A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased...A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased the dry matter of both shoot and root,the ratio of root to shoot,total root length,root surface area,root diameter,root volume,and root tip numbers,which are important for forming a strong root system.The elevated CO2 treatment also significantly improved root hair development and elongation,thus enhancing nutrient uptake.Increased indole acetic acid concentration in plant tissues and ethylene release in the elevated CO2 treatment might have resulted in root growth enhancement and root hair development and elongation.展开更多
Polyploidy is pursued in plant breeding programs due mainly to its ability to yield larger vegetative or reproductive organs. In controlled growth chamber experiments, a tetraploid turnip （cv. Aijiaohuang, 4n） and i...Polyploidy is pursued in plant breeding programs due mainly to its ability to yield larger vegetative or reproductive organs. In controlled growth chamber experiments, a tetraploid turnip （cv. Aijiaohuang, 4n） and its diploid progenitor （cv. Aijiaohuang, 2n） were evaluated for their tolerance to salinity stress via investigations on a group of physiological parameters. The results indicate that the tetraploid turnip exhibit better adaptation to a high concentration salt medium （200 mmol L-1）, as evidenced by a less-affected germination rate and a healthier morphological appearance at the seedling stage. Furthermore, an extension of salinity stress up to a certain period of time at the 5-7-leaf stage shows differences between the tetraploid turnip and its diploid progenitor. The former had a higher K＋/Na＋ ratio in the roots, higher glutathione concentration and antioxidant activities in the leaves, and smaller reductions in photosynthetic capacity in terms of leaf chlorophyll content. Studies on the differences between an autopolyploid and its respective relative, from which the autopolyploid originated, in terms of their tolerance to salinity and/or other abiotic stresses, have remained rather limited. The comparison is interesting due to a homogenous genetic background.展开更多
Soil drying and wetting impose significant influences on soil nitrogen (N) dynamics and microbial communities. However, effects of drying-wetting cycles, while common in vegetable soils, especially under greenhouse co...Soil drying and wetting impose significant influences on soil nitrogen (N) dynamics and microbial communities. However, effects of drying-wetting cycles, while common in vegetable soils, especially under greenhouse conditions, have not been well studied. In this study, two greenhouse vegetable soils, which were collected from Xinji (XJ) and Hangzhou (HZ), China, were maintained at 30% and 75% water-holding capacity (WHC), or five cycles of 75% WHC followed by a 7-day dry-down to 30% WHC (DW). Soil inorganic N content increased during incubation. Net N mineralization (Nmin), microbial activity, and microbial biomass were significantly higher in the DW treatment than in the 30% and 75% WHC treatments. The higher water content (75% WHC) treatment had higher Nmin, microbial activity, and microbial biomass than the lower water content treatment (30% WHC). Multivariate analyses of community-level physiological profile (CLPP) and phospholipid fatty acid (PLFA) data indicated that soil moisture regime had a significant effect on soil microbial community substrate utilization pattern and microbial community composition. The significant positive correlation between Nmin and microbial substrate utilization or PLFAs suggested that soil N mineralization had a close relationship with microbial community.展开更多
Water and nitrogen （N） are considered the most important factors affecting rice production and play vital roles in regulating soil microbial biomass, activity, and community. The effects of irrigation patterns and N...Water and nitrogen （N） are considered the most important factors affecting rice production and play vital roles in regulating soil microbial biomass, activity, and community. The effects of irrigation patterns and N fertilizer levels on the soil microbial community structure and yield of paddy rice were investigated in a pot experiment. The experiment was designed with four N levels of 0 （NO）, 126 （N1）, 157.5 （N2）, and 210 kg N ha^（-1） （N3） under two irrigation patterns of continuous water-logging irrigation （WLI） and water- controlled irrigation （WCI）. Phospholipid fatty acid （PLFA） analysis was conducted to track the dynamics of soil microbial communities at tillering, grain-filling, and maturity stages. The results showed that the maximums of grain yield, above-ground biomass, and total N uptake were all obtained in the N2 treatment under WCI. Similar variations in total PLFAs, as well as bacterial and fungM PLFAs, were found, with an increase from the tillering to the grain-filling stage and a decrease at the maturity stage except for actinomycetic PLFAs, which decreased continuously from the tillering to the maturity stage. A shift in composition of the microbial community at different stages of the plant growth was indicated by principal component analysis （PCA）, in which the samples at the vegetative stage （tillering stage） were separated from those at the reproductive stage （grain-filling and maturity stages）. Soil microbial biomass, measured as total PLFAs, was significantly higher under WCI than that under WLI mainly at the grain-filling stage, whereas the fungal PLFAs detected under WCI were significantly higher than those under WLI at the tillering, grain-filling, and maturity stages. The application of N fertilizer also significantly increased soil microbial biomass and the main microbial groups both under WLI and WCI conditions. The proper combination of irrigation management and N fertilizer level in this study was the N2 （157.5 kg N ha^（-1）） treatment under the water-controlled irrigation pattern.展开更多
基金supported by the National Natural Science Foundation of China (No.30871590)the National Key Basic Research Program (973 Program) of China (Nos.2009CB119003 and 2007CB109305)+1 种基金the Major Research Program of Zhejiang Province (No.2008C12061-1)the National "Eleventh Five Years Plan" Key Project on Science and Technology of China (No.2006BAD05B03)
文摘A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased the dry matter of both shoot and root,the ratio of root to shoot,total root length,root surface area,root diameter,root volume,and root tip numbers,which are important for forming a strong root system.The elevated CO2 treatment also significantly improved root hair development and elongation,thus enhancing nutrient uptake.Increased indole acetic acid concentration in plant tissues and ethylene release in the elevated CO2 treatment might have resulted in root growth enhancement and root hair development and elongation.
基金supported by the Special Grand National Science and Technology Project, China(2009ZX08009-076B)the Natural Science Foundation of China (30971700)the Natural Science Foundation of Zhejiang Province, China (Z3100130)
文摘Polyploidy is pursued in plant breeding programs due mainly to its ability to yield larger vegetative or reproductive organs. In controlled growth chamber experiments, a tetraploid turnip （cv. Aijiaohuang, 4n） and its diploid progenitor （cv. Aijiaohuang, 2n） were evaluated for their tolerance to salinity stress via investigations on a group of physiological parameters. The results indicate that the tetraploid turnip exhibit better adaptation to a high concentration salt medium （200 mmol L-1）, as evidenced by a less-affected germination rate and a healthier morphological appearance at the seedling stage. Furthermore, an extension of salinity stress up to a certain period of time at the 5-7-leaf stage shows differences between the tetraploid turnip and its diploid progenitor. The former had a higher K＋/Na＋ ratio in the roots, higher glutathione concentration and antioxidant activities in the leaves, and smaller reductions in photosynthetic capacity in terms of leaf chlorophyll content. Studies on the differences between an autopolyploid and its respective relative, from which the autopolyploid originated, in terms of their tolerance to salinity and/or other abiotic stresses, have remained rather limited. The comparison is interesting due to a homogenous genetic background.
基金Supported by the State Key Laboratory of Soil and Sustainable Agriculture, Chinathe National Basic Research Program (973 Program) of China (No. 2007CB109305)+1 种基金the National Natural Science Foundation of China (Nos. 30971859 and 30370840)the International Plant Nutrition Institute (IPNI), USA
文摘Soil drying and wetting impose significant influences on soil nitrogen (N) dynamics and microbial communities. However, effects of drying-wetting cycles, while common in vegetable soils, especially under greenhouse conditions, have not been well studied. In this study, two greenhouse vegetable soils, which were collected from Xinji (XJ) and Hangzhou (HZ), China, were maintained at 30% and 75% water-holding capacity (WHC), or five cycles of 75% WHC followed by a 7-day dry-down to 30% WHC (DW). Soil inorganic N content increased during incubation. Net N mineralization (Nmin), microbial activity, and microbial biomass were significantly higher in the DW treatment than in the 30% and 75% WHC treatments. The higher water content (75% WHC) treatment had higher Nmin, microbial activity, and microbial biomass than the lower water content treatment (30% WHC). Multivariate analyses of community-level physiological profile (CLPP) and phospholipid fatty acid (PLFA) data indicated that soil moisture regime had a significant effect on soil microbial community substrate utilization pattern and microbial community composition. The significant positive correlation between Nmin and microbial substrate utilization or PLFAs suggested that soil N mineralization had a close relationship with microbial community.
基金Supported by the National Basic Research Program (973 Program) of China (No.2007CB109305)the National Natural ScienceFoundation of China (No.3197859)
文摘Water and nitrogen （N） are considered the most important factors affecting rice production and play vital roles in regulating soil microbial biomass, activity, and community. The effects of irrigation patterns and N fertilizer levels on the soil microbial community structure and yield of paddy rice were investigated in a pot experiment. The experiment was designed with four N levels of 0 （NO）, 126 （N1）, 157.5 （N2）, and 210 kg N ha^（-1） （N3） under two irrigation patterns of continuous water-logging irrigation （WLI） and water- controlled irrigation （WCI）. Phospholipid fatty acid （PLFA） analysis was conducted to track the dynamics of soil microbial communities at tillering, grain-filling, and maturity stages. The results showed that the maximums of grain yield, above-ground biomass, and total N uptake were all obtained in the N2 treatment under WCI. Similar variations in total PLFAs, as well as bacterial and fungM PLFAs, were found, with an increase from the tillering to the grain-filling stage and a decrease at the maturity stage except for actinomycetic PLFAs, which decreased continuously from the tillering to the maturity stage. A shift in composition of the microbial community at different stages of the plant growth was indicated by principal component analysis （PCA）, in which the samples at the vegetative stage （tillering stage） were separated from those at the reproductive stage （grain-filling and maturity stages）. Soil microbial biomass, measured as total PLFAs, was significantly higher under WCI than that under WLI mainly at the grain-filling stage, whereas the fungal PLFAs detected under WCI were significantly higher than those under WLI at the tillering, grain-filling, and maturity stages. The application of N fertilizer also significantly increased soil microbial biomass and the main microbial groups both under WLI and WCI conditions. The proper combination of irrigation management and N fertilizer level in this study was the N2 （157.5 kg N ha^（-1）） treatment under the water-controlled irrigation pattern.
