studies reveal differences in accession performance across diverse environments. In semi-arid conditions of Namibia, M. oleifera and M. ovalifolia accessions exhibited divergent drought resilience, with survival rates ranging from 40–85% under water-limited regimes [24]. Similarly, field trials in South Africa (Limpopo Province) showed accession-specific yield responses to planting density, where leaf biomass varied between 0.5 and 7.3 t ha⁻¹ under identical management [25,26]. Studies in Ethiopia further highlighted M. stenopetala’s superior cold tolerance and growth parameters but lower biomass productivity compared to M. oleifera accessions in highland subtropics [10,11,27]. Parallel research in Asia confirmed genetic variability in photoperiod sensitivity, with certain accessions extending vegetative growth under shorter daylight [28,29]. Collectively, these findings validate the critical role of localized accession screening—particularly for stress adaptation and yield stability—while revealing persistent gaps in understanding genetic × environmental drivers of performance in frost-prone or highly variable rainfall zones.

The foundation for addressing these challenges lies in genetic variability, as it drives significant variation in agro-morphological and physiological traits for crop improvement. Moringa accessions exhibit profound diversity in plant height, leaf yield, branching architecture, leaflet morphology, flowering time, and pod characteristics [28,29]. This variation also extends to biochemical composition (nutrients, phytochemicals, and bioactive compounds) across species, ecotypes, cultivars, individual plants, and even plant parts [1,30,31]. Understanding this diversity among M. oleifera accessions is not just descriptive—it is essential in designing efficient breeding strategies focused on quantitative trait improvements. A study found considerable variability and high heritability for traits like pod yield, number of pods per tree, pod weight, total carotenoids, and iron content—indicating strong potential for selection gains [32]. Complementarily, another study identified traits such as pod size, plant height, pod girth, and branching as having high genetic variability and heritability, highlighting them as effective targets in breeding programs [33]. High heritability estimates for traits like stem diameter (h² > 0.8) and leaf yield (h² = 0.65–0.72) enable effective selection [1]. Furthermore, variation in root depth, stomatal density, and glucosinolates facilitates breeding drought-tolerant cultivars or lines optimized for specific medicinal and nutraceutical uses [31]. Therefore, systematic evaluation of these heritable traits possessing high heritability and economic value is critical for developing resilient and high-yielding Moringa cultivars.

Despite Moringa’s adaptability across diverse agroecological zones and its significant genetic potential, there remains a scarcity of long-term, site-specific research evaluating diverse accessions under defined environmental conditions. Consequently, the variability in adaptability, growth and yield is highly prevalent, which makes identifying resilient, high-yielding cultivars that are both resilient and high-yielding challenging, particularly those tailored for specific applications such as food, medicine, climate adaptation, industrial use, and livelihoods. Furthermore, it is crucial to understand how genetic and morphological variation influences Moringa’s performance in different climates. Thus, we hypothesize that significant genetic variability exists among selected M. oleifera and M. stenopetala accessions for key agro-morphological traits, leading to divergent adaptation, growth, and leaf yield performances under the subtropical conditions of Pretoria. Therefore, specific high-yielding genotypes with superior adaptability can be identified as suitable candidates for cultivation and breeding programs in comparable agro-ecologies. To test this hypothesis, this study aimed to evaluate the adaptation, growth characteristics, and leaf yield of selected Moringa accessions in Pretoria’s subtropical climate. The objective was to identify high-performing genotypes that exhibit a balance of adaptability-growth-yield traits suitable for large-scale cultivation or breeding programs. The findings are expected to enhance climate-resilience breeding efforts and establish agro-morphological baselines for superior cultivar development in comparable agro-ecologies.

2. Materials and Methods

2.1. Location of the Study

The study began by growing the seedlings at the Hatfield experimental farm glasshouse (25°44′ S, 28°15′ E; 1372 m.a.s.l.), part of the University of Pretoria, South Africa [34,35]. For field evaluation, seedlings were then moved to the Roodeplaat experimental site of the Agricultural Research Council (ARC), located approximately 30 km northeast of Pretoria (25°60′ S, 28°36′ E; 1159 m.a.s.l.). The site experiences a subtropical climate with four distinct seasons: summer (December to February), autumn (March to May), dry winter (June to August), and spring (September to November). Long-term climatic data indicates summer average daily maximum/minimum temperatures of 29.5 °C/16.0 °C in January and winter averages of 22.0 °C/4.5 °C in July. Annual precipitation ranges from 380 to 700 mm, averaging 646 mm, with over 80% of rainfall occurring between October and April [36,37].

The soil at the site is classified as a sandy clay loam (Clovelly soil form) by the Soil Classification Working Group [38] and is representative of the regions’ Cambisols/Luvisols [39], as cited in Maripa [40]. Key soil properties include a 0.21% water holding capacity, an infiltration rate of 1.52 × 10⁻⁴ m³, a hydraulic conductivity of 2.57 × 10⁻⁴ m s⁻¹, a bulk density of 1.40 × 10³ kg m⁻³, a pH range of 5.91–8.64, and a soil organic carbon content of 0.32–2.44% [40,41]. Roodeplaat’s lower elevation results in a slightly warmer microclimate and a longer frost-free season, which may enhance seedling establishment and survival. These conditions provide a representative subtropical environment for evaluating the adaptability, growth, and yield performance of Moringa accessions.

2.2. Germplasm Collection and Seedling Cultivation

Seeds for ten M. oleifera accessions and one M. stenopetala accession were obtained from the International Centre for Research in Agroforestry (ICRAF) gene bank in Kenya. These accessions originated from multiple sites in Mali (including Segou and Bamako) and Kenya (including Meru, Machakos, Ramogi, Kibwezi, and Ramisi). Seeds from an additional M. oleifera accession, sourced from a private farmer in Pretoria, South Africa, served as the study’s local control. Prior to sowing, all seeds were soaked in water for 24 h.

Following soaking, the seeds were planted at a depth of approximately 2 cm in seedling trays within the Hatfield experimental farm glasshouse in late August 2018, after the winter season [7]. The trays were filled with a sterile soilless growing medium, Hygromix™, produced by Hygrotech (Pty) Ltd. (Pretoria, South Africa), for seedling development. In accordance with the supplier’s recommendations, seedlings were watered twice daily. From the seventh day after germination until transplanting, they were also fertilized once daily with Hygrofert—a water-soluble fertilizer applied at 1 g per liter of water, as recommended by the producer, Hygrotech (Pty) Ltd. (Pretoria, South Africa). Throughout the glasshouse growth phase, seedlings were closely monitored for disease and pest incidence. Healthy seedlings were subsequently transplanted to the ARC Roodeplaat experimental site in South Africa for further evaluation.

2.3. Field Preparation, Transplanting, and Agronomic Management

The experimental field was cleared, levelled to achieve a fine tilth, and fenced to avoid damage from wild or domestic animals. The experimental layout was arranged in a randomized complete block design (RCBD) with three blocks. Each block contained twelve 8 m² (2 m × 4 m) plots, with each plot assigned to a single accession. Fifteen seedlings were planted per plot in three rows of five seedlings each, with 1 m spacing between plants and between rows. Blocks were separated by 2 m alley, while plots within a block were spaced 1.5 m apart.

Seedlings were transplanted to the field 4–5 weeks after germination [7]. For the first month post-transplanting, the field was irrigated daily using a sprinkler system to promote root establishment. Subsequently, irrigation was reduced to 2–3 times weekly for the remainder of the study. Weeds were managed continuously through manual hand-pulling and hoeing. The trial was monitored regularly for pest and disease; however, no incidents were observed, and no control measures were required. No supplemental fertilizer was applied during the study period.

2.4. Data Collection

Data were collected annually from 2019 to 2021. Key parameters were selected per the International Livestock Research Institute (ILRI) guidelines used for “Evaluation of Forage Legumes, Grasses, and Fodder Trees for Use as Livestock Feed” [42]. Whereas specific measurement techniques were adapted from a range of additional sources [43,44,45,46,47]. These parameters included the seedling survival rate, leaf yield (both fresh and dry), plant height, canopy diameter, stem diameter, number of primary branches, and post-winter frost tillering capacity. Additionally, visual assessments evaluated plant vigour, leaf greenness, leaf chlorosis, and the incidence of disease and pests.

2.4.1. Seedling Survival Rate

The seedling survival rate (% PSR) was determined as the percentage of surviving plants at various time intervals, using the formula:

$$\mathrm{P}\mathrm{S}\mathrm{R}(\mathrm{\%})={\displaystyle \frac{(\mathrm{T}\mathrm{N}\mathrm{S}\mathrm{D}1-\mathrm{N}\mathrm{S}\mathrm{C}\mathrm{t})}{\mathrm{T}\mathrm{N}\mathrm{S}\mathrm{D}1}}\times 100$$

where TNSD1 is the total number of seedlings transplanted on day one, and NSCt is the number of surviving plants at a time t.

2.4.2. Vegetative Growth and Morphological Traits

Plant height, canopy diameter, stem diameter, number of primary branches, and tillering capability were measured as vegetative growth and morphological traits. Plant height (from the soil surface to the highest point) of selected plants were measured using a meter stick, and the stem diameter was measured with a calliper [45]. The average canopy diameter was determined by measuring the widest cross-sectional width of the canopy and a second width perpendicular to the first at a standard height of 1.3 m above the ground level, following adapted standard forestry protocols for tree measurement [43]. The number of primary branches (develop from the seed’s primary axis) was counted in the first year [44]. However, secondary branch numbers and leaves on the primary axes were not recorded during this study. Tillering was assessed in subsequent years after winter frost by observing regrowth (new shoots/tillers) emerging from the base of Moringa plants after freeze-induced dieback [46]. Measurements were taken from 3–5 randomly chosen plants per plot: four months after transplanting to the field in spring in the first year, and after regrowth from winter frost in the second and third years.

2.4.3. Visual Scoring and Health Assessments

Scores for Leaf greenness and plant vigour were rated on a scale of 0 to 9, with 0 representing poor performance and 9 indicating excellent quality. Pests and disease incidence were also monitored on a regular basis. Disease/pest incidence was defined as the percentage of plants per plot showing the symptoms, whereas severity was the percentage of infected tissue on symptomatic plants [42,47]. But no notable pest or disease outbreaks occurred during the research period.

2.4.4. Leaf Yield Estimation

Leaf yield was measured twice yearly (six harvests total). The first harvest took place four months after transplanting to the field, and the second harvest followed two months later, just before winter frost arrived. All mature leaves were harvested, leaving behind 3–4 apical leaves to promote regrowth. Fresh leaf weight (FWt) was directly recorded per plot and converted to yield per hectare. To determine dry leaf weight (DLW), a 10–15 g fresh subsample (FWss) per plot was oven-dried at 105 °C for 24 h to achieve a constant weight [48,49]. The total dry leaf yield was determined as follows:

$$\mathrm{D}\mathrm{L}\mathrm{W}=\left({\displaystyle \frac{\mathrm{D}\mathrm{W}\mathrm{s}\mathrm{s}}{\mathrm{F}\mathrm{W}\mathrm{s}\mathrm{s}}}\right)\times \mathrm{F}\mathrm{W}\mathrm{t}$$

where FWt is the total fresh leaf per plot.

2.5. Statistical Analyses

One-way analysis of variance (ANOVA) for a randomized complete block design (RCBD) was conducted in SAS version 9.4 (SAS, Cary, NC, USA, 2013) to determine the statistical significance of the studied parameters among the accessions, using treatment as a fixed effect. The model was: Xij = μ + αi + βj + εij, where Xij is the observation of the parameters, μ is the grand mean, αi is the treatment effect, βj is the block effect, and εij is the random error. When the F-test showed significant variation, means were separated using Tukey’s test at p < 0.05. A combined analysis of variance (i.e., pooled ANOVA) was also conducted to evaluate the interaction effect of treatments across years or seasons using operational status (OPSTAT).

3. Results

3.1. Seedling Emergence and Growth Performance in the Glasshouse

Table 1. Days to seedling emergence (DSE; counts at 7, 14, 21, and 28 days after sowing) and emergence percentage of Moringa accessions grown in the glasshouse at the Hatfield Experimental Farm, University of Pretoria.

Species Name	Collection Area	Country	Accession Number & Code	NSS	DSE				% Emergence
					7	14	21	28
Moringa oleifera	Meru	Kenya	Bulk (A1)	100	0	6	14	41	41
Moringa oleifera	Machakos	Kenya	07229 (A2)	100	0	1	14	44	44
Moringa oleifera	Segou	Mali	07633 (A3)	100	0	25	44	54	54
Moringa oleifera	Bamako	Mali	07632 (A4)	100	0	15	31	33	33
Moringa oleifera	Not available	Kenya	07627 (A5)	100	0	6	16	44	44
Moringa oleifera	Mbbolo	Kenya	03295 (A6)	100	0	0	2	12	12
Moringa oleifera	Busia	Kenya	05536 (A7)	100	0	4	19	53	53
Moringa oleifera	Ramogi	Kenya	07717 (A8)	100	0	4	17	61	61
Moringa oleifera	Kibwezl	Kenya	07316 (A9)	100	0	11	36	81	81
Moringa oleifera	Ramisi	Kenya	07216 (A10)	100	0	36	57	69	69
Moringa oleifera	Pretoria	SA	Pretoria (A11)	100	0	46	72	87	87
Moringa stenopetala	Not available	Kenya	NA (MS)	110	0	60	72	108	98

MS: Moringa stenopetala; NA: Not available; DSE: days to seedling emergence; NSS: number of seeds sown; SA: South Africa.

shows the days to seedling emergence for the Moringa accessions observed in the glasshouse at the Hatfield experimental farm, University of Pretoria. No emergence occurred within the first seven days after sowing. The M. oleifera accessions Pretoria (A11), 07216 (A10), 07316 (A9), 07632 (A4), 07633 (A3) and M. stenopetala emerged early, with a significant number of their seeds emerging by the 14th day. However, more than 50% of the seedlings in most accessions appeared late between 21 and 30 days after sowing. Moringa oleifera accessions exhibited variable emergence rates (12% to 87%), while M. stenopetala achieved the highest seedling emergence rate (98%) in the glasshouse.

This reveals a clear dichotomy in emergence timing, with most accessions exhibiting delayed emergence after 21 days, and establishes a significant interspecific difference in emergence success, with M. stenopetala demonstrating superior performance under these conditions (Figure 1).

Researchers closely monitored disease symptoms, pest damage, nutrient deficiencies, wilting, chlorosis (yellowing), and physiological stress in the glasshouse. Some incidence of aphids was also detected on M. oleifera accession bulk (A1) from Kenya and 07633 (A3) from Mali. The issue resolved without chemical intervention, leaving plants undamaged.

3.2. The Survival Rate of Accessions in the Field

Table 2. Mean survival rates (%) of Moringa accessions across three consecutive years at the Roodeplaat experimental site of the Agricultural Research Council, Pretoria, South Africa.

Accessions	Year 1	Year 2	Year 3	Combined Mean
A1	52.33 c	50.67 bc	47.33 abc	50.33 bc
A2	78.00 a	76.00 a	68.33 a	74.00 a
A3	73.67 ab	64.67 ab	56.67 ab	65.33 ab
A4	75.33 ab	62.00 ab	53.33 abc	63.33 ab
A5	74.00 ab	63.33 ab	52.00 abc	63.33 ab
A6	61.67 abc	61.67 ab	52.33 abc	58.67 ab
A7	51.67 c	50.00 bc	42.67 bc	48.33 bc
A8	75.33 ab	60.33 ab	52.67 abc	62.67 ab
A9	58.33 bc	46.67 bc	30.33 cd	45.00 bc
A10	45.00 c	31.33 c	29.33 cd	35.00 c
A11	73.67 ab	63.00 ab	50.33 abc	62.33 ab
MS	59.33 bc	35.00 c	16.00 d	36.67 c
p value	0.005	0.048	0.014	0.015

Interaction (Year × Treatment): NS; Means within a column followed by different superscript letters differ significantly (p < 0.05). A1–A11: Moringa oleifera accessions; MS: Moringa stenopetala. NS: Non-significant (p > 0.05).

shows the survival rates (%) of Moringa accessions over three years at the Roodeplaat experimental site (Pretoria, South Africa) under the subtropical climate. During the first year, accessions recorded significantly different (p < 0.05) seedling survival rates ranging from 45% to 78%. Moringa oleifera accessions A2 (78%), A4 (75%), A8 (75%), A3 (74%) and A11 (74%) formed a similar statistical subgroup with significantly higher (p < 0.05) survival than A10 (45%), A1 (52%), and A7 (52%). Although M. oleifera A9, A10 and MS showed earlier emergence in the glasshouse, they exhibited lower survival rates than other accessions and failed to maintain their initial advantage after transplantation. Moringa stenopetala showed a lower survival rate (59%) compared to most M. oleifera accessions (A2, A3, A4, A5, A8, and A11), though some M. oleifera accessions (A1, A6, A7, A9 and A10) had statistically equivalent survival to MS. No accessions survived winter frost (May–September) intact; all experienced complete leaf and stems desiccation, with most plants regenerating from roots in spring 2020 and 2021.

Post-winter survival varied significantly (p < 0.05) in Year 2 (31% to 76%). Moringa oleifera A2 again showed the highest survival (76%), followed by A3 (65%), A5 (63%) and A11 (63%), while A10 (31%), A7 (47%), A9 (50%) and A1 (51%) had lower rates. By Year 3, survival further declined (29–68%), with A2 maintaining the highest survival (68%) followed by A3 (57%), A4 (53%) and A8 (53%). Accessions A10 (29%) and MS (16%) showed the poorest performance, indicating their limited medium-term tolerance to environmental stress.

Combined mean survival rates differed significantly (p < 0.05) among accessions. Accessions performed consistently across seasons or years, as evidenced by a non-significant (p > 0.05) accessions × years interaction. Accessions with higher survival in the first year maintained relatively higher rates in subsequent years. Moringa oleifera A2 demonstrated consistent vigour over three years (74%), followed by A3 (65.3%), A4 (63%), A5 (63%) and A8 (62.7%). In contrast, A10, A7, A9 and MS exhibited lower survival rates in all years and overall, indicating poor subtropical adaptation. Surprisingly, the locally collected accession (A11, Pretoria) showed lower survival (74%, 63%, 50.3% across years) than some African-sourced accessions (A2 from Machakos, Kenya; A3 from Segou, Mali), despite expectations of superior performance.

Over the three-year study, survival rates declined significantly for all accessions due to winter frost, yet a strong and consistent hierarchy of performance emerged, with M. oleifera accessions A2, A3, A4, A5, and A8 demonstrating superior and stable subtropical adaptation compared to the poor and declining performance of A10 and M. stenopetala.

3.3. Growth Performances of Accessions in the Field

Table 3. Growth performances of Moringa accessions over three years at the Roodeplaat experimental site (Agricultural Research Council), Pretoria, South Africa (subtropical climate). (A) Plant height and canopy diameter; (B) Stem diameter, number of primary branches, and tillering capacity.

(A)
Accessions	Plant Height (m)				Canopy Diameter (m)
	Year 1	Year 2	Year 3	Combined Mean	Year 1	Year 2	Year 3	Combined Mean
A1	1.54 abc	2.05 a	1.90 a	1.83 a	0.73 cd	0.93 a	0.88 bc	0.85 bc
A2	1.64 ab	1.88 ab	1.86 ab	1.79 a	0.79 bcd	0.88 ab	0.89 bc	0.85 bc
A3	1.88 a	1.72 abc	1.90 a	1.84 a	1.05 a	0.98 a	1.07 a	1.03 a
A4	1.60 ab	1.43 bc	1.62 ab	1.55 ab	0.96 ab	0.82 abc	0.94 ab	0.91 ab
A5	1.66 ab	1.75 abc	1.81 ab	1.74 ab	0.83 bc	0.90 ab	0.91 abc	0.88 bc
A6	1.28 bc	1.60 bc	1.54 ab	1.48 ab	0.68 cd	0.87 ab	0.83 bcd	0.79 bcd
A7	1.26 bc	1.56 bc	1.51 ab	1.44 ab	0.69 cd	0.73 bcd	0.76 cd	0.73 cd
A8	1.51 abc	1.79 abc	1.75 ab	1.68 ab	0.74 bcd	0.97 a	0.91 abc	0.87 bc
A9	1.38 bc	1.33 bc	1.46 b	1.39 ab	0.74 bcd	0.74 bcd	0.79 bcd	0.7 cd
A10	1.05 c	1.48 abc	1.36 b	1.30 b	0.59 d	0.66 cd	0.68 d	0.64 d
A11	1.47 ab	1.26 c	1.47 b	1.40 ab	0.69 cd	0.60 d	0.69 d	0.66 d
MS	0.47 d	0.60 d	0.63 c	0.56 c	0.60 d	0.64 cd	0.67 d	0.64 d
p value	0.002	0.009	0.002	0.002	0.010	0.001	0.002	0.002
(B)
Accessions	Stem diameter (mm)		Number of primary branches	Tillering capacity
	Year 1		Year 1	Year 2		Year 3	Combined Mean
A1	23.0		0.53 cde	2.14 bc		1.29 dc	1.72 bcd
A2	28.0		1.40 b	2.89 ab		2.17 abc	2.53 ab
A3	30.1		2.67 a	2.44 bc		2.44 a	2.45 abc
A4	26.4		0.80 bcde	2.11 bc		1.39 cd	1.75 bcd
A5	25.1		0.20 e	2.33 bc		1.28 cd	1.81 bcd
A6	18.9		0.68 bcde	1.87 c		1.05 d	1.47 d
A7	19.5		0.47 cde	1.77 c		1.22 d	1.5 d
A8	24.7		0.73 bcde	2.78 abc		1.83 abcd	2.31 abcd
A9	21.4		1.07 bcd	2.11 bc		1.83 abcd	1.97 bcd
A10	15.9		0.27 de	2.00 bc		1.17 d	1.58 cd
A11	21.2		0.87 bcde	1.90 bc		1.50 bcd	1.70 bcd
MS	16.7		1.27 bc	3.57 a		2.39 ab	2.97 a
p value	0.073		0.001	0.049		0.037	0.029

Interaction effect (Year × Treatment): NS. Means within a column followed by different superscript letters differ significantly (p < 0.05). MS: Moringa stenopetala; NS: non-significant (p > 0.05).

presents growth parameters of the accessions (i.e., plant height, canopy spread, stem diameter, number of primary branches and tillering capacity) over the study period. Plant height differed significantly (p < 0.05) among the accessions throughout the study. In the first year (fourth month post-transplant), height ranged from 1.05 m to 1.88 m. Accession A3 achieved the greatest height (1.88 m), followed by A5 (1.66 m), A2 (1.64 m) and A4 (1.60 m). These accessions substantially outperformed MS (shortest at 0.47 m), A10 (1.05 m), A7 (1.26 m), and A6 (1.28 m). In Year 2, heights varied from 2.05 m (M. oleifera A1) to 0.60 m (MS). While MS (0.60 m) and A11 (1.26 m) remained the smallest accessions, A1 (2.05 m), A2 (1.88 m), A8 (1.79 m), and A3 (1.72 m) showed pronounced height increase. By Year 3, A3 again reached the maximum height (1.90 m), whereas MS (0.63 m) and A10 (1.36 m) maintained poor performance. Combined ANOVA for plant height indicated non-significant variation (p > 0.05) across years, indicating genetic differences primarily drove height variation. Thus, MS consistently had the lowest mean height (0.56 m), while A3 (1.84 m), A1 (1.83 m), and A2 (1.79 m) recorded the highest combined means.

The canopy diameter also showed significant yearly differences (p < 0.01) (Table 3). In Year 1, diameters ranged from 0.59 m to 1.05 m, with A3 developing the widest canopy (1.05 m), followed by A4 (0.96 m), A5 (0.83 m) and A2 (0.79 m). Accessions A6 (0.68 m), A10 (0.59 m), A11 (0.69 m) and MS (0.60 m) showed inferior canopy growth when compared to A2, A3, A4, and A5. Accession A3 maintained the largest canopies in Years 2–3 (0.98 m; 1.07 m), while MS (0.64 m; 0.67 m), A11 (0.60 m; 0.69 m), and A10 (0.66 m; 0.68 m) consistently had the smallest. Non-significant accession × season interaction over the three years indicated consistent canopy trends. Thus, A3 showed the highest overall canopy diameter (1.03 m), followed by A4 (0.91 m) and A1 (0.85 m), whereas MS (0.64 m) and A10 (0.64 m) demonstrated the poorest adaptability.

Primary branch number varied substantially in Year 1 (p < 0.05). Accession A3 produced the highest number of branches (Mean 2.7), followed by A2 (1.4) and MS (1.3). In contrast, A5 (0.2) and A10 (0.3) exhibited restricted vegetative growth. Tillering capacity (measured in Year 2–3) also differed significantly among accessions. Moringa oleifera A3 and A2 (both combined mean 2.5) showed high vegetative propagation potential, while MS excelled in tillering (3.0), despite poor height and canopy performance. Moringa oleifera A6 (1.5) and A10 (1.6) showed the lowest tillering capacity, further demonstrating poor adaptation. The study found non-significant interaction effects (NS), confirming consistent growth trends across years with minimal annual variability influencing performance. Overall, A2, A3, and A8 demonstrated superior growth in height, canopy diameter, and tillering. In contrast, MS consistently underperformed in these metrics, indicating limited suitability for biomass production.

These findings demonstrate a strong and consistent genotypic influence on growth performance, with accession A3 excelling across nearly all metrics—height, canopy diameter, and tillering—establishing it as the most vigorous genotype. In contrast, M. stenopetala (MS) and accession A10 were consistently the poorest performers in height and canopy development, indicating a fundamental lack of vegetative vigour in this environment, though MS exhibited a unique strength in tillering capacity.

3.4. Plant Vigour, Leaf Greenness, and Leaf Chlorosis

Table 4. Mean performance scores for plant vigour, leaf greenness, and chlorosis of Moringa accessions across three years at the Roodeplaat experimental site (Agricultural Research Council), Pretoria, South Africa.

Accession Code	Plant Vigour Score (0–9 Scale)				Leaf Greenness Score (0–9 Scale)				Leaf Chlorosis Score (0–9 Scale)
	Year 1	Year 2	Year 3	Combined Mean	Year 1	Year 2	Year 3	Combined Mean	Year 1	Year 2	Year 3	Combined Mean
A1	5.3 bc	7.0 a	6.0 abcd	6.1 abcd	5.7 ab	6.7 a	5.7 bcd	6.0 abc	2.7	3.0	3.3	3.0
A2	7.0 ab	8.0 a	7.3 a	7.4 a	6.0 ab	7.0 a	6.3 ab	6.4 ab	2.7	2.7	3.3	2.9
A3	7.7 a	7.0 a	7.0 a	7.2 ab	6.3 a	6.3 ab	6.0 abc	6.2 abc	3.7	3.3	4.3	3.8
A4	7.0 ab	6.0 b	5.7 bcde	5.9 abcd	6.3 a	6.0 b	6.0 abc	6.1 abc	4.0	3.7	4.3	4.0
A5	6.3 abc	7.0 a	6.7 abc	6.7 bc	5.0 bc	7.0 a	5.7 bcd	5.9 abc	3.3	2.7	3.7	3.2
A6	5.7 bc	5.0 bc	5.0 de	5.2 cd	5.3 abc	4.3 c	4.7 e	4.8 d	2.7	3.3	3.7	3.2
A7	4.7 bc	5.3 bc	5.0 de	5.0 d	5.3 abc	6.0 b	5.3 cde	5.5 cd	3.3	3.3	4.3	3.7
A8	7.0 ab	7.3 a	6.7 ab	7.0 ab	6.3 a	7.0 a	6.7 a	6.7 a	3.3	2.7	3.7	3.2
A9	5.7 bc	5.0 bc	5.3 cde	5.3 cd	6.3 a	6.7 a	6.3 ab	6.4 a	4.0	3.3	4.3	3.9
A10	4.3 dc	5.3 bc	4.3 e	4.7 de	5.7 ab	6.3 ab	5.7 bcd	5.9 bcd	3.0	2.7	3.7	3.1
A11	6.0 abc	5.7 b	5.7 bcde	5.8 bcd	5.7 ab	7.0 a	6.0 ab	6.2 abc	4.0	3.0	4.3	3.8
MS	2.0 d	4.3 c	3.0 f	3.1 e	4.3 c	6.3 ab	5.0 de	5.2 de	1.7	3.0	3.3	2.7
p value	0.006	<0.001	0.001	0.001	0.027	<0.001	0.001	0.001	0.328	0.211	0.282	0.211

Interaction effect (Year × Treatment) was not significant (p > 0.05) for all parameters. Means within a column followed by different superscript letters differ significantly (p < 0.05). A1–A11: Moringa oleifera accessions; MS: Moringa stenopetala.

shows the plant vigour, leaf greenness, and chlorosis scores (on a 0–9 scale) for the accessions. In Year 1, accessions showed significantly different (p < 0.05) plant vigour scores, ranging from 2.0 (MS) to 7.7 (A3). Moringa oleifera A3 had the highest vigour (7.7), closely followed by A2 (7.0) and A8 (7.0); MS scored the lowest (2.0). Vigour differences remained significant (p < 0.05) in Year 2. Accessions A2, A3, A5, and A8 scored the highest vigour (7.0–7.3), while A6 (5.0) and MS (4.3) were weakest. This trend continued in Year 3: A2 (7.3) and A3 (7.0) performed best, while MS (3.0) and A10 (4.3) scored lowest. The non-significant (p > 0.05) accession × year/season interaction indicates vigour was consistent across years.

Leaf greenness also differed significantly (p < 0.05) (Table 4), though magnitudes were small. In Year 1, most M. oleifera accessions (A1, A2, A3, A4, A5, A8, A9, A11) showed better greenness, indicating healthy foliage, while M. stenopetala (4.3) scored the lowest greenness. In Year 2, A2, A5, A8, and A9 (6.7–7.0) again had higher greenness, but MS (5.3) and A6 (4.3) performed the poorest. By Year 3, A8 had the greenest leaves (6.7), followed by A2, A9, and A11 (6.3). Conversely, MS (5.0) and A6 (4.7) remained the least green. The combined mean confirmed that A8 (6.7) consistently produced the greenest foliage, with A2, A9, and A11 close behind (6.2–6.4). In contrast, A6 (4.8) and MS (5.2) exhibited the lowest greenness scores across all years.

All accessions developed chlorosis after the fourth month post-transplanting in Year 1 and after recovery from winter frost in Years 2–3. However, chlorosis severity did not differ significantly among accessions (p > 0.05). The absence of significant interaction effects across the three parameters confirms consistent annual trends, regardless of seasonal variations.

The results establish a clear and consistent genetic basis for vigour and leaf greenness, identifying A2, A3, and A8 as the most robust accessions and MS as the least. The universal but uniform occurrence of chlorosis indicates it was an environmental stressor to which all accessions were equally susceptible (Figure 2).

3.5. The Leaf Yield Performances of Accessions in the Field

Table 5. Mean fresh and dry leaf yields of Moringa accessions three growing years at the Roodeplaat experimental site (Agricultural Research Council), Pretoria, South Africa.

Accession Code	Fresh Leaf Yield (kg ha−1)				Dry Leaf Yield (kg ha−1)
	Year 1	Year 2	Year 3	Combined Mean	Year 1	Year 2	Year 3	Combined Mean
A1	4454 ab	6189 ab	5064 ab	5235 ab	1189 ab	1655 a	1305 abcd	1383 bc
A2	5749 a	6778 a	6089 a	6206 a	1599 a	1890 a	1695 a	1728 a
A3	4353 ab	5900 b	4763 bc	4971 b	1235 ab	1656 a	1356 abc	1416 b
A4	3431 bcd	3923 cd	3253 de	3536 cd	1025 bc	1156 b	966 def	1049 d
A5	4222 b	6065 ab	4901 b	5063 b	1164 b	1670 a	1347 abc	1393 b
A6	2079 d	3933 cd	2276 e	2763 d	592 d	1120 b	648 f	787 d
A7	3324 bcd	4204 c	3279 de	3602 cd	960 bcd	1208 b	947 ef	1038 d
A8	4368 ab	6200 ab	4886 b	5124 b	1249 ab	1743 a	1396 ab	1463 ab
A9	3554 bc	3966 cd	3400 de	3640 cd	979 bcd	1082 b	933 ef	998 d
A10	2571 cd	4291 c	2669 de	3177 cd	698 cd	1163 b	725 ef	862 d
A11	4043 b	3999 cd	3694 cd	3912 c	1130 b	1104 b	1027 dce	1087 cd
MS	3377 bcd	3398 d	2871 de	3215 cd	975 bcd	968 b	825 ef	923 d
p value	0.003	<0.001	<0.001	<0.001	0.007	<0.001	<0.001	<0.001

Interaction effect (Year × Treatment) was not significant (p > 0.05). Means within a column followed by different superscript letters differ significantly (p < 0.05). A1-A11: Moringa oleifera accessions; MS: Moringa stenopetala.

presents the fresh and dry leaf yields (kg ha⁻¹) for various Moringa accessions over three years. Field performance differed significantly (p < 0.01). Year 1: Fresh leaf yield ranged from 2079 kg ha⁻¹ (A6) to 5749 kg ha⁻¹ (A2). Moringa oleifera A2 (5749 kg ha⁻¹), A1 (4454 kg ha⁻¹), A8 (4368 kg ha⁻¹), and A3 (4353 kg ha⁻¹) produced equivalent high fresh leaf yields, significantly outperforming the other accessions. Moringa oleifera A6 (2079 kg ha⁻¹), A10 (2571 kg ha⁻¹), A7 (3324 kg ha⁻¹), and MS (3377 kg ha⁻¹) yielded less, though statistically comparable. Year 2: Most accessions yielded higher (3923–6778 kg ha⁻¹) than Year 1 (2079–5749 kg ha⁻¹). Accession A2 again led (6778 kg ha⁻¹), followed closely by A8 (6200 kg ha⁻¹), A1 (6189 kg ha⁻¹), A5 (6065 kg ha⁻¹), and A3 (5900 kg ha⁻¹). In contrast, A11 (3999 kg ha⁻¹), A9 (3966 kg ha⁻¹), A6 (3933 kg ha⁻¹), A4 (3923 kg ha⁻¹), and MS (3398 kg ha⁻¹) produced significantly lower yields, with MS and A4 the lowest. Year 3: A1 and A2 produced higher yields, while A3, A5, and A8 demonstrated statistically comparable amounts. Moringa oleifera A6 (2276 kg ha⁻¹) produced the least, but was statistically similar to A10 (2669 kg ha⁻¹), MS (2871 kg ha⁻¹), A4 (3253 kg ha⁻¹), A7 (3279 kg ha⁻¹), and A9 (3400 kg ha⁻¹). Pooled analysis of the fresh leaf yield showed no significant accession × year interaction (p > 0.05). Thus, A2 maintained the highest fresh leaf yield (6206 kg ha⁻¹), followed by A1 (5321 kg ha⁻¹), A8 (5243 kg ha⁻¹), A3 (5176 kg ha⁻¹), and A5 (5144 kg ha⁻¹), while A6 (2763 kg ha⁻¹) and MS (3215 kg ha⁻¹) yielded the lowest overall, indicating consistent performance across years.

Dry leaf yields showed similar trends with notable variations among accessions. Year 1: A6 produced the least yield (592 kg ha⁻¹), whereas A2 (1599 kg ha⁻¹), A1 (1189 kg ha⁻¹), A3 (1235 kg ha⁻¹), and A8 (1249 kg ha⁻¹) produced higher equivalent amounts. Year 2: A2 (1890 kg ha⁻¹), A8 (1743 kg ha⁻¹), A5 (1670 kg ha⁻¹), A3 (1656 kg ha⁻¹), and A1 (1120 kg ha⁻¹) produced higher yields, while A6 (1120 kg ha⁻¹) and A9 (1082 kg ha⁻¹) were the lowest. Year 3: A2 again produced the highest yield (1695 kg ha⁻¹), with A6 (648 kg ha⁻¹) and MS (825 kg ha⁻¹) remaining the lowest.

The absence of a significant accession × years interaction confirms consistent responses across seasons. Moringa oleifera A2 consistently outperformed others (6206 kg ha⁻¹ fresh; 1728 kg ha⁻¹ dry), followed by A8 (5124 kg ha⁻¹ fresh; 1463 kg ha⁻¹ dry) and A1 (5235 kg ha⁻¹ fresh; 1383 kg ha⁻¹ dry). But A6 and MS consistently yielded the least, indicating poor adaptation.

The leaf yield data reveal a strong and consistent genotypic hierarchy that was maintained across all three growing seasons. Accession A2 was the unequivocal top performer for both fresh and dry biomass production, establishing a clear yield advantage. A cohort of other accessions (A1, A3, A5, A8) also demonstrated robust and stable high yields. In direct contrast, A6 and M. stenopetala (MS) formed a distinct low-yielding group, consistently producing the smallest harvests and confirming their poor agronomic suitability for leaf production in this environment.

4. Discussion

4.1. Seedling Emergence and Growth of Accessions in the Glasshouse

In the glasshouse, Moringa oleifera accessions showed significantly different seedling emergence (12–87%). Emergence occurred between 14- and 30-days post-sowing, reflecting differences in seed viability, dormancy, and genetic traits. Most seedlings emerged late (21–30 days), though accessions A4, A10, A9, A11 and MS exhibited early emergence. This highlights their potential for rapid establishment—a valuable trait for breeding programs aimed at improving crop establishment. Compared to studies in Central Philippines (40–100% emergence; 6.3–10.6 days) [14], our M. oleifera accessions had lower seedling emergence percentage (12–87%) and longer emergence times (14–30 days). Moringa stenopetala (MS) achieved 98% seedling emergence, contrasting with the variable M. oleifera performance. Our study accession emergence period also exceeded the 14-day average reported by Leone et al. [7]. The causes for these variations between current and prior studies remain unclear and lie beyond this study’s scope.

Waterlogging and aphid infestations caused stress during the glasshouse phase. Accessions varied in waterlogging tolerance, with sensitivity observed only in A3. Most accessions demonstrated resilience, recovering without chemical interventions—aligning with Moringa’s preference for well-drained soils [19,22,50]. Variations in seedling emergence percentage, days to emergence, and the waterlogging response under identical conditions indicate substantial genetic variability among the studies accessions. However, discrepancies may also stem from unknown factors like seed maturity at harvest, drying process, storage duration/conditions before imported to South Africa, and environmental or methodological differences [51].

4.2. Survival Rate of Accessions in the Field

Field survival rates varied significantly across the growing area over three years. Survival ranged from 45% (A10) to 78% (A2) in Year 1, 31% (A10) to 76% (A2) in Year 2 and declined further to 29% (A10) and 68% (A2) in Year 3. Moringa oleifera A2 consistently had the highest survival rates among the accessions, with a combined mean of 74%. This shows its strong ability to regenerate after winter frost and suitability for long-term cultivation in frost-prone areas. Other accessions, such as A3 (65%), A4 (63%), A5 (63%), and A8 (63%), also demonstrated relatively high survival in the field, highlighting their adaptability for scaling production under similar conditions. In contrast, A10 had the lowest survival rates (45%, 31%, and 29% across years). Moringa stenopetala (MS) survival also declined sharply from 59% in Year 1 to 16% in Year 3, consistent with studies linking its sensitivity to frost, and it remains markedly underutilized in comparison [9,10,11]. The potential of MS lies in its specific adaptations and value within its native range, which deserves more dedicated research and development.

The survival rates of our study accessions were lower than those reported elsewhere: 100% (M. oleifera) and 97% (M. stenopetala) at the Bako Research Centre in Ethiopia [27] and 75–100% (M. oleifera) in the central Philippines [14]. However, our results were comparable with 40–85% survival rates recorded in semi-arid conditions of Namibia for M. oleifera and M. ovalifolia under water-limited regimes [24]. Direct comparisons remain difficult because of differences in environmental conditions, soil types, and management practices. All accessions in our study struggled during winter, as none retained foliage during the 3–4 months of cold or frost; leaves shed, and stems desiccated. Most plants regenerated from their roots in the spring, exhibiting higher recovery than the typical 20–30% seedling losses in Year 1 [52]. Ponnuswami [52] also noted that 3–5 new shoots may emerge from surviving seedlings after cutting, supporting our observation of regrowth. Crop persistence is therefore linked to perennial longevity and the ability to regenerate after frost [53]. Although Moringa lacks tolerance to prolonged freezing, it can survive short-term fluctuations from −1 to 48 °C [20,21]. This seasonal regrowth confirms the adaptability of studied accessions to Pretoria’s subtropical climate.

The consistent superior survival of accession A2 across all three years, along with the strong performance of A3, A4, A5, and A8, suggests inherent morphological and physiological adaptations to frost-prone conditions. We hypothesize that these adaptations may include deeper and more extensive root systems, which enhance resilience during dormancy and promote vigorous re-sprouting in spring. This mechanism is well-documented in other species; for instance, research in alfalfa has demonstrated that greater root depth and carbohydrate reserves significantly improve winter survival [54]. Conversely, the poor survival of A10 and M. stenopetala may be attributed to traits such as thinner bark, lower root carbohydrate reserves, or weaker root systems that increase their vulnerability to frost damage. This suggestion aligns with established principles of cold-hardening, whereby the strategic allocation of carbohydrates to roots is critical for developing freezing tolerance and supporting regrowth [55]. Therefore, the variation in survival among accessions suggests there are underlying differences in their physiological mechanisms of cold tolerance. This provides a foundation for future research to elucidate the specific traits responsible for this adaptation, thereby ultimately accelerating the improvement of Moringa for subtropical environments.

4.3. Leaf Greenness and Its Implications

Most previous studies on Moringa overlooked leaf greenness. However, the significant variation we observed in the current study serves as an indicator of nutrient status. Leaf greenness reflects the level of soil nutrients like nitrogen, magnesium, iron, and potassium [56,57] as well as leaf chlorophyll content [58]. Since most leaf nitrogen is found in chlorophyll molecules, greenness correlates strongly with nitrogen level [59]. While leaf greenness can also vary due to plant health, stress levels (disease, drought, or pest), growth stages (older vs. younger plants), environmental conditions (like drought or light), or measurement techniques; these factors were minimized through careful controlled conditions. Thus, the observed greenness differences among the accessions primarily reflect genetic variation influencing their nitrogen content. Though not this study’s focus, it is apparent that nitrogen differences affect other plant components, adaptability, and bioactive properties of Moringa products. Darker green leaves typically indicate higher nitrogen, magnesium, and iron availability, while lighter green leaves suggest greater potassium levels and/or deficiencies in these nutrients [56].

Leaf yellowing appeared four-month post-transplanting to the field in Year 1 and on regrowth after winter frost in Year 2 and Year 3. The yellowing started at the bottom of older leaves and gradually progressed upwards towards young leaves until drying occurred. However, the severity did not vary significantly among the accessions. Previous studies associated the problem to several causes: water stress (too much or too little), natural leaf ageing, poor drainage, high soil pH and nutrient deficiencies (iron, zinc, nitrogen or manganese) [60,61]. In our study, it likely resulted from senescence or nitrogen deficiency. Therefore, harvesting leaves earlier (from 3–4 months), implementing frequent harvests, and applying nitrogen fertilizer might be essential to enhance productivity and maintain leaf quality.

4.4. Growth and Leaf Yield Performance of Accessions in the Field

Significant variation in plant height, canopy diameter, and tillering capacity was observed among the accessions, reflecting genetic diversity and environmental interactions. Plant height at fourth months varied from 1.05–188 m in Year 1 (post-transplanting), 1.26–2.05 m in Year 2 and 1.36–1.90 m in Year 3 (after regeneration from winter frost). Moringa oleifera accession A3 (07633) showed the most vigorous growth. Its combined mean values were 1.84 m in height, 1.03 m in canopy diameter, and 2.5 in tillering capacity. Accessions A2 and A4 also demonstrated strong potential for large-scale cultivation in subtropical climates.

Heights recorded at 120 days after post-transplanting and regeneration from winter frost were comparable to the 2 m reported in central Philippines at 116 days post-transplant. However, they were lower than the 1.92–3.64 m height observed at 133 days post-pruning [14]. The maximum height for A3 (1.83 m) was also lower than the 3 m height reached in Zimbabwe at three months [7]. Notably, dwarf cultivars that reach only 2 m in their lifetime [15]. On the other hand, M. stenopetala (MS) had the lowest canopy diameter (0.64 m combined mean) and plant height (0.56 m combined mean), though it exhibited moderate tillering capacity (3.0 combined mean). This suggests that M. stenopetala may be better suited for niche applications requiring strong vegetative proliferation rather than high-volume biomass production. Moringa oleifera A10 consistently performed poorly across most growth parameters, indicating low adaptability to the study conditions. Although development stages at the time of data collection, management and environment may influence results, genetic variability is the most likely cause of the observed variations in growth performances. This result is supported by the lack of significant year × treatment interactions, indicating consistent trends over time.

Fresh leaf yield also differed significantly among accessions. It ranged from 2079–5749 kg ha⁻¹ in Year 1, 3923–6778 kg ha⁻¹ in Year 2, and 2276–6089 kg ha⁻¹ in Year 3. These yields exceed the 527 kg ha⁻¹ (low plant density) and 2867 kg ha⁻¹ (high planting density) reported for smallholder farms in Limpopo, South Africa [25]. However, our study yields were lower than the 2.2–7.3 t ha⁻¹ obtained from variable planting densities and different accessions in the Philippines [14]—though comparative harvesting frequencies/stages were unspecified. Yield discrepancies may stem from differences in management practices (fertilizer use, harvesting stage and frequency, watering frequency, plant density, growth stage and environmental conditions [24,25,62,63]. Nevertheless, accessions A2, A3 and A8 consistently produced higher yields, identifying them as candidates for large-scale cultivation and breeding programs focused on productivity improvement.

The significant variation in growth and yield among accessions is likely rooted in genetic differences in physiological processes. Superior accessions such as A2, A3, and A4 may exhibit higher photosynthetic efficiency, more efficient nutrient partitioning towards shoot development, and potentially a greater density of apical meristems that facilitate branching. Previous research has shown that genetic variation in photosynthetic traits—including stomatal and mesophyll conductance as well as electron transport and Rubisco carboxylation capacity—explains growth differences among genotypes [64]. Furthermore, genetic control of tillering, such as the “tillering inhibition” gene in wheat, can influence carbon allocation between roots and shoots and improve resource-use efficiency [65]. The compact morphology of M. stenopetala may reflect an alternative growth strategy, prioritizing vegetative propagation or root development over vertical expansion, consistent with principles of biomass partitioning [66]. This analysis of the probable physiological basis for growth differences moves beyond description and provides a framework for future research to quantify these specific traits.

5. Conclusions

This study evaluated diverse Moringa accessions under subtropical field conditions, providing valuable insights into their adaptability, growth performance, and yield potential. The differences are closely linked to the significant genetic variations among M. oleifera accessions and underpinned the observed performance differences, highlighting opportunities for enhancement of desired features. Accessions exhibiting a higher seedling emergence did not necessarily maintain their superior performance in the subsequent survival, growth and leaf yield performance in the field, indicating distinct genetic control over germination or seedling emergence versus field adaptability performances. In this study, accessions of A2, A3 and A8 should get priority for large-scale production, breeding or culture initiatives due to their consistent performance across important key study parameters. Conversely, M. stenopetala and A10 are unsuitable for cultivation in these regions due to their poor adaptation and low yields.

To strengthen the scientific scope and practical applications of these findings, explicit future research directions are recommended. Studies should focus on determining the genetic basis of the key traits to identify the molecular markers and genetic mechanisms that underlie the superior emergence, survival, growth, yield, and stress tolerance observed in accessions like A2, A3, and A8. To guarantee sustainability and productivity, optimization of agronomic practices (soil fertility management, optimal irrigation, and the optimal harvesting stage) requires further study to meet the unique requirements of high-performing accessions. Moreover, breeding programs should prioritize the introgression of these identified beneficial traits, such as yield potential, vigorous growth, and stress tolerance from accessions A2, A3, and A8, into elite genetic backgrounds to develop resilient cultivars capable of thriving in a variety of environmental circumstances.