Variability Estimate of Growth and Physiological Parameters among Commercially Important Tree Willows

Twenty-three tree willow clones comprising of seven species were studied for variability of photosynthetic traits and their relationship at one year age. Photosynthesis, transpiration and instantaneous water use efficiency (WUEi) were determined and the data were further subjected for the estimation of genotypic and phenotypic coefficient of variability (GCV and PCV), heritability and genetic gain (as per cent of mean). Variability estimates were calculated for growth parameters viz., height, collar diameter, volume index, number of branches, number of nodes, internodal length, leaf display and leaf area. Among all the parameters volume index showed widest range of values (9.29-721.50, mean 356.42). The narrowest range was recorded for leaf display (195.0-291.0, mean 238.17). The maximum GCV (39.99) was recorded for transpiration, followed by photosynthesis (38.36) and least in case of WUEi (19.71). Heritability (h² b.s.) was recorded maximum (85.30) for transpiration, (80.00) for photosynthesis and (26.55) for WUEi. A positive significant correlation (r= 0.754) was observed between photosynthesis and transpiration. WUEi showed significant negative correlation (r = -0.364) with transpiration whereas positive non significant (r = 0.209) with photosynthesis. Selection of both traits i.e. photosynthesis rate and WUE are important in order to make photosynthesis more effective using water efficiently to produce higher yield.