USING BLACK WALNUT ROOTSTOCK FOR CREATING HIGH-YIELDING WALNUT PLANTATIONS

Abstract

The comparative analysis of seed germination and growth of walnut and black walnut seedlings in the conditions of the Right-Bank Forest-Steppe of Ukraine was carried out. It was found that in rows with a sowing depth of 10 cm and 13 cm, the germination rate of walnut had the highest rates and amounted to 70% and 63%, respectively, and black walnut - 80% and 84%. The lowest germination rate was observed at a sowing depth of 17 cm for walnut and 6 cm for black walnut, 46% and 39%, respectively. The influence of the position of the walnut seeds on their germination was determined. In particular, when sown by the "top up" and "on the edge" methods, the germination rate was 70% and 72%, which is 24-26% higher than the "top down" and "side by side" methods. The germination energy of black walnut seedlings was found to be higher than that of walnut seedlings. The first signs of germination of black walnut were observed 7 days earlier than in field crops of walnut. It was found that the main growth of seedlings in height began from the end of the first decade of June and lasted until the first decade of August. The average height of black walnut seedlings was 50 cm, while the average height of walnut seedlings was 19 cm lower and amounted to 31 cm. The yield of standard black walnut seedlings was recorded at 69% of the total number of seedlings, while in walnut this figure was only 12%. The compatibility of the varieties 'Webu-6', 'Chandler' and 'Kazaku' with black walnut and walnut during the cultivation of grafted seedlings was studied. It was found that the selected experimental varieties of walnut, which were grafted onto black walnut seedlings, showed approximately the same formation of callus tissues, except for the variety 'Vebu-6'. This once again confirms the information that not all walnut varieties can participate in interspecific combinations. It was found that the length of the central root of the black walnut at the end of the first year of cultivation is 15 cm longer than the length of the central root of the walnut and averages 43 cm. The main branching of lateral roots in walnut occurs at a depth of 10 to 20 cm. The number of main skeletal roots is generally 3-4 units. At the end of the first year of cultivation, the seedlings had a significantly smaller root system compared to black walnut. The root system of standard black walnut seedlings is on average 60% larger than that of walnut. The main branching of lateral roots is on average at a root length of 7 to 30 cm. Similar to the walnut, the root system of black walnut has 2-3 tiers. The number of skeletal roots averages 8-10 pieces, and the length of the main skeletal roots ranges from 15 to 30 cm. According to the research results, it can be concluded that walnut seedlings grafted on black walnut seedlings have prospects for further introduction into production as they can bear fruit faster, have relatively restrained growth, allow for the formation of a crown at the 3rd year of life and have a more powerful root system.