Estimation of photosynthetic light energy conversion efficiency in winter wheat varieties under drought

Aim. Search for physiological characteristics of high-yielding varieties of winter wheat based on a comparative analysis of efficiency of solar energy conversion into biomass under natural drought during the grain filling period. Methods. Morphometric, actinometric, statistical. Results. It was found that high-yielding varieties of winter wheat had higher, than less productive ones, increment of aboveground dry matter and the radiation use efficiency in the reproductive period of development. A positive correlation was established between the radiation use efficiency of winter wheat varieties at that period and grain yield, and weight of 1000 grains. It has been suggested that the higher efficiency of light energy conversion to biomass at drought conditions in high-yielding varieties may be related to the higher demand for assimilate due to grain filling and high drought-tolerance of photosynthetic apparatus. Conclusions. A significant genotypic difference in the radiation use efficiency between winter wheat varieties of one maturity group at the reproductive period was established. Higher radiation use efficiency in the reproductive period contributed to the increase of grain productivity due to better grain filling, as evidenced by the positive correlation with the mass of 1000 grains. The presence of significant genotypic variability in this trait indicates that it can be used for genetic improvement of wheat productivity. It was found that the varieties of winter wheat Kyivska 17 and Horodnytsia can be used as donors of valuable breeding traits.