Coloured hailnets alter light transmission, spectra and phytochrome, as well as vegetative growth, leaf chlorophyll and photosynthesis and reduce flower induction of apple

Abstract

In view of alleged positive effects of coloured (red) hailnets on phytochrome, photosynthesis, yield and fruit quality, the objective of the present work was to investigate a range of red and green hailnets using apple as a model crop with cvs. 'Pinova' and 'Fuji Kiku 8'. Light transmission of green or red hailnets peaked between 500 and 570 nm (green) or above 570 nm (red-orange) and was reduced by 12% (white) or 14% (red-white), 18% (red-black) and 23% (green-black) hailnets; there were no effects on phytochrome. Leaf chlorophyll concentration increased under coloured hailnets by up to 46% under the green-black hailnet, while air temperature was reduced by 0.2°C. Under sunny conditions, photosynthesis of ca. 18 lmol CO 2 m -2 s -1 was not reduced under coloured hailnets, in contrast with a 21% reduction under cloudy conditions with a concomitant reduction in transpiration by 13%. Vegetative growth was affected in different ways: shaded trees showed smaller trunk diameter, but increased the number and length of their 1-year shoots under coloured hailnets, particularly with cv. 'Fuji' when grown under greenblack hailnet. Hailnets reduced flower induction in June and return bloom in the next spring to the same extent as they reduced the light transmission. Overall, tree growth under coloured hailnets was genetically influenced, with cv. 'Fuji' being more prone and sensitive to adverse effects of coloured hailnets than cv. 'Pinova', but is also influenced by the environment.

Light quality management in fruit orchards: physiological and technological aspects

“…Changes in leaf chlorophyll content were also detected under different light quality conditions in citrus trees: plants under nets with more B light proportion had the greatest leaf chlorophyll a, b and total chlorophyll content, compared to those with more R light proportion (Li and Syvertsen, 2006). In apple trees, leaf chlorophyll synthesis under nets with more R and G light transmission was up to 46% highest (Solomakhin and Blanke, 2008). Recent studies demonstrated prolonged exposition of apple leaves under nets with more light transmission in the B spectra increased the leaf stomatal conductance and leaf transpiration (Bastías et al, 2011), probably by direct effect of B light on stimulation of stomatal opening has been previously reported (Farquhar and Sharkey, 1982;Shimazaki et al, 2007).…”

“…In apple orchards, red net improved fruit size compared to black net (Shahak et al, 2008). Solomakhin and Blanke (2008) also reported increased apple fruit size under colored nets, but without effect on yield. In peach, fruit grown under red nets were firmer, sweeter and fruit size was also improved (Shahak et al, 2008), while in highbush blueberries (Vaccinium corymbosum L.), red and white nets increased the number of fruits and yield per plant in comparison with traditional black net (Retamales et al, 2008;Lobos et al, 2012).…”

“…In contrast, the red and blue nets altered widely the spectral light distribution. Red net increased the light transmission in R and FR spectra (600-800 nm), while the blue net enhanced the proportion of B light (400-500 nm) and reduced the R light proportion (600-700 nm) (OrenShamir et al, 2001;Shahak et al, 2004;Solomakhin and Blanke, 2008;Bastías et al, 2011;Lobos et al, 2012).…”

Influence of plant growth-promoting rhizobacteria (PGPR) on blackberry (Rubus glaucus Benth. cv. thornless) growth under semi-cover and field conditions

“…In experiments carried out with apple (Malus domestica Borkh. ), induction of flowering was inhibited by plastics of different colors, demonstrating that the quality of solar radiation is an important factor in variables of agronomic relevance in this crop (Solomakhin & Blanke, 2008).…”

Influencia Del Uso De Malla Perla Y Roja en Las Condiciones Micro-Climáticas, Daño Por Sol Y Desarrollo De Color De Frutos en Huertos De Manzanos Cvs. Gala Y Fuji

“…el efecto positivo de la radiación difusa sobre el intercambio gaseoso de la planta puede ser atribuido a que estas condiciones micro-climáticas de luz resultan favorables en la reducción de la temperatura de la hoja promoviendo así la apertura estomática (URBaN et al, 2007).…”