The Inheritance and Variation of Gum Content in Guar [Cyamopsis tetragonoloba (L.) Taub.]

Guar [Cyamopsis tetragonoloba (L.) Taub.] is one of the most important industrial crops due to its richness in gum. Understanding the inheritance of gum content is a key to its successful genetic improvement. Gum content expression is reported to be controlled by additive, dominant, and epistatic effects, and modified by the environment. fg%, a relative gum content calculated by comparing with the gum content of Kinman was used as gum content (%) in this experiment. Reciprocal crosses of two lines of guar, PI 217923 and Lewis, were made to study the heritability of gum content (fg%). fg% of four plant introductions and four commercial varieties were studied in Lubbock in 1999–2002. Estimates of broad-sense heritability (h2 b.s.) of fg% in Lewis × PI 217923 and PI 217923 × Lewis were 75.53 and 52.74%, respectively. Estimates of narrow-sense heritability (h2 n.s.) of fg% were 40.00 and 29.00% for Lewis × PI 217923 and PI 217923× Lewis, respectively. At least one pair of genes were estimated to control the fg% expression in these two crosses. Significant differences of fg% were found among these eight entries. PI 217923 was found to have the highest fg% among the eight entries.