Inheritance of Protein and Sulfur Content in Seeds of Chickpeas¹

Abstract

Seeds of 33 genotypes of chickpeas ( Cicer arietinum L.), were assayed for total protein and one aspect of protein quality, sulfur content. Since the sulfur‐containing amino acids in protein of chickpea are first limiting in human dietary requirements, a barium sulfate turbidimetric method was developed for rapid determination of sulfur content. Using five genotypes, a coefficient of determination of 0.89 was obtained between the total‐sulfur content determined by this turbidimetric method and sulfur‐containing amino acids as percent of protein determined by an amino‐acid analyzer. Evaluation of these 33 genotypes over 2 years for 8 morphological, agronomic, and protein characters revealed significant genotypic effects and highly significant year‐by‐genotype interactions for all variables. Percent protein ranged from 14.5 to 28.9 with a mean of 21.8. A highly significant negative phenotypic correlation (r = —0.57) was determined between percent protein and 100‐seed weight. To avoid the pseudosuperiority of small, sometimes shrivelled, unfilled seeds, protein weight per seed was calculated. Protein weight per seed was positively correlated (P < .01) with sulfur as percent of protein and 100‐seed weight. Broadsense heritability estimates based on the phenotypic variance of means of genotypes over years ranged from 0.51 to 0.74 for the eight variables. Protein weight per seed revealed a value of 0.70, with percent sulfur and sulfur as percent of protein values of 0.64 and 0.51, respectively. Highly significant general and specific combining ability effects in F 1 and F 2 populations were evident for 100‐seed weight, percent protein, and protein weight per seed. Less definite results were obtained for percent sulfur and sulfur as percent of protein. Heterosis values were calculated comparing F 2 with midparental values.