Supplemental light and silicon improved strawberry fruit size and sugars concentration under both full and deficit irrigation

Light, water and nutrient are essential factors influencing fruit quality of strawberry plants grown in commercial greenhouse. The aim of this study was to investigate the effect of supplemental light on the fruit quality as well as the effect of incorporating deficit irrigation and silicate spray on the plant nitrogen assimilation and fruiting of strawberry plants. The experimental plants were subjected to two light conditions, supplemental lighting (LED) and natural lighting environment (N), combining with two irrigation regimes, full irrigation (FI) or deficit irrigation (DI) and two foliar spray treatments, silicate spray (Si) or water spray (W), resulting in 8 treatments in total, viz., FIWN, FISiN, FIWLED, FISiLED, DIWN, DISiN, DIWLED, DIWLED. The Light treatment significantly elevated fruit polyphenols by 15.5% in the early season, and elevated fruit total sugar, glucose and fructose concentrations by 10.0%, 10.9% and 10.2% in the late season, respectively. The DI increased fruit anthocyanins concentration by 25% in the early season, and increased fruit glutamate concentration by 12.3% in the late season. The Si increased fruit anthocyanins, polyphenols and citrate concentrations by 41.7%, 14.7% and 8.2% in the early season, respectively, and increased single fruit mass by 8.8% in the late season. Furthermore, the Si enhanced the leaf GOGAT activity and glutamate concentration by 56.3% and 25.8%, respectively. The FISiLED and DIWLED had comparable advantages in elevating the fruit glucose, fructose, polyphenols and ascorbate concentrations in both seasons. Therefore, the silicate spray combined with supplemental lighting was recommended for growers to produce high quality strawberry fruit, and the deficit irrigation could be incorporated for the purpose of water conservation. The influence of supplemental light on the nitrogen metabolizing cycle and the carbohydrates transportation when the plants subjected to silicate spray or drought stress deserve further study.

Automated summary

Supplemental light can improve the fruit quality of strawberry plants by increasing polyphenols in early season and total sugars and glucose and fructose concentrations in late season. Deficit irrigation increases anthocyanins concentration in early season and glutamate concentration in late season. Silicate spray increases anthocyanins, polyphenols, and citrate concentrations in early season and single fruit mass in late season.