Early Selection of Promising High Yielding Hevea Progenies based on Selected Physiological and Stomatal Characteristics

摘要

Leaf physiological and stomatal parameters were studied from immature plants grown in the ground nursery. These Hevea clones differed widely in mature yield. Significant differences were detected in some of the parameters such as light saturated photosynthesis (Psat), stomatal conductance (SC), transpiration rate (TR), mesophyll conductance (MCond) and instantaneous water use efficiency (WUEg) among the clones. The variation in mature yield, girth at opening as well as physiological parameters and stomatal characteristics were not affected by weather. The mature yield showed a positive correlation with Psat, SC, TR and MCond while the girth at opening was positively correlated with instantaneous WUEg. A step-wise multiple regression confirmed results of the simple correlation. About 34% of the differences in mature yield was explained by Psat. The addition of potential conductance index (PCI), a product of stomatal frequency (SF) and square of length of stomatal complex (LSC), as an independent variable increased the predictive power for mature yield by about 55%. The results indicated that Psat singly could identify high yielding clones with 63% accuracy and an error rate of 17% for wrongly identifying low yielders as high yielding clones. When both Psat and PCI were used, all high yielding clones could be identified. It is concluded that both Psat and PCI, which together have successfully identified high yielding clones, have a potential to be used as indirect selection criteria for yield of Hevea progenies during the early stages of growth in the nursery.