The effect of shading on dry matter remobilization, yield and yield components in different rice (Oryza sativa L.) cultivars

In order to study the effect of shading (source limitation) on dry matter remobilization, yield and yield components in different rice cultivars, a field experiment was carried out in farm of Agriculture Service Center of Rezvanshahr Township in 2007-2008 year. Statistical design was factorial on the basis of randomize complex block design. Factor of variety was in two levels including (Hashemi and Hybrid 1) and factor of treatments were in four levels including (1.Control, 2.Light shading, 3.Modereat shading and 4.Heavy shading) in three replications. All treatments have been started from 10 days before anthesis up to 10 days after anthesis. The results have shown significant effect at 1 percent level on yield, biological yeild, harvest index, panicle length, number of grain, number of spikelet on panicle and 1000- grain weight. Highest grain yield was in hybrid1 about 8962/3 kg/ha in control condition and the lowest was in hashemi about 1503/3 kg/ha in heavy shading condition. Heavy shading has shown lowest grain yield in both the cultivars. Shading stress has shown significant effect on remobilization of dry matter of stem and leaves. The share of stem was more than other part of plants. Remobilization was less in hashemi that was probably because of little amount of sink capacity and the ability in source production, there were less remobilization. Results have shown sink limitation in hashemi as compare to hybrid.