Nitrogen(N), the major forms of which are nitrate(NO3–) and ammonium(NH4+), plays an important role in plant growth and mediation of root development. However, the role of auxin in root growth in response to differen...Nitrogen(N), the major forms of which are nitrate(NO3–) and ammonium(NH4+), plays an important role in plant growth and mediation of root development. However, the role of auxin in root growth in response to different NH4+/NO3– ratios remains unclear. Two tobacco cultivars(Nicotiana tabacum L.) were adopted in this study, which displayed variant growth features under the situations with sole NO3– nutrition ratio(NH4+/NO3– ratio: 0/100), low NO3– nutrition ratio(NH4+/NO3– ratio: 97/3), and optimal NH4+/NO3– ratio(50/50). We investigated the effects of the different NH4+/NO3– ratios on the formation and elongation of lateral roots(LRs), auxin concentration, DR5::GUS expression, 3 H-labeled indole acetic acid([3 H]IAA) transport, and the expression of six PIN genes in tobacco roots. We also examined the effects of exogenous auxin and a transport inhibitor on LRs growth. The results are shown as follows, compared to optimal N nutrition conditions, the biomass and nitrogen(N) accumulation were largely reduced by sole and low NO3– nutrition treatment in NC89, but no difference was observed in Zhongyan 100. In most cases, sole and low NO3– nutrition impaired the elongation and formation of firstorder lateral roots(1° LRs), only in NC89, thus reducing the root growth. IAA concentration and DR5::GUS expression levels decreased in roots when NC89 was subjected to sole and low NO3– nutrition media, suggesting that different NH4+/NO3– ratios affect the transport of auxin from leaves to roots. Results were similar following exogenous NAA application to low NO3– nutrition treated seedlings. Based on direct [3 H]IAA transport measurement, the transport of polar auxin from shoots to roots decreased due to low NO3– nutrition. PIN4 expression levels were markedly decreased in roots of NC89by sole and low NO3– nutrition, while they were unaffected in Zhongyan 100 roots. Overall, our findings suggest that LRs formation in tobacco seedlings is regulated by NH4+/NO3– ratios via modifying polar transpor展开更多
The influence of different NH 4 +/NO 3 - ratios on nitrogen metabolism of cotton was studied under controlled hydroponics.The results showed that compared with single nitrate nutrition,solutions with 25/75,50/50,75/25...The influence of different NH 4 +/NO 3 - ratios on nitrogen metabolism of cotton was studied under controlled hydroponics.The results showed that compared with single nitrate nutrition,solutions with 25/75,50/50,75/25 and 100/0 of NH 4 +/NO 3 - significantly increased the soluble protein accumulation in leaves and roots of cotton,and the maximum content of soluble protein in leaves and roots appeared respectively in the solution with 50/50 and 75/25 of NH 4 +/NO 3 -.The soluble protein content in roots was increased with the increase of NH + 4 percentage,but was slightly less in the solution of 100/0 than 75/25,which was probably related to the excess NH + 4 limiting boot metabolism.With the increase of NH + 4 percentage,the nitrate content in petiole and the nitrate reductase activity in functional blade declined,but ammoniac nitrogen content increased in every organ of cotton.These results showed that foreign nitrogen affected the nitrogen metabolism of cotton in a different way,and the nitrogen absorption by cotton was probably related to different forms of foreign nitrogen.展开更多
Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an increase in crop yield. However, little is known abou...Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an increase in crop yield. However, little is known about the combined effect of elevated CO2 and N species on plant growth and development. Two growth-chamber experiments were conducted to determine the effects of NH4^＋/NO3^- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings. Tomato was grown for 45 d in containers with nutrient solutions varying in NH4^＋/NO3^- ratios and CO2 concentrations in growth chambers. Results showed that plant height, stem thickness, total dry weight, dry weight of the leaves, stems and roots, G value （total plant dry weight/seedling days）, chlorophyll content, photosynthetic rate, leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment. Plant biomass, plant height, stem thickness and photosynthetic rate were 67%, 22%, 24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration, depending on the values of NH4^＋/NO3^- ratio. These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4^＋-N （in nutrient solution） on the tomato seedlings. At both CO2 levels, NH4^＋/NO3^- ratios of nutrient solutions strongly influenced almost every measure of plant performance, and nitrate-fed plants attained a greater biomass production, as compared to ammonium-fed plants. These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.展开更多
Cadmium(Cd)pollution in agricultural soils has exerted a serious threat due to continuous application of pesticides,fertilizers,and wastewater irrigation.The present study aimed to test the efficiency of KOH-modified ...Cadmium(Cd)pollution in agricultural soils has exerted a serious threat due to continuous application of pesticides,fertilizers,and wastewater irrigation.The present study aimed to test the efficiency of KOH-modified and non-modified rice straw-derived biochar(KBC and BC,respectively)for reducing Cd solubility and bioavailability in Cd-contaminated soil.Cadmium-contaminated soil was incubated for 60 d with 15 and 30 g kg-1 BC and KBC.At the end of incubation,Cd mobility was estimated by the European Community Bureau of Reference sequential extraction and toxicity characteristic leaching procedure(TCLP),while bioavailability was determined using 1 molL-1 NH4NO3 extraction.The bioavailability risk index and bioaccessibility,assessed by a simple bioaccessibility extraction test,of Cd were used to examine the potential effects of Cd on living organisms.The results indicated that application of both KBC and BC significantly increased soil p H,cation exchange capacity,nutrients,and organic carbon.The soluble fraction of Cd was significantly decreased by 30.3%and 27.4%,respectively,with the addition of KBC and BC at 30 g kg-1 compared to the control(without biochar addition).Similarly,the bioaccessible Cd was significantly decreased by 32.4%and 25.2%,respectively,with the addition of KBC and BC at 30 g kg-1 compared to the control.In addition,both KBC and BC significantly reduced Cd leaching in the TCLP and NH4NO3-extractable Cd in the amended soil compared to the control.The reduction in Cd solubility and bioaccessibility by KBC and BC may be due to significant increases in soil pH and surface complexation.Overall,KBC at an application rate of 30 g kg-1 demonstrated positive results as soil amendment for Cd immobilization,and reduced bioaccessible Cd in contaminated soil.展开更多
基金funded by the Agricultural Science and Technology Innovation Program, Chinese Academy of Agricultural Sciences (ASTIP-TRIC03)the Science Foundation for Young Scholars of Tobacco Research Institute of Chinese Academy of Agricultural Sciences (2018B01)+2 种基金the National Nature Science Foundation of China (3601818)the Liangshan Branch of Sichuan Tobacco Corporation, China (LSYC201805)the Hongyunhonghe Tobacco (Group) Co., Ltd., China (HYHH2016YL02)
文摘Nitrogen(N), the major forms of which are nitrate(NO3–) and ammonium(NH4+), plays an important role in plant growth and mediation of root development. However, the role of auxin in root growth in response to different NH4+/NO3– ratios remains unclear. Two tobacco cultivars(Nicotiana tabacum L.) were adopted in this study, which displayed variant growth features under the situations with sole NO3– nutrition ratio(NH4+/NO3– ratio: 0/100), low NO3– nutrition ratio(NH4+/NO3– ratio: 97/3), and optimal NH4+/NO3– ratio(50/50). We investigated the effects of the different NH4+/NO3– ratios on the formation and elongation of lateral roots(LRs), auxin concentration, DR5::GUS expression, 3 H-labeled indole acetic acid([3 H]IAA) transport, and the expression of six PIN genes in tobacco roots. We also examined the effects of exogenous auxin and a transport inhibitor on LRs growth. The results are shown as follows, compared to optimal N nutrition conditions, the biomass and nitrogen(N) accumulation were largely reduced by sole and low NO3– nutrition treatment in NC89, but no difference was observed in Zhongyan 100. In most cases, sole and low NO3– nutrition impaired the elongation and formation of firstorder lateral roots(1° LRs), only in NC89, thus reducing the root growth. IAA concentration and DR5::GUS expression levels decreased in roots when NC89 was subjected to sole and low NO3– nutrition media, suggesting that different NH4+/NO3– ratios affect the transport of auxin from leaves to roots. Results were similar following exogenous NAA application to low NO3– nutrition treated seedlings. Based on direct [3 H]IAA transport measurement, the transport of polar auxin from shoots to roots decreased due to low NO3– nutrition. PIN4 expression levels were markedly decreased in roots of NC89by sole and low NO3– nutrition, while they were unaffected in Zhongyan 100 roots. Overall, our findings suggest that LRs formation in tobacco seedlings is regulated by NH4+/NO3– ratios via modifying polar transpor
文摘The influence of different NH 4 +/NO 3 - ratios on nitrogen metabolism of cotton was studied under controlled hydroponics.The results showed that compared with single nitrate nutrition,solutions with 25/75,50/50,75/25 and 100/0 of NH 4 +/NO 3 - significantly increased the soluble protein accumulation in leaves and roots of cotton,and the maximum content of soluble protein in leaves and roots appeared respectively in the solution with 50/50 and 75/25 of NH 4 +/NO 3 -.The soluble protein content in roots was increased with the increase of NH + 4 percentage,but was slightly less in the solution of 100/0 than 75/25,which was probably related to the excess NH + 4 limiting boot metabolism.With the increase of NH + 4 percentage,the nitrate content in petiole and the nitrate reductase activity in functional blade declined,but ammoniac nitrogen content increased in every organ of cotton.These results showed that foreign nitrogen affected the nitrogen metabolism of cotton in a different way,and the nitrogen absorption by cotton was probably related to different forms of foreign nitrogen.
基金Project supported by the National Natural Science Foundation of China(No.30230250).
文摘Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an increase in crop yield. However, little is known about the combined effect of elevated CO2 and N species on plant growth and development. Two growth-chamber experiments were conducted to determine the effects of NH4^＋/NO3^- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings. Tomato was grown for 45 d in containers with nutrient solutions varying in NH4^＋/NO3^- ratios and CO2 concentrations in growth chambers. Results showed that plant height, stem thickness, total dry weight, dry weight of the leaves, stems and roots, G value （total plant dry weight/seedling days）, chlorophyll content, photosynthetic rate, leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment. Plant biomass, plant height, stem thickness and photosynthetic rate were 67%, 22%, 24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration, depending on the values of NH4^＋/NO3^- ratio. These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4^＋-N （in nutrient solution） on the tomato seedlings. At both CO2 levels, NH4^＋/NO3^- ratios of nutrient solutions strongly influenced almost every measure of plant performance, and nitrate-fed plants attained a greater biomass production, as compared to ammonium-fed plants. These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.
基金financially supported by the National Science and Technology Support Program of China(No.2015BAD05B02)
文摘Cadmium(Cd)pollution in agricultural soils has exerted a serious threat due to continuous application of pesticides,fertilizers,and wastewater irrigation.The present study aimed to test the efficiency of KOH-modified and non-modified rice straw-derived biochar(KBC and BC,respectively)for reducing Cd solubility and bioavailability in Cd-contaminated soil.Cadmium-contaminated soil was incubated for 60 d with 15 and 30 g kg-1 BC and KBC.At the end of incubation,Cd mobility was estimated by the European Community Bureau of Reference sequential extraction and toxicity characteristic leaching procedure(TCLP),while bioavailability was determined using 1 molL-1 NH4NO3 extraction.The bioavailability risk index and bioaccessibility,assessed by a simple bioaccessibility extraction test,of Cd were used to examine the potential effects of Cd on living organisms.The results indicated that application of both KBC and BC significantly increased soil p H,cation exchange capacity,nutrients,and organic carbon.The soluble fraction of Cd was significantly decreased by 30.3%and 27.4%,respectively,with the addition of KBC and BC at 30 g kg-1 compared to the control(without biochar addition).Similarly,the bioaccessible Cd was significantly decreased by 32.4%and 25.2%,respectively,with the addition of KBC and BC at 30 g kg-1 compared to the control.In addition,both KBC and BC significantly reduced Cd leaching in the TCLP and NH4NO3-extractable Cd in the amended soil compared to the control.The reduction in Cd solubility and bioaccessibility by KBC and BC may be due to significant increases in soil pH and surface complexation.Overall,KBC at an application rate of 30 g kg-1 demonstrated positive results as soil amendment for Cd immobilization,and reduced bioaccessible Cd in contaminated soil.
