Natural early and mid-senescence and agronomical traits in wheat at two locations

Wheat is one of the main cereal crops for ensuring food security for the 21st century. Thus, increase of grain yield is a major target for breeders, where insights into wheat productivity can be achieved by studying the activity of components of the photosynthetic apparatus, such as chlorophyll fluorescence kinetics. The present study was conducted in a set of three winter wheat varieties (Triticum aestivum L.) (Tika Taka, El Nino, and Vulkan) at two experimental sites in the vegetation season 2019/2020. Chlorophyll fluorescence measurements were used to evaluate the onset and rate of the flag leaf and head senescence every few days, beginning at the heading stage (0 day after heading, DAH) until mid-senescence stage (26 DAH) on field-grown varieties with similar grain yield capacity and maturation time. The objectives of this study were to evaluate the agronomical performance of wheat varieties and to test photosynthetic efficiency across different environments. Consequently, this research was focused on how Alternaria and Fusarium infections affected chlorophyll a parameters along with grain yield. The analysis of variance demonstrated significant effects of locations on the grain yield and its components. Tika Taka exhibited the highest yield reduction (27.1%) at Tovarnik, compared to Osijek, followed by El Nino (20.5%) and Vulkan (18.7%). Beside, significant differences for locations, 1000 kernel weight showed significant differences for varieties. Although there were not any significant differences in the grain yield between varieties, higher reductions over locations could be due to earlier senescence and contracted grain fill duration at location Tovarnik due to prolonged wet conditions which provoked natural infection by Fusarium or Alternaria species at the grain filling stage. This is supported by the evidence that at Tovarnik there were increased amounts of tentoxin, deoxynivalenol (DON), don-3-glucoside (D3G), 3-acetyldeoxynivalenol (3-ADON), zearelenone (ZEN), culmorin and 15-hydroxyculmorin and therefore the energy fluxes ratios ABS/RC, TR0/RC, ET0/RC, DI0/RC increased in effect of dual-stress. Opposite to that, at location Osijek, ‘staygreen’ traits positively affected grain size, and thus overall grain yield, through maintenance of grain fill.