The review referred to below examines what is known about their effects on the local environment of crops and on the crops themselves and the varied uses to which these nets have already been put.
One consequence of covering plants with any form of netting is that less light reaches them. This can be an advantage in summer, as it helps in reducing heat stress, but it will usually be a disadvantage in winter as light loss produces poorer growth and yield.
Nets also scatter light and there is some evidence that this can improve light interception, branching and compactness in some plants.
The particular merit of coloured nets is that they modify the colour of the light reaching the plants and this can modify branching, stem length, leaf size and flowering.
Furthermore, the nets can be manufactured to produce whatever light quality is required.
The review briefly discusses all of these matters and summarises the outcome of using coloured nets on crops in protected cultivation as well as on crops in the field, such as apple.
Use of Coloured Shade Netting in Horticulture by Stamps (2009). HortScience 44 (2): 239-241. Members of ISHS can view HortScience from the website www.ishs.org.