CALLUS FORMATION AS A PHYSIOLOGICAL SIGN OF AUXIN LACK IN THE COMPOSITION OF A RHIZOGENESIS STIMULANT (BASED ON THE EXAMPLE OF IN VIVO ROOTING OF CONIFEROUS CROPS CUTTINGS)

Characteristics of the effectiveness of rooting of coniferous crops are the percentage of rooting, the number of roots formed and their length. Callus formation often accompanies the rooting process, but research data on the relationship of this process with the effectiveness of rooting is contradictory. In the conditions of film cuttings equipped with heated substrate, studies were carried out on the relationship between the rooting of cuttings of coniferous crops and callus formation. To stimulate the rooting of semi-lignified cuttings of Juniperus scopulorum S. cultivar Skyrocket, growth powders Chrysatop and Rizapon 1% containing indolyl-3-butyric acid (IBA) in different concentrations were used. In the control treatment without a stimulant, all cuttings formed callus without rooting; when the bases of the cuttings were dusted with Chrysatop containing 0.25% IBA, callus formation decreased by 3.8 times, and the survival rate was 76%. In the variant with Rizapon powder containing 1% IMC, no callus formation was observed at all, the survival rate reached 81.4%. To stimulate the rooting of green cuttings of Juniperus scopulorum S. variety Blue Arrow, aqueous solutions of potassium salt IMC (IMC-K) were used in the concentration range from 0 to 150 mg/l when the bases of the cuttings were soaked for 16 hours. In the concentration range from 0 to 100 mg/l, an increase in survival rate by 1.89 and 3.87 times was observed, respectively, callus formation decreased by 3.38 times. To stimulate the rooting of semi-lignified cuttings of Thuja occidentalis L. variety Smaragd, Juníperus sabina L. species form and green cuttings of Thuja occidentalis L. variety Brabant, Kornevin growth powder containing 0.5% IBA was used. To obtain a concentration gradient, the powder was diluted with talc. Against the background of high survival rate of cuttings of Thuja occidentalis L. of both varieties – 82.85–96.9%, callus formation decreased from 92.9% in the control variant to 6.3% in the variant with pure Kornevin in cuttings of the Smaragd variety and from 71.88% in the control variant to 19.1% in variant Kornevin:talc 1:1 in cuttings of the Brabant variety. When rooting cuttings of Juniperus sabina L. with an increase in the concentration of IBA in the powder from 0 to 0.25% IBA, the survival rate increased from 10.71 to 89.29%, and the formation of callus on the cuttings decreased from 44.59 to 0%. The data obtained indicate that calus formation can serve as a sign of a lack of exogenous auxin in the rooting stimulator and, accordingly, an increase in the auxin content, all other things being equal, within the effective range is one of the ways to increase the percentage of survival of cuttings of coniferous crops.