Effect of sowing date and planting methods on some qualitative and quantitative traits of onion (Texas Early Grano 502 cv.) in Iran

In order to study the effect of sowing date and planting method on some qualitative and quantitative traits of onion (Texas Early Grano cv.), this study was conducted in 2010-2011 as a randomized complete blocks design with nine treatments and six replications in Isfahan (Iran). Treatments were six sowing dates (October 2 nd, October12th, October 22 nd, February 24th, March 6th, and March 16th) with direct seeding and three sowing dates(January 25th,February 4th,and February 14th) with transplanting. Results showed that the effect of experimental treatments on studied traits were highly significant and the highest neck thickness and length to diameter ratio were obtained in last sowing date of direct seed sowing, whereas the least amounts of these traits were obtained in first sowing date of direct sowing and first transplanting date. Also, the highest number of edible layers, dry matter percentage, and Bulb plurality were obtained in first transplanting whereas the last sowing date (seed planting) had the lowest amount of these. The highest and the lowest bulb yields were obtained in fourth date (49.79 ton/ha) and last date (28 ton/ha), respectively. According to results, late September and late January are respectively recommended for direct seed sowing and transplanting for this region and other similar regions.