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nondestructive estimation of bok choy nitrogen status with an active canopy sensor in comparison to a chlorophyll meter

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Pedosphere 2020年第6期30卷 769-777页

作者： Rongting JI Weiming SHI Yuan WAnG Hailin ZHAnG Ju MIn State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China University of Chinese Academy of Sciences Beijing 100049China Department of plant and Soil Sciences Oklahoma State UniversityStillwater OK 74078-6028USA

Precise estimation of vegetable nitrogen(n)status is critical in optimizing n fertilization ***,nondestructive and accurate n diagnostic methods for vegetables are relatively *** our two-year field experiment,we evaluated whether an active canopy sensor(GreenSeeker)could be used to nondestructively predict n status of bok choy(Brassica rapa ***)compared with a chlorophyll *** showed that the normalized difference vegetation index(nDVI)and ratio vegetation index(RVI)generated by the active canopy sensor were well correlated with the aboveground biomass(AGB)(r=0.698–0.967),plant n uptake(PnU)(r=0.642–0.951),and root to shoot ratio(RTS)(r=-0.426 to-0.845).Compared with the chlorophyll meter,the active canopy sensor displayed much higher accuracy(5.0%–177.4%higher)in predicting AGB and PnU and equal or slightly worse(0.54–1.82 times that of the chlorophyll meter)for *** sensor-based nDVI model performed equally well in estimating AGB(R2=0.63)and PnU(R2=0.61),but the meter-based model predicted RTS better(R2=0.50).Inclusion of the days after transplanting(DAT)significantly improved the accuracy of sensor-based AGB(19.0%–56.7%higher)and PnU(24.6%–84.6%higher)estimation *** findings suggest that the active canopy sensor has a great potential for nondestructively estimating n status of bok choy accurately and thus for better n recommendations,especially with inclusion of DAT,and could be applied to more vegetables with some verification.

关键词： aboveground biomass GreenSeeker model prediction n diagnosis normalized difference vegetation index plant n uptake root to shoot ratio ratio vegetation index soil and plant analyer development(SPAD)

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Arbuscular mycorrhizal fungi reduce ammonia emissions under different land-use types in agro-pastoral areas

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Pedosphere 2024年第2期34卷 497-507页

作者： Huaisong WAnG Rui GUO Yibo TIAn nan CUI Xinxin WAnG Lei WAnG Zhongbao YAnG Shuying LI Jixun GUO Lianxuan SHI Tao ZHAnG Institute of Grassland Science Northeast Normal UniversityKey Laboratory of Vegetation EcologyMinistry of EducationJilin Songnen Grassland Ecosystem National Observation and Research StationChangchun 130024China Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agricultural SciencesKey Laboratory of Dryland AgricultureMinistry of AgricultureBeijing 100081China Mountainous Area Research Institute of Hebei Province Hebei Agricultural UniversityBaoding 071001China College of Agronomy Liaocheng UniversityLiaocheng 252059China The Key Laboratory of plant Development and Environmental Adaptation Biology Ministry of EducationSchool of Life ScienceShandong UniversityQingdao 266237China Forestry and Grassland Bureau of Aohan Banner Chifeng 024005China

Ammonia(nH3)emissions,the most important nitrogen(n)loss form,always induce a series of environmental problems such as increased frequency of regional haze pollution,accelerated n deposition,and n *** mycorrhizal(AM)fungi play key roles in n ***,it is still unclear whether AM fungi can alleviate n losses by reducing *** potential mechanisms by which AM fungi reduce nH_(3)emissions in five land-use types(grazed grassland,mowed grassland,fenced grassland,artificial alfalfa grassland,and cropland)were explored in this *** showed that AM fungal inoculation significantly reduced nH3emissions,and the mycorrhizal responses of nH3emissions were determined by land-use *** equation modeling(SEM)showed that AM fungi and land-use type directly affected nH_(3)*** addition,the reduction in nH_(3)emissions was largely driven by the decline in soil nH_(4)^(+)-n and pH and the increases in abundances of ammonia-oxidizing archaea(AOA)amoA and bacteria(AOB)amoB genes,urease activity,and plant n uptake induced by AM fungal inoculation and land-use *** present results highlight that reducing the negative influence of agricultural intensification caused by land-use type changes on AM fungi should be considered to reduce n losses in agriculture and grassland ecosystems.

关键词： agricultural intensification grassland management functional genes plant n uptake n leaching n loss

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Elucidating Variations in nitrogen Requirement According to Yield, Variety and Cropping System for Chinese Rice Production

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Pedosphere 2017年第2期27卷 358-363页

作者： ZHAnG Yi CHEn Xinping MA Wenqi CUI Zhenling Centre for Resources Environment and Food Security China Agricultural University Beijing 100193 (China) College of Bioscience and Biotechnology Hunan Agricultural University Changsha 410128 (China) College of Resources and Environmental Science Hebei Agricultural University Baoding 071001 (China)

Better understanding of the factors that influence crop nitrogen(n) requirement plays an important role in improving regional n recommendations for rice(Oryza sativa L.) production. We collected data from 1 280 plot-level measurements in different reaches of the Yangtze River, China to determine which factors contributed to variability in n requirement in rice. Yield, variety, and cropping system were significantly related to n requirement. The n requirement remained consistent at about 18.6 kg n Mg^(-1)grain as grain yield increased from 7 to 9 Mg ha^(-1), then decreased to 18.1, 16.9, and 15.9 kg n Mg^(-1)grain as yield increased to 9–10, 10–11, and > 11 Mg ha^(-1), respectively. The decreased requirement for n with increasing yield was attributable to declining n concentrations in grain and straw and increased harvest index. Super rice variety had lower n requirement(17.7 kg n Mg^(-1)grain) than ordinary inbred and hybrid varieties(18.5 and 18.3 kg n Mg^(-1)grain, respectively), which was a result of lower grain and straw n concentrations of super rice. The n requirements were 19.2, 17.8, and 17.5 kg n Mg^(-1)grain for early, middle, and late rice cropping systems, respectively. In conclusion, the rice n requirement was affected by multiple factors, including yield, variety, and cropping system, all of which should be considered when planning for optimal n management.

关键词： grain and straw n concentrations grain yield harvest index n management plant n uptake reciprocal internalefficiency

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