Genetic and Physiological Studies Of Heat Tolerance In Cowpea.

Cowpea is a popular food crop in Texas and other Southern States of USA, and it is a good source of protein, minerals, vitamins, and antioxidants providing good nutrition as well as health benefits. The cultivation of cowpea in the State is declining due to numerous production constraints including drought, heat, and pests. Therefore, a systematic program has initiated to develop improved cowpea varieties with tolerance to heat and drought, and resistance to aphid. A total of 41 cowpea varieties were planted at College Station on June 12, 2011. The temperature in July and August covering the reproductive phase of cowpea was above 100⁰F. This temperature range provided excellent opportunity to screen cowpea varieties for heat tolerance. The differences among varieties became clear after flowering when the heat susceptible lines started dropping the flowers. The results indicated major genetic differences among varieties. The most promising varieties with no damage due to heat were IT82D889-1, IT98K-1111, and IT98K-205-8 in early maturing group, and IAR-48, IT98K-277-2, and IT98K-1092-1 in the medium maturing group. The most susceptible varieties to heat were IT98K-589-2, IT82D-889, and IT86D-1010 in early maturing group, and Big John, IT98K-476-8, and IT98K-1069-6-1 in the medium maturing group. IT98K-205-8 (P1) and IT98K-589-2 (P2) were selected to develop F2, BC1F1P1, and BC1F1P2 populations. P1, P2, F1, BC1F1P1, and BC1F1P2 populations will be grown in summer 2013 to study heritability of the heat tolerant trait. Photosynthetic rate, temperature, ethylene exchange, and membrane thermo stability will also be studies on the selected parents. This will provide us a deeper understanding about physiological changes of the parents under heat treatment.