Effect of regulated deficit irrigation at different growth stages on water consumption and fruit quality of wine grape

Soil drought notably influences fruit quality, yield and water use efficiency of wine grape. It is therefore important to clarify the effect of drought stress at different growth stages on soil water precision management and water-saving irrigation schedules in wine grape fields. To explore this effect, an experiment was carried out in 2014 at Weilong vineyard in Qingyuan Town in Liangzhou District, which belongs to Wuwei City in Hexi Corridor. The study evaluated the effects of drought stress caused by regulated deficit irrigation at different growth stages on water consumption and fruit quality of vine grape. In the experiment, 12 treatments were set up, 10 of which were moderate soil water stress (relative soil water content maintained at 60%–65% field capacity) and severe soil water stress (relative soil water content maintained at 50%–55% field capacity), respectively, at germination, vine growth period, florescence period, berry enlargement and coloring maturity periods with other growth stage under normal water condition (relative soil water content maintained at 70%–75% field capacity). Meanwhile, a full irrigation (relative soil water content maintained at 80%–85% field capacity) during berry enlargement period was also carried out and the normal water supply (relative soil water content maintained at 70%–75% field capacity) during the whole growth period was as the control. The results showed that the variation trend in soil water content within the 0100 cm soil layer were similar in different treatments, i.e., the soil water increased with increasing soil depth. The effects of drought stress controlled with regulated deficit irrigation was weakened with increased soil depth, and the soil layer of 4060 cm was with largest soil water reduction compared with CK. Soil water content along profile was lowest at berry enlargement period for all the treatments. The timely change trend of water consumption rate of wine rape was similar for different treatments. The minimum and maximum daily water consumption rates of wine grape occurred respectively during germination period (0.130.33 mm·d^-1) and berry enlargement period (2.30–4.09 mm·d^-1). Maximum yield and water use efficiency appeared under moderate water stress at grape germination period, which were 15 228 kg·hm^-2 and 3.62 kg·m^-3, respectively. This was followed by grape enlargement period full irrigation treatment (7 128 kg·hm^-2 and 2.26 kg·m^-3), while minimum rate was under severe soil water stress at grape enlargement period. Anthocyanins, total reducing sugar, tannin and total phenol contents in wine grape under severe soil water stress at coloring maturity stage were respectively 2.7% and 6.56%, 17.91% and 23.23% higher than that of under the full irrigation treatment, and titratable acid content effectively was restrained (P < 0.05). There was no significant difference (P > 0.05) in wine grape quality between the control and other treatments. In terms of integrated yield, water productivity efficiency and fruit quality, the optimum irrigation pattern of wine grape was moderate soil water stress at coloring maturity (relative soil water content maintained at 60%–65% field capacity) in combination with normal water supply (relative soil water content maintained at 70%–75% field capacity) during the other growth periods. Therefore, reasonable regulated deficit irrigation significantly improved water productivity efficiency of wine grape. This was not only water-saving, but high in water use efficiency and beneficial for grape quality improvement which was important for vine grape cultivation in Hexi Corridor.