Compared to natural light condition

Compared to natural light condition, UV-B radiation decreased seed ABA concentration of H339 by 64%; that of HN35 by 37% and that of KN18 by 32% throughout seed growth period. Regardless of cultivars and light conditions, the concentrations of ABA in seed showed a one-peak curve, i.e. highest values were observed at 30 DAF at 10,000–20,000 ng/g fresh weight, depending on cultivar,and then declined to 200–4000 ng/g fresh weight at physiological maturity (Fig. 1). The peak of ABA concentration in the large-seeded cultivar was greater than that of the moderate-seeded and small seeded cultivars. Under natural light condition, the ABA concentration in the large-seeded cultivar seed was 23% greater than the average ABA concentration of middle- and small seeded cultivars at 30 DAF. As is shown in the Fig. 1, seed ABA concentration of large seeded cultivar was more affected by UV-B radiation com-pared to moderate-seeded and small seeded cultivars.