Air temperature and relative humidity profiles in Indian mustard (Brassica juncea) under various crop environments

Field experiments were conducted at Research Farm, Chaudhary Charan Singh Haryana Agricultural University during two consecutive rabi seasons of 2002–03 and 2003–04 to study the temperature and relative humidity profiles in Indian mustard (Brassica juncea L. Czern. & Coss.) under different growing environments, viz. sowing dates with growth manipulations. Daily soil temperatures in morning were less than those during evening at 5 and 15 cm soil depths. During morning hours air temperature profiles were nearly isothermal and then followed an inverse shape after 0800h and it was the most prominent at 1200 h. But, during late afternoon hours air temperature profiles were lapsed. The temperature of bare field were higher than cropped field and varied from 8.8 to 24ºC and 9.8 to 20.3ºC during 2002–03 and 2003–04 crop seasons, respectively. In early morning the relative humidity profiles were nearly isohumic; however, with advancement of time the shapes of humidity profiles were lapsed till 1700 h. The humidity values of bare field varied from 42 to 96% and 41 to 98% during 2002–03 and 2003–04 crop seasons, respectively. The humidity values in the cropped field were higher than bare field. At lower canopy levels poor vapour exchange resulted in higher relative humidity in cropped field.