The effects of different inorganic fertilizers （Urea and Triple Super Phosphate （TSP）） on seedling growth and nodulation capabilities of four agroforestry tree species （Albizia chinensis, A. saman, Acacia nilotic...The effects of different inorganic fertilizers （Urea and Triple Super Phosphate （TSP）） on seedling growth and nodulation capabilities of four agroforestry tree species （Albizia chinensis, A. saman, Acacia nilotica and Sesbania sesban） were compared. The nodulation of these seedlings were treated with different fertilizer treatments （at the rate of urea 40 kg·hm^-2, urea 80 kg·hm^-2 TSP 40 kg·hm^-2, TSP 80 kg·hm^-2, （urea＋TSP） 40 kghm 2 and （urea＋TSP） 80 kg·hm^-2） after one month of seed germination. The results revealed that the seedling growth was enhanced significantly with moderate fertilizer treatment. In some cases, the higher levels of fertilizers reduced the seedling growth. The study also revealed that the nodulation in nodule number and size was significantly inhibited by the application of N fertilizer （Urea）, while it was increased significantly with the application of P fertilizer （TSP）. This study improved our understanding and provided insights that would be useful to the farmers in their efforts to amend the soil with inorganic fertilizers in order to enhance plant growth and biological nitrogen fixation.展开更多
【Objectives】Rose(Rosa hybrida L.)is a beautiful and widely cultivated flowering plant around the world whose quality is of great commercial importance.The objective of this study was to investigate the impact of fol...【Objectives】Rose(Rosa hybrida L.)is a beautiful and widely cultivated flowering plant around the world whose quality is of great commercial importance.The objective of this study was to investigate the impact of foliar application of calcium nitrate on the quality and postharvest life of two rose varieties(cvs.Samurai,and Jumilia)in a soilless culture system.【Methods】The research used a hydroponic culture method,the roses plants were grown in Hoagland nutrient solution containing 50%less Ca for a total span of 4 months.One month was dedicated to plant acclimatization,and 3 months for spray treatment.Two rose varieties(Rosa hybrida L.),cvs.Samurai and Jumilia plants were used as test materials and planted in pots containing 100%perlite(3-5 mm).After one month of culture,160 mg/kg CaNO3 solution was sprayed,and each treatment corresponded to the first,second,and third harvests,respectively.The plant and flower growth indicators and flower vase life were investigated after each harvesting immediately.【Results】A positive impact of foliar-applied Ca on stem characteristics,pedicel dimensions,corolla size,flower attributes,and vase life was found.Furthermore,a general trend was observed,wherein an increase in the number of harvesting stages led to improved traits.Notably,Jumilia rose consistently exhibited lower values for all studied traits,except for flower vase life,in comparison to the Samurai rose.While there were no significant differences in length values between Samurai and Jumilia roses due to calcium foliar application across the three harvesting stages.Duncan’s grouping revealed a specific effect on Jumilia roses during the third harvest stage.Calcium fertilizer significantly increased photosynthesis rates of of rose leaves in the calcium treatments compared with the control treatment.【Conclusions】Foliar spraying of calcium nitrate is an effective measure to promote the growth of roses and improve the yield,quality and bottle life of fresh cut flowers.展开更多
Tropical forests store more than half of the world's terrestrial carbon(C)pool and account for one-third of global net primary productivity(NPP).Many terrestrial biosphere models(TBMs)estimate increased productivi...Tropical forests store more than half of the world's terrestrial carbon(C)pool and account for one-third of global net primary productivity(NPP).Many terrestrial biosphere models(TBMs)estimate increased productivity in tropical forests throughout the 21st century due to CO_(2)fertilization.However,phosphorus(P)liaitations on vegetation photosynthesis and productivity could significantly reduce the CO_(2)fertilization effect.Here,we used a carbon-nitrogen-phosphorus coupled model(Dynamic Land Ecosystem Model;DLEM-CNP)with heterogeneous maximum carboxylation rates to examine how P limitation has affected C fluxes in tropical forests during1860-2018.Our model results showed that the inclusion of the P processes enhanced model performance in simulating ecosystem productivity.We further compared the simulations from DLEM-CNP,DLEM-CN,and DLEMC and the results showed that the inclusion of P processes reduced the CO_(2)fertilization effect on gross primary production(GPP)by 25%and 45%,and net ecosystem production(NEP)by 28%and 41%,respectively,relative to CN-only and C-on ly models.From the 1860s to the 2010s,the DLEM-CNP estimated that in tropical forests GPP increased by 17%,plant respiration(Ra)increased by 18%,ecosystem respiration(Rh)increased by 13%,NEP increased by 121%per unit area,respectively.Additionally,factorial experiments with DLEM-CNP showed that the enhanced NPP benefiting from the CO_(2) fertilization effect had been offset by 135%due to deforestation from the 1860s to the 2010s.Our study highlights the importance of P limitation on the C cycle and the weakened CO_(2)fertilization effect resulting from P limitation in tropical forests.展开更多
Effects of two media and fertilizer levels on the growth of Cymbidium hybridium were studied. Results demonstrated that peanut\|hull mixed sand (abbreviated as PH/S=1/1) medium had higher total porosity and larger...Effects of two media and fertilizer levels on the growth of Cymbidium hybridium were studied. Results demonstrated that peanut\|hull mixed sand (abbreviated as PH/S=1/1) medium had higher total porosity and larger air space and lower water holding capacity in comparison with sphagnum (abbreviated as SP) medium. Leaf growth rate, chlorophyll contents, fresh weight and photosynthetic rate change along with the changes of nitrogen concentrations of both SP and PH/S media. According to the investigation,when the nitrogen concentration was 222 75?mg·L -1 , the photosynthetic rate of SP\|medium reached the highest. The practical nitrogen content was 180 00?mg·L -1 for PH/S medium . The maximum of flower quantity (number per spike) was gotten by treating of N/P 2O 5/K 2O=10/30/20 on PH/S medium, and N/P 2O 5/K 2O=0/23/29 treatment was the lowest on PH/S medium. The differences in small flowers, stem length and flower quantity among the two media and the three fertilization methods reached significant at 0 05 level,respectively.展开更多
A study was conducted to test the influence of different inorganic fertilizers （phosphorous and potassium） on the nodulation and growth of Dalbergia sissoo grown in the nursery. Before seeds sowing, different combin...A study was conducted to test the influence of different inorganic fertilizers （phosphorous and potassium） on the nodulation and growth of Dalbergia sissoo grown in the nursery. Before seeds sowing, different combinations of P, K fertilizers were incorporated with the nutrient-deficient natural forest soils, and then amended with cowdung （soil： cowdung = 3：1）. Nodulation status （nodule number, shape, fresh weight, dry weight and color） in the roots and the plant growth parameters （length of shoot and root, collar diameter, fresh and dry weight of shoot and root） were recorded 60 days after seeds sowing. Nodulation status and growth of the plants varied significantly （P〈0.05） in the soils amended with fertilizers in comparison to the control. The highest nodule number （62）, fresh （0.50 g） and dry （0.07 g） weights were recorded with the dose of PK at the rate of 160 kg/hm2. Nodule shape and color also varied widely in different treatments. In case of plant growth parameters, shoot and root length, collar diameter, fresh and dry weight of the plants took on a significant difference （P〈0.05） among various combination of fertilizers. From the study, it is revealed that PK at the rate of 160 kg/hm^2 fertilizer with soil and cowdung mixture （soil： eowdung = 3：1） is recommended for optimum growth and nodule formation of D. sissoo in degraded soils at a nursery level.展开更多
The challenges of a changing climate have directed greater attention to afforestation,but the effects of afforestation on soil fertility and soil biota have not been fully clarified.To explore changes in the soil cond...The challenges of a changing climate have directed greater attention to afforestation,but the effects of afforestation on soil fertility and soil biota have not been fully clarified.To explore changes in the soil conditions in two 20-year-old forest plantations established in formerly intensively fertilized plots of agricultural land,we focused on the current developmental state of the sites that received the most fertilizer and evaluated soil properties and Collembola(springtails)communities.Sessile oak(Quercus petraea)and black locust(Robinia pseudoacacia)that had been planted in the afforestation sites were assessed for differences between plantations of native and invasive species.Five adjacent reference associations,including forests and open habitats,were also analyzed and compared.Results showed that the soils in the two afforested sites were similar in their properties and Collembola communities to those of the control cultivated forests,but differed from each other in pH,calcium,phosphorus,and ammonium content.The available potassium and phosphorus contents in the soil of the sessile oak plantation were still high,while the soil organic matter content was adequate(SOM>2.0%)in both plantations.Species richness of Collembola ranged from 18 in the cultivated arable land to 43 in the relict forest.Only a few species typical for forests(e.g.,Neanura muscorum,Isotomiella minor,Entomobrya muscorum)were detected in the young plantations,while species characteristic of open habitats(e.g.,Protaphorura campata,Lepidocyrtus cyaneus)occurred as well.Although more individuals and species of Collembola were present in the soil of young plantations than in arable fields,their community diversities were significantly lower compared to the control forest stands.Collembola community diversity differed significantly also between the two plantation types(with native and non-native tree species).Mean abundance in the afforested sites was about 2.5 times higher than in the cultivated arable land,yet far lower than the mean abundance in the control forests.展开更多
Rare earth elements (REEs) enriched fertilisers are currently used in China for soil and foliar applications to crops, but little is known about the effect of REEs applications on the growth of beneficial and detrimen...Rare earth elements (REEs) enriched fertilisers are currently used in China for soil and foliar applications to crops, but little is known about the effect of REEs applications on the growth of beneficial and detrimental soilborne microorganisms. The growth of biological control agents Trichoderma atroviride strain P1, Trichoderma harzianum strain A6 and strain T22, plant pathogens Botrytis cinerea, Alternaria alternata, Fusarium solani, Rhizoctonia solani and Sclerotinia sclerotiorum was investigated in the presence of REEs. An in vitro assays was used to monitor the effect of different concentration levels of either a mix of REEs (La, Ce, Pr, Nd) nitrates or lanthanum alone in comparison to treatments conducted with potassium nitrate and water. Although all fungi were affected when the REEs mix or lanthanum were present at concentrations higher than 100 mM, the growth inhibition depended mainly upon the combination of compounds, the dose and the fungal species or strains tested. Trichoderma strains and B. cinerea were more sensitive than A. alternata, F. solani, R. solani or at higher concentrations. Differing growth responses of some fungi to treatments with REEs mix vs. lanthanum alone indicated that in given situations the effect of the REEs compounds may be caused by elements other than lanthanum or by element mixtures. Further investigations are in progress to determine the effect of REEs on important interactions in the soil community between beneficial fungi, pathogenic fungi and/or the plant. REEs are naturally present in the environment and in biological systems but accumulation in soil can take place following successive applications. Therefore, it would be useful to achieve a better understanding of the effect of REEs accumulation on the activity of rhizosphere microorganisms given the widespread use in some regions of rare earths as fertilizers and their presence as fertilizer contaminants.展开更多
Every February,across the country,candy,flowers,and gifts are exchanged between loved ones,all in the name of St.Valentine.But who is thismysterious saint and why do we celebrate thisholiday?
(All of us eat every day,but mostof us don’t understand nutrition.How much do you know about good nutrition?Pleaseanswer these twelve questions based on current ideasabout food and health.The answers may surprise you...(All of us eat every day,but mostof us don’t understand nutrition.How much do you know about good nutrition?Pleaseanswer these twelve questions based on current ideasabout food and health.The answers may surprise you.) Are the following statements true or false? 1.You’ll get proper nourishment if you just eat avariety of foods. False.Variety is not a guarantee of good nutri-tion.But adults can generally get a balanced diet byincluding several servings daily from the four main展开更多
A provenance trial of Michelia chapensis Dandy in the south of China was carried out in three sites to assess yield and stability analyses. The trials were conducted as randomized, complete block designs with four rep...A provenance trial of Michelia chapensis Dandy in the south of China was carried out in three sites to assess yield and stability analyses. The trials were conducted as randomized, complete block designs with four replications at each site. Additive main effects and multiplicative interaction（AMMI） and genotype main effect and genotype 9 environment interaction（GGE） were employed in the evaluation of provenances; AMMI analyses showed that significant genotype 9 environment interaction effects（P ／ 0.05） existed between provenances, capturing 15.11 % of the total sum of squares. The AMMI stability value revealed that provenance 2 was stable, but had low yield. GGE-biplot models showed that provenances 7, 8, 10, and 11 were more stable and highyielding. The GGE results also confirmed that among the three sites, site Jiu Qu Shui was the most ideal environment for representation and discrimination.展开更多
To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,...To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,and potassium fertilizers),each with four levels,using an orthogonal experimental design.A logistic model was used to estimate growth in height.The growth curves for tree height were sigmoid,and the model R^2 values were greater than 0.9,which indicated that the fit was highly significant.ANOVA results for tree height and basal diameter indicated that all sources of variance showed significant differences(p<0.001).The average tree height and basal diameter for all the four clones under the different treatments ranged from 155.39 to 235.04 cm,and from 13.71 to 17.42 mm,respectively.A highly positive correlation between the extreme k value and tree height was observed,suggesting that the k value was an accurate estimation of tree height.For model parameters,the earliest average time point for the onset of the rapid growth period of poplar clones was 131 d,and the highest average increment in tree height during the rapid growth period was 138.78 cm.The highest average tree height for all clones under each factor was 219,210.51,200,and 201 cm when treated with either 1200 mL of water applied every third day,3 g of nitrogen,0 g of phosphorus,or 0 g of potassium,respectively.The most suitable treatment for the early growth of hybrid poplar cuttings,as suggested by the developed logistic model,was 1200 mL of water applied every third day and three applications of 1 g nitrogen(in the form of CH4N2O).展开更多
To select maternal parents with high fertility and high combining ability during cross breeding of Populus tomentosa Carr., the ploidy level of 75 female clones was determined using flow cytometry. In addition, geneti...To select maternal parents with high fertility and high combining ability during cross breeding of Populus tomentosa Carr., the ploidy level of 75 female clones was determined using flow cytometry. In addition, genetic variations and phenotypic correlations of seed traits and early growth traits, as well as the general combining ability(GCA) for seedling height(SH) and basal diameter(BD) of all diploid half-sib families were examined. A total of 26 natural triploid clones were identified. For all diploid families, family effects were significant for inflorescence length(IL), thousand kernel weight(TKW), seedling emergence rate(SER), and for SH and BD. There was a positive correlation between TKW and other traits,excluding IL. The seed-bearing coefficient(NS 9 SER)ranged from zero to 32.4%. Clones 3-10-2, 2-8, 3119,3206, and 3-10-1 had the best performance of the GCA for SH and BD. Based on the fertility and GCA for SH and BD, clone 3-10-2 and clone 3119 could be used as female parents for controlled cross-breeding of P. tomentosa.展开更多
This paper puts forward a valuation model for the flexibility of revamping urea plants based on the substitutability of switching between the internationally accepted fertilizer feedstock fuel oil and natural gas. The...This paper puts forward a valuation model for the flexibility of revamping urea plants based on the substitutability of switching between the internationally accepted fertilizer feedstock fuel oil and natural gas. The paper first builds a stochastic mean-reversion model for fuel oil prices and natural gas prices respectively, then estimates and tests the parameters using the fuel oil and natural gas prices data from the U.S. market. This paper also conducts a sensitivity analysis with important parameters. The results show that the real option method can be applied successfully to evaluate the flexibility in decision- making for revamping installations in fertilizer plants or other similar plants.展开更多
Tree competitiveness generally depends on trait plasticity in response to environmental change.The effects of nitrogen(N)and phosphorus(P)on leaf trait variability by species is poorly understood,especially in China’...Tree competitiveness generally depends on trait plasticity in response to environmental change.The effects of nitrogen(N)and phosphorus(P)on leaf trait variability by species is poorly understood,especially in China’s subtropical forests.This study examined the seedling leaf traits and net primary productivity of all trees>5 cm DBH of two dominant species,Schima superba and Castanopsis carlesii,in an evergreen broadleaved forest fertilized with nitrogen(+N),phosphorus(+P),and nitrogen plus phosphorus(N+P).The effect of N on seedling leaf traits was stronger than P,while fertilization in general was species dependent.Leaf mass per unit area decreased with N for S.superba seedlings but not for C.carlesii.Leaf N,P,and N/P ratios changed with N addition for both species.All four N fractions of carboxylation,bioenergetics,cell wall,and other N metabolites in C.carlesii leaves responded significantly to fertilization,while only the cell wall in S.superb a leaves responded.Other leaf functional traits,including light-saturated photosynthetic rates,water,N,and P use efficiencies,chlorophyll and non structural carbohydrate contents increased with N addition in S.superb a and by P addition in C.carlesii.Canopy closure at the stand-level increased due to N.Litter biomass and relative growth rate of S.superb a was not affected by any treatments,while both for C.carlesii significantly decreased with N+P addition.Collectively,nutrient limitation may vary at a small scale among species in a subtropical forest based on their responses of seedling traits and net primary productivity to fertilization.Seedling traits are not correlated with the net primary productivity of larger trees except for N fractions,because low light conditions induced by fertilization reduces the proportion of N allocated to photosynthesis in seedlings.In addition,acclimation differences of tree species may increase the uncertainty of community succession.展开更多
How to improve the water use efficiency of rice in black soil regions was studied. The black soil region in paddy fields was chosen as the research object. The research showed the fertilizer coupling mathematical mode...How to improve the water use efficiency of rice in black soil regions was studied. The black soil region in paddy fields was chosen as the research object. The research showed the fertilizer coupling mathematical model with N,P,K,irrigation water( W) and water use efficiency( WUE),which was set up under the condition of controlled irrigation with quadratic D- 416 optimized saturation design. The results show that the decending order of single factor' s influence on the WUE was N,K,P and W. All the interactions between N&P,N&K,N&W,K&P,P&W and K&W on the WUE were raised initially,and when reached a certain value,they began to decline. The decending order of each interaction on the WUE was K&P,K&W,N&K,N&P,P&W and N&W. When the WUE was targeted within 1. 8- 2. 5 kg / km^3,an optimized proportion plan was obtained in the 95% confidence interval,i. e. N 87. 76- 103. 32 kg / hm^2,K_2 O 52. 37- 66. 53 kg / hm^2 and P_2O_536. 80- 46. 71 kg / hm^2. Furthermore,the late tillering of the soil moisture content was 70. 07%- 72. 57% of the saturated moisture content.展开更多
Allocation of biomass and nutrient elements including Nitrogen to above and belowground compartments of beech seedlings （Fagus sylvatica L.） treated by labeled nitrogen fertilizer in the form of 15NH4 and 15NO3 were...Allocation of biomass and nutrient elements including Nitrogen to above and belowground compartments of beech seedlings （Fagus sylvatica L.） treated by labeled nitrogen fertilizer in the form of 15NH4 and 15NO3 were investigated at the end of two successive growing seasons. Pot cultured beech seedlings were grown at a green house on intact soil cores sampled from three adjacent stands including beech, Norway spruce and mixed beech-spruce cultures of Soiling forest, Germany. Comparing biomass allocation and nutrients concentrations of the seedlings between the control and 15N-fertilized treatments revealed no significant effect of N fertilization on nutrients uptake by seedlings over the experiment. The form of N input influenced its movement into plant pools. It was demonstrated that beech seedlings take up nitrogen mainly in the form of nitrate, which is then reduced in the leaves, although the differences between the retention of NO3^--N and NH4^＋-N in plants were not statistically significant. Percent recoveries of 15N in trees were typically greater after 15NO3 than after 15NH4 additions. It was indicated that immobilization of ~SN tracer in fine roots was a slower process comparing other plant compartments such as stem and coarse roots, but a powerful sink for N during the course of study.展开更多
文摘The effects of different inorganic fertilizers （Urea and Triple Super Phosphate （TSP）） on seedling growth and nodulation capabilities of four agroforestry tree species （Albizia chinensis, A. saman, Acacia nilotica and Sesbania sesban） were compared. The nodulation of these seedlings were treated with different fertilizer treatments （at the rate of urea 40 kg·hm^-2, urea 80 kg·hm^-2 TSP 40 kg·hm^-2, TSP 80 kg·hm^-2, （urea＋TSP） 40 kghm 2 and （urea＋TSP） 80 kg·hm^-2） after one month of seed germination. The results revealed that the seedling growth was enhanced significantly with moderate fertilizer treatment. In some cases, the higher levels of fertilizers reduced the seedling growth. The study also revealed that the nodulation in nodule number and size was significantly inhibited by the application of N fertilizer （Urea）, while it was increased significantly with the application of P fertilizer （TSP）. This study improved our understanding and provided insights that would be useful to the farmers in their efforts to amend the soil with inorganic fertilizers in order to enhance plant growth and biological nitrogen fixation.
文摘【Objectives】Rose(Rosa hybrida L.)is a beautiful and widely cultivated flowering plant around the world whose quality is of great commercial importance.The objective of this study was to investigate the impact of foliar application of calcium nitrate on the quality and postharvest life of two rose varieties(cvs.Samurai,and Jumilia)in a soilless culture system.【Methods】The research used a hydroponic culture method,the roses plants were grown in Hoagland nutrient solution containing 50%less Ca for a total span of 4 months.One month was dedicated to plant acclimatization,and 3 months for spray treatment.Two rose varieties(Rosa hybrida L.),cvs.Samurai and Jumilia plants were used as test materials and planted in pots containing 100%perlite(3-5 mm).After one month of culture,160 mg/kg CaNO3 solution was sprayed,and each treatment corresponded to the first,second,and third harvests,respectively.The plant and flower growth indicators and flower vase life were investigated after each harvesting immediately.【Results】A positive impact of foliar-applied Ca on stem characteristics,pedicel dimensions,corolla size,flower attributes,and vase life was found.Furthermore,a general trend was observed,wherein an increase in the number of harvesting stages led to improved traits.Notably,Jumilia rose consistently exhibited lower values for all studied traits,except for flower vase life,in comparison to the Samurai rose.While there were no significant differences in length values between Samurai and Jumilia roses due to calcium foliar application across the three harvesting stages.Duncan’s grouping revealed a specific effect on Jumilia roses during the third harvest stage.Calcium fertilizer significantly increased photosynthesis rates of of rose leaves in the calcium treatments compared with the control treatment.【Conclusions】Foliar spraying of calcium nitrate is an effective measure to promote the growth of roses and improve the yield,quality and bottle life of fresh cut flowers.
基金partially supported by the US National Science Foundation(1903722,1243232)。
文摘Tropical forests store more than half of the world's terrestrial carbon(C)pool and account for one-third of global net primary productivity(NPP).Many terrestrial biosphere models(TBMs)estimate increased productivity in tropical forests throughout the 21st century due to CO_(2)fertilization.However,phosphorus(P)liaitations on vegetation photosynthesis and productivity could significantly reduce the CO_(2)fertilization effect.Here,we used a carbon-nitrogen-phosphorus coupled model(Dynamic Land Ecosystem Model;DLEM-CNP)with heterogeneous maximum carboxylation rates to examine how P limitation has affected C fluxes in tropical forests during1860-2018.Our model results showed that the inclusion of the P processes enhanced model performance in simulating ecosystem productivity.We further compared the simulations from DLEM-CNP,DLEM-CN,and DLEMC and the results showed that the inclusion of P processes reduced the CO_(2)fertilization effect on gross primary production(GPP)by 25%and 45%,and net ecosystem production(NEP)by 28%and 41%,respectively,relative to CN-only and C-on ly models.From the 1860s to the 2010s,the DLEM-CNP estimated that in tropical forests GPP increased by 17%,plant respiration(Ra)increased by 18%,ecosystem respiration(Rh)increased by 13%,NEP increased by 121%per unit area,respectively.Additionally,factorial experiments with DLEM-CNP showed that the enhanced NPP benefiting from the CO_(2) fertilization effect had been offset by 135%due to deforestation from the 1860s to the 2010s.Our study highlights the importance of P limitation on the C cycle and the weakened CO_(2)fertilization effect resulting from P limitation in tropical forests.
文摘Effects of two media and fertilizer levels on the growth of Cymbidium hybridium were studied. Results demonstrated that peanut\|hull mixed sand (abbreviated as PH/S=1/1) medium had higher total porosity and larger air space and lower water holding capacity in comparison with sphagnum (abbreviated as SP) medium. Leaf growth rate, chlorophyll contents, fresh weight and photosynthetic rate change along with the changes of nitrogen concentrations of both SP and PH/S media. According to the investigation,when the nitrogen concentration was 222 75?mg·L -1 , the photosynthetic rate of SP\|medium reached the highest. The practical nitrogen content was 180 00?mg·L -1 for PH/S medium . The maximum of flower quantity (number per spike) was gotten by treating of N/P 2O 5/K 2O=10/30/20 on PH/S medium, and N/P 2O 5/K 2O=0/23/29 treatment was the lowest on PH/S medium. The differences in small flowers, stem length and flower quantity among the two media and the three fertilization methods reached significant at 0 05 level,respectively.
文摘A study was conducted to test the influence of different inorganic fertilizers （phosphorous and potassium） on the nodulation and growth of Dalbergia sissoo grown in the nursery. Before seeds sowing, different combinations of P, K fertilizers were incorporated with the nutrient-deficient natural forest soils, and then amended with cowdung （soil： cowdung = 3：1）. Nodulation status （nodule number, shape, fresh weight, dry weight and color） in the roots and the plant growth parameters （length of shoot and root, collar diameter, fresh and dry weight of shoot and root） were recorded 60 days after seeds sowing. Nodulation status and growth of the plants varied significantly （P〈0.05） in the soils amended with fertilizers in comparison to the control. The highest nodule number （62）, fresh （0.50 g） and dry （0.07 g） weights were recorded with the dose of PK at the rate of 160 kg/hm2. Nodule shape and color also varied widely in different treatments. In case of plant growth parameters, shoot and root length, collar diameter, fresh and dry weight of the plants took on a significant difference （P〈0.05） among various combination of fertilizers. From the study, it is revealed that PK at the rate of 160 kg/hm^2 fertilizer with soil and cowdung mixture （soil： eowdung = 3：1） is recommended for optimum growth and nodule formation of D. sissoo in degraded soils at a nursery level.
基金supported financially by the project (EFOP-3.6.1–16-2016–00,018)
文摘The challenges of a changing climate have directed greater attention to afforestation,but the effects of afforestation on soil fertility and soil biota have not been fully clarified.To explore changes in the soil conditions in two 20-year-old forest plantations established in formerly intensively fertilized plots of agricultural land,we focused on the current developmental state of the sites that received the most fertilizer and evaluated soil properties and Collembola(springtails)communities.Sessile oak(Quercus petraea)and black locust(Robinia pseudoacacia)that had been planted in the afforestation sites were assessed for differences between plantations of native and invasive species.Five adjacent reference associations,including forests and open habitats,were also analyzed and compared.Results showed that the soils in the two afforested sites were similar in their properties and Collembola communities to those of the control cultivated forests,but differed from each other in pH,calcium,phosphorus,and ammonium content.The available potassium and phosphorus contents in the soil of the sessile oak plantation were still high,while the soil organic matter content was adequate(SOM>2.0%)in both plantations.Species richness of Collembola ranged from 18 in the cultivated arable land to 43 in the relict forest.Only a few species typical for forests(e.g.,Neanura muscorum,Isotomiella minor,Entomobrya muscorum)were detected in the young plantations,while species characteristic of open habitats(e.g.,Protaphorura campata,Lepidocyrtus cyaneus)occurred as well.Although more individuals and species of Collembola were present in the soil of young plantations than in arable fields,their community diversities were significantly lower compared to the control forest stands.Collembola community diversity differed significantly also between the two plantation types(with native and non-native tree species).Mean abundance in the afforested sites was about 2.5 times higher than in the cultivated arable land,yet far lower than the mean abundance in the control forests.
文摘Rare earth elements (REEs) enriched fertilisers are currently used in China for soil and foliar applications to crops, but little is known about the effect of REEs applications on the growth of beneficial and detrimental soilborne microorganisms. The growth of biological control agents Trichoderma atroviride strain P1, Trichoderma harzianum strain A6 and strain T22, plant pathogens Botrytis cinerea, Alternaria alternata, Fusarium solani, Rhizoctonia solani and Sclerotinia sclerotiorum was investigated in the presence of REEs. An in vitro assays was used to monitor the effect of different concentration levels of either a mix of REEs (La, Ce, Pr, Nd) nitrates or lanthanum alone in comparison to treatments conducted with potassium nitrate and water. Although all fungi were affected when the REEs mix or lanthanum were present at concentrations higher than 100 mM, the growth inhibition depended mainly upon the combination of compounds, the dose and the fungal species or strains tested. Trichoderma strains and B. cinerea were more sensitive than A. alternata, F. solani, R. solani or at higher concentrations. Differing growth responses of some fungi to treatments with REEs mix vs. lanthanum alone indicated that in given situations the effect of the REEs compounds may be caused by elements other than lanthanum or by element mixtures. Further investigations are in progress to determine the effect of REEs on important interactions in the soil community between beneficial fungi, pathogenic fungi and/or the plant. REEs are naturally present in the environment and in biological systems but accumulation in soil can take place following successive applications. Therefore, it would be useful to achieve a better understanding of the effect of REEs accumulation on the activity of rhizosphere microorganisms given the widespread use in some regions of rare earths as fertilizers and their presence as fertilizer contaminants.
文摘Every February,across the country,candy,flowers,and gifts are exchanged between loved ones,all in the name of St.Valentine.But who is thismysterious saint and why do we celebrate thisholiday?
文摘(All of us eat every day,but mostof us don’t understand nutrition.How much do you know about good nutrition?Pleaseanswer these twelve questions based on current ideasabout food and health.The answers may surprise you.) Are the following statements true or false? 1.You’ll get proper nourishment if you just eat avariety of foods. False.Variety is not a guarantee of good nutri-tion.But adults can generally get a balanced diet byincluding several servings daily from the four main
基金supported by Guangdong Forestry Science and Technology Creative Special(2015KJCX003)
文摘A provenance trial of Michelia chapensis Dandy in the south of China was carried out in three sites to assess yield and stability analyses. The trials were conducted as randomized, complete block designs with four replications at each site. Additive main effects and multiplicative interaction（AMMI） and genotype main effect and genotype 9 environment interaction（GGE） were employed in the evaluation of provenances; AMMI analyses showed that significant genotype 9 environment interaction effects（P ／ 0.05） existed between provenances, capturing 15.11 % of the total sum of squares. The AMMI stability value revealed that provenance 2 was stable, but had low yield. GGE-biplot models showed that provenances 7, 8, 10, and 11 were more stable and highyielding. The GGE results also confirmed that among the three sites, site Jiu Qu Shui was the most ideal environment for representation and discrimination.
基金financially supported by the National Key Research and Development Program of China(Grant No.2016YFD0600404)the Fundamental Research Funds for the Central Universities(2572017DA02)
文摘To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,and potassium fertilizers),each with four levels,using an orthogonal experimental design.A logistic model was used to estimate growth in height.The growth curves for tree height were sigmoid,and the model R^2 values were greater than 0.9,which indicated that the fit was highly significant.ANOVA results for tree height and basal diameter indicated that all sources of variance showed significant differences(p<0.001).The average tree height and basal diameter for all the four clones under the different treatments ranged from 155.39 to 235.04 cm,and from 13.71 to 17.42 mm,respectively.A highly positive correlation between the extreme k value and tree height was observed,suggesting that the k value was an accurate estimation of tree height.For model parameters,the earliest average time point for the onset of the rapid growth period of poplar clones was 131 d,and the highest average increment in tree height during the rapid growth period was 138.78 cm.The highest average tree height for all clones under each factor was 219,210.51,200,and 201 cm when treated with either 1200 mL of water applied every third day,3 g of nitrogen,0 g of phosphorus,or 0 g of potassium,respectively.The most suitable treatment for the early growth of hybrid poplar cuttings,as suggested by the developed logistic model,was 1200 mL of water applied every third day and three applications of 1 g nitrogen(in the form of CH4N2O).
基金supported by the Special Fund for Beijing Common Construction Project
文摘To select maternal parents with high fertility and high combining ability during cross breeding of Populus tomentosa Carr., the ploidy level of 75 female clones was determined using flow cytometry. In addition, genetic variations and phenotypic correlations of seed traits and early growth traits, as well as the general combining ability(GCA) for seedling height(SH) and basal diameter(BD) of all diploid half-sib families were examined. A total of 26 natural triploid clones were identified. For all diploid families, family effects were significant for inflorescence length(IL), thousand kernel weight(TKW), seedling emergence rate(SER), and for SH and BD. There was a positive correlation between TKW and other traits,excluding IL. The seed-bearing coefficient(NS 9 SER)ranged from zero to 32.4%. Clones 3-10-2, 2-8, 3119,3206, and 3-10-1 had the best performance of the GCA for SH and BD. Based on the fertility and GCA for SH and BD, clone 3-10-2 and clone 3119 could be used as female parents for controlled cross-breeding of P. tomentosa.
文摘This paper puts forward a valuation model for the flexibility of revamping urea plants based on the substitutability of switching between the internationally accepted fertilizer feedstock fuel oil and natural gas. The paper first builds a stochastic mean-reversion model for fuel oil prices and natural gas prices respectively, then estimates and tests the parameters using the fuel oil and natural gas prices data from the U.S. market. This paper also conducts a sensitivity analysis with important parameters. The results show that the real option method can be applied successfully to evaluate the flexibility in decision- making for revamping installations in fertilizer plants or other similar plants.
基金National Natural Science Foundation of China(grant numbers 31870427&31730014)by Jiangxi Province 2019 Graduate Innovation Fund Project(grant number YC2019-b061)。
文摘Tree competitiveness generally depends on trait plasticity in response to environmental change.The effects of nitrogen(N)and phosphorus(P)on leaf trait variability by species is poorly understood,especially in China’s subtropical forests.This study examined the seedling leaf traits and net primary productivity of all trees>5 cm DBH of two dominant species,Schima superba and Castanopsis carlesii,in an evergreen broadleaved forest fertilized with nitrogen(+N),phosphorus(+P),and nitrogen plus phosphorus(N+P).The effect of N on seedling leaf traits was stronger than P,while fertilization in general was species dependent.Leaf mass per unit area decreased with N for S.superba seedlings but not for C.carlesii.Leaf N,P,and N/P ratios changed with N addition for both species.All four N fractions of carboxylation,bioenergetics,cell wall,and other N metabolites in C.carlesii leaves responded significantly to fertilization,while only the cell wall in S.superb a leaves responded.Other leaf functional traits,including light-saturated photosynthetic rates,water,N,and P use efficiencies,chlorophyll and non structural carbohydrate contents increased with N addition in S.superb a and by P addition in C.carlesii.Canopy closure at the stand-level increased due to N.Litter biomass and relative growth rate of S.superb a was not affected by any treatments,while both for C.carlesii significantly decreased with N+P addition.Collectively,nutrient limitation may vary at a small scale among species in a subtropical forest based on their responses of seedling traits and net primary productivity to fertilization.Seedling traits are not correlated with the net primary productivity of larger trees except for N fractions,because low light conditions induced by fertilization reduces the proportion of N allocated to photosynthesis in seedlings.In addition,acclimation differences of tree species may increase the uncertainty of community succession.
文摘How to improve the water use efficiency of rice in black soil regions was studied. The black soil region in paddy fields was chosen as the research object. The research showed the fertilizer coupling mathematical model with N,P,K,irrigation water( W) and water use efficiency( WUE),which was set up under the condition of controlled irrigation with quadratic D- 416 optimized saturation design. The results show that the decending order of single factor' s influence on the WUE was N,K,P and W. All the interactions between N&P,N&K,N&W,K&P,P&W and K&W on the WUE were raised initially,and when reached a certain value,they began to decline. The decending order of each interaction on the WUE was K&P,K&W,N&K,N&P,P&W and N&W. When the WUE was targeted within 1. 8- 2. 5 kg / km^3,an optimized proportion plan was obtained in the 95% confidence interval,i. e. N 87. 76- 103. 32 kg / hm^2,K_2 O 52. 37- 66. 53 kg / hm^2 and P_2O_536. 80- 46. 71 kg / hm^2. Furthermore,the late tillering of the soil moisture content was 70. 07%- 72. 57% of the saturated moisture content.
基金supported by Institut für Bodenkunde und Waldernhrung,Georg-August-Universitt,Gttingen,Germany.
文摘Allocation of biomass and nutrient elements including Nitrogen to above and belowground compartments of beech seedlings （Fagus sylvatica L.） treated by labeled nitrogen fertilizer in the form of 15NH4 and 15NO3 were investigated at the end of two successive growing seasons. Pot cultured beech seedlings were grown at a green house on intact soil cores sampled from three adjacent stands including beech, Norway spruce and mixed beech-spruce cultures of Soiling forest, Germany. Comparing biomass allocation and nutrients concentrations of the seedlings between the control and 15N-fertilized treatments revealed no significant effect of N fertilization on nutrients uptake by seedlings over the experiment. The form of N input influenced its movement into plant pools. It was demonstrated that beech seedlings take up nitrogen mainly in the form of nitrate, which is then reduced in the leaves, although the differences between the retention of NO3^--N and NH4^＋-N in plants were not statistically significant. Percent recoveries of 15N in trees were typically greater after 15NO3 than after 15NH4 additions. It was indicated that immobilization of ~SN tracer in fine roots was a slower process comparing other plant compartments such as stem and coarse roots, but a powerful sink for N during the course of study.
