ColorNets: A new approach for light manipulation in fruit trees

We introduce here a new approach for improving the utilization of solar radiation by fruit trees. This approach is based on selective filtration of the light by plastic shade nets (cloths) with special optical properties that modify the quality of natural radiation. A series of colored shade nets (ColorNets) were developed to specifically modify the incident radiation (spectrum, scattering and thermal components). Depending on the pigmentation of the plastic and the knitting design, the nets provide varying mixtures of natural, unmodified light, with spectrally modified scattered light. Use of the nets aims to optimize desirable physiological responses, in addition to providing physical protection. Following the substantial effects of several ColorNets on shoot elongation, branching and flowering in ornamentals (Oren-Shamir et al., 2001), we have applied the colored netting to deciduous fruit trees. The experiments were carried out in commercial apple and peach orchards, using ColorNets with reduced shading factors (15-30%, compared with the 50-80% used in ornamentals). The first year results show positive effects on flowering, fruit-set, fruit size, colour and internal quality, in addition to non-specific reduction of water stress, superficial damage, and sunburn. This approach opens new perspectives for improved performance of fruit tree orchards under specialized protection.