Estádios de maturação de frutos, secageme conservação de sementes de abobrinha (Cucurbita pepo L.)

Abstract

Zucchini has the greatest genetic variability among species of the genus Cucurbita. This culture stands out in Brazil as one of the ten most economically important vegetables, both by its commercialization and by generating jobs in the field. For any culture, like the zucchini, uniformity and emergence speed are some of the main factors that affect the product’s productivity and quality. Harvesting and drying procedures are essential for obtaining high quality seeds, as well as for its conservation during storage. The aim of this research was to evaluate the effect of fruit maturation stages and drying rates on the quality of freshly picked zucchini seeds and seeds stored for 6 months. Hortiagro Sementes Company produced zucchini seeds of variety Caserta and the analysis was carried out at the Central Seed Laboratory and at the Seed Pathology Laboratory in the Federal University of Lavras. It was used a completely randomized design with four replications, in a factorial scheme involving three maturity stages (49, 56 and 63 DAA - days after anthesis), two drying speeds (slow and fast) and two storage periods (0 and 6 months). The seeds were evaluated for physical (water content, mass of thousand seeds and filled with seeds), physiological (germination, first count, accelerated aging, tetrazolium, electrical conductivity, seedling emergence and emergence speed index) and sanitary quality. It was also evaluated the activity of heat-resistant proteins (LEA proteins) and superoxide dismutase (SOD), catalase (CAT), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH) and esterase (EST). Zucchini seeds reach maximum quality at 49 DAA. Slow and fast drying do not affect the physiological quality of seeds harvested at 49 DAA. Delayed harvest of fruits reduces the quality of seeds. The lower expression of LEA proteins and CAT enzyme indicates better results in slow drying. Fast drying reduces the incidence of the fungus Alternaria, Cladosporium, Phoma and Fusarium, and increases the occurrence of Aspergillus and Penicillium.