HYGROSCOPICITY OF MATURE GRAIN AS A MARKER OF WINTER BARLEY AND SUNFLOWER FROST RESISTANCE
In the review article we present a comparative analysis of frost resistance of varieties of winter barley and sunflower (Helianthus annuus L.) by the results of freezing in the refrigerating chambers and by the hygroscopicity of mature grain. On the example of a number of varieties of both cultures, it is shown that the higher the frost resistance of the variety, the smaller the volume of the supernatant can be obtained by extracting the press cake with a solution containing magnesium cations. It is assumed that increased hygroscopicity of winter barley and sunflower press cake is associated with a relatively high content of so - called "water-soluble starch" - β-glucan polysaccharides in its grain. The possibility of regulation of the degree of hygroscopicity under the influence of potassium (KNO3), zinc (ZnSO4) and gibberellic acid (GA3) was studied on a number of sunflower varieties. It was shown that treatment with a solution of potassium (a concentration of 50 ppm KNO3) of sunflower plants at the stage of 4 leaves leads to a significant increase in hygroscopicity of grain and hardiness of plants, little effect was given treatment with zinc (30 ppm ZnSO4) and a lesser effect was observed when treating plants gibberellovaja acid (20 ppm). Potassium treatment significantly intensified the biosynthesis of free Proline, phenolic compounds and soluble proteins. When processing zinc significantly increased the content of carbohydrates in sunflower plants. Hygroscopicity showed a significant correlation with the content of free Proline (R2=0.621), phenolic compounds (R2=0.907), total carbohydrates (R2=0.673) and soluble proteins (R2=0.708). It is assumed that the treatment of plants with potassium and zinc plays a key role in increasing the hygroscopicity of grain. The results of comparative studies of frost resistance on the degree of survival of plants during freezing in cold rooms and the degree of hygroscopicity of mature grain showed that these two methods of assessing frost resistance give very close data. At the same time, in terms of simplicity and low economic costs, the proposed method of assessing frost resistance is many times superior to the method of direct freezing of plants