INFLUENCE OF IRRIGATION AND NITROGEN ON PLANT WATER STATUS AND THERMAL RESPONSES OF MAIZE, Zea mays

Abstract

Stomatal conductance, transpiration rate and canopy temperature served as indicators of stress and were measured using a steady state porometer and infrared thermometer, respectively, in different treatments of maize (Zea mays L.) grown on moderately well drained sandy clay loam soil of Coimbatore. In general, stomatal conductance and transpiration rates were increased from 25 to 50 days after sowing thereafter declined upto maturity. Higher stomatal conductance and transpiration rates were associated with irrigation scheduling based on 0.75 IW/CPE ratio due to more frequent and adequate water availability. Among the methods of irrigation, every furrow method recorded highest stomatal conductance and transpiration rate irrespective of the stages of the plant growth, Nitrogen application increased the transpiration rate and stomatal conductance. Increased canopy temperature was recorded with irrigation scheduled based on 0.50 IW/CPE ratio due to less frequent and inadequate irrigation. Cooler canopies were associated with adequate moisture content and canopy temperature was progressively higher with increasing soil moisture stress at all stages of the growth. Higher does of nitrogen application reduced the canopy temperature at all stages of the crop growth. Higher grain yield was recorded at 0.75 IW/CPE ratio with all furrow method of irrigation and with 175 kg N ha-1. ha-1.