Aims Nutrient resorption is a crucial component of plant nutrient use strategy,yet the controls on the responses of community-level nutrient resorption to altered nutrient availability remain unclear.Here,we addressed...Aims Nutrient resorption is a crucial component of plant nutrient use strategy,yet the controls on the responses of community-level nutrient resorption to altered nutrient availability remain unclear.Here,we addressed two questions:(1)Did leaf and stem nutrient resorption respond consistently to increased nutrient availability?(2)Was community-level plant nutrient resorption response after nutrient enrichment driven by the intraspecific plasticity in plant nutrient resorption or by altered species composition?Methods We investigated the changes in aboveground biomass,and leaf and stem nutrient resorption of individual species after 3-year nitrogen(N)and phosphorus(P)additions,and assessed community-level nutrient resorption response to 3-year nutrient additions in a graminoid-dominated temperate wetland,Northeast China.Important Findings For both leaves and stems,N and P additions did not affect nutrient resorption efficiency,but they decreased respective nutrient resorption proficiency.Similarly,community-level N and P resorption proficiency declined with respective nutrient addition.Community-level N and P resorption efficiency was reduced by N addition primarily due to altered community composition and declined leaf:stem ratio.These results suggest that leaf and stem nutrient resorption processes exhibit consistent responses to increasing nutrient availability in the temperate wetland.These findings highlight the importance of altered species composition and biomass allocation between leaf and stem in driving community-level nutrient resorption response to nutrient enrichment.展开更多
[ Objectives ] The aim was to optimize the configuration of seedling density and line spacing of forage sweet sorghum （ Sorghum blcolor （ L. ） Moench） and explore its high-yield cultivation techniques. [ Methods] ...[ Objectives ] The aim was to optimize the configuration of seedling density and line spacing of forage sweet sorghum （ Sorghum blcolor （ L. ） Moench） and explore its high-yield cultivation techniques. [ Methods] Effects of such two influencing factors as line spacing and seedling density on the leaf-stem ratio, DW/FW ratio and grass yield of forage sweet sorghum were analyzed by using split-plot experiment design experiment method and LSD method of IBM. SPSS. Statis- tics. v22 stati, stics software. [ Results ~ Seedling density and line spacing had no obvious effect on the leaf-stem ratio and DW/FW ratio of forage sweet sorghum but had obvious influences on the grass yield. Moreover, the optimal combination of seedling density and line spacing for high yield of forage sweet sorghum was A2 B4, that is, seedling density was 225 000 plants/hm2, and line spacing was 40 cm. [ Conclusions] The results provided a theoretical basis and technical support for high-yield cultivation techniques of forage sweet sorghum.展开更多
This work aimed to evaluate the effects of different individual heights of cut on structural characteristics of Brachiaria hibrida cv. Mulato I in four periods of the year. The study was carried out at the Fazenda Exp...This work aimed to evaluate the effects of different individual heights of cut on structural characteristics of Brachiaria hibrida cv. Mulato I in four periods of the year. The study was carried out at the Fazenda Experimental Vale do Acaraú, in Sobral, Ceará, Brazil, from January to December, 2008. The experimental design was a split plot, with the plots representing four pasture conditions through manual cuts of 10 cm, 20 cm, 30 cm and 40 cm heights, which were done every 30 days. Each treatment had three replications. The subplots were represented by four periods of evaluation: January-February-March, April-May-June, July-August-September and October-November-December. Fertilization was performed with 350 kg of N/ha, divided into monthly applications. Irrigation was conducted in alternate days during the dry season. The variables studied were: mean height before cutting (cm);dry matter content (%);total dry matter production (t/ha);percentage of leaves;percentage of stems;percentage of dead material;leaf blade/stem ratios;number of total leaves per tiller;number of live leaves per tiller;average size of leaves;and tiller density. Cutting at 10 cm caused a decrease in total dry matter production, underestimating the potential production. Cutting heights between 20 and 30 cm contributed positively to increase the total number of leaves, number of green leaves, average size of the leafs and total dry matter production. Under the present experimental conditions, cutting around 40 cm was not recommended because of a decreasing in the leaf/stem ratio and a increasing in stem fraction and dry matter content, compromising the structure of the canopy.展开更多
文摘Aims Nutrient resorption is a crucial component of plant nutrient use strategy,yet the controls on the responses of community-level nutrient resorption to altered nutrient availability remain unclear.Here,we addressed two questions:(1)Did leaf and stem nutrient resorption respond consistently to increased nutrient availability?(2)Was community-level plant nutrient resorption response after nutrient enrichment driven by the intraspecific plasticity in plant nutrient resorption or by altered species composition?Methods We investigated the changes in aboveground biomass,and leaf and stem nutrient resorption of individual species after 3-year nitrogen(N)and phosphorus(P)additions,and assessed community-level nutrient resorption response to 3-year nutrient additions in a graminoid-dominated temperate wetland,Northeast China.Important Findings For both leaves and stems,N and P additions did not affect nutrient resorption efficiency,but they decreased respective nutrient resorption proficiency.Similarly,community-level N and P resorption proficiency declined with respective nutrient addition.Community-level N and P resorption efficiency was reduced by N addition primarily due to altered community composition and declined leaf:stem ratio.These results suggest that leaf and stem nutrient resorption processes exhibit consistent responses to increasing nutrient availability in the temperate wetland.These findings highlight the importance of altered species composition and biomass allocation between leaf and stem in driving community-level nutrient resorption response to nutrient enrichment.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(20120304201)
文摘[ Objectives ] The aim was to optimize the configuration of seedling density and line spacing of forage sweet sorghum （ Sorghum blcolor （ L. ） Moench） and explore its high-yield cultivation techniques. [ Methods] Effects of such two influencing factors as line spacing and seedling density on the leaf-stem ratio, DW/FW ratio and grass yield of forage sweet sorghum were analyzed by using split-plot experiment design experiment method and LSD method of IBM. SPSS. Statis- tics. v22 stati, stics software. [ Results ~ Seedling density and line spacing had no obvious effect on the leaf-stem ratio and DW/FW ratio of forage sweet sorghum but had obvious influences on the grass yield. Moreover, the optimal combination of seedling density and line spacing for high yield of forage sweet sorghum was A2 B4, that is, seedling density was 225 000 plants/hm2, and line spacing was 40 cm. [ Conclusions] The results provided a theoretical basis and technical support for high-yield cultivation techniques of forage sweet sorghum.
文摘This work aimed to evaluate the effects of different individual heights of cut on structural characteristics of Brachiaria hibrida cv. Mulato I in four periods of the year. The study was carried out at the Fazenda Experimental Vale do Acaraú, in Sobral, Ceará, Brazil, from January to December, 2008. The experimental design was a split plot, with the plots representing four pasture conditions through manual cuts of 10 cm, 20 cm, 30 cm and 40 cm heights, which were done every 30 days. Each treatment had three replications. The subplots were represented by four periods of evaluation: January-February-March, April-May-June, July-August-September and October-November-December. Fertilization was performed with 350 kg of N/ha, divided into monthly applications. Irrigation was conducted in alternate days during the dry season. The variables studied were: mean height before cutting (cm);dry matter content (%);total dry matter production (t/ha);percentage of leaves;percentage of stems;percentage of dead material;leaf blade/stem ratios;number of total leaves per tiller;number of live leaves per tiller;average size of leaves;and tiller density. Cutting at 10 cm caused a decrease in total dry matter production, underestimating the potential production. Cutting heights between 20 and 30 cm contributed positively to increase the total number of leaves, number of green leaves, average size of the leafs and total dry matter production. Under the present experimental conditions, cutting around 40 cm was not recommended because of a decreasing in the leaf/stem ratio and a increasing in stem fraction and dry matter content, compromising the structure of the canopy.
