Response to Water Stress of Novel and Widely Spread Citrus Rootstocks

Drought is a problematic abiotic stress affecting citrus crops in the Mediterranean basin and the rootstock plays a fundamental role in adopting adaptive mechanisms in response to water deficit. The aim of this study is to evaluate the response of eight rootstocks under three treatments imposed: control (100% Et0), 66% Et0 and 50% Et0. Among the rootstock genotypes studied, some have been recently spread and so far little studied, i.e. Bitters, Carpenter and Furr, while others have been widely used especially in Mediterranean cit-rus industry, i.e. Citrus macrophylla, C. volkameriana, Swingle citrumelo, Carrizo and C35 citrange. Morphological analyses, leaf chlorophyll content determination, physiological measurement, proline accumulation, malondialdehyde determination and antioxidant enzyme activities were measured. The results exhibited that Bitters and Furr showed an increment in leaf area to reduce the effects of drought conditions. A decrement in gas ex-changes and xylem water potential was noticed in Carrizo and C35 citrange at both water shortage treatments. Bitters and Furr performed better than the other rootstocks with re-grads to enzymatic and hormonal assays, C. volkameriana showed a decrease in xylem water potential, while overall Carrizo and C35 citranges showed a susceptible response to water stress reducing morphological and physiological measurements.