Characterization of Indian clusterbean (Cyamopsis tetragonoloba (L.) Taub.) genotypes using qualitative morphological traits

Abstract

Clusterbean (Cyamopsis tetragonoloba (L.) Taub.) is commonly known as guar, a legume with drought hardiness suited to arid regions remained a neglected and underutilized crop till the shale rush began, of late it got momentum in the international market, and it became one of the most promising industrial crops in India. Seeds of clusterbean are used for extraction of gum which is called guar gum or guaran. Guar gum—a galactomannan polysaccharide—has many uses such as in the oil and petroleum industries (shale energy production or oil fracking), food industries, pharmaceutical industries, paper industries and mining fields. India is the major producer and exporter of guar to the world market. There is a tremendous variability available in Indian clusterbean germplasm, our objective of the present study to characterize and evaluate the Indian clusterbean genotypes using morphological qualitative traits. Forty-two genotypes collected across India were characterized for seven morphological traits: stem type, growth habit, leaflet texture, leaflet margin, leaflet size, flower colour and seed colour across three locations during kharif (rainy season) 2013. Coefficients of variation and principal component analysis revealed variability among the genotypes for the qualitative traits evaluated. PCA analysis showed that genotypes namely PNB, T local, HGS 884, RGC 471, MRSG6 were very different from each other. Cluster analysis separated genotypes into two major groups: one of vegetable genotypes (PNB, T local, M local, HVG2-30 and Amrit 11), and the other of gum genotypes. Among the gum genotypes RGC1066, RGC197 and FS277 formed a distinct sub cluster as they possess single stems (unbranched type), while the genotypes with white flower colour namely RGC936 and RGC471 formed a different sub cluster. The genotype MRSG6 showed brown seed with distinct grade of N 200 B which was distinctly unique and differed from the predominant grey-seeded group Correlation analysis among the traits showed that leaflet texture (pubescence) and leaflet shape (narrow) correlated highly with gum genotypes, on the contrary glabrous broad leaflets were linked with vegetable genotypes.