Ethylene evolution from soybean seeds podded and depodded related to seed desiccation tolerance during maturation

Seed desiccation tolerance is acquired late during seed development to enable the seeds to maintain their germination capability after drying down to low moisture content. The objective of the research was to study the relationship between seed desiccation tolerance and the evolution of ethylene from the podded and depodded seeds of soybean during maturation. Soybean pods were harvested at four developmental stages: 1) full-size green pods, FS; 2) greenish-yellow pods, GY; 3) yellow pods, Y; and 4) brown pods, B. Ethylene evolution rate was measured at each harvest date and during the drying period for the isolated seeds, isolated pod walls and intact, detached pods. Rates of ethylene evolution from isolated seeds and the isolated pod walls at the time of harvest were higher than that from intact, detached pods when seeds were harvested at the FS and GY stages (immature seeds). As seeds progressed in maturity (Y and B pod stages), the rates of ethylene evolution from the isolated seeds, isolated pod walls and intact, detached pods dropped to zero. Drying immature seeds within the pods for 4-6 days decreased the release of ethylene from isolated seeds and improved the desiccation tolerance of the seeds to the maximum.