Determination of the optimal heterotic model of mid-ripening maize hybrids in the Northern Steppe of Ukraine

Abstract

Topicality. Currently, we can use more effectively the initial material of the working collection due to targeting certain heterosis models. Information about the advantages of different heterotic models in certain cultivation areas makes it easier to search for successful combinations and the selection of promising initial material. Issues. Тo identify of the most promising heterotic models of maize hybrids developed with using lines of different genetic plasms, which characterized by high yields and low grain moisture content compared to standard hybrids adapted to cultivation in the Northern Steppe. Aim. To determine the economic value of maize hybrids developed with using different germplasm lines and the most promising heterotic models for each genoplasm group. To investigate how the plant growing conditions influence on economic valuable indicators of hybrids depending on their genetic origin. Materials and Methods. Visual Method was used for phenological observations; Field and Laboratory Method was used to determine of morphobiological characteristics of plants; Measuring Weight Method – to determine the plant yield and metric characteristics; Mathematical and Statistical Method – to determine the reliability of results, the trait variability indicators, correlation dependence of traits; Analysis of Variance (ANOVA); comprehensive assessment of morphobiological and economically valuable characteristics of inbred lines and hybrids based on different genetic plasms. Results. It was found that testcrosses based on the Lancaster x Iodent model were the most stable by grain yield. However, in the average of three years of research, the highest average level (6.31 t/ha) was recorded in Mixed x Lancaster testcrosses. It was selected testcrosses with a higher grain yield compared to standard hybrids, such as DK3044xDK315, DK3151xDK4454, DK3151xDK3155 and DK365xDK6356 which had a yield of 8.0; 7.59; 7.18; 7.17 t/ha, respectively. We observed the best ratio of yield to grain moisture content (harvest index RH/M) in hybrid combinations of Lancaster x Mixed. Conclusions. It was determined the best testcrosses according to the ratio of yield to grain moisture content: DK315CxDK3821 (Mixed x BSSS) – 0.51; DK633/325xDK365 (Mixed x Iodent) – 0.51; DK365xDK6356 (Iodent x Lancaster) – 0.51; DK3044xDK315 (Lancaster x Mixed) – 0.56; DK3151xDK3155 (BSSS x Mixed) – 0.55; DK633/325xDK3155 (Lancaster x Mixed), based on which are developing the mid-ripening maize hybrids adapted to Steppe zone of Ukraine. Key words: maize, hybrid, line, germplasm, heterotic model, testcross, grain yield and moisture content at harvesting.