1.Introduction: Cultivation of summer crops is the high cost process, so the produced crops should have suitable quantitative and qualitative characteristics to compensate production costs. Selection the plants with the best morpho-physiological characteristics and productivity rate can lead to enhance economic efficiency and resistance rate to biotic and abiotic stresses. With population growth, demand for eggplant as an excellent source of iron, calcium, potassium, phosphorus, and vitamins A and B has increased. In addition to use as food, eggplant also has medicinal characteristics leading to its consumption for medicinal purposes. Eggplant is considered as widely cultivated crop with edible fruits in tropical, subtropical and warm regions, especially in Southern Europe and South America. The total cultivated area of eggplant is about 1.65 million hectares, its production rate is about 48.5 million tons, and its average yield is about 29.3 tons per hectare, worldwide. China, India and Iran are respectively the top producers of this crop with 28.8, 12.2 and 1.3 million tons production rates. Khuzestan, Hormozgan, Tehran, Fars, Sistan and Baluchistan, Razavi Khorasan, Bushehr, Jiroft and Kahnuj are some regions in Iran with the highest cultivation and production rate of eggplant.
2.Materials and Methods: The adaptability and stability of four advanced Iranian eggplant lines including D1, D7, D13 and BJ30, along with three controls including “Black Beauty” cultivar, Qasri Dezful landrace and round Brazjan landrace were studied based on randomized complete blocks design (RCBD) with three replications at five different locations during two years. Seedlings were transplanted at 4-6 leaf stage when their height reached to more than 10 cm. The field was irrigated before transplantation. The distance between rows was 60 cm and seedlings were transplanted at a distance of 75 cm in each row. The total yield was evaluated as a cumulative parameter for each plot from the beginning of fruiting to the end of the harvest period. Analysis of variance was performed using SAS software. Mean comparisons were conducted based on Duncan method at 1 % probability level. Stability analysis was performed by AMMI method.
3.Results and Discussion: The mean comparisons results demonstrated that the highest total yield was recorded in BJ30 line (34.08 ton ha^-1), followed by D1 (33.72 ton ha^-1) and D7 (31.42 ton ha^-1) lines. Total yield in Karaj region (58.39 ton ha^-1) was higher than other studied regions (Jiroft with 34.34, Dezful with 25.52, Orumieh with 22.74 and Qarakhil with 14.49 ton ha^-1, respectively). The highest yield was observed in B J30 line and Borazjan landrace cultivated in Karaj region and the lowest yield was recorded in D7 line, ‘Black Beauty’ cultivar, D13 line and Borazjan landrace, all cultivated in Qarakhil region. Based on AMMI analysis, D1 and D7 were the most stable lines with the high yield which could be recommended for cultivation in all studied regions. The uniformity of the D7 line as a pure line has given it the ability to introduce a promising line. As reported by several researchers, the difference between total yields of eggplants cultivated in different studied regions of this experiment could be related to different climates and meteorological parameters of these regions. The significant interaction effect of region and genotype on total yield indicated that different eggplant genotypes had different reactions to changes in meteorological parameters, and on the other hand, the lack of significant interaction of year and genotype on this trait demonstrated that genotypes reacted the same way to different years. AMMI model was useful in interpreting the results and the model was able to fit the observed data well, which was in line with those reported by several researchers.
4.Conclusion: Given the high stability and total yield of D1 and D7 lines, they could be recommended for cultivation in all studied regions. Among the studied regions, Karaj with 58.39 ton ha-1 had the highest total yield, and on the other hand the lowest value of this trait was recorded in Qarakhil region. The BJ30 line has special compatibility with the Karaj region and is recommended for this region. BJ30 had completely sweet fruits and was significantly different compared to all controls. D1 had green cylindrical fruits with the best taste and the least bitterness comparing to the other lines.