Conversão e regeneração de sementes sintéticas de batata-doce

Abstract

Sweet potato (Ipomoea batatas L. Lam.) is a plant recognized worldwide as being of great importance for human and animal nutrition. Sweet potato propagation occurs predominantly vegetatively through the use of stem or tuber cuttings. This method, despite being practical and economically viable, faces challenges related to the proliferation of pests and diseases that affect the production and availability of healthy planting material. Therefore, it is necessary to use approaches that can reduce the aforementioned problems, such as in vitro propagation techniques. One of these techniques, synthetic seeds, is considered a crucial biotechnological method for the in vitro conservation and propagation of sweet potato. The objective of this study was to evaluate the conversion rate and biometric factors of synthetic sweet potato seeds, in matrix compositions (water and MS liquid medium), sowing media (water, empty, MS solid and MS liquid), temperatures (4 and 25 °C), luminosities (light and dark) and periods after sowing (45 and 60 days). The research was carried out separately for the two synthetic seed matrices studied. In the first, the synthetic seeds were grown in matrices with MS liquid medium supplemented with 1 g L-1 of sucrose and in the second with only water. In total, there were 9 treatments for each matrix composition, the first with four and the second with eight replicates and five seeds per vial in both. Explants encapsulated in matrix with MS liquid medium were sown in test tubes with distilled water, empty or with MS solid medium, and those in matrix with water, in medium with distilled water, MS liquid and MS solid. According to each treatment, the tubes were placed in a refrigerated environment (4 °C) or in a growth room (25 °C), in the presence (light) or absence (dark) of light. After 45 and 60 days of sowing, the conversion rate (%) and biometric characteristics, length of the largest shoot (cm) and number of shoots and leaves at 45 and 60 days after sowing (DAS) and fresh and dry weight of the plant (g) at 60 DAS were evaluated. The seeds stored at 25 °C and under a 16h photoperiod regime for 60 days had the highest conversion percentage (100%) and the highest number of leaves, number of shoots, length of the largest shoot, and highest fresh and dry weight of the plant. Those stored at a temperature of 4 °C, in the dark and with prolonged storage (60 days), had a lower conversion rate (0%) and growth. The storage of synthetic seeds of Ipomoea batata cv. Italiana branca for up to 60 days in tubes with MS solid medium at 25 °C and in a light environment, regardless of the encapsulation matrix composition, allowed the highest conversion rates and biometric characteristics.