RÉSUMÉ
This study aimed to optimize irrigation scheduling for maize (Zea mays L.) using the crop water stress index (CWSI) to improve water use efficiency and yield. The study was conducted in the South farm of the School of Agricultural Sciences, Karunya Institute of Technology and Sciences, Coimbatore during the Kharif and Rabi seasons of 2022. A randomized block design was used with seven treatments, including a control T1 no irrigation). Irrigation at all critical stages (T2) and other five irrigation treatments (T3 to T7) based on different CWSI values ranging from 0.2 to 1.0. Infrared thermometry was used to measure canopy temperatures for estimating the CWSI. The results showed that irrigation at 0.2 CWSI (T3) had a significant positive effect on kernel and stover yield when compared with all the other treatments during both the seasons, with the highest kernel yield of 7138.83 Kg ha-1 and 8014.8 Kg ha-1, stover yield of 11134 Kg ha-1 and 12765 Kg ha-1, respectively and lowest kernel yield of 2267 Kg ha-1 and 2325 Kg ha-1, stover yield of 8156 Kg ha-1 and 6491 Kg ha-1, respectively. The other treatments had intermediate values and did not show any consistent pattern. Irrigation at 0.2 CWSI resulted in the highest water use efficiency (WUE) of 14.7 Kg ha-cm-1 and 17.6 Kg ha-cm-1, and irrigation usage of 31.73% and 22.26% during the Kharif and Rabi seasons of 2022, respectively and the lowest water use efficiency (WUE) of 7.72 Kg ha-cm-1 and 17.6 Kg ha-cm-1 was found in T7 during the Kharif and Rabi seasons of 2022, respectively. The results suggest that irrigation at 0.2 CWSI could be a promising option for achieving higher kernel and stover yields with minimal water use and maximum WUE and IUE.