Screening of plant growth substances on cowpea (Vigna unguiculata) for waterlogging stress tolerance

In the India, cowpea (Vigna unguiculata) is primarily cultivated after the summer rains, depending on rainfall or supplemental irrigation for its water supply. However, when there is excessive rainfall or inadequate soil drainage, the plants may experience waterlogging, which reduces the oxygen available to their submerged roots. Although cowpea is vulnerable to waterlogged conditions, too much moisture early in its growth can trigger several detrimental physiological and structural changes. These changes often hinder plant growth and lead to a decrease in yield potential. Use of plant growth substances is a very effective and cost benefit method to reduce the detrimental effect of the waterlogging condition. The presence study aimed to find out the effect of different plant growth substances at different concentration NAA (10 & 20 ppm), GA (15 & 25 ppm), Brassinolide (2 & 4 ppm) and 4CPPU (10 &20 ppm) on cowpea (Vigna unguiculata) in waterlogging condition. Two foliar sprays of these plant growth substances are given at 30 and 45 days after sowing. Plant height, number of leaves, number of branch per plant, leaf area, days to 50% flowering, number of flower per cluster, days required to first harvest, days required to last harvest, number of green pods per plant, average weight of green pod, green pod yield per plant, green pod yield per plot, green pod yield per hector, green pod length, green pod width, chlorophyll content of leaves were observed. The results showed that plant height and leaf area increased significantly with GAA 25 ppm, while branch and leaf number were higher with Brassinolide 2 ppm. GA 15 ppm led to early 50% flowering, and the highest flower clusters were found with NAA 10 ppm. NAA 20 ppm required the lowest days to harvest, followed by NAA 10 ppm. Brassinolide 2 ppm produced the highest yield for green pods per cluster, plant, plot, and hectare. GAA 15 ppm improved pod length and width, while 4CPPU resulted in higher chlorophyll content. The identified waterlogging tolerant plant growth substances Brassilonoides can serve as potential candidate for production of cowpea in waterlogging area and it can be used in climate resilient cultivation practices.