SU MMARYThis study was conducted to determine the effects of plastic film mulch on percentage of abortive tillers and harvest index (HI) in two spring wheat populations, and to explore its mechanism in relation to size inequality and life-history strategies theory. Field-grown spring wheat mulched with plastic film shows a remarkable increase in grain yield (an average increase of 38 . 5 % over nonmulched control), which mainly results from the significant increase in above-ground biomass (+44 . 7 %). At the same time, however, reproductive allocation (spike weight/above-ground biomass, x5 . 2 %) and harvest index (x4 . 5 %) were significantly lower (P<0 . 05) in mulched than unmulched populations in both of the two cultivars used. Meanwhile, the number and weight of barren shoots and the ratio of barren shoot biomass to total shoot biomass were significantly greater in mulched populations than unmulched controls both at booting, flowering and ripening stages. From tillering to ripening stages, the tendency of G (Gini coefficient) shows obvious differences between mulched populations ('^' type with the peak of G at booting stages) and non-mulched controls ('_' type with the lowest G at flowering and rebounded at ripening stage). At booting and flowering, the G was significantly higher in mulched populations than unmulched controls, and it was just contrary at ripening. Reproductive allocation and HI were both negatively correlated to average G of the populations, which indicated that resource use efficiency of a crop is inversely related to plant-to-plant variability and also provided further evidence for the views that stand uniformity of field crops is an important aspect of high yield formation. From these results, it was concluded that appreciable growth redundancy occurred in spring wheat populations mulched with plastic film, which may result from the exacerbated inter-plant competition and self-thinning (evidenced by the increased degree of Gini coefficient at booting and flowering stages). Thus, spring wheat cultivation with plastic film mulching does not always mean efficiency, although there is a remarkable increase in grain yields.
SU MMARYGrass pea (Lathyrus sativus) is a potentially valuable feed and food crop in semi-arid regions. Much work has been done on lowering toxicity and on selection of low toxicity varieties, while research on the eco-physiological characteristics of grass pea is very rare. Stomatal character, photosynthetic character and seed chemical composition were measured in four varieties of L. sativus to investigate their relationships at different water availabilities. For L. sativus cv. Yongshou (YS), L. sativus cv. Dingxi (DX), L. sativus cv. Heilongjiang (HLJ) and L. sativus cv. Xide (XD), stomatal density was in the order XD>HLJ>DX>YS under both control and drought conditions. Stomatal aperture, photosynthetic rate (Pn), transpiration rate (E), and the concentrations of seed b-N-oxalyl-L-a, b-diaminopropionic acid (ODAP), protein and starch were in the order YS>HLJ>DX>XD, while the opposite order was found for water use efficiency (WUE). Under drought conditions, stomatal aperture, Pn and E were lower than those under the control, while the other parameters were higher. A significant positive correlation was observed between stomatal density and WUE, while negative correlations were found between stomatal density and the remaining parameters. Obvious positive correlations were also observed between stomatal aperture and Pn, E, the concentrations of seed ODAP, protein and starch, while a negative correlation appeared between stomatal aperture and WUE. Under drought conditions, R 2 values were more comparable with the control. Intriguingly, the R 2 values of stomatal aperture were higher than of stomatal density, especially under drought conditions. These results indicate that stomatal aperture may be more closely related to photosynthetic character and seed chemical composition in grass pea, and water deficit may enhance the correlations.
Huang Q‐Q, Wang G‐X, Hou Y‐P & Peng S‐L (2011). Distribution of invasive plants in China in relation to geographical origin and life cycle. Weed Research51, 534–542. Summary At a continental scale, research on which areas are more likely to be invaded has often found that human socio‐economic factors and biogeographic factors are important. This general pattern also holds for China, where invasive plant species richness at a provincial scale has often been found to be significantly correlated with both socio‐economic (e.g. human population size and total GDP) and biogeographic factors (e.g. latitude and native plant species richness). However, these patterns are based on studies that considered invasive plants collectively rather than examining patterns within major subgroups. Here, we examine the potential role of species differences in mediating these distribution patterns in Chinese provinces. We show that distribution of invaders from Central and South America, especially perennials, is mainly determined by biogeographic factors, whereas distribution of invaders from North America and Eurasia, especially annuals, is mainly determined by socio‐economic factors. The predictive power of biogeographic factors for invaders from Central and South America is stronger than socio‐economic factors for invaders from North America and Eurasia. The role of socio‐economic and biogeographic factors is not entangled; instead, their relative importance is dependent on species characters, such as their geographical origin and life cycle. Management and prevention policies at a national scale should consider the interactions between species characters and socio‐economic and biogeographic conditions of the environment. Our results indicate that by examining the role of species differences, we may get a more realistic understanding of the cause of distribution patterns of biological invaders.
Trehalose can reduce stomatal aperture by a hydrogen-peroxide-dependent pathway in Vicia faba L. (cv. Daqingpi) resulting in significantly lower values of net photosynthetic rate (P N ), stomatal conductance (g s ), and transpiration rate (E). At 8 and 24 h, the lower P N in trehalose-treated plants was accompanied by significant decrease in intercellular CO 2 concentration (c i ) suggesting that the reduction of P N was caused by stomatal limitation. At 48 and 72 h, trehalose decreased apparent carboxylation efficiency (P N /c i ) and did not decrease c i and g s compared with controls; therefore the reduction in photosynthesis was caused by non-stomatal limitation. Trehalose treatment resulted in significantly higher effective photochemical efficiency of PS II (Φ PSII ) and did not affect maximum photochemical efficiency of PS II (F v /F m ). At 24, 48, and 72 h, trehalose decreased non-photochemical quenching (NPQ) and increased photochemical quenching (qP). Our results suggest that trehalose did not damage photosynthetic reaction centers.
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