The potential relationship between the number of root nodules and pod yield in cowpea cultivars subjected to water deficit under greenhouse conditions

The relationship between root nodules and pod yield, especially under water stress, requires understanding to guide farmers' choices and optimise yields in water-stressed environments. This study was initiated to explore the correlation between root nodule density and pod yield in four cultivars of cowpea (KVX745-11P, Tiligre, Gourgou, and KVX780-6) under water deficit conditions. Plants were exposed to three levels of water content: 100% field capacity (FC), 60% FC, and 12.5% FC. The water content levels of 60% FC (moderate water deficit) and 12.5% FC (severe water deficit) represented the various degrees of water deficit imposed on the plants from sowing to wilting. A three-block FISHER device was installed in the greenhouse. Data collection involved manually counting the number of root nodules and pods produced per plant at the end of the growth cycle. The results indicate a relationship between the number of nodules and the number of pods in cowpea cultivars subjected to water stress, with a strong correlation coefficient value of over +0.95. cultivar KVX745-11P produced the highest number (15) of nodules, while the lowest number of root nodules was recorded in the Tiligre and KVX780-6 cultivars with one root nodule each, respectively. These findings are beneficial for farmers by guiding them in selecting cowpea cultivars best suited for water-stressed areas while highlighting the importance of root nodules in plants' ability to withstand water stress while maintaining optimal yields.