The wonders of yellow netting

Photoselective netting is an innovative technology, by which chromatic elements are incorporated into netting materials in order to gain specific physiological and horticultural benefits, in addition to the initial protective purpose of each type of net (shade-, anti-hail- wind-, insect-proof, etc.). Field studies of plant responses to the photoselective filtration of solar radiation by these nets had provided vast amounts of productive horticultural knowledge, which is already being applied by growers, worldwide. Yet, the particular physiological mechanisms behind the apparent responses could not always be revealed, since these studies were carried under the ever changing environments of light, microclimate and agricultural practices. Physiological understanding can, however, be deduced by analyzing the similarity and variability in the responses of different crop species/cultivars grown in different environments to particular photoselective nettings, and by linking the field results with the molecular knowledge gained under fully controlled conditions. We had previously reported that while Blue shade nets slow down vegetative growth and induce dwarfing in ornamental foliage and cut-flower crops, Red and Yellow nets that reduce the relative content of blue light, are stimulating vegetative vigor. Between the latter two nets, the Yellow repeatedly exceeded the Red net in its stimulating effects. Studies in table grapes revealed that both the Red and Yellow nets delayed fruit maturation, and again the effect of the Yellow exceeded the Red net. The Yellow net additionally surpassed the Red net in its berry enlarging effect. In sweet peppers both Red and Yellow shade nets increased productivity. However, the Yellow, but not the Red net additionally reduced pre- and postharvest fungal decay of the fruit. The latter effect coincided with elevated anti-oxidant accumulation under the Yellow net. This paper discusses crop responses to Yellow netting, and infers a possible connection with the recently proposed green photoreceptor, awaiting its discovery.