(352) Genetic and Environmental Effects Related to Water Use Efficiency in Peach

Abstract

Two unpruned willow leaf and two unpruned standard leaf peach [Prunuspersica(L.) Batsch.] selections were evaluated for physiological components related to water use efficiency (WUE). The purpose of the study was to assess the value of willow leaf phenotypes to improve water use efficiency in peach and separate the environmental from the genetic components. The willow leaf characteristic itself did not confer improved water use efficiency. Light interception was a key determinant of WUE in these genotypes and the relationship of WUE with intercepted photosynthetically active radiation (PAR) by the entire canopy indicated a significant negative correlation. Internal shading of the tree by excessive leaf area reduced WUE and canopies that intercept more than 60% of the PAR have reduced WUE. While WUE is improved by reducing the amount of PAR interception of the canopy, productivity is reduced. Neither of the willow leaf genotypes had a significant correlation of WUE with yield (leaf and fruit weight); however, the standard leaf type cultivars, `Bounty' and `Redhaven', had significantly different regressions that indicate greater productivity in `Bounty' for a given level of WUE. `Redhaven' was the least productive cultivar; `Bounty' was the most productive, and the two willow leaf genotypes were intermediate in the relationship of intercepted PAR with yield. Therefore, genetic differences in peach growth types can be selected for both increased WUE as well as increased productivity. Future work in peach breeding to improve WUE and productivity must take into consideration light interception, productivity, and WUE in an integrated manner to make progress in the efficient use of water and light.