Estimation of crop coefficient for Marigold (Tagetes erecta (L.)) under drip irrigated greenhouse

Crop water consumption (ETc) varies from region to region depending on crop type, growth stages, soil, and climate conditions. In order to obtain full yield and avoid unnecessary water usage, the water demand of the cultivated plants should be accurately calculated, and irrigation water should be applied in accordance with plant needs. In this, the study was carried out in field No.C3 of Central farm at Agricultural Engineering College and Research Institute, Kumulur, Trichy district to determine the growth stage-specific crop coefficient (Kc) and pan coefficient (Kp) for the greenhouse grown marigold (Tagetes erecta (L.). Since, a large area was occupied by a ClassA pan, the reduced-size evaporative pans (20 and 60 cm compared with Class A pan) was used and pan coefficient was determined as 0.93 and 0.96 respectively. A pan coefficient (Kp) was used to convert pan evaporation (Epan) to grass reference evapotranspiration (ETo). Based on the tensiometer readings, the depleted moisture content was taken to reckon the crop coefficient for different growth stage. The results revealed that crop coefficient (Kc) for marigold was observed as 0.37 during the initial stage (Kcin), 0.8 during mid-stage (Kcmid) and 0.47 (Kcfin) during the final stage. These results would be helpful for crop water requirement and irrigation scheduling for similar condition