Assessing correlations between leaf and root traits of Prunus rootstocks under water deficit and salinity stress

SX Zhou, E Edwards and R Walker

CSIRO Agriculture, PMB 2, Glen Osmond, SA 5064

Recent interest in trait-based plant ecology has sparked the search for a root economics spectrum (RES) and the evidence of RES mirroring the leaf economics spectrum. However, studies exploring these correlations under abiotic stress, and the differential magnitude of correlations among congeneric plant taxa, are limited. By imposing water and salinity stresses on seven Prunus rootstock varieties, this study aimed to test the hypothesis that fine-root traits would match leaf traits, which are typically coordinated along an axis from resource acquisitive to resource conservative traits. Seedling plants of seven Prunus rootstock varieties were randomly allocated into three water and salinity stress treatments for two months in a glasshouse. Plants in the well-watered treatment were irrigated to the point of run-off daily. The severe drought treatment was imposed by adding 33% of evapotranspiration of well-watered plants daily. Plants in the salinity treatment were supplied with mixed chloride solution (with electrical conductivity 3.3 dS m–1) to the point of run-off daily. Besides plant biomass, measurements included key above- and below-ground plant traits (leaf mass area, root density, root diameter, root length, root surface area), stem water potential and leaf gas exchange. The seven Prunus rootstocks differed in the extent of growth responses to stresses, with the effects of severe drought generally being larger than those of salinity stress. Meanwhile, their differential sensitivity to stress is correlated between above- and below-ground plant traits. The findings showed important correlations between above- and below-ground plant traits under abiotic stress. This study contributes to knowledge of differential responses of plant traits between congeneric plant taxa under abiotic stress, useful for plant physiologists and modellers.