The improvement in zucchini growth in climatic conditions of Poland can be achieved by drip irrigation of plants. The effect of drip irrigation on zucchini plants of ‘Soraya’ variety during different growth phases on size of fruits and content of L-ascorbic acid, nitrates (V) and carotenoids was estimated. In the research plants were irrigated according to different variants: irrigated during a whole cultivation, irrigated during vegetative growth till fruit sets forming and not irrigated during yielding, not irrigated during vegetative growth till fruit sets forming and irrigated during yielding, not irrigated at all (water in soil came only from precipitation). Irrigation during whole cultivation period and during intensive vegetative growth phase increased yield. Regardless the irrigation method significant values of correlation coefficient for these features were noted. The chemical analysis of zucchini fruits composition showed differentiation of marked elements depending on irrigation method used. The highest content of L-ascorbic acid was in fruits harvested from plants that were not irrigated. Establishment of optimal aquatic-air conditions through improvement in soil humidity during a whole cultivation period of zucchini plants increased content of nitrates in zucchini fruits and decreased carotenes content.

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