Micrometeorological dynamics within mustard(Brassica juncea) crop canopy under semi- arid conditions of northern India.

Abstract

Field experiments were conducted for two years (2005-06 and 2006-7) at IARI New Delhi, India research farm to assess the variations of micrometeorological parameters under differential hydrothermal regimes in mustard crop. Changes in sowing time and branch removal/defoliation treatments were imposed in order to create variations by hydrothermal regimes under phenology based irrigation scheduling. It was inferred that near ground surfaces in the debranched plot where microenvironment was modified, air temperatures were higher(2 to 3 degree celcius) as compared to control plots, decreased at 35 cm and remained almost similar with further increase in height at 1130 hrs while at 1430 hrs the magnitude of temperature variations was relatively higher. In contrast to air temperature, the relative humidity in debranched plot was less than that of control plot. At near ground, even at higher canopy height about 10% higher RH variations were observed in control plot as compared to debranched plot both in morning and afternoon hours. Furthermore, leaf area index could explain variations in temperature and RH to the tune of 45-50% radiation penetration and soil moisture depletion pattern also indicated significant impact of microclimatic variations near the ground.