Effect of Radiation, Temperature and Humidity on Photosynthesis, Transpiration and Water Use Efficiency of Chickpea (Cicer arietinum L.)

The chick pea (Cicer arietinum L.-CV T. 87) plants were tested for net photosynthesis (F), transpiration (Q) and water use efficiency (F/Q) under different sets of environmental conditions by gas exchange technique. The plants were in full blooming/pod initiation stage of growth during the time of investigation. The environmental conditions consisted of various levels of photosynthetically active radiation (120 to 2800 µE m⁻² s⁻¹ PAR), air temperature (10 to 42°C) and vapour pressure deficit (8 to 60 mb VPD) of air in leaf chamber. The peak rates of F were recorded at 1800 µE M⁻¹ s⁻¹ PAR, 22°C air temprature and 14 mb VPD of air in the chamber. The rate of Q increased due to increase in PAR, air temperature and VPD of air. However, the F/Q remained higher and almost static from 600 to 1800 µE m⁻²s⁻¹ PAR, but declined at lower and upper end of radiation intensity curve. F/Q reduced progressively due to elevating the air temperature and VPD of air in the chamber.