Open top chamber: an innovative screening technique for temperature stress tolerance of morpho-physiological and fodder yield traits in forage cowpea varieties

Abstract

A proper screening technique was needed to identify fodder crops with high green fodder yield suitable forelevated temperature. Accordingly, the changes in morpho-physiological characteristics and green fodderyield of forage cowpea [Vigna unguiculata (L.) Walp.] varieties (Kohinoor, BL-1, BL-2, BL-4 and EC-4216),were investigated under ambient as well as elevated (2 C higher than ambient) temperatures at vegetative to omaturity stage in open-top chambers. Elevated temperature decreased plant height, leaf length, leaf width,shoot fresh weight, leaf fresh and dry weights. Leaf length reduction (15.89 to 23.81%) was more than leafwidth reduction (8.57 to 11.67%) and the highest leaf fresh weight reduction was recorded as (28.6%). Highestshoot dry weight reduction was observed in variety BL-2 (22%) followed by BL-4 (21%), EC-4216 (16%), BL-1(15%) and least reduction was recorded in Kohinoor (13%). The long duration varieties' life cycles wereshortened under elevated temperatures compared to ambient conditions, the highest percentage of reductionwas observed in BL-2 (24%) and the least was recorded in BL-4 (17%). Significant interactions were foundbetween variety and elevated temperature in leaf length and leaf width, total chlorophyll, relative water contentand membrane stability index. Shoot biomass showed a highly positive significant correlation with elevatedtemperature, leaf fresh weight and ambient leaf width and a positive significant correlation with ambient leaffresh weight, leaf length and elevated temperature leaf width. Kohinoor and BL-1 varieties were foundrelatively tolerant to temperature stress than EC-4216, BL-2 and BL-4.