To determine the average distance of apple roots from the tree bole for calculation and substantiation of the layout of drip and under-crown irrigation, the technique was developed. We considered two variants of calculating the average distance of roots from the tree bole. According to the first one, the whole circle of the root system was divided by small sectors pursuant to the dissolution angle of radial sides (1/2 or 1/4 of the circle according to the given scheme). According to the second variant, the area of root system projection was determined. The average distance of roots from the tree bole was according the first calculation variant as follows: for ‘Lithuanian Pepinka’ grafted on doucin III (360°) – 0.79 m, for ‘Anise Gray’ grafted on the forest apple (180°) – 4.04 m, and for ‘Reinette Simirenko’ grafted on the forest apple (90°) – 3.92 m; according to the second calculation variant: 0.66 m (relative error for measuring parameter is 13 %), 3.96 m (relative error – 2 %), and 3.91 m (relative error – 0.25 %), correspondingly. Assuming for practical use the values of relative errors for measurements, it is possible to determine the average root system radius for schemes with sector of 90° using sectors of 15°, 180° using sectors of 30°, 360 using sectors of 60°. When the asymmetry of the root system scheme is evident, small sectors of 10° should be used for digging sectors of 90°, 20° – 180°, 45° – 360°, correspondingly. The variant, which provides finding the average distance of roots from the tree bole by determine the area of root system projection, is better appropriate for incomplete schemes, which have the sectors of 90° and 180°.
Keywords: stock, graft, root system, root distance, section, tree bole.
