THE EFFECT OF A PLANT GROWTH STIMULATOR (RIBAV-EXTRA) AND GRAFTING TERMS ON THE ROOTABILITY OF CLONAL PEAR ROOTSTOCKS

Ribav-Extra is a drug used to increase seeds germination and planting material, it stimulates growth processes throughout the growing season, thus, thanks to it, the root system builds up on various cuttings (softwood, hardwood), provides balanced plants nutrition with mineral elements and increases plant resistance to pests, diseases and various stressful conditions. It also increases yield and product quality. Investigation of terms of reproduction by softwood cuttings was carried out at I.V. Michurin Federal Scientific Centre Breeding and Genetic Centre – I.V. Michurin Russian Research Institute of Genetics and Fruit Plants Breeding. Object of research: clonal pear rootstocks – PG 2, PG 17-16, PG 333, ‘Kavkazskaya’, K-1, K-2, 4-26, 4-39, OHF 333, Piro II. The regionalized pear form PG 12 was used for control. An aqueous solution Ribav-Extra (1.0 mg/10 l) for 18 hours was used as substances stimulating the processes of root formation. As a result of the conducted studies, it was found that when softwood pear cuttings were taken from parental bushes in early June (June 07), as well as in mid-June (June 20) and when sections were treated with a plant growth stimulator Ribav-Extra (1.0 mg /10 l) for 18 hours and without the growth stimulator, plants PG 17-16, PG 12 (k), PG 2, PG 333 were recorded as ones having the highest rooting ability and yield of standard layers. The highest rates of growth height, number and length of roots in early June (June 07), as well as in mid-June (June 20) when using the plant growth stimulator Ribav-Extra and without tha plant growth stimulator were recorded in clonal pear rootstocks PG 17-16, PG 12 (k), PG 2, PG 333.