Salinity tolerance at germination of some main cultivated cowpea (Vigna unguiculata) genotypes from Western Cameroon

Abstract

This study investigates the effect of salt (NaCl) on the germination of seeds of 10 genotypes of cowpea (Vigna unguiculata). The experiment carried out on petri dishes was done using a completely randomized design comprising three replications. The germination of the cultivars was studied using distilled water as control and under osmotic potentials of 50, 100, 150 and 200mM NaCl. The results indicated that the Mean Germination Time (MGT), Time to 50% Germination (T50), Germination Index (GI), Coefficient of Velocity of Germination (CVG), and Germination Percentage (GP), varied between 2.33 and 5.51 days; 2.83 and 14.87 days; 16.66 and 1.63; 0.53 and 0.11; 87.11 and 27.98% respectively. The variables GI, CVG and GP tended to decrease with increasing NaCl concentration while MGT and T50 tended to increase with increasing salt concentrations. For all the germination variables, significant differences at 0.001 probability levels were found among salinity treatments, cowpea genotypes and their interaction. Four genotypes (KEB-CP118, OU59A, OU100 and ICV12) were tolerant to salt stress and performed well under salinity conditions. Four other genotypes were found to be moderately tolerant (ET11, NO1036, MTA22 and KEB-CP009) and two genotypes (KEB-CP098 and NO193) were susceptible to salt stress and were most affected by salinity. At 0.001 probability level, positive correlations were observed between GP and GI (r = 0.792); GP and CVG (r = 0.774); GI and CVG (r = 0.955) and negative correlations were observed between GP and T50 (r = - 0.845); GI and MGT (r = - 0.894); CVG and MGT (r = - 0.895).