EFFECTIVENESS OF CYTOKININ PREPARATIONS FOR IMPROVING CALLUSOGENESIS AND PHYSIOLOGICAL STATE OF GRAPE CUTTINGS (VITIS VINIFERA L.)
Authors: Artyukh M. M. , Yakuba I. P. , Ruzhytska O. M. , Nazarchuk Yu. S. , Stepanenko N. І. 
Published: February 2024

Problem. Cytokinin hormones are not only regulators of cell division, growth and organogenesis of plants, but also factors of stress resistance, response to adverse environmental factors and adaptation to growth conditions. Propagation and cultivation of valuable varieties of grafted grape seedlings requires testing of new forms of release of the cytokinins in vivo in the conditions of southwestern Ukraine.
Aim. Research of the effectiveness of the use of preparations containing cytokinins for the induction of callogenesis and the improvement of the state of grape cuttings of the grape variety Sukholimanskyi white.
Methods. In the study we used grape scions and seedlings obtained from: scion – Sukholimanskyi white grapes from stepsons 1 cm in diameter; rootstock Riparia x Rupestris 101–14. Rootstocks and scions were treated with growth stimulator X–Cyte produced by Stoller (containing 0.04% kinetin) and with growth stimulator MS Set from Valagro (containing 0.06% zeatin), according to the scheme: 1 – soaking the rootstock and scion rootstocks for 18 hours; 2 – pouring the solution of the growth stimulator into the boxes before planting the scions in the nursery; 3 – three-time vegetation treatments of graft growth with an interval of one month. The control was treated with water. Determination of the intensity of callus and root formation was carried out 21 days after stratification. After the seedlings were dug up, they were sorted, records of the development of the root system were carried out by visual assessment in accordance with GSTU 4390:2005. The influence of treatments with cytokinin- containing preparations on the physiological and biochemical indicators of the development of grape cuttings was determined by physiological and biochemical analyzes using generally accepted methods: indicators of the water regime by the weight method of L. I. Sergejev, K. O. Sergejeva, V. K. Melnikova; the intensity of leaf respiration was determined by the amount of released carbon dioxide according to the Boysen-Jensen method; the content of chlorophylls a and b in the leaves were determined in the alcohol extract with spectrophotometry and calculated according to Wintermans de Mots formulas in the interpretation of Musienko (2001); the content of sugars in the vine was determined by the Bertrand method; the content of starch in the vine was determined according to Pochynk.
The main results. Treatment with cytokinin-containing preparations stimulated rootstock and scion overgrowth with callus around the perimeter, increasing the number of cuttings that formed a complete ring and reducing the number of cuttings in which the callus occupied less than half of the stem perimeter. Also, soaking with cytokinin-containing preparations increased the volume and mass of calluses by 26% to 100%. At the same time, the growth of graft components improves: the number of well-fused grafts increases under the influence of the treatment, and there are almost no grafts with missing signs of growth. Along with the stimulation of callogenesis in the cuttings, an enhancement of organogenesis by X–Cyte and MC Set treatment was observed: the number of root mounds and roots increased by 21 and 61%, respectively, the length increased by 29% under the influence of MC Set, and the weight increased by 39 and 87%; the length of sprouts increased by 62 and 71%, the average weight of the sum of sprouts on the scion increased by 39 and 61%.
In laboratory conditions during the growth of the rootstock with the scion the positive effect of X–Cyte and MC Set treatment is the result of stimulation of cell division, which is a typical manifestation of the action of cytokinin’s. However, in the conditions of the open ground, the possibility of a positive effect of cytokinin drugs on the grafts was observed for the first time in the study area. Treatment, which lasted throughout the summer, increased the survival of grafts in the nursery by a third on average. Under the influence of the drug X–Cyte, the content of chlorophyll increased by an average of 33%, under the influence of MC Set – by 42%. The increase in the content of chlorophyll occurred due to chlorophyll “a”. The indicated effect of spraying with cytokinins corresponds to the classic mechanism of action of this phytohormone – greening of leaves and restoration of chloroplasts. Improving the state of the photosynthetic apparatus as a source of respiratory substrates contributes to an increase in the intensity of respiration by 28 and 22% under the action of X–Cyte and MC Set, respectively. Under the influence of MC Set, the watering of leaf tissues increased by 7%. The easily retained water content was reduced by 24 and 21% with X–Cyte and MC Set, respectively. The water-holding capacity of leaves increased by 21 and 26%. This effect of these cytokinin drugs on physiological parameters was observed in southern Ukraine for the first time.
The action of a complex of stressors during the cultivation of cuttings in a nursery in the conditions of southern Ukraine can reduce the natural level of cytokinins in plants. Exogenous application promotes growth recovery and, as a result, better stress tolerance of plants. It is the more intensive growth that is evidenced by the improvement of the agrobiological indicators of the plants. The length of the shoots increased by 34 and 26%, the diameter and degree of maturation of the shoots increased by a quarter under the influence of MC Set. There is a tendency to increase the number of shoots on the plant, which is a consequence of the stimulation of bud development by cytokinins. The photosynthetic surface of plants increases by increasing the area of individual leaves by 24 and 29% and their number by 26 and 35% under the influence of X–Cyte and MC Set, respectively.
The improvement of the physiological state of the plants of grape cuttings during the growing season contributed to the accumulation of a larger amount of reserve carbohydrates during the transition to the state of winter dormancy. The content of reducing sugars and sucrose increased by 39 and 47% and by 50 and 55% under X–Cyte and MC Set treatments, starch content by 17 and 16%. The main economic result of the use of X–Cyte and MC Set drugs is the yield of standard seedlings, which increased by 27% under the influence of X–Cyte, and by 35% with MC Set.
Conclusions. Treatment of grape buds with X–Cyte and MC Set cytokinins promoted callogenesis and the growth of graft components, organogenesis, and graft survival in the nursery. An improvement in the parameters of the physiological state of Sukholimanskyi white grape seedlings was observed: the content of chlorophyll, the intensity of leaf respiration, indicators of the water regime of leaves and plant growth indicators. Seedlings contained more reserve carbohydrates. Treatment with drugs with cytokinins made it possible to obtain one-third more standard seedlings. The most efficacy was demonstrated by MC Set preparations from Valagro with a cytokinin content of 0.06%.