ASSESSMENT OF THE SALT RESISTANCE OF FIELD CULTURES
Krivobochek Vitaly Grigoryevich — Penza Research Institute of Agriculture.
Sttsenko Alexander Petrovich — Penza State University.
Alexandr P. Statcenko.
ScD (Doctor in Agriculture). professor.
ScD (Doctor in Biology). professor.
Penza State Agriculture Universiti
Vitalij V. Kostinevich.
ScD. associate professor.
Penza State Universiti
Natalija V. Kamardina.
ScD. associate professor.
Penza State Universiti
Rauzat D. Ulbasheva.
ScD. associate professor.
Kabardino-Balkarian State Universiti n.a. K.M. Berbekov
Great damage to global agricultural production is caused by soil salinity, in which the salt content (mainly chlorides and sulphates) exceeds 0.25% by mass. On our planet, 25% of the soil is precisely saline. In the Russian Federation, saline soils occupy 36 million hectares, which is 18% of the total area of irrigated land. These soils are widespread in the southeast of the European part of the country. Significant areas of saline soils occupy in the Volga region. It is known that the salinization process is intensified with irrigation of land. This is a real disaster in the Middle Volga region, where 6% of arable land is saline and 17% is salted 
The most important scientific problem is the development of objective diagnostic methods for assessing the salt tolerance of agricultural plants. The most promising direction for solving this problem is the improvement of methods for comparative assessment of salt tolerance, when a plant variety with high salt-resistance is used as a standard. Moreover, comparative methods can be used in assessing the salt tolerance of plants of close systematic groups, preferably within the same species.
Methods of diagnostics of salt tolerance of plants acquire in recent times of great importance in the breeding and seed-growing industries. Moreover, the selection of seeds of salt-tolerant plants should be carried out among the forms with the highest yield on saline soils.
A promising direction in assessing the salt tolerance of plants is the germination of seeds on saline substrates . However, a significant disadvantage of this method is that it allows one to assess the plant resistance to plants only during the initial phases of their development. Meanwhile, for a complete understanding of the process, it is necessary to assess the salt tolerance of plants during the whole ontogenesis. The fact is that salt tolerance in plants varies significantly depending on the phases of their development.
The method of determining the salt tolerance of plants according to the intensity of chlorophyll destruction in leaves placed by the petioles in salt solutions deserves attention. The basis of this method is the presence of a stable bond of the «chlorophyll-protein» system in plants with high salt-resistance. Indicator of the degree of assessment of salt tolerance of plants is the rapidity of salt spots due to the destruction of chlorophyll under the influence of salts. Moreover, in salt-tolerant forms, the disintegration of chlorophyll begins later and proceeds less intensively.
Also known is a microscopic method for determining salt tolerance, the estimated indicator of which is the rate and size of the appearance of spots from salt burns on leaves of plants placed for 30 minutes by means of 0.1 M sodium sulfate solution. In addition, a method for assessing salt tolerance has been developed, which involves counting plasmolized cells after immersing for two hours sections of the epidermis of plant leaves in a 0.1 M solution of sodium chloride.
Recently, direct and indirect methods for determining the salt tolerance of plants have been developed, providing for the assessment of yield and productivity, the rate of physiological and biochemical processes in vegetative and generative organs. In this case, the main indicator of the degree of salt tolerance of a seed plant, the intensity of plasmolysis of cells, the rate of chlorophyll fading in the leaves of seedlings placed in salt solutions [3,5,6]. However, the mentioned methods are not always objective, since the germination rate, seed germination depends not only on salt tolerance, but also to a significant degree on the state of the embryo, seed membranes, the depth of rest of the seeds, etc. In addition, some of them are laborious and long-term in execution.
A widely used method for assessing salt tolerance for seed germination in salt solutions . The main indicator of resistance in this case is the percentage of germinated seeds over a period of time from 5 to 15 days in saline conditions compared to water control. However, the practical use of this method is limited due to the fact that the mandatory condition for its execution is a high laboratory yield of seeds. In addition, the seed used for sprouting should be grown in the same climatic and weather conditions, which is not always possible in practice. Along with this, there is evidence that the amino acid Proline combines protective (in particular, salt protective) properties with the ability to accumulate in the vegetative organs of plants under stress, in particular, salinity [2,4,7.8, ten]. In this regard, the degree of accumulation of free proline in vegetative organs (seedlings) is proposed by us in the diagnosis of salt tolerance of cultivated plants.
The purpose of the research is to study the effect of soil salinity on the content of amino acids (proline) in the leaves of agricultural crops and to develop a method for assessing the salt tolerance of plants.
Research methodology. Ten-day seedlings of cereals, cereals, oilseeds, and legumes that were subjected to stressful effects — salinization — were used as an object of research.
Preliminary, samples of 50–100 seeds each are taken from the seed batch of the test plants. Then the seeds were soaked for half an hour in warm (30 — 35 C) water and germinated in a thermostat for 10 days in germinators on moist multilayer filter paper at a temperature of 25 — 28 C. The control sample was germinated on a bed, moistened with water, and subjects — on a 0.5-molar solution of sodium chloride. After germination in seedlings of control and test samples, the content of free proline was determined by the method of Bates . For this purpose, 0.5 g of plant material was crushed using a homogenizer, and it can be ground in a mortar with quartz sand in 10 ml of a 3% aqueous solution of sulfosalicylic acid. Then, 2 ml of the homogenate filtered through a dense paper filter was mixed with 2 ml of acid ninhydrin and 2 ml of glacial acetic acid. Sour ninhydrin was prepared in advance, one day prior to analysis, by boiling 1.25 ninhydrin in 30 ml of glacial acetic acid and 20 ml of phosphoric acid until complete dissolution. The mixture was kept in test tubes for one hour in a water bath at 100 C. The reaction was limited to cooling in an ice bath, after which 4 ml of toluene (or benzene) was poured into each tube and vigorously stirred for 15-20 seconds until complete bleaching of the mixture -sie. After 15 minutes of settling, the chromophore (the colored upper layer) was evaluated using a photoelectric colorimeter (FEC-56M) for the density of staining. Absorbance was measured on a blue light filter at a wavelength of 520 nm. Toluene or benzene was used as a control.
Research results. The content of free proline in the samples was determined by the standard curve and calculated in mg% on wet weight. The standard curve was constructed on the basis of solutions of the factory preparation of the proline of various concentrations. After that, we calculated the salt tolerance coefficients, on the basis of which three groups of plants were distinguished: highly resistant to salt stress (salt tolerance coefficients 3.0 and above); medium resistant (2.0 — 2.9); weakly resistant (1.9 and below).
The table shows the results of a comparative assessment of the salt tolerance of field plants of various systematic groups.
|New method||Solestability coefficient|
|Seed germination in saline||Content of proline, mg%|
The analysis shows that the content of free proline in the seedlings of the test cultures and the salt tolerance factors calculated on its basis allow us to differentiate test plants in more detail by the level of resistance to salinity. As a result of the assessment, three groups of plants were identified: highly resistant to salt stress (podsoniechnik, barley, sugar beet, triticale, mustard, rye); medium resistant (rice, oats, corn, millet); weakly resistant (peas, winter wheat, beans, beans, flax, sorghum, lupine, buckwheat, soybean)
When assessing the salt tolerance of a breeding material, it is recommended to use differentiator varieties with a known degree of salt tolerance, which will allow the breeder to carry out culling of weakly resistant lines.
1.Valkov, V.F. Soil salinization / V.F. Valkov, K.Sh.Kazeev, S.I. Kolesnikov // Rostov-on-Don.: Phoenix. 2014. — 165s.
2.Britikov, E.A. The biological role of proline in plants / Ye.A. Brit-kov // M.: Science. 1975. — 88c.
3. Diagnosis of plant resistance to stress, / ed. GV Udovenko // L. 1988. — 228s.
4. Kuznetsov, E.A. Proline under stress: biological role, metabolism and regulation / E.A.A. Kuznetsov, N.I. Shevyakov // Plant Physiology. 1999. v.4. Issue 2. C.305-320.
5.Methodika diagnostics of plant resistance / ed. G.V. Udovenko. — L., 1970. — 74 s.
6. Methodical instructions when using vegetative methods when studying the salt tolerance of annual agricultural plants. — L., 1977. — 20.
7. Rubin, B.A. Plant physiology. — 4th ed., Pererab. and add. — M .: Higher School, 1976. — 576 p.
8.Savitskaya N.N. On the biological role of proline in plants // Reports of the Higher School. — 1976. — № 2. — P.49 — 61.
9. Physiology of agricultural plants / ed. B.A. Rubin. — M., 1967. — 411 s.
10.Bates L.S. Woldren R.P. Teare G.D. Rapid determination of proline fer water-stress studies // Plant and soil. 1973. T.39. No 1. P. 105 -107.
11.Shobert B.F. Schesche H. Unusal solution of proline proteins and its in-teraction with proteins // Biochem. et biophis. acta. 1978. T. 541. No 2. P.1341 — 1344