ISHS Acta Horticulturae 732: VIII International Symposium on Canopy, Rootstocks and Environmental Physiology in Orchard Systems
ATTEMPTS ON IMPROVING LIGHT RELATION AND APPLE FRUIT QUALITY BY REFLECTIVE MULCH |
| Authors: | A. Mika, W. Treder, Z. Buler, K. Rutkowski |
| Keywords: | 'Jonagold', 'Pinova', apple, canopy, mulch, reflective light |
| Abstract:
Canopies of 'Pinova' apple trees on M.9 rootstock, planted in 1999 at 3.5 x 1.4 m and trained as spindles, were subdivided in the spring of 2003 with bamboo canes into 60 cubes (0.5 x 0.5 x 0.5 m) per tree. In each cube, the number of fruits, fruit quality and leaf area were determined. In the summer of 2003, light levels in 5 horizontal zones were measured four times. The results of light measurements were converted to the percentage of light within the tree canopy in relation to that above the tree. To increase canopy illumination, the soil under trees was mulched at the end of May with reflective sheets consisting of polypropylene fabric with aluminium foil. Two sheets 0.7 m wide were spread on both sides of tree trunks along the tree row. Trees grown on bare soil maintained by herbicides served as the control. The experiment was also conducted on 'Jonagold' apple trees on P22 rootstocks planted in 1990 at a distance of 3.5 x 1 m, trained as spindles. All measurements were done in 3 horizontal layers: 0 to 0.75 m, 0.75 to 1.50 m and 1.50 to 2.25 m above the ground. Leaf shading reduced light intensity in 'Pinova' trees to 26% at 0.5 m, 31% at 1 m, 42% at 1.5 m and 48% at 2.0 m above the ground compared to above the tree canopy. Reflective mulch increased reflective light 8-fold at 0.5 m, 4-fold at 1 m, 2-fold at 1.5 m, and 10% at 2 m compared to bare soil. Reflective mulch improved red colour of 'Pinova' apples only in the bottom zone of the tree canopy. There was no effect of reflective mulch on number of apples or mean fruit weight. In 'Jonagold' trees, leaf shading reduced light intensity to 18% at 0.75 m, 24% at 1.5 m and 36% at 2.25 m compared to above the tree canopy. Reflective mulching increased reflective light 7-fold at 0.75 m, 2-fold at 1.5 m and 10% at 2.25 m above the ground compared to bare soil. In the bottom zone, up to 75 cm from the ground, there were 3 times more well colored fruit (red blush on over 50% of the surface) on mulched compared with unmulched trees. Mulching had no influence on apple number or mean fruit weight. The highest leaf area was found at the horizontal layer between 1.5 and 2.0 m. Leaf area index assessed per canopy cast to the ground was 0.45. | |
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