Evaluation of strategies to reduce water use in pinto bean (Phaseolus vulgaris L.) cultivation under severe water deficit conditions

Abstract

In this study, the effects of superabsorbent polymer, mycorrhizal fungi, nano-potassium fertilizer, and hydrogen peroxide on yield, yield components, and some physiological traits of pinto bean (Phaseolus vulgaris L. ‘C.O.S16’) under severe water deficit conditions during the years 2018 and 2019 were examined. The experiments were carried out as a split plot based on a randomized complete block design with three replications. The studied irrigation factor included three levels (control or normal irrigation, irrigation disruption at the end of flowering stage, and irrigation disruption at the end of podding stage) in the main plots, and methods of reducing water consumption at five levels (control or no treatment, using superabsorbent polymer, inoculation with mycorrhizal fungi, using nano-potassium fertilizer, and seed priming with hydrogen peroxide) in subplots were considered. The results showed that the effect of irrigation disruption and methods of reducing water consumption on seed yield, yield components, water use efficiency, total chlorophyll, and proline levels were significant. Furthermore, the interaction effect of irrigation disruption and methods of reducing water consumption on seed yield, water use efficiency, and leaf proline content was also significant. In this study, the highest seed yield (2133.24 kg ha⁻¹) was achieved under the normal irrigation treatment along with the use of a superabsorbent polymer. However, the irrigation disruption treatment at the end of the podding stage with the application of a superabsorbent polymer (1564.3 kg ha⁻¹) showed only a 3.87% reduction in seed yield compared to the normal irrigation treatment (1627.21 kg ha⁻¹), which was not statistically significant. This research demonstrates significant water savings; the application of a superabsorbent polymer has led to a reduction in water consumption by approximately 1600 m³ ha⁻¹. Additionally, the irrigation disruption treatment at the podding stage using mycorrhizal fungi resulted in a 12.3% reduction in seed yield compared to the normal irrigation treatment. This shows the superior effectiveness of the superabsorbent polymer in mitigating the negative impacts of drought stress on seed yield compared to mycorrhizal fungi. Moreover, water use efficiency in the normal irrigation treatment decreased by approximately 19% compared to the treatment with irrigation disruption at the podding stage and the use of superabsorbent polymer. This result emphasizes increased water use efficiency under drought stress conditions with the use of superabsorbent polymers.