Control of stomatal aperture and carbon uptake by deficit irrigation in two grapevine cultivars

Abstract

Improvements in water use efficiency of crops are essential under the scenarios of water scarcity predicted by global change models for the Mediterranean region. In recent years, deficit irrigation, including partial root drying (PRD), has been proposed as an irrigation technique to improve water use efficiency and standardize grapevine yield and quality. The objective of this study was to evaluate the impact of deficit irrigation on photosynthetic responses of field grown grapevines of cv. Moscatel and Castelão. The treatments were: full irrigation (FI), corresponding to 100% ET c ; non-irrigated, but rain fed (NI) and partial root zone drying (PRD) and deficit irrigation (DI), both corresponding to an irrigation of 50% ET c . While in the DI treatment water was applied to both sides of the root system, in the PRD treatment, water was supplied to only one side of the root system, alternating sides periodically. In both cultivars, PRD and DI vines showed intermediate pre-dawn leaf water potential (c pd ) values (around À0.4 MPa) while FI vines, showed c pd around À0.2 MPa during the growing season. NI showed the lowest c pd , reaching À0.6 MPa in Moscatel and À0.8 MPa in Castelão, at the end of growing season. Water status of PRD vines remained closer to FI than DI, especially at midday. Photosynthetic rates and fluorescence parameters of the deficit irrigation treatments (PRD and DI) did not show significant differences from FI vines, for most of the season. In Moscatel, although PRD generally showed g s , relative stomatal limitation (RSL) and intrinsic water use efficiency (A/g s ) values closer to NI than DI, most of the differences between PRD and DI were not statistically significant. Our results showed a stability of the photosynthetic machinery in grapevines under low-to-moderate water availabilities, as demonstrated by the maintenance of the activity of three Calvin Cycle enzymes and of the V cmax values. However, a decline in J max was observed in NI vines, that can be a result either of a decrease in ATP production or, alternatively, of decreased mesophyll conductance to CO 2 diffusion. In general terms, stomatal limitation of photosynthesis is likely to be dominant in non-irrigated plants. Deficit irrigation had no negative impact on CO 2 assimilation, despite less water application than in full-irrigation. Differences among varieties may be related to differences in sensitivity of stomata, shoot growth and/or the interaction between rootstock and cultivar to soil water availability. #

Physiological responses and production of 'Syrah' vines as a function of training systems

“…Furthermore, the greater trunk height in GDC system (1.90 m) as compared to VSP (1.0 m) and also the differences in branch orientation could have contributed to hinder water transport to the grapevine canopy. Schubert et al (1999) showed that shoot hydraulic conductivity is negatively affected by downward branch orientation in contrast with upward growing (Deloire et al, 2004), the photosynthesis was unaffected as shown by other authors for grapevine (Souza et al, 2005b) and other crop species (Fereres and Soriano, 2007). The differences between seasons of CO 2 assimilation rates were probably due to weather conditions (temperatures) during gas exchange measurements, as explained above for results of leaf water potential.…”

Comparison of irrigation scheduling strategies for achieving water use efficiency in highbush blueberry

“…Unlike fixed partial wetting, however, PRD involves alternations of wetting and drying to each side of the root system with alternations initiated before the soil has dried to the point where vascular damage might occur. Root damage by desiccation would also remove the ability of roots to produce and transport abscisic acid (ABA), a plant hormone that acts as the primary mechanism driving the plant's physiological response to PRD (Stoll et al 2000;Davies et al 2002;de Souza et al 2005;Dodd et al 2006;Liu et al 2006). With each PRD cycle, ABA is produced in roots on the drying side of the plant and when irrigation is resumed to these roots, the water that they transport into the plant carries a pulse of ABA to the leaves.…”

Improving water use efficiency of vineyards in semi-arid regions. A review

“…On the other hand, partial root zone drying has the effect of controlling excessive vegetative growth in grapevines leading to a reduction in canopy density and a better plant balance with decreased input costs (water and nutrients). This effect leads to an increase of grape quality presumably without yield modification ; De la Hera et al 2007;dos Santos et al 2003dos Santos et al , 2007Dry and Loveys 1999;Intrigliolo and Castel 2009;Romero et al 2010Romero et al , 2014Santos et al 2005;Souza et al 2005). However, when a big set of existing data is compared, no relationship between total water applied and yield is observed (Fig.…”

“…Red line represents the theoretical maximum water use efficiency (WUE) for each soil total water availability level. Black line in b represents linear regression (r 2 = 0.76) Koundouras et al 2008;Pou et al 2008;Prieto et al 2010;Rogiers et al 2011;Schultz 2003;Souza et al 2005;Tomás et al 2012Tomás et al , 2014bZsófi et al 2009). This variability is mostly associated to different g s responses, as shown by Tomás et al (2014a), which assessed 74 different cultivars under irrigation and drought conditions.…”