The effect of hydrothermal coefficient on productivity of maize hybrids of various groups of ripeness

Abstract

The improvement of the breeding programs, selection of the optimal group of ripeness depends on the soil and climatic conditions for which varieties and hybrids are developed. One of the most important indicators of climatic conditions is the hydrothermal coefficient (HTC). The purpose of the current study was to analyze the effect of HTC on the productivity of maize hybrids of various groups of ripeness. The studies were carried out in 2014–2019 at the Agricultural Research Center “Donskoy” located in the southern zone of the Rostov Region, characterized by unstable moisture. The objects of the study were 96 interlinear maize hybrids of three groups of ripeness, namely an early ripening group (FAO 150), a middle-early ripening group (FAO 200) and a middle ripening group (FAO 300). There was a systematic use of variants in the trials. The weather conditions of the years 2014 and 2018 could be estimated as arid (HTC = 0.32–0.57). The years 2015, 2016, 2017 and 2019 were of medium aridity (HTC = 0.58–0.89). The HTC determined only for the entire vegetation period did not allow estimating objectively the growing conditions. There has been required a more detailed analysis of the HTC for the periods (months) of vegetation. On average, over the years of study, the middle ripening maize hybrids were characterized with the largest grain productivity (3.98 t/ha). The early ripening maize hybrids were characterized with the smallest productivity (3.31 t/ha). The middle-early ripening hybrids were characterized with the average value (3.80 t/ha). However, in different years, the maximum grain yields were produced by the hybrids of various groups of ripeness, including by the early ripening varieties, that depended on the amount of HTC in different vegetation periods. There have been identified average positive correlation coefficients between the HTC values and maize hybrids’ productivity (r = 0.64–0.74). The use of maize hybrids of various groups of ripeness can stabilize the gross harvest of maize.