The effect of cultivation conditions on the growing processes of grape plants in vitro

. One of alternative ways to maintain valuable genetic material is to develop optimal conditions for cultivation in an in vitro system. The goal was to evaluate the condition of plants based on changes in the shoot length indicator in order to explore the maintaining mode of the collection. We took the experimental samples from the “Vegetating collection of plants in vitro of promising varieties and clones of grapes”: 13 local Crimean varieties and 9 varieties of the Institute Magarach selection. Plant containing culture bottles were in the cold storage without internal lighting at 10-12°C for 6 months. The cultivation findings demonstrated that grape varieties differed in viability and intensity of morphogenesis. Moreover, after storage, they had a high regenerating ability of the buds.


Introduction
One of alternative ways to maintain valuable genetic material is to develop optimal conditions for cultivation in an in vitro system [1][2][3][4][5]. The preservation of viable samples in the form of vegetating collection in vitro gives the opportunity to maintain samples of viable grape plants of promising varieties and clones in sterile environment. When the storage mode is optimal, the collection takes up little space, requires minimal concentrations of mineral substances and rare replantation of plant samples [5][6][7][8]. To preserve, improve and further mass reproduce, a "Vegetating collection of plants in vitro of promising varieties and clones of grapes" has been created at the Institute Magarach [9]. The collection includes varieties, hybrid forms of the Institute Magarach selection, rootstock varieties, as well as clones of wine grapes. The collection is supported in increased growth mode and in a true dormancy without the use of osmotic adjustment agents and retardants. Today it has more than 100 samples.
The process modes have been developed to preserve the plants of vegetating collection without additional replantation for one year in two cultivation modes: in the light and in the dark [10]. The optimization activities for the maintenance of the collection are in progress.
For defining the optimal characteristics of the main cultivation factors affecting the morphogenesis of plants in the in vitro system, it is reasonable to trace changes in growing processes in a long-time interval. Our paper aims to evaluate the condition of plants on the The plant samples were propagated by micrografting. They were cultured for four weeks on a hormone-free PG medium, at a 16-hour photoperiod; the temperature was +25-27 o C [11]. Afterwards, plant containing culture bottles were in the cold storage without internal lighting at 10-12°C for 6 months. We monthly recorded changes in the plant shoot length indicator.
To identify regenerating ability of the bud, two-eyed sprouting explants of shoots were planted in a medium MS with 6-benzylaminopurine (BAP) at a concentration of 0.5 mg/l [12]. They were cultivated for a month in a light room at +27 o C and a 16-hour photoperiod.
The findings were assessed basing on changes in the shoot length indicator.

Results and discussion
It is known that the main factors affecting plant morphogenesis are lighting, temperature, photoperiod, and cultivation environment. Decreasing the temperature in extremely low light should have resulted in deceleration of growing processes. The growing processes have partially been decelerated. Nevertheless, they have not stopped. Among the plants of the studied varieties, the pattern was mixed (table 1). After plants were transferred to cultivation conditions at +10-12 о C, without additional lighting, shoot growth in all the studied varieties has practically stopped. The plants were under stress. Following five months of cultivation, the pttern has fundamentally changed ( fig. 1). Under such conditions some varieties were viable for five months. In the sixth month of cultivation, leave decay and branch necrosis of plants of the varieties 'Shira Izium', 'Khalil Izium' and 'Kokur Krasnyi' had begun.
In the remaining plants of other local varieties, both the suspension of morphogenesis and a certain shoot growth were observed ( fig. 2). According to the rate of shoot growth, the experimental samples were divided into three groups, characterized by a lack of growth, a weak growth increase, and a significant growth increase.   The exception was the plants of 'Antei Magarachskiy' variety. Morphogenesis has practically stopped in them (table. 2). According to the change in the number of internodes, we have observed mainly the apical growth. The initial length of shoots by varieties ranged from 1.34 cm ('Spartanets Magaracha') to 3.58 cm ('Granatovyi Magaracha'), which did not further influence the morphogenesis. The plants were marked by a weak, medium, and significant growth of shoots, depending on the variety. After six months of cold storage cultivation at +10-12 о C without additional lighting, the bud viability of local varieties was tested. In most varieties, the good viability of buds was preserved ( fig.4). Some varieties had partial wilting of regenerated shoots.