EFFECTS OF ORCHARD MULCHING WITH REFLECTIVE MULCH ON APPLE TREE CANOPY IRRADIATION AND FRUIT QUALITY

A B S T R A C T Effects of reflective mulch spread under apple trees on irradiation within tree canopy and fruit quality of ‘Pinova’, ‘Jonagold’ and ‘Jonagored’ cvs was studied during three growing seasons. The results showed that in ‘Pinova’ trees irradiation within a canopy was reduced by leaf shading to 26% at 0.5 m, 31% at 1.0 m, 42% at 1.5 m and 48% at 2.0 m above the ground as compared to solar irradiation above the tree. Reflective mulch increased reflected light intensity 8 times at 0.5 m, 4 times at 1.0 m, 2 times at 1.5 m and by 10% at 2.0 m when compared to bare soil. Reflective mulch improved red color of ‘Pinova’ apples in the bottom zone of tree canopy only. There was no effect of reflective mulch on quantity of apples and mean fruit weight. In ‘Jonagold’ trees light intensity was reduced by leaf shading to 18% at 0.75 m, 24% at 1.5 m, and 36% at 2.25 m as compared to that above the tree canopy. Reflective mulching increased reflective light 7 times at 0.75 m, 2 times at 1.5 m and by 10% at 2.25 m above the ground. In the bottom zone, up to 75 cm from the ground, there were 2 times more well colored fruit (with red blush on surface over 50%) on trees mulched than on the control. Mulching had no influence on quantity of apples and mean fruit weight. The biggest 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. Irradiation within ‘Jonagored’ apple canopy, fruit and leaf distribution was similar to these in ‘Pinova’. In the season 2004, reflective mulching improved significantly red blush on ‘Jonagored’ apples, and in the next season there was no effect because on mulched and control trees all apples had 100% of red skin. There was no significant influence of mulching in June on fruit bud setting, fruit set, mean fruit weight and fruit firmness.