Optimized crop microenvironments for enhanced growth and physiological parameters of kharif paddy (Oryza sativa L.) in Assam

Abstract

A 2-year-long field experiment was conducted to study the effect of crop microenvironments on growth and physiological parameters of kharif paddy (Oryza sativa L.). The experiment incorporated two establishment methods-System of Rice Intensification (SRI) and Conventional Rice Cultivation (CRC), three transplanting dates (June 26th, July 10th, and July 25th) and four crop densities (20 cm × 15 cm, 20 cm × 20 cm, 25 cm × 20 cm, and 25 cm × 25 cm). The two years of comprehensive studies concluded that paddy cultivated under SRI consistently demonstrated clear advantages over CRC, including greater plant height and a higher number of tillers per square meter. Except for early stage, SRI recorded significantly higher LAI and chlorophyll content throughout the growth, the highest at flowering while CRC had the highest at maximum tillering stage (MTS). Likewise, early planting and wider spacing also scored higher magnitudes. Throughout the crop growth, SRI registered increased CGR while lower density of 25 cm × 25 cm had a higher value during the MTS to grain filling stage. During the initial vegetative stage, both SRI and wider spacing showed significantly higher RGR and NAR. Significantly superior growth and physiological parameters have been observed when the kharif paddy was transplanted early under SRI management with a crop density of 25 cm × 25 cm.