Study the Bulbing Date and Morphological Characters of Landrace Populations and Onion Commercial Cultivars in Khuzestan region

Onion is one of the most important vegetable in Iran. Harvested area of onion is 63685 hectars. Significant amount of short day onion seed is imported to Iran that caused genetical deperssion of landraces onion. However, high diversity have been reported in Iranian landraces onioin. Populations that produced high yield, exhibited long storability and resistant to pests have been observed in landraces onion. Therefore study the qualitative and quantitative characters of landraces onion are very important. This research was conducted to study bulbing date, morphological characters and correlation coefficient among characters in landraces onion of southern Iran and commercial cultivars.

This research was conducted in randomized complete block deign including eight populations (Behbahan, padook, Ramhormoz, Iranshahr and Borazjan landraces, Texas early grano and Primavera cultivars and Behbahan bred onion) with four replications at Behbahan Agriculture Research Station for two years (2012-14). Seeds were sown in nursery in early October and seedling transplanted (at two or three leaf stage) in mid Novenmber. Earliest time of bulbing was estimated using bulbing ratio and cumulative sums. Bulbs were harvested when 50-80% of foliage top had fallen and collapse. Results were analyzed by MSTATC statistical software and comparison of meanes were done using Duncan,s Multiple Range Test.

In the first year of experiment bulbing occurred from photoperiod of 11 h and 56 min (19 March) to 12 h and 5 min (22 March). Bulbing dates were from photoperiod of 12 h and 32 min (31 March) to 13 h and 5 min (18 April) in the second year. The highest total yield were produced by Padook landrace and Texas early grano cultivar in the first and second year respectively. Parimavera cultivar produced the highest marketable yield. Bolting was not observed in Perimavera and Texas early grano cultivars. Primavera cultivar and Borazjan landrace showed the highest and lowest doubling bulb respectively. The highest bulb dry matter percentage belong to Behbahan bred onion. Results of correlation coefficient indicated total and marketable yield exhibited significant negative correlation with bolted plants and doubling bulb. Bulb dry matter percentage had positive and significant correlation with total soluble solid percentage.

Bulbing occurred on short day in all studied populations. According to results Texas early grano is The best cultivar for onion production in Khuzestan province. Among landrace populations, Behbahan bred onion in regard to low sensitivity to doubling bulb and high bulb dry matter percentage is superior population.