Medicinal, Aromatic and Underexploited Plants Section Department of Plant Breeding, Haryana Agricultural University, Hisar-125 004 (Haryana).
Analysis of variance for twelve quantitative characters in 10 genotypes of guayule showed significant variability and potential for improvement through breeding. Plant height, basal branches per plant, main stem diameter, and leaf length and width had high genotypic coefficient of variability, high heritability and high genetic advance (% of mean). This shows that effective selection for improvement of these characters is possible in guayule. Rubber content had negative significant correlations with stem diameter. Rubber yield plant−1 showed positive significant correlation with plant circumference, basal branches plant−1, fresh and dry shrub yield plant−1 and plant diameter. Basal branches plant−1 also recorded highest GCV (30.00), GA (61.72%) and high heritability (99.4%), thuscan be used as a non-destructive predictor of high rubber yield. Possibilities to improve number of basal branches by selection are good. As stem diameter showed negative correlation with rubber content (%), the plant breeders will have to compromise at certain co-level of stem thickness and number of stems (basal branches) to get higher rubber yield per unit area from guayule cultivation.
