A Simple and Cost-effective Approach for Salt Tolerance Evaluation in Cowpea (Vigna unguiculata) Seedlings

Abstract

<jats:p>Little has been done with respect to breeding for salt-tolerant cowpea (<jats:italic>Vigna unguiculata</jats:italic>) cultivars despite of salt stress being a growing threat to cowpea production. Seedling stage is one the most susceptible stages to salt stress in cowpea. Establishing a streamlined methodology for rapidly screening a large number of genotypes will significantly contribute toward enhancing cowpea breeding for salt tolerance. Therefore, the objective of this study was to establish and validate a simple approach for salt tolerance evaluation in cowpea seedlings. A total of 30 genotypes including two controls (PI582468, a salt-tolerant genotype, and PI255774, a salt-sensitive genotype) were greenhouse-grown under 0 m<jats:sc>m</jats:sc> and 200 m<jats:sc>m</jats:sc> NaCl. A total of 14 above-ground traits were evaluated. Results revealed: (1) significant differences were observed in average number of dead plants per pot, leaf injury scores, relative salt tolerance (RST) for chlorophyll, plant height, and leaf and stem biomass among the 30 genotypes; (2) all PI255774 plants were completely dead, whereas those of PI582438 were fully green after 2 weeks of salt stress, which validated this methodology; (3) RST for chlorophyll content was highly correlated with number of dead plants and leaf injury scores; (4) RST for leaf biomass was moderately correlated with number of dead plants and leaf injury scores; and (5) RST in plant height was poorly correlated with number of dead plants and leaf injury scores Therefore, less number of dead plants per pot, high chlorophyll content, and less leaf injury scores were good criteria for salt tolerance evaluation in cowpea. This study provided a simple methodology and suggested straightforward criteria to evaluate salt tolerance at seedling stage in cowpea.</jats:p>

Constraints and Prospects of Improving Cowpea Productivity to Ensure Food, Nutritional Security and Environmental Sustainability

“…In order to evaluate salinity stress impact on cowpea cultivars (Ravelombola et al, 2019), investigated a simple protocol that could be deployed to assess the response of 30 cowpea genotypes to salinity constraint at seedling growth stage in a greenhouse experiment that profile 14 above ground traits response to sodium chloride (NaCl)-induced salinity. The findings indicated that relative salinity tolerance (RST) of cowpea genotype PI255774, all the plants were completely dead, while PI582438 performed best and the leaves were all green and had higher chlorophyll content.…”

Genetic Architecture of Salt Tolerance in Cowpea (Vigna unguiculata (L.) Walp.) at Seedling Stage Using a Whole Genome Resequencing Approach

“…Salt tolerance evaluation was conducted under greenhouse conditions at the University of Arkansas, Fayetteville, with average day/light temperatures of 26 • C/21 • C and an average daylight length of 14 hours. Salt tolerance was performed using a previously described methodology [37]. Briefly, a total of four cowpea seedlings were established in pots filled with 100 g Sunshine Natural & Organic (Agawam, MA, USA).…”

“…A total of 12 pots were established on a rectangular plastic tray to facilitate irrigation. Salt treatment (NaCl) began at the first trifoliate leaf stage (V1 stage) [38] and was conducted by supplying a solution of 200 mM NaCl to each rectangular plastic tray [37]. Two-thirds of pot's height was fully soaked with either deionized water or salt solution during irrigation [37].…”

“…Salt treatment (NaCl) began at the first trifoliate leaf stage (V1 stage) [38] and was conducted by supplying a solution of 200 mM NaCl to each rectangular plastic tray [37]. Two-thirds of pot's height was fully soaked with either deionized water or salt solution during irrigation [37]. A salt-tolerant genotype ('09-529') and a salt-susceptible genotype (PI255774) [37] were used as checks.…”

Breeding of Vegetable Cowpea for Nutrition and Climate Resilience in Sub-Saharan Africa: Progress, Opportunities, and Challenges

“…When the night temperature reaches about 16 • C, cowpea flowers abort due to poor pollen development, which causes a 4 to 14% loss in leaves, immature pods and grain yield and quality [18]. In general, using conventional, physiological, phenomic, functional genomic, proteomic, and metabolomic breeding techniques [66][67][68][69][70] and viable approaches to developing heat stress tolerance and to sustain cowpea yield under increasing high-temperature stress, the cowpea germplasm needs to be screened to identify 'stress adaptive' traits across various gene pools.…”