INFLUENCE OF ACQUIRED TOLERANCE IN IMPROVING PRODUCTIVITY OF COWPEA GENOTYPES UNDER HIGH TEMPERATURE STRESS
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Date
2023-03-29
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University of Agricultural Sciences, Bangalore
Abstract
Cowpea is mainly grown in the arid and semiarid regions at the global level. Studies have shown that temperature above 35oC affects the physiological processes and decreases the grain yield of cowpea. Hence, identification of thermotolerant genotypes is necessary. In this regard, one hundred ninety-one genotypes were screened for yield attributes under field conditions at two
locations (Bangalore and Raichur). The crop was exposed to a higher mean maximum temperature by 7.2oC at Raichur compared to Bangalore during the entire crop growth period. The plants experienced high levels of heat stress at Raichur compared to that of Bangalore which led to increase in mean leaf temperature, decreased mean SPAD chlorophyll meter reading (SCMR), total
dry matter (TDM) and other yield attributing traits studied. Tolerant cowpea genotypes showed minimum reduction in total dry matter compared to susceptible genotypes between two locations. Further 20 contrasting genotypes differing in total dry matter were identified and screened for cellular level tolerance using temperature induction response approach (TIR). The contrasting
genotypes selected at the field level exhibited similar levels of thermotolerance, wherein the tolerant genotypes showed minimum reduction in root length and maximum seedling survival compared to the susceptible genotypes. The tolerant genotypes IC-402172, EC-458453, EC- 458470, NBC-21, NBC-14, EC-394708, CB-10, IC-458430, IC-249588 and EC-458490 which exhibited the tolerance for high temperature at both field and TIR can be used for further crop improvement programme. Present study revealed that few cowpea genotypes can sustain the temperature up to 35oC without compromising the total dry matter.