Genetic variation of plant water status, water use efficiency and grape yield and quality in response to soil water availability in grapevine ( Vitis vinifera L.).

摘要

The variability of water use efficiency was evaluated in a collection of 22 grapevine cultivars growing in an experimental farm near Palma. Gas exchange parameters (net photosynthesis, stomatal conductance and transpiration) were measured in leaves from May to August. Additionally, water relation parameters (soil water potential, stem water potential), and grape yield and quality were also analyzed. The results show that intrinsic water use efficiency (WUE, relation between net photosynthesis and stomatal conductance) measured in grapevine ranged from 42 to 78 micro mol mol-1 in well watered plants, with most cultivars showing values around 60 micro mol mol-1. When water deficit was progressively imposed, WUE increased while decreased stomatal conductance to 150 micro mol mol-1. Under those conditions with very low soil water availability (soil water potential of -1,5 MPa), stomatal conductance ranged from 72 micro mol mol-1 ('Macabeo' cultivar) to 156 micro mol mol-1 ('Argamusa'). Plant water status measured as stem water potential ( Psi stem) under severe water stress conditions, ranged from -0.97 to -1.67 MPa, depending of the cultivar. Interestingly, the cultivar 'Macabeo' showed the lowest WUE and the highest Psi stem (-0.975 MPa). Nevertheless, this cultivar had the highest yield (fruit production per plant). On the opposite, 'Argamussa' was the cultivar with highest WUE under water stress, because of a stronger stomatal adjustment under those conditions, maintaining high net photosynthesis rates. This cultivar also showed a very low stem water potential (-1.48 MPa). The higher capacity of carbon fixation of this cultivar under water stress, was reflected in a high plant yield (7.8 kg grape per plant), although sugar concentration in must was very low. Certain relationships were obtained between leaf carbon fixation and total yield and sugar content in must.