ИЗМЕНЕНИЕ ТЕРМИЧЕСКИХ РЕСУРСОВ ВЕГЕТАЦИОННОГО ПЕРИОДА И УРОЖАЙНОСТЬ ЯРОВОЙ ПШЕНИЦЫ В УСЛОВИЯХ СРЕДНЕГО ПОВОЛЖЬЯ

Abstract

The article presents the results of long-term studies (1982-2018) on the assessment of changes in thermal resources during the growing season and the indication of their impact on the yield of spring wheat. The work was carried out in the conditions of the northern part of the Middle Volga region on gray forest soils. The soil of the experimental site is gray forest medium loamy, the content of humus (according to Tyurin) is 2.8...3.2%, mobile phosphorus and potassium (according to Kirsanov) - 105...184 and 79...149 mg /100 g of soil, respectively, pH- 5.6...5.8. During the observation period, the highest temperature increase was recorded in July (2.4°C) and May (2.2°C), and the lowest in June (1.0°C). The sum of effective temperatures over 10°C increased by 500°C during the study period. The yield of spring wheat grown without fertilizers varied greatly in different years, ranging from 0.99 to 2.97 t/ha. The highest value of this indicator was observed at an average monthly air temperature of about 13 0C in May, 17 0C in June, 18 0c in July, and the sum of active temperatures was 1800 0c. The studied thermal resources, in accordance with the significance of the impact on the yield of spring wheat, can be arranged in the following descending order: average air temperature in June > average air temperature in July > the sum of effective temperatures above 10 °C > average air temperature in May. To describe the dependence of the yield of spring wheat grain on thermal resources, in three cases out of four, a polynomial equation of the second degree was better suited, and in one case, an exponential equation.