In order to evaluate effect of weedy rice on the photosynthesis and grain filling of cultivated rice, cultivated rice ‘Nanjing 44‘ was planted in the field under different densities of weedy rice ‘JS-Y1‘ for two years. The results showed that net photosynthetic rate (PN), net assimilation rate, grain filling rate, and the grain yield of cultivated rice all decreased with increasing weedy rice density. Furthermore, yield component analysis revealed that increasing weedy rice density had the most significant effect on the percentage of filled grains and the number of rice panicles. The correlation analyses indicated that the yield of cultivated rice was highly correlated with the net photosynthetic rate and the net assimilation rate. Our results illustrated that high density of weedy rice might cause yield losses in cultivated rice by inhibition of photosynthesis and grain filling., X. M. Xu, G. Li, Y. Su, X. L. Wang., and Obsahuje bibliografii
Our experiment was carried out in order to explore effects of plant growth regulators (PGR; thidiazuron, paclobutrazol, and ascorbic acid) on physiological traits of wheat genotypes under water surplus and deficit conditions. Study revealed that relative water content, membrane stability index, chlorophyll content, photosynthetic rate (PN), and maximal quantum yield of PSII improved with PGRs application across the genotypes both under irrigation and water stress. The response of HD 2733 genotype was more positive toward PGRs treatment as compared to other genotypes under water stress. Higher PN and chlorophyll contents were observed in HD 2987 followed by C 306 genotype under water-stress conditions. Moreover, Rubisco small subunit (SSU) expression was lower in wheat genotypes under water stress as compared to irrigated conditions. Application of PGRs led to upregulation of SSU under water stress, while no significant change was found in Rubisco level and activity under irrigated condition in dependence on PGRs treatments. Yield-related traits showed also significant reduction under water-stress conditions, while application of PGRs enhanced the yield and its components. Results indicated that the PGRs exhibited a positive interaction and synergetic effect on water stressed wheat plants in terms of photosynthetic machinery and yield., S. K. Dwivedi, A. Arora, V. P. Singh, G. P. Singh., and Obsahuje bibliografii
Two foxtail millet (Setaria italica L.) varieties were subjected to different shading intensity treatments during a grain-filling stage in a field experiment in order to clarify physiological mechanisms of low-light effects on the yield. Our results showed that the grain fresh mass per panicle, yield, photosynthetic pigment contents, net photosynthetic rate, stomatal conductance, effective quantum yield of PSII photochemistry, and electron transport rate decreased with the increase of shading intensity, whereas the intercellular CO2 concentration increased in both varieties. In addition, shading changed a double-peak diurnal variation of photosynthesis to a one-peak curve. In conclusion, the lower yield of foxtail millet was caused mainly by a reduction of grain mass assimilated, a decline in chlorophyll content, and the low photosynthetic rate due to low light during the grain-filling stage. Reduced light energy absorption and conversion, restricted electron transfer, and reduced stomatal conductance might cause the decrease in photosynthesis., X. Y. Yuan, L. G. Zhang, L. Huang, X. Qi, Y. Y. Wen, S. Q. Dong, X. E. Song, H. F. Wang, P. Y. Guo., and Obsahuje bibliografii