A Low cost and high throughput spectroscopic method for quantification of seed coat colour differences in plain seeded bean (Phaseolus vulgaris L.) germplasm from Western Himalayan Kashmir

Abstract

Seed phenotyping is routinely done using visual assessment that suffers from subjectivity. In the present study we phenotyped 278 Western Himalayan bean accessions using a low cost spectroscopic method based on quantification of seed colour in terms of L*,a*,b* and δ E. There was substantial variation for L*, a*, b* and δ E parameters for all seven colour classes. The mean value for L* was lowest for red (31.31) and highest for white (78.17) and reverse in case of a*. Similarly, mean value for b* was lowest for black (-0.29) and highest for yellow (40.86). In terms of deviations from standard colours depicted by δ E, highest mean value was observed in red colour (6012.16) and lowest was recorded for green (18.36) with a mean of 2525.72 across all colours. The first two principal components accounted for 86.74% of variation. contributed by colour and L* in PC1 and b*, L* and a* in PC2. In the present study, based on the factor loading graph, colour is strongly correlated with L* as is evident from its significant contribution in both PC1 and PC2. The multivariate analysis clearly delineates the diversity panel of 278 genotypes into distinct colour groups as shown by concentration of genotypes of similar colour class into specific regions of four coordinates of biplot based on L*, a* and b* values and their observed relationship with colour scores. The method removes the subjectivity in visual colour specifications, is quantitative and can help in exact quantification of varietal differences.