Genotypic differences in aluminum tolerance of cowpea accessions utilizing germination parameters

Abstract

One of the major factors which limit the productivity of cowpea on acid soils is aluminum toxicity. Reliable methods for identifying genetic variation for its tolerance is indispensable. Genetic variability for aluminum tolerance in 10 accessions of cowpea were studied in the laboratory. Fifteen seeds of each accession were sown in sterilized petri dishes containing filter papers and 5 ml of AlCl3 at four levels (0, 50, 100 and 200 µm) and replicated three times in a completely randomised design (CRD). Petri dishes were incubated under room temperature in the dark for 48 hours. After 48 hours, they were exposed to photoperiod of 12 hr. / 12 hr. (day/night) at room temperature for another 48 hours. At day four after sowing, data were collected on percentage germination, number of roots per shoot, fresh weight of shoot, root length and hypocotyl length and fresh weight of shoot. Data were subjected to statistical analysis and accessions were arranged on their tolerance to aluminum stress by means of tolerance indices. Analysis of variance revealed significant effect of accessions on all parameters. Treatment was significant for all excluding percentage germination. Treatment by accession was significant for number of roots and root length. The observed genetic variation in cowpea for aluminum stress could be exploited by hybridisation to establish tolerant lines. Selection based on high heritability and GAM in percentage germination, hypocotyl length and number of roots in cowpea under aluminum stress can be exploited for selection.