effects of different size and age of transplans on marketable and biological yield, harvest index and some qualitative characters of long – day and intermediate- day onion (allium cepa l.) cultivars

abstract suitable seedling is one of the most important factors of onion growth and yield in transplanting method (tm). in order to investigation effects of different seedling size and age on marketable yield , biological yield, harvest index and some qualitative characters in onion an experiment was couducted at the agricultural research center of east azarbayjan in 2008. the factorial was conducted based randomized complete block design (crd) with four replications. the experimental factors were four seedling size 9, 12, 15 and 20 cm and two varieties of onion: azar-shahr (red hull and long – day) and gooli-ghesseh zanjan(bright-red skin, intermediate- day). in this research characters as: marketable yield (my), biological yield (by), harvest index(h.i), percentage of class i, ii and iii onion, bulb fresh weight(bfw), bulb dry weight(bdw), percentages of dry matter (dm) and total soluble solids (tss), specific gravity (sg), bulb volume(bv), texture tightness(tt) and bulb shape index (bsi) were studied. analysis of variance for the measured traits indicated that except for the sg, other studied characters were significant in 1% level. with increasing of seedling length except for bsi all evaluated characters increased. the red azar-shahr was superior cultivar in all attributes, and gooli-ghesseh zanjan was lower. comparsions of the means of treatments show that the seedling size of 20cm had highest values of my, by, h.i in azar-shahr(41.29 t/ha, 233.84 g/p, 89.57% respectively) and lowest was seedling size of 9cm in gooli-ghesseh zanjan(10.91t/ha, 95.89 g/p, 65.69% respectively). also among of the cultivars that except for the bulb volume, other traits were significant. the seedling size × cultivar interaction were not significant. the data suggest that seedling size of 20cm was superior than other seedling size. therefore seedling size of 20cm is recommended of onion planting in tm for the places with the environmental same conditions of this experiment. keyword: onion, transplanting method, seedling size, total yield, bulb characteristics