Effect of naturalized rootstocks on growth and physiology of Syrah and Cabernet-Sauvignon under water deficit

Abstract

Grapevine production in Chile is facing increasing water deficit problems related to aridization. We studied the use of rootstocks as a strategy for enhancing the performance of cv. Syrah (Sy) and Cabernet Sauvignon (Cs) grapevines under water deficit. Plants were grafted onto four naturalized grapevine genotypes (selected in hyper-arid zones of Chile). Own-grafted plants and plants grafted onto the commercial drought-tolerant rootstock Ruggeri-140 were also included. Plants were grown in 30 L containers and submitted to optimal (100% ETc) and deficit (30% ETc) irrigation throughout two seasons. Components of shoot and root growth and physiology traits (leaf gas exchange, xylem water potential and maximum quantum use efficiency) were monitored along both growing seasons. We used shoot leaf area as a proxy for performance. As a general trend, water deficit reduced all of the growth and physiological variables, especially in Cs. Under water deficit, the naturalized genotype P32 induced significantly higher values for most of the shoot growth components than all other rootstocks irrespective of cultivar and seasons. This was associated to higher root growth irrespective of cultivar during season one and only Cs during season two; but only associated to higher values of physiological traits in Cs during season one. We conclude that P32 is a promising rootstock for enhancing grapevine performance under water deficit both for near isohydric (Cs) and anisohydric (Sy) cultivars and that its drought tolerance is mainly related to enhanced root growth and not to enhanced physiological performance.