Mother bulb size and planting pattern effects on seed quality and quantity of onion (allium cepa l.) Cv. Texas early grano 502

In order to study effects of plant density and mother bulb size on onion seed yield, a split-factorial experiment with a randomized complete block design with three replications was conducted in Kabootar Abad Research Station of Isfahan during two cropping seasons (1998-1999 and 1999-2000).Main plot was different row spaces (50, 60 and 70cm) and sub plot formed from factorial combination of two mother bullb sizes (3-6 and 6.5-9.5cm) with three plant spaces on rows (15,25 and 35cm). The results showed that 50 and 60cm row spaces had not significant differences in the seed yield and yield components (umbels/m2, capsules/umbel, seeds/capsule and 1000 seeds weight) but seed yield and umbels/m2in 70cm row space was significantly lower than the those of other two row spaces. The treatments of 15 cm plant space and 6.5-9.5cm mother bulb size had the highest seed yield and umbls/m2.Seeds/capsule in 15cmplant space was significantly higher than that of 35 cm plant space.1000 seeds weight and capsules/umbel decreased as plant space increased from 15 to 35cm. Among yield components, umbels/m2 had the most contribution in the seed yield and this yield component explained about 0.67 of seed yield variations. Plant density and mother bulb size had not significant effects on seed germination.