Yield quantity and quality of field cultivated eggplant in relation to its cultivar and the degree of fruit maturity.

Eggplant cultivars differ from one another in a number of properties, among others, earliness of fruiting and the length of fruiting period. A considerable problem regarding eggplant field cultivation in Poland is relatively high failure due to characteristics of our climate. Two-factorial field experiment established according to randomized splitplot method in three replications, aimed at the assessment of yielding of five eggplant cultivars: Avan F1, Black Beauty, Classic F1, Epic F1 and Vernal F1 (I factor). Plants were planted between 4th – 7th June, on the experiment years. Fruits were harvested in the stage of optimum harvesting maturity (every 7 days) and after exceeding this stage (every 10 days) (II factor). There was recorded significant diversity in eggplant yield in the years of the experiment, as well as in relation to its cultivar and the stage of fruit harvesting maturity. High temperature and sufficient amount of precipitation favored eggplant development in 2008, which was proved by yield (23.48 t ha-1) higher than that in next years, average by 71.4% in the case of marketable yield and by 7.5 times higher for early yield (11.87 t ha-1). Vernal F1, Epic F1 and Avan F1 cultivars produced yield ranging from 23.79–18.89 t ha-1, while Classic F1 and Black Beauty featured yield lower by half. The marketable yield of elder fruits was higher than the one regarding fruits harvested in their optimum maturity stage. The results of chemical analysis proved that fruits in optimum maturity contained higher dry matter and reducing sugars in comparison to elder fruits. Yet no proof was found involving differences in biological value of the examined eggplant cultivars.