Impact of Microclimatic Regime on Growth, Yield and Requirement of Growing Degree Days of Kharif Rice (Oryza sativaL.) under System of Rice Intensification (SRI) in the Brahmaputra Valley, Assam

Abstract:

A field experiment was carried out in 2016 and 2017 in the farmers’ field in Assam, India to find out the effect of varied crop microclimate imposed by two crop establishment methods viz. System of Rice Intensification(SRI) and conventional, three different transplanting dates (26th June, 10th and 25th July) and four hill densities (20cm x 10cm, 20cm x 20cm, 25cm x 20cm & 25cm x 25cm). Throughout the growing period, crops grown under SRI system showed improved plant statures such as plant height, tillers number per unit area, leaf area and dry matter production per hill as compared to conventional one. SRI registered a significantly higher grain yield which was found to be 17 percent over the conventional system. However, accumulation of growing degree days (GDD) was found to be significantly lower in SRI establishment while the highest accumulation was registered in both early date of transplanting (26th June) and lower density (16 hills m-1), as well. Irrespective of methods of crop establishment and hill densities, early transplanted crops showed superior growth attributes and grain yield. Likewise, the lowest hill density recorded better crop growth traits and yield which got reduced with the increase in hill density.