Determination of Water Requirement and Irrigation Scheduling of Groundnut (Arachis hypogaea L.) Crop under Trickle Irrigation

Irrigation water shortage is a major limiting factor for groundnut production. Determination of water requirement of groundnut crop and development of irrigation scheduling are prerequisite to enhance the water productivity and groundnut yield under water-deficit conditions. Hence, an experiment was conducted with five irrigation treatments in strip plot design (SPD). The groundnut variety GG20 with duration of 120–125 days was selected for the study. There were five treatments with different frequencies of irrigation water. Test for emission uniformity of trickle irrigation system in the field was about 85%. Average transpiration rate (T_d) of at initial stage (0–25 days), vegetative (25–75 days), reproduction and maturity stages (75–105 days) were estimated to be 2.1, 3.2 and 2.0 mm day⁻¹ respectively. Leaf area index at 104 and 120 days after sowing were highest (3.64) in the treatment T₁. Highest pod (3.82 t ha⁻¹) and haulm (7.56 t ha⁻¹) yield, water use efficiency (1.21 kg m⁻³) and the maximum irrigation water use efficiency (2.42 kg m⁻³) were recorded in the treatment T₁. The best irrigation scheduling was found to be daily and its depth of irrigation was equal to the daily water use rate in real time. The total crop water requirement under trickle irrigation was estimated to be 312.5 mm.