Assessment of Eggplant ( Solanum melongena L.) Genotypes and Selection of Parameters for Better Yield †

: One of the goals in eggplant breeding ( Solanum melongena L.) is higher yield. This study included 20 different genotypes that are part of the collection of the Institute for Vegetable Crops Smederevska Palanka. Sixteen genotypes originated from Serbia, two originated from the Netherlands, one originated from Italy, and one originated from Israel. The experiment was conducted at Vranovo (44 ◦ 36 (cid:48) 6.35 (cid:48)(cid:48) N, 20 ◦ 59 (cid:48) 55.47 (cid:48)(cid:48) E, altitude 87 m) using a randomized complete block design and three replications. The yield parameters (earliness, plant height/centimeter, number of fruits per plant, fruit weight/gram, fruit length and width/centimeter, and fruit yield per genotype/kilogram) were examined to study the relationships among traits and their effects on eggplant yield. The number of fruits per plant had a positive and signiﬁcant correlation with yield (r = 0.685 **). Additionally, the results showed positive correlations between plant height and fruit length (r = 0.812 **), between plant height and fruit weight (r = 0.147), and between fruit width and fruit weight (r = 0.523 *). These characteristics had direct or indirect positive effects on yield, so they can be used as selection criteria to increase the ﬁnal yield of eggplant. Because there is genetic variability between the tested genotypes, progress in breeding will depend on this variation. Earliness had a negative correlation with yield (r = − 0.044) and with all other parameters. a negative correlation between days to ﬂowering (earliness) and fruit yield was found.


Introduction
Eggplant (Solanum melongena L.) is an agronomically and economically important member of the Solanaceae family. It is important as a source of various nutritional compounds and as a raw material for the pharmaceutical industry [1]. In 2018, the world production of eggplants was 54 million tonnes on more than 1.8 million ha, led by China, with 63% of the total, and India, with 24% of the total [2].
The presence of good fiber, and various vitamins and minerals in fruits (rich source of iron and manganese) is of great benefit to human health. Eggplant also contains high phenolic contents that act as antioxidants [3,4]. The color of purple-skin cultivars is due to the anthocyanin nasunin [5]. The browning of eggplant flesh results from the oxidation of polyphenols, such as the most abundant phenolic compound in this fruit, chlorogenic acid [6].
Foods that contain antioxidants may help prevent a variety of diseases. Various studies have shown that eggplant extracts have superb healing effects on different disorders such as burns, warts, inflammatory infections, gastritis, stomatitis, and arthritis [7]. Chlorogenic acid has anticarcinogenic functions by promoting apoptosis in many human cancer cells, such as leukemia and lung cancer cells [8].
Some of the goals of eggplant breeding are to obtain a higher yield and better-quality fruits as well as to improve adaptation to various environments [9]. Many varietes are created in response to adaptation to environmental conditions. Variability is observed even within the same variety in terms of plant height, fruit size, and yield depending on the climate, exposure, and place and method of cultivation [10].
The aim of this study was to examine the relationships among yield parameters (earliness, plant height/centimeter, number of fruits per plant, fruit weight/gram, fruit length and width/centimeter, and fruit yield per genotype/kilogram) and their effects on eggplant yield.

Materials and Methods
This study included 20 different genotypes that are part of the collection of the Institute of Vegetables, Smederevska Palanka. Sixteen genotypes originated from Serbia, two originated from the Netherlands (K22 and K25), one originated from Italy (K19), and one originated from Israel (K38) ( Table 1). The experiment was conducted at Vranovo (44 • 36 6.35 N, 20 • 59 55.47 E, altitude 87 m). Sowing was carried out in individual pots, 11 cm in diameter; filled with a sterile substrate; and kept in a protected area. The seedlings were maintained in a common manner, i.e., every 15 days fertilized with NPK 20:20:20 (25 g/10 L of water) and treated with pesticides as needed. Planting was carried out at the beginning of June. The area of the basic plot was 56 m 2 . In each replication, 10 plants were placed in a row for each genotype. The length of the rows was 4 m, the distance between the rows was 0.70 m, and the distance between the plants in each row was 0.40 m.
The yield parameters (earliness, plant height/centimeter, number of fruits per plant, fruit weight/gram, fruit length and width/centimeter, and fruit yield per genotype/kilogram) were examined to study the relationships among the traits and their effects on eggplant yield. The trials were conducted with a randomized complete block design (RCBD) in three replicates. The correlations and path coefficients were studied using StatSoft Inc. (Tulsa, OK, USA) STATISTICA, version 8.0.

Results and Discussion
This study included 20 genotypes that differed in origin, color and shape of the fruit, and yield (Table 1 and Figure 1). The experiment was conducted in Vranovo during a year when the average air temperatures were higher than the ten-year average. During the period when the vegetative organs developed and the eggplant plants flowered, average temperatures were in the range of 21.0-27.8 • C. The total amount of precipitation at in Vranovo (139.6 mm) was lower compared with the multi-year average precipitation ( Table 2). Number of fruits per plant had a positive and significant correlation with yield (r = 0.68 *) ( Table 3). The same results were obtained in a similar study [11]. Additionally, the results showed positive correlations between plant height and fruit length (r = 0.81 *), between plant height and fruit weight (r = 0.147), and between fruit width and fruit weight (r = 0.52 *). These characteristics had direct or indirect positive effects on yield, so they can be used as selection criteria to increase the final yield of eggplant. The correlation between fruit length and weight, and yield was positive but not significant. This is in line with the results of other groups of researchers [11][12][13]. Earliness had a negative correlation with yield (r = −0.044) and with all other parameters. Our results are in accordance with those of an earlier report [14] in which a negative correlation between days to flowering (earliness) and fruit yield was found.

Conclusions
All characteristics that had direct or indirect positive effects on yield can be used as selection criteria to increase the final yield of eggplant. Because there is a genetic variability between the tested genotypes, progress in breeding will depend on this variation.
Author Contributions: J.D., S.P. and Z.G. was involved in the study design, data collection, results analysis and interpretation, and manuscript writing and revisions. J.M. was involved in the study design and in the writing, drafting, and review of the manuscript. V.Z. was involved in the study design and data analysis. M.U. was involved in the data analysis. T.Ž. was involved in review of the manuscript. All authors have read and agreed to the published version of the manuscript.