低氮磷胁迫对五个玉米品种幼苗的影响

为了探求低氮、磷胁迫对玉米幼苗的影响,在不同低氮、磷间进行组合,对金穗98、先玉508、三峡玉9号、高瑞171和金13-2 5个玉米品种幼苗在低氮、磷胁迫下的丙二醛、可溶性糖、过氧化氢酶、过氧化物酶和超氧化物歧化酶5个指标进行检测。结果表明,氮和磷元素缺乏程度与由此而造成的损伤直接相关;不同氮、磷缺乏的胁迫对玉米幼苗的损伤呈现波动性变化,不同组合对所测定各生化指标的影响及程度不同;在不同氮、磷缺乏组合下,5个品种所观察各指标数值的变化趋势基本一致,但不同品种间数值大小存在差异。对生长逆境敏感的生理和生化指标的分析显示,最耐氮、磷缺乏的是先玉508,而三峡玉9号和金穗98对氮、磷缺乏较为敏感。

Sex-specifically responsive strategies to phosphorus availability combined with different soil nitrogen forms in dioecious Populus cathayana

Aims Phosphorus(P)availability and efficiency are especially important for plant growth and productivity.However,the sex-specific P acquisition and utilization strategies of dioecious plant species under different N forms are not clear.Methods This study investigated the responsive mechanisms of dioecious Populus cathayana females and males based on P uptake and allocation to soil P supply under N deficiency,nitrate(NO3−)and ammonium(NH4+)supply.Important Findings Females had a greater biomass,root length density(RLD),specific root length(SRL)and shoot P concentration than males under normal P availability with two N supplies.NH4+supply led to higher total root length,RLD and SRL but lower root tip number than NO3−supply under normal P supply.Under P deficiency,males showed a smaller root system but greater photosynthetic P availability and higher leaf P remobilization,exhibiting a better capacity to adaptation to P deficiency than females.Under P deficiency,NO3−supply increased leaf photosynthesis and P use efficiency(PUE)but reduced RLD and SRL in females while males had higher leaf P redistribution and photosynthetic PUE than NH4+supply.Females had a better potentiality to cope with P deficiency under NO3−supply than NH4+supply;the contrary was true for males.These results suggest that females may devote to increase in P uptake and shoot P allocation under normal P availability,especially under NO3−supply,while males adopt more efficient resource use and P remobilization to maximum their tolerance to P deficiency.

Symbionts in Mucuna pruriens stimulate plant performance through nitrogen fixation and improved phosphorus acquisition

Aims South Africa is mainly dominated by savanna and grasslands ecosystems which have been previously reported to be acidic and nutrient deficient,specifically with regard to phosphorus(P)and nitrogen(N).Mucuna pruriens(L.)DC,commonly known as velvet bean,is an indigenous legume in most African countries and has been reported to withstand these adverse soil conditions.The legume is used in many countries of the world for their medicinal value as well as for soil fertilization purposes.Although there are reports on M.pruriens growth and establishment in nutrient stressed ecosystems,no investigation has been conducted on M.pruriens symbiotic interactions,N source preference and associated growth carbon costs when subjected to P deficiency.In this study,we determined the impact of microbial symbionts on N nutrition and growth carbon costs of M.pruriens under P deficiency.Methods Microbe inoculation soils were collected from four geographical distinct KwaZulu-Natal locations.Thereafter,seeds were germinated in these natural soils and in early stages of nodule development,then seedlings were transferred in sterile quartz sand and supplied with Long Ashton nutrient media with varying P concentrations.Important Findings The 16S RNA sequence results revealed that M.pruriens was nodulated by Burkholderia sp.,Paenibacillus sp.and Bacillus irrespective of P concentrations.Even though P deficiency resulted in decreased overall biomass/growth,the root biomass,nodule number and carbon costs increased.In addition,low P supplied saplings showed the highest arbuscular mycorrhiza fungi percentage root colonization.In M.pruriens,nitrogen derived from atmosphere had a positive correlation with P level and the saplings had a dual reliance on atmospheric derived N and soil derived N with increased reliance on soil N in low P supplied plants.Therefore,M.pruriens exhibited different morphological and microbial symbiosis when subjected to P deficiency.