The purpose. To study features and to adapt rated method of determination of total evaporation «PenmanMonteith» for conditions of drip irrigation of Steppe of Ukraine. Methods. Field short-term experiments, conventional analytical research techniques; dispersion, correlation, regression and variation analysis. Results. With the use of modern tooling (Internet-meteorological station iMetos®, station of soil moisture iMetos® SM/ECHO/TNS/ECOD2) they determined specific benchmark ETo, rated and actual values of total evaporation ETc. On the basis of results of field experiment they adjusted quotient of crop Kc according to phases of growth of plants of corn with the use of deflexions from reference conditions. Conclusions. It is fixed that value of actual quotient of crop Kc for grain corn in conditions of drip irrigation of Steppe of Ukraine differs from standard Kc (FAO). Considering precise correlation between Kc (FАО) and Kc (cor.) for determination of actual evapotranspiration (ETc) of plants of corn they recommend to use corrected values of Kc.Key words: evapotranspiration, quotient of crop, irrigation requirement, drip irrigation, corn for grain. Problem statement and literature reviewThe biological basis of irrigation's mode is a total water consumption of plants or evapotranspiration (ETc). Under the ET S we understand the total volume of water that evaporates during the vegetative period by plants and soil surface (physical evaporation -K e ) infiltrate into the lower soil's horizons and spends by plants on transpiration (K cb ).Determining factors that influence the value of the ETc are the climate of zone and weather conditions of current or calculated growing season of their cultivation.Determination of agricultural crops' water consumption is a key issue from the solution of which depends the values of irrigation's rates, efficiency and ecological consequences of irrigation.In the practice of irrigated agriculture water consumption is calculated using different methods: by the data of special experiments, by the coefficients of transpiration and water consumption, on the base of water balance's equations and so on.At present there are many methods by which evapotranspiration has determined on the basis of meteorological parameters and biological characteristics of agricultural crops. At the irrigated conditions of the Steppe zone of Ukraine at different times practically applicated the following methods: bioclimatic method of A.M. Alpatyeva (1954) [1], and later it was improved by S.M. Alpatyev (1965) [2] and V.P. Ostapchykom (1989) In the world for a long time been widespread methods of Penman (1956) [6] and Blaney-Criddle (1950) [7]. Taking into account a certain inexactness of these methods in the 1990 council of experts in FAO had recommended approving of the combined method of «Penman-Monteith» as the standard for calculation of an etalon total evapotranspiration (ETo).The method predicts determination of ETo of a hypothetical culture with a height of 0,12 m, the surface resistance of 70 cm ...

Goal.To study the influence of environmental factors on the transpiration intensity of tomato plants and to build a model of transpiration intensity based on the multiple linear regression (MLR). Methods. General scientific: vegetation, laboratory, measurement-calculation, and mathematical-statistical analysis. Results. It was found that there was a close correlation between the intensity of transpiration of tomato plants by solar radiation, relative humidity, and air temperature, the correlation coefficients are 0.99, 0.96, and 0.94, respectively. The intensity of transpiration increases linearly with increasing solar radiation and air temperature and decreases with increasing relative humidity. The maximum values of transpiration intensity were at 12 and 14 h, and reached 538.1 and 574.1 g/m2•h, respectively, and between 12 and 14 h there was a noon depression of transpiration. Based on multiple linear regression, they obtained a model of transpiration intensity of tomato plants during the day with a coefficient of determination R2=0.91, standard error STr=27.5. A comprehensive statistical analysis of the obtained model was performed, which confirmed that the obtained model was statistically significant with a reliability of 95% and confirmed the hypothesis of the influence of climatic factors on the intensity of transpiration of tomato plants. The average absolute percentage error (AAPE) was 7.4%. Conclusions. Based on the conducted researches the daily periodicity of transpiration intensity of tomato plants and linear dependence of transpiration intensity on the action of solar radiation, temperature, and relative humidity of air is confirmed. The influence of ecological factors on the intensity of transpiration is established based on a multiple linear regression model. The greatest influence on the intensity of tomato transpiration has solar radiation, and the smallest -air temperature, standardized regression coefficients are equal to 1.169 and 0.028, respectively. The conducted comprehensive statistical analysis confirmed the high accuracy of the obtained model: the AAPE error is less than 10%.