ENVIRONMENTAL RESPONSE IN SUNFLOWER HYBRIDS: A MULTIVARIATE APPROACH

Seed yield stability, being strong influenced of environmental factors, remains the most important objective of sunflower breeding. In present research have been assessed 8 yield related traits at 25 sunflower hybrids, in two growing season (2019, 2020), under different weather conditions in Soroca district from the northeast of the Republic of Moldova. The principal component analysis, correlative and multicollinearity statistics highlighted their clustering according to different categories: commercial, experimental and in testing phase for hybrid performance, indicating the diverse nature of hybrids. The correlation profile of yield related traits at the commercial hybrids contrasts with that of the tested and experimental hybrids which in both evaluated years, is more heterogeneous in context of the strength and direction of correlation. The parameters achene weight per head and number of achene per head, followed by seed yield and head diameter have the highest degree of variation related to growing season. Most negative correlations are found for correlation pairs with variables 1000 seed weight and hectolitre mass of seeds, which are moderate and high for the tested and experimental hybrids, and predominantly low for the commercial ones. The commercial hybrids were more sensitive to the drought stress of the 2020 growing season, responding by a greater decrease of the majority of analyzed agronomic indices. At the same time the correlations between different traits indicated a pattern similar to previous year. Contrary, the experimental hybrids and those in the testing phase showed small changes in the values of agronomic traits that suggest a greater tolerance to drought conditions, as well as less correlations between different indices. The results have several implications for the future breeding, genotype evaluation and recommendation of sunflower hybrids for production in the local regions of growth.