DETERMINATION OF THE BEST SOWING TIME, BULB DIAMETER AND INTRA-ROW SPACING OF AZARSHAHR RED ONION, A NEW VARIETY IN IRAN

Iran because of having vast areas and various climates is one of the suitable producing regions of vegetable crops such as onion (Allium cepa L.) in the world and can be one of the major exporters of this crop. In order to determine the best sowing time, bulb diameter and intra-row spacing of Azarshahr Red onion variety in Tabriz region, we conducted this research using a factorial experiment based on a randomized complete block design with four replications at Islamic Azad University of Tabriz. Bulbs were planted at four sowing times (5, 20 Mar. and 6, 21 Oct.), four bulb diameters (3.5-4.5, 4.5-5.5, 5.5-6.5 and bigger than 6.5 cm) and three intra-row spacing (20, 25 and 30 cm). Measured variables were seed yield, 1000-seed weight, remaining plants percentage, stem lodging percentage, umbrella diameter, seed yield of single plant and stem height. Variance analysis indicated that variables of seed yield, stem lodging percentage, umbrella diameter and seed yield of single plant and stem height were influenced by sowing times, all variables were influenced by bulb diameters and all variables except remaining plants percentage were influenced by intra-row spacing. Interactions between sowing time and bulb diameter on seed yield, stem lodging percentage, seed yield of single plant and stem height were significant. Interactions between sowing time and intra-row spacing on variables of seed yield, stem lodging percentage, umbrella diameter and seed yield of single plant, and also interactions between sowing time and bulb diameter and/or intra-row spacing on variables of seed yield, umbrella diameter and seed yield of single plant were significant. There was significant correlation between seed yield with remaining plants percentage, umbrella diameter, seed yield of single plant, and stem height. With attention to obtained results, in Azarshahr Red onion variety, cultivation with seed bulbs of 6.5 cm or bigger in diameter on 20 March with planting spacing of 35×20 cm is recommended, which is similar to those practiced in Tabriz region, India.