Response of maize and black gram yield and water productivity to variations in canopy temperature and crop water stress index

In order to evaluate the ability of the crop water stress index to estimate grain yield and water productivity of maize and black gram in the climatic conditions of Urmia (Iran), research was conducted under the conditions of single-row drip irrigation. This study was conducted in a randomized complete block design with four irrigation levels including 50 (I1), 75 (I2), 100 (I3) and 125 (I4) percent of the water requirements of the plants with three replications. The mean crop water stress index values for the I1, I2 and I3 treatments were 0.53, 0.44, and 0.28, respectively during the growth period of maize, and 0.37, 0.23, and 0.15 for black gram, respectively. In the present study, the correlation between the crop water stress index and the grain yield and also the water productivity of maize and black gram was high. According to the results, the highest grain yield for maize and black gram was obtained at crop water stress index values of 0.28 and 0.15, respectively. Therefore, these values are recommended for the irrigation scheduling of the plants. It should be noted that the maximum water productivity index for maize and black gram was obtained at crop water stress index values of 0.44 (I2) and 0.37 (I1), respectively, which are the values recommended for irrigation scheduling under restricted access to water