Diurnal variations in net photosynthetic rate (PN), transpiration rate (E), stomatal conductance (gs), internal CO2 concentration (Ci), and water use efficiency (WUE) were studied on individual leaves of coffee plants to determine the effect of climatic factors on photosynthetic capacity. PN and E showed bimodal behaviour with the maximum values of PN at mid-morning. At noon, under saturating photosynthetically active radiation (PAR) and high leaf temperature (Tl), PN declined. In the afternoon (14:00), PN slightly recovered in association with a decrease in Tl and in leaf-to-air vapour pressure deficit (VPD). Reductions in E during the morning were associated with decreases in gs. Higher WUE in the morning was related to higher PN and lower E. The reverse occurred in the afternoon. Goudriaan's simulation model, adapted for coffee canopy photosynthesis, was tested at the level of whole plant (Ppl). Three methods were used: (a) Whole plant net photosynthesis (Ppl) under semi-controlled conditions in a chamber. (b) Ppl estimation following Goudriaan's method (Gaussian integration) of instantaneous PN in single leaves at three canopy depths and at three different hours assuming a photosynthesis unimodal behaviour. (c) Ppl using Goudriaan's method but at five different hours according to the bimodal behaviour reported above. Results of Ppl estimates using Goudriaan's model adapted for coffee canopy confirm the observed Ppl bimodal behaviour with high fitness degree of the measured whole plant photosynthesis. The high fitness found among observed and simulated data indicates that the modified model may be used as a subroutine for the general simulation model of coffee crop growth. and L. F. Gómez ... [et al.].
Tobacco plants accumulating high levels of soluble sugars due to the cytosolic expression of an inorganic pyrophosphatase from Escherichia coli were ušed to study adaptation to the osmotic stress that these plants are continuously faced with. In the course of differential RNA screening between wild type and transgenic plants three cDNA dones could be isolated, which after sequencing were identified as pathogenesis-related proteins (PR-proteins). Two cDNAs, PRlb and PR-P, belong to the acidic PRl and PR3 groups of PR-proteins, and the third cDNA, SAR8.2, has so far been associated with systemic acquired resistance in tobacco plants. The expression of PR-proteins transcripts in generál was well correlated with the steady- state level of total soluble sugars present in the tobacco plants. The induction of PR protein transcripts resulted in an accumulation of corresponding proteins. Moreover, the complete set of acidic PR-proteins induced by potato virus Y was also present in the sugar-accumulating transgenic plants. The induction of PR-proteins might be a generál response to the osmotic stress in tobacco plants.
In this paper, we study the structure of polycyclic groups admitting an automorphism of order four on the basis of Neumann’s result, and prove that if α is an automorphism of order four of a polycyclic group G and the map φ: G → G defined by gφ = [g,α] is surjective, then G contains a characteristic subgroup H of finite index such that the second derived subgroup H″ is included in the centre of H and CH(α2) is abelian, both CG(α2) and G/[G, α2] are abelian-by-finite. These results extend recent and classical results in the literature., Tao Xu, Fang Zhou, Heguo Liu., and Obsahuje seznam literatury