Evaluation of single and single modified early maize hybrids developed in the heterotic model iodent X BSSS-B37

This article reports on the research results concerning: 1) the climatic conditions influence on the productivity of the single cross and modified single early maize hybrids based on the related crosses A x A1; 2) the modification of the single cross hybrid Porumbeni 310; 3) the inbred lines and related crosses tolerance to low soil temperatures. The investigations included 309 single crosses and 255 single modified hybrids tested in 2021-2024 under extremely contrasting meteorological conditions. Inbred lines and related crosses of Iodent heterotic group have been used as female components of the hybrids. The experimental date of single crosses and modified single hybrids show insignificant differences concerning the duration of the emergence-silking and physiological maturity period, moisture and grain production in different meteorological conditions of the testing years. The comparative analysis of 12 inbred lines and 15 related crosses in 2021 and 2023 demonstrates the meteorological conditions influence on kernel size, differences being recorded for the weight of 1000 kernels (TKW). For this indicator, related crosses are superior to inbred lines, their TKW being 49,2 g (25,5%) higher in the favorable 2021 and 22,9 g (15,1%) higher in 2023. The related crosses manifested a heterozis effect on the plant hight, silking, grain yield and tolerance to lower soil temperatures. Investigations concerning the modification of single cross hybrid Porumbeni 310 resulted in creation of its analogue Porumbeni 309 with a significantly higher grain yield under stressing environmental conditions.