Effects of planting date and density on yield and yield components and allicin content of two garlic (Allium sativum L.) ecotypes

To study the effect of planting date and density on the yield, yield components and allicin content of two garlic ecotypes (Allium sativum L.), an experiment was conducted in a farmland in Damghan, Iran during the 2011-2012 growing season. The experiment was arranged as a split-split-plot in a randomized complete block design with three replications. Three planting dates (17-Oct, 11-Nov, 6-Mar) were main plots. Two ecotypes (Kavire Damghan and Hamedan) were subplots, and three planting densities (35, 45 and 55 plants per m2) were sub-sub-plots. The effect of planting date on plant height, fresh and dry weight of bulbs, yield, diameter and dry weight of cloves was significant, and delay in planting date decreased these traits. The values of dry and fresh weight of bulbs, plant yield, dry weight and diameter of cloves and allicin content were significantly higher in Hamedan ecotype in comparison with Kavire Damghan ecotype. The planting density had significant effect on fresh and dry weight of bulb and dry weight and diameter of cloves, as these traits were reduced by increasing the density. Furthermore, the effect of planting density on height and yield of plant and number of cloves in bulb was significant. To achieve the highest fresh yield (1.7kg.m-2) and dry yield (0.27 kg.m-2), 17-Oct was identified as the best planting date. Hamedan ecotype was more favorable as it had higher bulb fresh and dry weight, diameter and dry weight of cloves, allicin contents and yield. The most desirable planting density was 55 plants per m2 due to having higher values of plant height, number of cloves in bulb and yield.