Study the Effect of Harvesting Time and Drying Method on Allium cepa Seed Germination Quality

In order to determine the best harvest time and method of drying onion seeds, the experiment was performed as factorial experiment in the form of randomized completely design with three replications in the research laboratory of Isfahan Agricultural Research Center in 2014. Factors include two types of onions: the native landrace of Dorcheh Isfahan (long day) and Texas Early Granu 502 varieties (short day), the harvest time consists of five levels: green capsule, yellow capsule, five percent of capsule splitting, 50% splitting of capsules and 100% splitting of capsules and the drying method in two level: dry shade and sun drying was performed. The measured traits included germination percentage and germination rate, 1000-length and weight traits of onion seedlings. The results showed that all traits except of the weight of 1000 seeds were affected by the treatments. For Dorcheh Isfahan, the highest germination percentage (96%) was obtained in the second and fifth harvests and the dry shade method and the highest germination rate (1.34 ) was obtained in the third harvest and dry shade. For Texas variety, the highest germination percentage (94.5%) was obtained in the second harvest and dry shade method and the highest germination rate (0.92) was obtained in the fourth harvest and dry shade, which was not significantly different from the second harvest. In Texas cultivar, the highest size for plant length, stem length and root length (53.88 cm, 16.22 cm and 37.84 cm, respectively) was allocated to the third harvest time and dry shade method. In both varieties, the lowest values of each of the measured traits were related to the first stage of harvest and the dry sun method. Therefore, according to the results, the second stage (yellow capsule) by the shade method, is the best harvest time that prevents seed shedding due to delayed harvest to full maturity of all umbrellas and capsules and severe yield loss.