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Title: GROWTH RESPONSE OF MAJOR USA COWPEA CULTIVARS. I. BIOMASS ACCUMULATION AND SALT TOLERANCE

Author
item WILSON, CLYDE
item Liu, Xuan
item LESCH, SCOTT - UC RIVERSIDE, DEPT OF ES
item Suarez, Donald

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2005
Publication Date: 2/10/2006
Citation: Wilson, C., Liu, X., Lesch, S.M., Suarez, D.L. 2006. Growth response of major usa cowpea cultivars. I. Biomass accumulation and salt tolerance. HortScience. 41:225-230.

Interpretive Summary: Over the last several years, there has been increasing interest in amending the soil using cover crops, manures, composted yard wastes, and other organic matter; especially in desert agriculture. One cover crop of interest in the Coachella Valley of California is cowpea. Cowpea is particularly useful in that it fixes abundant amounts of nitrogen which can nreduce fertilizer costs. In desert agriculture, salinity is the most widespread and prevalent problem and soil salinity problems are of increasing concern in the Coachella Valley of California where the Colorado River water is a major source of irrigation water. Thus, we investigated the growth response of 12 major cowpea cultivars (CB5, CB27, CB46, IT89KD-288, IT93K-503-1, IRON CLAY, SPECKLED PURPLE HALL, UCR 134, UCR 671, UCR 730, 8517, and 7964) to increasing salinity levels to determine if some cultivars are more salt tolerant than others. Seven salinity concentrations sfrom 2.6 (low salinity) to 20.5 (high salinity) dS/m were used to simulate Colorado River water salt composition. The plants were harvested when the plants flowered (53 days after planting) for growth measurements and response to salinity. With the help of a statistical analysis method, we found that salinity significantly reduced leaf area, leaf dry weight, stem dry weight and root dry weight. More importantly, we found that salinity affected these growth parameters more in some cultivars than others. Thus, we concluded that differences do exist among the 12 tested cultivars such that some cultivars are more salt tolerant than other cultivars.

Technical Abstract: Over the last several years, there has been increasing interest in amending the soil using cover crops, manures, composted yard wastes, and other organic matter; especially in desert agriculture. One cover crop of interest in the Coachella Valley of California is cowpea. In desert agriculture, salinity is the most widespread and prevalent problem and soil salinity problems are of increasing concern in the Coachella Valley of California where the Colorado River water is a major source of irrigation water. Thus, we investigated the growth response of 12 major cowpea cultivars (CB5, CB27, CB46, IT89KD-288, IT93K-503-1, IRON CLAY, SPECKLED PURPLE HALL, UCR 134, UCR 671, UCR 730, 8517, and 7964) to increasing salinity levels. Seven salinity levels ranging from 2.6 to 20.5 dS/m were constructed, based on Colorado River water salt. The osmotic potential ranged from -0.075 to -0.82 Mpa. The plants were harvested during flowering period for biomass measurement (53 days after planting). Data analysis using SAS ANOVA indicates that the salinity significantly reduced leaf area, leaf dry weight, stem dry weight and root dry weight. We applied the data to a salt-tolerance model and found that the model accounted for 97%, 96%, 99% and 96% of salt effect for cowpea leaf area, leaf dry weight, stem dry weight and root dry weight, respectively.Since a significant salt cultivar interaction effect was also found on leaf area and leaf dry weight, we concluded that salt tolerance differences exist among the tested cultivars.