Study of deficit irrigation on physiological indices, seed yield and yield components traits of chitti bean (Phaseolus vulgaris L.) in Yasouj climate conditions

The common bean (Phaseolus vulgaris L.) is considered one of the most important legume crops in the world. It is a staple food for over 300 million people in Latin America and Africa and an important source of protein, fiber, carbohydrates, and trace minerals. Common bean is grown predominantly by small farmers, often in marginal regions, where crop yields are frequently affected by many abiotic factors, in particular water deficit. This study aimed to investigate the effect of water scarcity stress on vegetative and reproductive growth stages on contrary to physiological and agronomic processes in four pinto bean cultivars which evaluated these four cultivars against water scarcity stress.

In order to study the effect of drought stress levels on some physiological characteristics, yield, and yield components of different bean cultivars, an experiment was conducted with three replication in the crop year of 2014 at as a split-plot in a randomized complete block design Yasouj University. The main factor of the experiment included normal irrigation (Irrigation after 4 days), mild stress (Irrigation after 7 days) and sever stress (Irrigation after 10 days) and the sub-factor included four bean genotypes (Talash cultivar, Sadri cultivar, Khomein local cultivar, Koosha cultivar). Evaluation traits studied physiological characteristics including chlorophyll index, water use efficiency, leaf proline, Yield and yield components (number of pods in plant, number of grain per plant, number of garin per pod, 100-grain weight, grain yield, biological yield, and harvest index).

The results this research showed that the effect interaction drought stress × cultivar on grain yield, biological yield, harvest index, chlorophyll, leaf proline, and water use efficiency were not significant, but on characteristics number of pods per plant, number of grain per plant, number of grain per pod, and 100-grain weight was significant. The results showed a decrease in the mean of characteristics in drought stress conditions compared to normal irrigation conditions. So that the highest grain yield under normal irrigation conditions with an average of 2304.17 kg/ha and the lowest belonged to severe stress with an average of 1931.25 kg/ha. The rate of decrease in chlorophyll and biological yield in the Talash cultivar compared to the Koosha cultivar was about 26 and 17%, respectively, and the increase in proline in the Talash cultivar compared to the Koosha cultivar was 60%.

Talash cultivar in most plant traits, including yield and yield components, had the highest amount among other cultivars of pinto beans, in such environmental conditions, this cultivar can be introduced as drought-tolerant, and considering that cultivar Koosha in Most plant traits, including yield and yield components, had the lowest rate among other cultivars of pinto beans. In such environmental conditions, this cultivar can be introduced as drought sensitive.