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The 2011 ASHS Annual Conference

Photoselective Netting: The Concept, Research and Implementation In Various Crops

Sunday, September 25, 2011: 4:00 PM
Queens 6
Yosepha Shahak, ARO The Volcani Center, Bet Dagan 50250, Israel
Netting is frequently used to protect agricultural crops from excessive solar radiation (shade-nets), environmental hazards (hail, wind, frost), or pests (insects, birds, fruit bats). The nets are either applied as the sole cover (in net-houses), or combined with other covering materials (in greenhouses). The Photoselective Netting represents an innovative concept that promotes the netting technology a few steps beyond the mere protective function. In collaboration with Polysack Plastics Industries, we have developed a series of photoselective (colored) products based on introducing various chromatic additives, light dispersive, and reflective elements into the plastic netting materials. The different ColorNet products selectively screen out defined spectral bands of the solar radiation in the UV and/or visible spectral ranges, concomitantly with transforming direct light into scattered/diffused light. The spectral manipulation is aiming at specifically promoting desired physiological responses, while the scattering improves the penetration of the spectrally-modified light into the inner plant canopy, thus increasing the efficiency of light-dependent processes. Additional aspects of the technology relate to photoselective effects on plant pests and diseases.

Our studies in ornamental crops (foliage, cut-flowers) revealed pronounced effects of the photoselective shading relative to the traditional black shading. These include stimulated vegetative vigor, dwarfing, enhanced branching, and effects on leaf size and variegation, time-to-flowering, and flower quality. In vegetables (bell peppers, tomatoes) we found certain photoselective nets to markedly increase the productivity, compared with the common-practice protection. Moreover, the photoselective features of the shade nets affected the crop infestation by insect-pests and their carried viral diseases, as well as the occurrence of pathogenic fungal diseases. The combined effects resulted in better crop yields, improved fruit quality (both pre- and post-harvest) and lower susceptibility to decay during storage. Netting studies of fruit tree crops, traditionally grown un-netted (e.g. apples, pears, table-grapes) revealed multiple benefits of the netting. The photoselective responsive parameters included productivity, fruit maturation rate, fruit size, and fruit quality.

The lecture will summarize major breakthroughs achieved in ornamentals, vegetables, and fruit crops in Israel, and illustrate practical applications by growers worldwide.