Radiometric properties of coloured nets for peach tree protected cultivation

Alteration of spectral wavelength distribution of the solar radiation influence plant growth, development and productivity, thus the nets can be used for the purpose of vegetative control for tree cultivated under covering materials instead of use of growth regulators. Changes in red radiation (R, 600-700 nm), in far-red radiation (FR, 720- 740 nm), or in blue radiation (B, 400-500 nm) in the growing environment affect plant photomorphogenesis, involving the activation of photoreceptors, such as the phytochrome. The phytochrome response is studied in terms of the bichromatic R/FR ratio of the photon fluence rate in the red to that in the far-red. The aim of this paper is to investigate the influence of the radiometric properties of coloured nets on peach tree morphogenesis, by studying the modification of the spectral distribution of the transmitted radiation and thus the effects on the tree vegetative cycle. The radiometric properties of the nets were evaluated by means of laboratory tests. A field experimental test using different coloured nets (BLUE, RED, PEARL, GREY and YELLOW) for the protection of peach trees was carried out. Peach trees in OPEN FIELD conditions were used as control. The RED and BLUE nets influenced mainly the B/FR ratio: the former net decreased and the latter increased the B/FR ratio. The growth of the trees cultivated in OPEN FIELD was lower in comparison to the growth of the trees grown under the nets. The RED, PEARL, YELLOW and GREY nets increased the growth of the trees more than the other nets