Estimating of Planting and Supplemental Irrigation on Dry Matter Distribution In Canola Cultivars (Brassica napus L.)

In the area with terminal heat and drought stress such as Gonbad, allocation ofproduced dry matter to reproductive organs is of great importance. In order to evaluatethe effect of different temperature and moisture regimes on dry matter distribution andharvest index ofcanola an experiment wasconducted at Agricultural Research Station ofGonbad during 2005-2007. The experiment was a RCBD arranged in a split-plot intwoconditions, i.e. supplemental irrigation and rainfed. Five sowing dates (6 Nov., 6Dec., 4 Jan., 5 Feb. and 5 Mar.) were selected as main plots and tow cultivars(Hyola401 and RGS003) werechosen as subplots. In both years of the experiment, at thebeginning of seed filling period, the mean accumulated dry matter in reproductiveorgans, green leaves and stem at supplemental irrigation was more than that ofrainfedconditions. There was not any difference for stem accumulated dry matterbetween the beginning of flowering and seed filling. The considerable differencesbetween these two stages were a decrease in realative proportion of accumulated drymatter in green leaves and an increase in accumulated dry matter in reproductive organs.Supplemental irrigation did not significantly affect the mean harvest index, but itincreased seed yield, due to an increase in aboveground dry matter. In all treatments,seed yield of Hyola401 hybrid was more than that of RGS003, due to higher harvestindex. The relations of sowing date and supplemental irrigation with dry matterdistribution, can be used incrop modeling.