Polymer and photo-selective covers on plant and fruit development: A review

Growers have increasingly adopted protected cropping in tunnels or greenhouses to ensure sustainability and continuous crop productivity against a backdrop of climate change. The predominant types of covers used in controlled-environment agriculture are polymer-based shade nets or structures covered with polymer sheets. These have three main functions: (1) physical protection from birds, hail, and excessive radiation; (2) modification of the environment by controlling humidity, shade, and temperature; and (3) increasing the proportion of diffuse light. In order to address concerns regarding the amounts of useful light potentially blocked by these covers, researchers and growers have suggested several innovative solutions that involve altering the light received by plants. This includes supplementation of artificial illumination, filtering solar radiation with colored films, or altering the incident spectrum with spectral-shifting covers containing light-emitting fluorescent compounds embedded within a polymer matrix. In principle, any of these methods have the potential to selectively modify the spectrum of incident light and subsequently induce plant physiological responses, resulting in increased crop yield, improved fruit quality, and reduced susceptibility to pests and diseases. This review focuses on the benefits offered by passive covers in terms of their variable shading and light transmittance properties and their effects on vegetative growth and fruit development in various crops. It is anticipated that through a better understanding of photo-selective covers in protected cropping, primary producers will be better equipped to make informed decisions regarding their deployment and thereby achieve better yields and more nutritious produce from their crops. Experimental covers with photovoltaics limit horticultural production.Light-shifting covers with perylene dyes or nanocrystals require further development.Photo-selective covers suit high light intensities and light-shifting ones suit low light.Photo-selective covers promote yield but block UV, limiting secondary metabolites.Supplementary blue light-emitting diodes may increase flavonoids under photo-selective films.

Automated summary

Growers are using protected cropping to ensure sustainability and continuous crop productivity amidst climate change. Polymer-based shade nets and structures with polymer sheets are being used for physical protection, modification of the environment, and increasing diffuse light. Innovative solutions like artificial illumination, colored films, and spectral-shifting covers are being explored to address concerns about blocked useful light. These methods have the potential to increase crop yield, improve fruit quality, and reduce susceptibility to pests and diseases. This review focuses on the benefits of passive covers in terms of shading, light transmittance, and their effects on vegetative growth and fruit development in different crops.