Towards a simple indicator of water stress in grapevine (Vitis vinifera L.) based on the differential sensitivities of vegetative growth components

Abstract

Responses of grapevine vegetative growth components to mild, medium and severe soil water deficits were used to identify simple and sensitive indicators for early diagnosis of water stress. Soil water deficit was characterised as the fraction of transpirable soil water (FTSW) remaining in a water‐depleted rootzone. Growth components included the number of emerged leaves on first (Ist) and second (IInd) order lateral branches, the leaf area and internode length of each phytomer of Ist order lateral branches, and the frequency of IInd order lateral branching. These components were measured in a greenhouse on Shiraz (syn. Syrah) grapevines, over a 38‐day period of stabilised soil water regimes. Leaf emergence rate, final leaf area and final internode length of lateral branches I were relatively insensitive to mild and medium water deficits. They only decreased in response to severe water deficits. The frequency of IInd order lateral branching showed a similar trend, but was inhibited at severe water deficits. The leaf emergence rate of lateral branches II was highly sensitive to FTSW, and decreased even in response to mild water deficits. Because measurement of leaf emergence rate is a time consuming process, further analysis of the data was undertaken to identify a simpler but similarly effective indicator of cumulative water deficit. Accordingly, we established that the final length of lateral branches I was sensitive to medium water deficits, while the final ratio of the number of leaves on lateral branches II to the number of leaves on lateral branches I, was sensitive to even mild water deficits. Both of these composite indicators (derived variables) were relatively easy to measure and showed potential as early indicators of water deficits. They were more sensitive to FTSW than was predawn leaf water potential. Moreover, the final ratio of the number of leaves on lateral branches II to the number of leaves on lateral branches I was even more sensitive to FTSW than was stomatal conductance.

Evaluation of grapevine water status from trunk diameter variations

“…The phenological changes in the sink-source relations are then a particularly important factor to consider when attempting to use TGR as a water stress indicator. Recently, some reports (Hardie and Martin 2000;Pellegrino et al 2005) have suggested monitoring shoot growth of defruited vines for irrigation scheduling, mainly to avoid the interaction between fruit and vegetative growth. In this sense TGR might behave similarly as shoot growth of a de-fruited vine.…”

Interrelationships between seed yield and 20 related traits of 49 canola (Brassica napus L.) genotypes in non-stressed and water-stressed environments

“…Thus, drought was applied by withholding water when the first pod appeared at the beginning of pod filling and seed-filling. Also in these stages total leaf water potential was used as the index of soil water status according to Williams and Araujo (2002) and Pellegrino et al (2005). Total leaf water potential was measured using a pressure chamber (PMS, Instrument Company, Corvallis, Oregon).…”

Leaf number indicates salt tolerance of young seedling families of European aspen (Populus tremula L.) growing in different soils

“…Leaf number is an easily measured and non-destructive external index that enables comparison among plants grown in different environments (Zalesny et al 2007). Earlier studies have explored the relationship between leaf number, plant growth and stress tolerance (e.g., Kodani 1999, Pellegrino et al 2005), but our study is among the first to find a clear correlation among these factors. More studies are needed but the basis for salt tolerant selections could come initially from leaf counts.…”