Metabolite profiling of shoot extract,root extract,and root exudate of rice under nitrogen and phosphorus deficiency

ABSTRACT

Root exudate is derived from plant metabolites and its composition is affected by plant nutrient status. A deficiency of mineral nutrients, such as nitrogen (N) and phosphorus (P), strongly affects the type and amount of plant metabolites. We applied a metabolite profiling technique to investigate root exudates of rice plants under N and P deficiency. Oryza sativa was grown in culture solution containing two N levels (0 and 60 mg N L^?1) or two P levels (0 and 8 mg P L^?1). Shoot extracts, root extracts, and root exudates were obtained from the rice plants 5 and 15 days after transplanting and their metabolites were determined by capillary electrophoresis/time-of-flight mass spectrometry. Shoot N concentration and dry weight of rice plants grown at ?N level were lower than those of plants grown at +N level. Shoot P concentration and dry weight of rice plants grown at ?P level were lower than those of plants grown at +P level. One hundred and thirty-two, 127, and 98 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two N levels. One hundred and thirty-two, 128, and 99 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two P levels. Seventy-seven percent of the metabolites were exuded to the rhizosphere. The concentrations of betaine, gamma-aminobutyric acid, and glutarate in root exudates were higher at both ?N and ?P levels than at their respective high levels. The concentration of spermidine in root exudates was lower at both ?N and ?P levels than at their respective high levels. The concentrations of the other metabolites in root exudates were affected differently by plant N or P status. These results suggest that rice roots actively release many metabolites in response to N and P deficiency.     

对同城化发展的几点思考

同城化作为城市发展的一种新的现象,在实践和理论层面都存在大量需要研究讨论的问题。笔者针对同城化的内涵、发展前提以及存在问题等方面进行简单探讨,以求取得一些有益的启示。     

水稻硅素失调症及防治技术探讨

介绍了水稻硅素失调症的症状、发生条件,以及诊断和防治方法,以期为水稻科学生产提供理论依据。     

河西农田磷钾养分平衡及肥料利用率长期定位研究

采用连续24年田间定位试验和养分差减法研究了河西农田磷钾养分投入产出平衡及肥料利用率,结果表明,磷素养分投入始终大于产出为正平衡,化学磷肥连施(NP、NPK)平均盈余率43.3% ~ 97.0%;小麦、玉米化肥磷总利用率平均为37.3% ~ 40.5% 和22.3% ~ 30.5%,比短期试验利用率分别增加12.8% ~ 22.9% 和5.9% ~ 9.5%。有机肥与化学磷肥配施(MNP、MNPK)平均盈余率211.3% ~ 277.9%;小麦、玉米磷素总利用率分别为18.0% ~ 18.3%?和16.3% ~ 19.4%,比试验初利用率增加5.4% ~ 8.5% 和5.8% ~ 6.6%。连施有机肥适量减少化学磷肥用量是平衡施磷的科学之举。钾素投入始终不抵作物携带量,农田钾素为负平衡,长期施用有机肥(MN、MNP)不能平衡土壤钾素,平均亏缺?-38.6% ~ -47.2%,小麦、玉米作物有机肥钾总利用率57.8% ~ 59.8% 和34.1% ~ 54.1%,比试验初增加8.4% ~ 22.3%;连施化学钾肥平均亏缺?-36.2% ~ -67.8%,小麦、玉米钾肥利用率53.1% 和29.5%,比试验初增加7.4% ~ 36.4%。在有机肥基础上增施化学钾肥是现代作物生产的必需措施。     

拉萨河谷冬春季放牧与舍饲彭波半细毛羊牧草、血液及被毛矿物质含量

为分析拉萨河谷冬春季放牧与舍饲彭波半细毛羊采食牧草、血液及被毛中主要矿物质元素的含量,试验选用1.5岁左右彭波半细毛羊母羊60只,随机分为放牧组(GZ)和舍饲组(IF)进行试验。结果表明:试验所用牧草矿物质元素,除钼外其他元素含量均为绿麦草>冬季天然牧草。冬季天然牧草磷、镁、硫、铜、锰、锌和硒及绿麦草镁含量低于正常范围。(2)舍饲组血清钙(P=0.026)、硫(P=0.030)、铜(P=0.011)和钼(P=0.014)含量高于放牧组,镁(P=0.090)、铁(P=0.071)、锌(P=0.083)和碘(P=0.066)含量有增高的趋势;其被毛钙(P=0.003)、磷(P=0.006)、镁(P<0.001)、铁(P=0.022)、锰(P<0.001)和碘(P=0.012)含量均高于后者,铜含量有增高的趋势(P=0.068)。在血液和被毛中,放牧组血清铜、锰及被毛铜、锰和硒含量及舍饲组血锰及被毛锰、硒含量均低于推荐值。以上结果表明,拉萨河谷冬春季放牧彭波半细毛羊钙、铁、钼和碘充足,但磷、镁、硫、铜、锰、锌和硒缺乏或不足;舍饲(以谷物为主的精补料+绿麦草干草)能有效解决磷、镁、硫、铜、锌和硒的缺乏问题,但锰仍需补充。     

苍溪梨果实褐斑病研究

近年来湖北襄阳一带苍溪梨果实上的褐斑病害,经研究证明,系磷、硼双缺引起。及时合理施硼,能迅速控制此病;保持土壤速效磷水平较高,可显著减轻受害程度     

奶牛脾虚慢草症的治疗体会

饮喂失调或劳伤过度,耗损气血,致使脾虚胃弱,引起水谷运化失常,不能输布精气,营养全身,久则畜体日渐瘦弱,食欲减少,即成脾虚慢草之症。中兽医经验方“扶脾散”由党参、黄芪、白术(土炒)、茯苓、泽泻、青皮、木香、厚朴、甘草、苍术(炒)组成,有补中益气、下气利水的功能,适用于脾虚慢草症,笔者在此方基础上加入当归、山药、扁豆、砂仁、枳壳、柴胡、升麻、陈皮、焦三仙等药物治疗奶牛脾虚慢草症效果显著。     

Ecophysiological Differentiation of Two Mosla Species in Response to Nitrogen and Water Levels

Terrestrial ecosystems are experiencing increased inputs of nitrogen (N) and temporal fluctuations in precipitation, causing flooding or drought, and this could strongly affect the fate of terrestrial plant species, as they might have different abilities to adapt to the changing environment. We grew Mosla dianthera (a widespread species) and M. hangchowensis (an endangered species) under three water treatments (drought, sufficient water, and waterlogging) in combination with three levels of N supply (low, intermediate, and sufficient N) to study the ecophysiological responses of the congeneric species to those simulated environmental changes. The two species showed different responses to waterlogging and drought treatments, particularly when there was abundant N supply in the system. For example, under sufficient N but drought or waterlogging conditions, M. dianthera increased root mass ratio (RMR) and decreased leaf mass ratio (LMR), total leaf area (LA), and leaf area ratio (LAR); such changes can enhance water acquisition and reduce water loss under both drought and waterlogging conditions, in contrast to the general lack of change in those parameters with M. hangchowensis. These differentiations in traits suggest that increased N availability might worsen drought and waterlogging injury to M. hangchowensis and thus accelerate the decline of this population. However, M. dianthera maybe better adapted to high N availability and both drought and waterlogging conditions. We hypothesize that the different adaptive abilities to high N availability and drought and waterlogging conditions are partly responsible for the ecological differentiation observed between these two species in the field and may determine their fate in their native habitat. Further research should test this hypothesis in field experiments.     

关于防雷检测工作的思考

防雷检测作业是各级防雷检测机构的主要工作,也是整个防雷装置安全性能检测工作中的重点,随着技术的发展防雷检测工作的科学性、可靠性、可行性越来越强,在此对濮阳防雷工作开展的情况及检测工作中仍存在的一些问题进行了分析,并针对濮阳防雷检测工作提出了几点思考,提高人们对防雷安全工作的认识,并逐步树立安全防范意识.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.