Search

To see the effect of ultra desiccation on seed survival, cowpea (Vigna unguiculata L.) seeds were conditioned to various moisture contents ranging from 8-2%. When monitored after one year of storage, variability was observed in seed viability in the seeds conditioned to different moistures. Seeds conditioned to very low moisture contents exhibited greater loss in viability. Therefore, efforts were made to see the possibility of germinating the embryo under artificial condition using various media and growth regulators. The effect of various combinations of hormone in plant tissue culture media were evaluated on the growth of excised embryonic axis in vitro to develop an embryo rescue protocol. An efficient protocol was developed for in vitro shoots regeneration from cowpea embryonic axis to improve the survival of low viability seeds to avoid the loss of potentially valuable genes. Shoots were developed in most of the explants on medium containing MS salts and B5 vitamins supplemented with 0.2 mg/l BAP. All the regenerated shoots were rooted on the same medium and in vitro plantlets were acclimatized in pots containing soilrite at room temperature. All the plants produced healthy seeds after 2 months in greenhouse. This protocol can be used to rescue cowpea germplasm with low germination percentage which results in successful regeneration. [ABSTRACT FROM AUTHOR]

A total of 52 accessions of cowpea including two checks (Pusa Komal and Local variety) were screened for resistance to pulse beetle, Callosobruchus chinensis under no-choice artificial infestation conditions. There were significant differences among the accessions in terms of number of eggs laid, development period, adult emergence, number of emergence holes, weight loss and growth index of C. chinensis on cowpea. Based on growth indices, Pusa Komal (0.04081) and IC328859 (0.04112) were resistant while IC106033 (0.06819) and Local variety (0.06816) were most susceptible to C. chinensis. Of the 52 accessions screeened, 11 accessions were resistant, 15 moderately resistant, 13 moderately susceptible, 8 susceptible and 5 were highly susceptible to C. chinensis. Correlation between growth index and growth parameters of pulse beetle on different cowpea accessions indicated that growth index had significant negative relationship with mean development period (r = -0.68) and significant positive relationship with adult emergence(r = +0.80). Adult emergence had a positive relationship with weight loss (r = +0.22). [ABSTRACT FROM AUTHOR]

Laboratory studies were conducted in 52 accessions of cowpea including check (Local variety) for variability in physical parameters of seed viz., colour, shape, texture, length, width, hardness, seed coat hardness and 100 seed weight and biochemical parameters namely, moisture, phenols, tannins and α-amylase inhibitor activity to understand the basis of resistance against pulse beetle. Significant differences among the cowpea accessions were observed for all the physical and biochemical parameters. Based on growth index of pulse beetle, Callosobruchus chinensis, eleven accessions viz., IC107466, 106815, 106037, 106812, 106816, 106817, 108749, 311138, 328859, 381583 and Pusa komal were found to be resistant to the beetle. Correlation coefficients between growth index (GI) of pulse beetle and physical and biochemical parameters of cowpea indicated that GI of C. chinensis had insignificant relation with seed hardness and seed coat hardness. The GI of beetle had a positive relation with seed length-width ratio, 100 seed weight and seed moisture. Phenol and tannin had negative relation with GI of C. chinensis while amylase inhibitor had a positive relation. [ABSTRACT FROM AUTHOR]