Deficit irrigation and silicate spray applied since blooming period improved strawberry fruit quality without reducing fruit size

The drought stress created by deficit irrigation has been widely introduced into production for fruit quality improvement, whilst silicon is considered as a functional element in plant antistress process. To explore the influence of deficit irrigation and silicon application on the strawberry fruit quality and the plant's response to drought stress, a split-plot experiment was conducted. The impacts of the treatments start-time was also evaluated. The plants were subjected to two irrigation regimes, deficit irrigation (DI) or full irrigation, and two foliar sprays, 0.01 mol L- 1 Na2SiO3 (Si) or water, with two treatment start-time, as after first bloom (Fr) or after transplanting. Therefore, there were 6 different treatments (considering treatment start-time) and a control group, which were DI, FrDI, Si, FrSi, DISi, FrDISi and CK. As a result, the DI significantly increased the leaf ascorbate, leaf anthocyanins and specific leaf weight by 93.5%, 109.9% and 24.5%, but it also reduced fruit reducing sugars concentration and single fruit mass by 25.1% and 12.6%, respectively. Whilst the FrDI increased specific leaf weight by 27.9% and had no negative effect on fruit quality. The timing of starting silicate spray didn't influence leaf morphology or fruit quality, but the FrSi significantly increased the percentage of leaf sucrose to total sugars by 9.0%, and the Si didn't. The DISi and FrDISi tended to increase the concentration of fruit sugars, glutamate, polyphenols, and organic acids. Although the DISi showed more obvious effect on improving the fruit nutritive values, the FrDISi tended to have lighter negative impact on fruit size, compared to CK. We concluded that the combination of deficit irrigation and silicate spray started after the first bloom could effectively improve the fruit sugars, glutamate and polyphenols, without reducing the fruit size, due to the mitigation of plant antistress response.