Plant Density Effect in Different Planting Dates on Growth Indices, Yield and

In order to determine the appropriate plant density in different planting dates for sweet corn cultivar\ud KSC403su, an experiment was conducted using a randomized complete block design in split plot lay out with\ud three replications at Seed and Plant Improvement Institute in Karaj in 2006. Three planting dates (22 May, 5\ud June and 22 June) were assigned as main plots and three plant densities (65000, 75000 and 85000 plants per\ud hectare) were considered as sub plots. Effect of planting date on row/ear, 1000 kernels weight, biological yield\ud and harvest index was significant at 1% probability level and it was significant at 5% probability level for\ud kernels/ear row and grain yield. All traits decreased with postponement of planting date to 5 June except for\ud row/ear, kernels/row and grain yield. More delay in planting from 22 May to 22 June caused that grain yield was\ud decreased significantly about 32.5% (from 14.45 to 9.78 ton/ha). Effect of plant density was significant at 1%\ud probability level for all the traits. All of the traits decreased significantly with increasing plant density except for\ud biological yield. The highest grain yield was resulted from 65000 plants per hectare density (14.20 ton/ha).\ud Interaction effect of planting date and plant density was significant at 5% probability level for biological yield\ud and harvest index but it wasn’t significant for the other traits. Growth indices decreased with delay in planting\ud date and increasing plant density. Only leaf area index increased in more plant densities. From the results of this\ud experiment it might be resulted that appropriate planting date to produce the highest grain yield is 22 May to 5\ud June for sweet corn cultivar KSC403su and also the highest grain yield can obtain from 65000 plants per hectare\ud density