2019 ASHS Annual Conference

Accurate phenotyping has been a key component in plant breeding and genetics. Improper phenotyping strategy can be money wasting and lead to inaccurate genetics/genomics-related studies in the downstream analysis. Salt leaf injury score and assessment of chlorophyll content have been widely used for evaluating salt tolerance in various crops. Since salinity has been shown to significantly impair cowpea production, developing salt-tolerant cowpea cultivars will be vital. Therefore, the objective of this study was to evaluate salt leaf injury score and chlorophyll content in cowpea seedlings under salt stress. The experiment was a randomized completely block design (RCBD) with 3 blocks and 2 replications for each block, and involved a total of 331 cowpea genotypes including advanced breeding lines from the University of Arkansas, Fayetteville. The experiment was conducted using a previously reported methodology. Two tolerant controls (09-529 and PI582468) and one susceptible check (PI255774) were used. Salt stress was applied when the first trifoliate leaf began to expand and pursued until the susceptible control (PI255774) was completely dead. Salt leaf score injury was based on 1-7 scale as previously reported (1: healthy plants, 7: dead plants). Chlorophyll content was measured before and after salt stress. Salt tolerance index and stress indicator were computed for chlorophyll content. In addition, average dead plants per genotype was evaluated. ANOVA will be conducted and Pearson’s correlation coefficient and trend association test between any pair of traits will be conducted using a M² test. We expect a large variation in these traits and a good correlation between traits. This study can help improve phenotyping strategy and trait selection for cowpea breeding programs working on salt tolerance.