IMPROVING SOLAR ENERGY UTILIZATION, PRODUCTIVITY AND FRUIT QUALITY IN ORCHARDS AND VINEYARDS BY PHOTOSELECTIVE NETTING

Nets are frequently used to protect agricultural crops from excessive solar radiation, environmental hazards or pests. We have developed a new concept, by which the nets are designed to specifically filter sunlight, concomitant with providing the desired physical protection. A series of photoselective nets (ColorNets) was developed for outdoor use, each one absorbing different spectral bands, and at the same time increasing the relative proportion of scattered/diffused light. The spectral manipulation is aimed at specifically promoting physiological responses, while light scattering improves light penetration into the inner canopy. The relative enriching of the intercepted light with "good" parts of the spectrum, while reducing "bad" parts, may allow better utilization of the solar energy. Earlier studies of ornamental crops, traditionally grown under black shade nets, revealed differential responses to the photoselective shading. Ongoing studies of low-shading ColorNets in numerous fruit crops and climatic regions showed that nets of the same shading factor but different chromatic properties can differentially affect various attributes of tree performance, including production, fruit size and quality, and advancement or delay in the timing of harvest. The netting further ameliorates extreme climatic fluctuations, reduces heat/chill stresses, and improves the resulting canopy activity and water use. The results demonstrate the potency of photoselective netting for improving the agro-economical performance of horticultural crops, especially (but not only) in harsh climates and arid zones.