ACQUISITION OF DESICCATION TOLERANCE IN FABA BEAN (VICIA FABA) AS AFFECTED BY MATURITY STAGES, HARVESTED ORGAN TYPE, AND DRYING METHOD

摘要

A field experiment was carried out to investigate the effects of harvesting organ type and drying method on the acquisition of desiccation tolerance during different development stages of faba bean (cv. Shami) seed. The plants were harvested in three pod developmental stages including Mid-Full Sized Seeds (MS), Full-Sized Seed (FS), and Greenish- Yellow pod (GY) were divided into three organ forms (depodded, podded detached, and podded attached to the plants). Finally, they were dried using two methods including shade-drying and sun-drying. An extra harvesting was also done at yellowish-brown (YB) stage according to the conventional harvest of local farmers as a control. The results showed that as the seeds become more mature, from MS stage to GY stage, germination percentage (GP), natural seedling percentage (NS), content of soluble sugars (SS), and activity of catalase (CAT) and glutathione (GR) enzymes was increased while the mean germination time (MGT) and ascorbate peroxidase (APX) was decreased. From GY stage to YB stage, MGT and soluble protein (SP) were increased while other were traits decreased. In MS, FS, and GY stages, the highest and lowest GP, NS, SS, CAT, and GR enzymes activity were observed in the podded attached shade-dried seed and depodded sun-dried seed treatments, respectively. We found that among all treatments, MGT had an opposite behavior. Overall, the seeds showed desiccation tolerant behavior, a higher amount of SS, CAT, and GR, and lower APX activities compared to those of sensitive seeds. Therefore, it was concluded that harvesting, organ type, and drying method play important roles in the acquisition of desiccation tolerance and promoting seed quality, especially in the early stages of maturity of faba bean seeds.