Relationship between physiological traits and yield of rice (Oryza sativa L.) under modified system of rice intensification

Abstract

A field experiment was conducted to study influence of high-density planting on physiological parameters and yield of rice during late Samba (September-January) season of 2018-19. The treatments comprised of T1 - 25 × 25 cm with 100% Recommended Dose of Fertilizer (RDF) (SRI), T2 - 25 × 20 cm with 100% RDF, T3 - 25 × 15 cm with 100% RDF, T4 - 25 × 15 cm with 125% RDF, T5 - 20 × 20 cm with 100% RDF, T6 - 20 × 15 cm with 100% RDF, T7 - 20 × 15 cm with 125% RDF and T8 - Conventional cultivation with 100% RDF. Physiological parameters were recorded at four critical stages (active tillering, panicle initiation, flowering and maturity stages) of rice. The results revealed that photosynthetic rate (µmol CO2/m2/s), transpiration rate (mmol H2O/m2/s), stomatal conductance (mol H2O/m2/s) and chlorophyll index were increased in rice planted at a row spacing of 25 cm (T1, T2 and T3) over other treatments in all the stages. Lower rates were noted in conventional method of planting (T8) followed by T6 and T7.  During 0600 hrs and 1000 hrs, closer spacing levels (T5, T6, T7 and T8) had higher leaf temperature, while during later at 1400 hrs and 1800 hrs, warmer leaf temperature (°C) was noted in wider spacing levels (T1 and T2) during all time of weekly observation. The grain yield of rice was higher with 20 × 20 cm spacing level compared to other closer and wider spacing levels with either 100% or 125% RDF. By correlation analysis, all parameter had a significant influence on yield.