The article presents the results of the laboratory investigation of the influence of high temperatures on water regime of red currant in Institute of Fruit Selection. It shows the dependence of water loss by leaves on the phenophase of plant development. High water loss by leaves occurs during the phase of ripening berries (July). Low water loss is noted during the active growth of shoots (June). Red currant genotypes: «Valentinovka», «Bayna» have a high percent of water loss in June and July. Genotypes «Shedraya», «Gollandskay krasnay», «Orlovchanka», «Dar Orla», «Selyanochka», «Osipovskay», «Belka» and «Jonker van Tets» have a low percent of loss water. The loss of water at the temperature shock is the important protective mechanism from over heat and death of plants. The results of the investigation of a degree of water restoration by red currant leaves in the periods of berry ripening and active growth of shoots are given. The most part of genotypes of red currant leaves have a high percent (>50%) of water restoration. Genotypes «Selyanochka» ,«Orlovchanka», «Dana», «Shedraya», «Belka» have a more 100% of water restoration. On the ground of the obtained results the following genotypes: «Belka», «Selyanochka», «Gollandskay krasnay», «Shedraya», «Orlovchanka», «Dar Orla», «Osipovskay» and «Jonker van Tets» are mostly heat resistant.

Pourpose. Establish compliance of heat and moisture resources to biological requirements of sunflower hybrids (Helianthus annuus), reveal criteria for assessing weather conditions in the northern regions of Ukraine; establish links between temperature, precipitation and yield. Methods. Field and mathematical methods were used. Field multifactorial experiment was conducted during 2016–2018 in the Left Bank of Ukraine, on the border of two soil and climatic zones of Ukraine - Forest-Steppe and Polissya. Peculiarities of plant growth and development, formation of "hybrids" yield (factor A) were studied: 'Ukrainskyi F1', 'P63LL06', 'NK Brio', 'NK Ferti' depending on "plant density" (factor B): 50, 55 , 60, 65 thousand pieces/hectare. We calculated and analyzed the sums of active, effective temperatures for two biological minima - 5 and 10 ° C; the sum of thermal units according to the method of Brown and Bootsma, 1993; coefficients of materiality of elements deviations of the agrometeorological mode of the current year from long-term averages; plasticity and yield stability according to the method of Eberthart S.A., Russel W.Q. (1966). Results. To pass the full cycle of sunflower plants development, the sum of active temperatures (t = 10 °C) for hybrid 'Ukrainskyi F1' – 2354.6; P63LL06 – 2306.4; 'NK Brio' – 2401.3; 'NK Ferti' – 2379.7; and the sum of effective temperatures for 'Ukrainskyi F1'- 1081.5; 'P63LL06' – 1056.9; 'NK Brio' – 1104.9; 'NK Ferti' – 1109.1 is required. The sum of temperatures, both at a biological minimum temperature 10 °C and 5 °C, meet biological needs of sunflower plants and is not a limiting factor for this crop growing. The sum of thermal units for the period April–October is 3780 on average for three years. During the period of active sunflower vegetation (April–August) the sum of thermal units is 2868–3258, significantly exceeding the sum of active and effective temperatures at biologically active temperatures 5 °С and 10 °С. The most determined limits of changes in active, effective temperatures and thermal units were observed in May – September. Conclusions. Plasticity and stability of sunflower yield more depending on hybrid and plants density than on conditions of the year. Yield stability coefficient for hybrid 'Ukrainskyi F1' was 1.68 - 2.30; 'P63LL06'- 2.51 - 3.14; 'NK Brio'- 3.15 - 4.63; 'NK Ferti' - 2.70 - 3.75 for yields, respectively: 2.16 - 3.11; 2.58 - 3.52; 3.20 - 4.12; 2.70 - 3.79 t/ha.

The article provides results of efficiency of double screening by quantity of normally developed germs affected of unfavorable abiotic factors, namely decreased temperatures of seeds sprouting and embryogenesis at extremes (heat, shortage of water).