Field-grown plants of spring barley (Hordeum vulgare L. cv. Akcent) in the growth phase 30 DC (beginning of stem extension) were exposed to a one-shot application of a commercial product containing cyanazine (Bladex 50 SC) in two doses, C30 and C60 (30 and 60 mg m-2). The reaction of the plant photosynthetic system was followed non-destructively using chlorophyll fluorescence induction (the O-J-I-P transient) within three weeks after the application in the fifth developed leaf and three further gradually appearing leaves. An immediate response of plants to the application of cyanazine and a regeneration of plants from cyanazine action were detected. The biological (plant dry mass) and crop yield production (the number and mass of grains in a spike) were analyzed in time of full ripeness. The crop yield was lowered by the herbicide effect to the same level for the two doses used. and M. Matoušková, J. Nauš, M. Flašarová.
a1_The Pantanal is the largest wetland in the world with extremely high plant and animal diversity, but large areas have been invaded by Vochysia divergens Pohl (Vochysiaceae), a tree that is native to the Amazon Basin, and Curatella americana L. (Dilleniaceae), a tree that is native to the Brazilian savanna (cerrado). V. divergens is reportedly floodadapted, thus its ability to invade the Pantanal may not be surprising, but the invasion of C. americana is counterintuitive, because this species is adapted to the
well-drained soils of the cerrado. Thus, we were interested in comparing the photosynthetic capacity, in terms of CO2 conductance, carboxylation, and electron transport of these species over a seasonal flooding cycle. Given that V. divergens is reportedly flood-adapted, we predicted that this species would have a higher photosynthetic capacity than C. americana, especially under flooding. To test this hypothesis we measured the photosynthetic CO2 response (PN/Cc) of V. divergens and C. americana within 1 year to determine, if photosynthetic capacity varied systematically over time and between species. Contrary to our hypothesis, V. divergens did not always have a higher photosynthetic capacity than C. americana. Rather, species differences were influenced by temporal variations in flooding and the leaf age. Leaf CO2 assimilation and photosynthetic capacity of both species were lower during the flood period, but the differences were not statistically significant. The physiological performance of both species was strongly related to leaf N and P concentrations, but P limitation appeared to be more important than N limitation for these species and ecosystem. Photosynthetic capacity was higher and more stable for V. divergens, but such an advantage did not result in a statistically significant increase in PN., a2_Our results suggest that both species are tolerant to flooding even though they are adapted to very different hydrological conditions. Such physiological plasticity, especially for C. americana, might be a key feature for the ability to survive and persist in the seasonally flooded Pantanal., H. J. Dalmagro ... [et al.]., and Obsahuje bibliografii