Анотация: Iron-deficiency chlorosis brings about significant yield losses in numerous crops. The introduction of resistant genotypes is one possible solution to the problem. In this study the development of Fe deficiency symptoms (growth depression and yellowing of the youngest leaves) at early stages of growth in five Bulgarian cultivars of bread wheat grown hydroponically was compared. Chlorophyll fluorescence measurements were also carried out in order to assess the extent to which the stress had damaged the photosynthetic apparatus. Although at day 10 some effects of Fe deficiency on root length and chlorophyll content were observed, a differentiation among the cultivars could not be found. At day 17 the shoot growth was also affected and the chlorophyll as well as the carotenoid contents were lower. Sadovo 1, which is standard for the registration of new varieties in Bulgaria, was the most Fe-efficient among the studied cultivars, characterized by the smallest decrease in root length, shoot biomass, chlorophyll and carotenoid contents, and relative growth for the 7-day period. In Gladiator 113, Iskur 45 and Sadovska belija, together with a greater drop in the abovementioned parameters, lower actual PS II efficiency and higher amount of light, dissipated thermally by the PS II antenna were found, thus suggesting a greater susceptibility to Fe deficiency. Under optimum Fe supply Lozen 6 had the greatest biomass and relative growth, and high chlorophyll content. Under Fe deficiency it was characterized by the largest reduction in relative growth and in root length, but by a comparatively low decrease in chlorophyll content and by unchanged fluorescence parameters. The detected variability in the early responses of the studied cultivars to Fe deficiency might be important for the early establishment of seedlings and thus, it might be related to iron-efficiency in field conditions

Забележки: Proceedings of the XI National Conference on Plant Physiology, 18-19 november 2009, Sofia, Bulgaria