The effects of rain shelter coverings on the vegetative growth and fruit characteristics of Chinese cherry (Prunus pseudocerasus Lindl.)

Abstract

Throughout the whole process from the onset of blossoming to fruit maturity, rain and hail can cause severe losses in cherry (Prunus pseudocerasus Lindl.) yields, e.g., up to 90%, under the conventional shelter-free (control) conditions in Southwest China. Recently, rain shelters have been increasingly applied worldwide to prevent flowers and fruit from damage by excessive rainfall and hail, and the utility of rain shelters was preliminarily proven to benefit cherry production due to yield improvements, especially in Southwest China. However, the effects of rain shelter coverings on the vegetative growth, photosynthesis and fruit characteristics of cherry have not yet been fully explored. In the present study, the 5-year-old field-grown plants were covered with polyethylene (PE) film from the preflowering stage until fruit harvested for one year (1a-shelter) or two years (2a-shelter) as part of trials in Guizhou Province, Southweste China. Compared with that under the control conditions, the leaf area under 1a- and 2a-shelter conditions significantly increased by 23.0% and 26.87%, respectively, at the 55 days after flowering (DAF) (DAF55); conversely, the leaf thickness clearly decreased by 17.67% and 19.7%, respectively. Similar trends in leaf area and thickness were also observed under the 2a-shelter, but no marked differences occurred between the 1a-shelter and 2a-shelter. Regardless of the covering cycle, the rain shelters somewhat promoted shoot elongation, although the differences were not statistically significant. Compared with the control, the 1a-shelter and 2a-shelter caused considerable increases in chlorophyll contents in the leaves. Interestingly, the rain shelters strongly increased the carotenoid (Cx) contents in the leaves under both the 1a- shelter and 2a-shelter, indicating an obvious improvement in the ability to use weak sunlight. Compared with those in the control, the diurnal fluctuations in the photosynthetic rate (Pn) of the leaves under both 1a- shelter and 2a-shelter characterized by a single peak; the Pn of the control exhibited a typical noon-slump pattern, which accordingly led to an increase in the total daily photosynthetic accumulation within the sheltered leaves. Compared with those in the control, the mean weight and size of fruit from plants under the shelters significantly increased, and the cracking rate greatly decreased from 95% (control) to approximately 4% (1a-shelter and 2a-shelter), giving rise to an approximately fourfold increase in yield of the sheltered trees. Furthermore, the contents of the total soluble solids (TSSs), soluble sugars (SSs), ascorbic acid (AsA) and anthocyanins of the sheltered fruit differentially increased; conversely, the rain shelters reduced the titratable acid (TA) titers. Therefore, rain shelter cultivation may substantially contribute to the total photosynthetic accumulation and increased fruit yield and has no obvious negative effects on the vegetative growth or fruit quality of cherry trees in Southwest China, which may benefit the cherry industry in this region.