Physicochemical basis of resistance in certain green gram genotypes to pulse bruchid, Calloso bruchus chinensis (L.)

A study was conducted to know the influence of physical and biochemical parameters on development of the pulse bruchid in green gram at RARS, Lam during 2017-18. The physical parameters of seed viz., colour, shape, surface texture, seed length and width, seed coat hardness and 100 seed weight and biochemical parameters such as protein content, phenol content and total sugars were evaluated for twelve genotypes of greengram. The greengram genotypes with smooth texture, oblong or globose shape and light coloured seed might be less preferred by the pulse bruchid for egg laying. The data showed that genotypes having low sugar and protein contents and high phenol content were resistant to pulse bruchid. The correlation studies showed that biological parameters i.e., number of eggs, adult emergence and growth index had significant positive association with protein content, sugar content, moisture content and electrical conductivity and negative correlation phenol content, 100 seed weight and seed coat hardness. In contrast, mean development period had negative association with protein content, sugar content, electrical conductivity and moisture content and positive correlation with phenol content, 100 seed weight and seed coat hardness. Multiple linear regression studies revealed that all the physical and biochemical properties of seed together were contributing to a large and significant variation (65 to 87 %) in growth parameters of pulse bruchid.