Simulating the Response of Red Bean Yield to Deficit Irrigation and Plant Densities by Applying the Rbean Model

The Rbean Model was simulated for deficit irrigation conditions and plant density by using experimental data collected over two consecutive years regarding the cultivation of red bean in the Badjgah region of Shiraz, Iran. A split plot arrangement was conducted in a complete randomized block design during two years. The foremost variable was four levels of irrigation including 60 (I4), 80 (I3), 100 (I2), and 120% (I1) of the potential evapotranspiration under surface irrigation. A second variable was the spacing of 5 cm (S1), 10 cm (S2) and 15 cm (S3) between the plants within each row, and the distance of 30 cm between the rows. The experiment layout was conducted in three replications. Results of the first and second growing seasons of red bean (phaseolus vulgaris L. cv. Akhtar) were used for the calibration and validation of the Rbean model, respectively. According to the NRMSE and the d value indices, the Rbean model presented a very good to fair estimation of actual evapotranspiration, soil water content, canopy cover, dry matter, crop yields and water productivity (WP). The advantage of this model is its simplicity and easy calibration in a range of climatic conditions for the cultivation of bean crop. The prediction of bean yield by this model can be used for a better irrigation management under different plant densities.