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UDC 634.11:631.526.32:581.19:111.6
PARAMETERS OF APPLE TREE VARIETY RESISTANT TO WINTER UNFAVORABLE CONDITIONS
Krasova N.G., Doctor of Agricultural Sciences State Scientific Institution of All-Russian Research Institute of Horticultural Crops Selection of the Russian Academy of Agricultural Science, Orel City, Russia Phone: +7 (4862) 42-11-39, E-mail: info@vniispk.ru
ABSTRACT
Uncontrolled factors of the environment significantly reduce apple yielding power. Tree winter resistance is considered to be one of the basic indexes of adaptation. Certain resistant apple varieties have been revealed. The problem of manifestation of the mechanism of the resistance to winter unfavorable conditions is considered in this paper. A positive tendency has been revealed at the relationship between the contents of saccharose, proline, anthocyans, cyanidines and proteins in one-year shoots and winter resistance of apple varieties. A pattern of the apple variety resistant to winter unfavorable conditions is suggested.
KEY WORDS
Apple; Variety; Winter resistance; Saccharose; Proline; Anthocyans; Pattern of winter resistance.
One of the main factors defining the possibilities of variety cultivation in definite conditions is the tree ability to resist to unfavorable winter conditions. Winter-hardiness is defined with a complex of processes and reactions taking place in the plant organism and defining formation of resistance to unfavorable conditions. Development of fruit tree frost resistance takes place in the autumn period as a result of long preparation connected with intensity and orientation of physiological processes and transition from growth to rest. In this period as a result of decrease of metabolism activity during autumn hardening the accumulation of starch with the following its hydrolysis, accumulation of sugars, tanning substances, protein synthesis in shoots and buds and their complexing with other compounds - nucleic acids, lipids and etc. takes place [9].
The active synthesis of some other low molecular organic compounds is observed. The special role is played by the amino acid proline that together with saccharose protects proteins from inactivation in the dehydration conditions and decreases the temperature of protoplast content freezing. Anthocyans especially in the form of cyanidines influencing the light and temperature mode of a cell provide plant preservation at low temperatures [7].
The goal of this research is finding out the mechanism of resistance to winter unfavorable conditions of apple tree varieties on the basis of application of field and indirect physiological and biochemical methods of testing and development of basic parameters of apple tree variety resistant to winter unfavorable conditions.
MATERIALS AND METHODS OF RESEARCH
The researches are done on the areas of the primary and production study of apple tree of State Scientific Institution of All-Russian Research Institute of Horticultural Crops Selection of the Russian Academy of Agricultural Science (GNU VNIISPK) applying the methods of field evaluation of winter resistance (1972-2012 years) and by means of modeling of damaging factors in the freezing chamber «ESPEC» PSL-2 KPH (2009-2012 years) [8, 10] taking into account the main components of frost resistance: ability for fast hardiness and resistance to premature frosts (I component), resistance to critical frosts in the middle of winter (II), ability to keep hardiness in thaw periods (III), ability for returned acquisition of hardiness and frost resistance after thaws (IV). Damage evaluation is done by
the method of growing of branches in the vessels with water at room temperature taking into consideration the degree of fabric on longitudinal and cross sections using six rating scale (from 0 to 5), where 0 points- damages are absent, 5 points - fibers and buds died.
Together with traditional methods biochemical methods were used [3, 4]. The varieties of different genetic and geographic origin are included into the research, among them there are varieties of All-Russian Research Institute of Horticultural Crops Selection. The variety selected by local inhabitants “Antonovka” was taken as a plant sample and deficiently winter resistant variety Priam was taken for comparison.
RESULTS AND DISCUSSION
Natural and climatic conditions of the Orel region are good for apple tree growing. Absolute temperature minimum in the Orel region is minus 38 -44°C, but in 90% of year’s absolute minimum can be from minus 24°C to minus 28°C, but absolute maximum to 30-33°C. Average air temperature of the coldest month - January is from minus 8,7°C to minus 11,1°C. Annual precipitation is from 480 to 610 mm. Average annual long-term air temperature is 4,6°C, average temperature of summer months is minus 8,4°C.
According to the data of meteorological station of All-Russian Research Institute of Horticultural Crops Selection of the period from 1968 to 2012 years there were 16 winters with the average temperature of winter months lower than the average long-term temperature and 6 times lower -10°C.
For this period there were 11 winters with the sum of average daily negative temperatures more than 1000°C, from them four winters with the sum of average daily negative temperatures more than 1200°C. Temperature minima lower minus 30°C were repeated 17 times, among them 3 times - lower minus 35°C in the air and 7 times - on snow surface. Maximum air temperature minus 40,0°C was recorded in winter 2011/2012. Minimum temperature on snow surface was minus 39,3°C (winter 2005/2006) and minus 40,0°C (winter 2011/2012) in the air.
Different types of winters according to unfavorable conditions combination were distinguished. The most unfavorable conditions for apple tree over wintering were winter conditions in the years with the sum of average daily negative temperatures more than 1200°C, with long frosts lower minus 30°C and average temperature of winter months lower minus 10°C. Serious subfreezing of aboveground part of some apple tree varieties were found out also in severe winters, if frosts were in after long thaws (1975/76 years), when trees woke up from deep dormancy and the fiber ability to hardiness and keeping frost resisting condition was lost. At such kind of winters with snow cover branches woody tissue, bark of a stem and boughs forks and fruit formation were damaged first of all.
As the result of study of resistance to winter unfavorable conditions the apple tree varieties of different genetic and geographic origin are distributed into the winter resistance groups (Table 1).
Many new varieties of national selection demonstrated sufficient winter resistance, their insufficient winter damages did not cause much harm and did not decrease yield amount. High resistance to winter unfavorable conditions at their different combinations in local varieties is found out (Cinnamon striatus, Grushovka moskovskaya, Skryzhapel, Babushkino, etc.). These varieties are characterized with high resistance not only to low temperature, but they do not lose this resistance even after thaws. Bark on stem and boughs of these varieties doesn’t suffer from burns, in some winters only light subfreezing of ends of annual growth.
The majority of new apple tree varieties of selection of All-Russian Research Institute of Horticultural Crops Selection in the horticulture middle zone showed sufficient winter resistance.
With some little damages, without yield loses varieties Veteran, Mezenskoye, Orlovskoye striatus, Orlik, Orlovim, Orlinka, Kulikovskoye, Pamyat’ voinu, Sinap orlovsky, Orlovskaya zarya, Pamyat’ Semakinu, Prishvinskoye, etc. endue unfavorable winter conditions in the run of many years. New immune varieties of selection of All-Russian Research Institute of Horticultural Crops Selection (with gene Vf), obtained from crossing of
local adapted varieties and immunity donors, also showed good winter resistance: Bolotovskoye, Zdorovye, Imrus, Svezhest’ Kandil orlovsky, Stroevskoye, Orlovskoye Polesye, Solnyushko, Venyaminovskoye, Rozhdestvenskoye, Start - in winters 2005/06 and 2011/2012 years subfreezing of fibers of buds and shoots on the level of Antonovka obyknovennaya is marked. It didn’t cause any sufficient harm to trees [5].
Table 1 - Distribution of apple tree varieties according to winter resistance groups (%)
Variety Number of studied varieties Also according to winter resistance groups, %
Highly winter resistant Winter resistant Moderately winter resistant Insufficiently winter resistant Non winter resistant
West European and american 235 - - 9,4 75,3 15,3
National selection of middle Russia 461 0,9 44,9 46,2 8,0 -
selected by local inhabitants 105 15,2 57,1 24,8 2,9 -
Ural-Siberian 54 16,7 74,0 9,3 - -
Total 855 3,4 35,9 31,3 25,2 4,2
As the result of artificial freezing at modeling different damaging factors of winter period high resistance of vital fabric (bark, woody tissue, cambium) was found out using 4 winter resistance components with reversible damage with not more than 2 points in varieties Antonovka obyknovennaya, Avgusta, Bolotovskoye, Vita, Imrus, Nadezhnoye, Sinap orlovsky, Yablichny spas, and also - Afrodita, Darena, Venyaminovskoye, Pamyat’ voinu. Freezing temperature minus 42 °C in the middle of winter with bark and woody tissue damage which does not exceed 2,5 points was endured by varieties Avgusta, Afrodita, Venyaminovskoye, Vita, Darena, Imrus, Nadezhnoye, Sinap orlovsky, Yablichny spas.
Realization of potential frost resistance of fruit plants is connected with their preparation to wintering and their reaction to medium unfavorable factors that decrease resistance level in cold time. High winter resistance is formed gradually, increasing after growth cessation, transition into the rest state, hardening by low positive temperatures and at considerable increase of frost resistance at final stage. Among various substances forming biological systems the main role belongs to macromolecules containing nitrogen atoms -proteins and nucleic acids. Protein metabolism is the most important and complicated process in the tree organism life activity. During deep dormancy protein storage and complicated structural metabolic process increasing winter resistance and creating energy implications for vegetation take place in plants. At winter end in the most critical for tissues and buds period of unstable temperatures the accommodation reaction of increase of protein and free amino acids (FAA) number in buds and bark is developed after low temperatures impact. Among FAA the considerable role in protection from abiotic stressors is played by praline. Low praline content in bark and its sharp decrease after freezing is typical for low resistant apple tree varieties [1].
In the period of deep dormancy in apple tree tissues as a result of starch hydrolyze oligosaccharides and also saccharose that plays protective role in formation of winter resistance to unfavorable conditions are synthesized. The higher saccharose content is defined in that period in annual branches (especially in bark) of winter resistant varieties of Antonovka obyknovennaya, Imrus, Sinap orlovsky, Svezhest’ and other in comparison with low winter resistant west European variety Priam.
The increase of bound water form in shoots tissues and longer deep dormancy are typical for winter resistant apple tree varieties in that period. One of the indicators of plant adaptation to winter unfavorable conditions is coordinated, quick response system of oxidation respiratory enzyme. In the course of plant adaptation the change of enzyme systems activity - activity increase of ones and activity decrease of others takes place. In autumn and winter period winter resistant apple tree varieties are characterized with
respiration intensity decrease, peroxydase activity drops, and peroxydase activity of non winter resistant apple tree varieties remains at high level. In December 2010 peroxydase activity of winter resistant variety Imrus decreased from 40-47 to 8,5 relative units, as for non winter resistant variety Priam remained at the level of the previous months. It is connected with incompleteness of tissue hardening processes and their damage at decrease or air thermal shocks.
Under the influence of low temperatures at decrease of metabolism activity in wintering organs the protection mechanisms are activated, simultaneously biosynthesis of substances of phenol origin occurs, part of them is referred to anthocyans, playing the role of protection from unfavorable conditions of winter period [2, 9].
The result of the investigation is the statement that under the influence of low temperatures in wintering apple tree organs the anthocyans content increased actively in autumn period, reaching maximum in January and February The shoots of winter resistant apple tree varieties the anthocyans content was considerably higher in comparison with non winter resistant ones during all study period, reaching in winter months 160 - 229 mg/100g in shoots and 450 - 565 Mr/% in bark (January of 2010), exceeding these data in non winter resistant variety Priam in 3 - 5 times.
CONCLUSIONS
The carried out researches allow finding out the main damaging factors of autumn and winter period, define the apple tree varieties resistant to winter unfavorable conditions. The adaptation mechanism to unfavorable conditions of winter period is defined. Complexing and protecting mechanisms of apple tree activate in the process of hardening in autumn at decreasing metabolism activity and accumulation of energy material - carbohydrates, proteins, praline, polyphenols increasing adaptation and protection mechanism takes place. This process of winter resistant apple tree varieties runs faster. The change of oxidizing enzymes activity in autumn and winter period is included into adaptive features combination in apple tree metabolism.
Positive tendency of the interconnection of content of saccharose, praline, anthocyans, cyanidines, proteins in annual shoots and winter resistance of apple tree varieties is defined.
AKNOWLEGEMENTS
The work is done at finance support of the Russian Foundation of Fundamental Research (project № 12-04-97505 r_center_a) and the Orel region Authority. The author expresses acknowledgement to senior research fellows of All-Russian Research Institute of Horticultural Crops Selection of the Russian Academy of Agricultural Science Galasheva A. M., Golyushkina L. V., Makarkina M. A., Ozherelyeva Z. E. for assistance in research.
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