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Early Nutrient Diagnosis of Kentucky Bluegrass Combining Machine learning and Compositional Methods

American Journal of Plant Sciences 2022年第9期13卷 1247-1260页

作者： Abdo Badra léon etienne parent Department of Soils and Agri-Food Engineering Université Laval Québec Canada

Kentucky bluegrass (Poa pratensis l.) is the most common perennial turfgrass species grown on playgrounds, municipal and residential lawn areas, and golf tees, fairways and roughs. Fertilization is the most efficient way to improve and maintain turfgrass aesthetic quality. Tissue diagnosis can guide fertilization, but tissue concentration ranges are biased by not taking into consideration nutrient inter-relationships, carryover effects and other key features. The centered log-ratio transformation reflects nutrient interactions in plants and avoids statistical biases. Machine learning (Ml) models relate the target variable to the key features ex ante, and can predict future events from prior knowledge. The objective of his study was to predict turfgrass quality from key features and rank nutrients in the order of their limitations. The experimental setup comprised four N, three P, and four K rates applied on permanent plots during three consecutive years. Soils were a loam and an USGA sand. Eleven elements (N, S, P, K, Ca, Mg, B, Cu, Zn, Mn, Fe) were quantified in clippings collected during spring, summer and autumn every year. Turfgrass quality was categorized as target variable by color rating. Concentrations were centered log-ratioed (clr) partitioned into four quadrants in the confusion matrix generated by the xgboost Ml model. The area under curve (AUC) and model accuracy were high to predict turfgrass color from the nutrient analyses of clippings collected in the preceding season, facilitating the seasonal adjustment of the fertilization regime to sustain high turfgrass quality. We provide a computational example to run the Ml model and rank nutrients in the order of their limitations.

关键词： Centered log Ratio Data Set Machine learning Turfgrass Foliage Color Turfgrass Shoot Density Xgboost

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Foliar Nutrient Balance Standards for Maize (<i>Zea mays</i>l.) at High-Yield level

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American Journal of Plant Sciences 2014年第4期5卷 497-507页

作者： Viviane Cristina Modesto Serge-étienne parent William Natale léon etienne parent Departamento de Solos e Adubos Unesp Universidade Estadual Paulista Jabotocabal Brazil ERSAM Department of Soils and Agrifood Engi-neering Université Laval Québec Canada

Maize is one of the most nutrient demanding staple crops. Tissue nutrient diagnosis of maize is currently conducted using critical nutrient concentration or dual ratio ranges, but such diagnoses are pathological as biased by data redundancy, sub-compositional incoherence and non-normal distribution. The use of orthogonal balances, a compositional data analysis technique, avoids such biases. Our objective was to develop foliar nutrient balance standards for maize. We collected 758 grain yields (15.5% moisture content) and foliar samples at silk stage in maize fields of southern Quebec, Canada, and analyzed ten nutrients in tissues (N, P, K, Ca, Mg, B, Cu, Zn, Mn, Fe). Nutrients were arranged into ad hoc balances and computed as isometric log ratios (ilr). An optimized binary classification performed by a customized receiver operating characteristic procedure showed that a critical Mahalanobis distance of 4.21 separated balanced from imbalanced specimens about yield cut-off of 11.83 Mg grain·ha-1 with test performance of 86%. Quebec maize balance standards differed from published standards computed from DRIS norms collected in other agroecosystems. The Redfield N/P ratio in maize leaves was found to be the least variable balance across regions of the world. The DRIS dual ratios and raw concentration values were found to be geometrically inadequate for conducting diagnosis. The unbiased nutrient balance diagnosis combined the critical Mahalanobis distance and a mobile representation of nutrient balances with ilr means of true negative (TN) specimens centered at fulcrums and back-transformed ilr values of TN specimens into raw concentrations loading the buckets below. Nutrients can be appreciated as relative shortage, adequacy or excess in the concentration domain following statistical analysis and diagnosis in the unbiased balance domain.

关键词： Compositional Data Analysis Critical Range Diagnosis and Recommendation Integrated System DRIS Ionomics Nutrient Balance Nutrient Interactions

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Mineral Balance Plasticity of Cloudberry (<i>Rubus chamaemorus</i>) in Quebec-labrador Bogs

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American Journal of Plant Sciences 2013年第7期4卷 1508-1520页

作者： léon etienne parent Serge-étienne parent Valérie Hébert-Gentile Kristine Naess line lapointe Centre d’études de la Forêt Department of Biology Université Laval Québec Canada Centre d’études de la Forêt Department of Biology Université Laval Québec Canada Centre de Recherches les Buissons Pointe-aux-Outardes Canada. Department of Soils and Agrifood Engineering Université Laval Québec Canada

The “ionome”, or plant elemental signature, is the elemental composition of an organisms, that may vary with genotypic traits and phenotypic plasticity. Cloudberry (Rubus chamaemorus l.) is a circumboreal wild berry naturally growing in oligotrophic oceanic bogs ofQuebecandlabrador. Our objective was to relate cloudberry stand productivity to the ionomes of female ramets and explore the cause of nutrient imbalance in low-performing stands. We analyzed 13 elements in female ramets collected in 86 natural sites where crop productivity varied widely. We computed orthogonally arranged balances reflecting plant stoichiometric rules and soil biogeochemistry. Balances were expressed as isometric log ratios (ilr) between ad hoc sub-compositions. Balances were synthesized into a Mahalanobis distance optimized based on receiving operating characteristics (ROC). The critical Mahalanobis distance was found to be 5.29 for cutoff berry yield of3.8 g.m-2 with test performance of 0.88, as measured by the area under the ROC curve. Although past research on cloudberry focused mainly on the N/P ratio, this exploratory mineral balance analysis indicated that imbalance in the [P,N | S,C] and [Al | Nutrients] partitions appeared to be the factors limiting the most cloudberry productivity in the bogs. Some highly productive stands showed relatively high C fixation and K use efficiency. Due to the complexity of interactions, diagnosis should be conducted computing first a global imbalance index (Mahalanobis distance), then examining in the balance domain binary partitions departing most from reference, and finally appreciating relative shortage, sufficiency or excess of elements in the concentration domain.

关键词： Al Toxicity Cloudberry Compositional Data Analysis Isometric log Ratio Nutrient Balance Ionome

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Kinetic Characterization of Trichoderma reesei Cl847 TR3002： An Engineered Strain Producing Highly Improved Cellulolytic Cocktail

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Journal of Chemistry and Chemical Engineering 2012年第2期6卷 109-117页

作者： Fadhel Ben Chaabane etienne Jourdier Rachel licht Celine Cohen Frederic Monot IFP Energies nouvelles 1 et 4 avenue de Bois-Preau Rueil-Malmaison 92852 France

Enzymatic hydrolysis of lignocellulose is often considered to be the major economic bottleneck of the production process of bioethanol from lignocellulose. It is generally admitted that the most efficient organism for the production ofcellulolytic enzymes is the fungus Trichoderma reesei, mostly due to its high secretion capacity. Unfortunately, this fungus secretes very low concentrations of β-glucosidase, thereby often requiring β-glucosidase supplementation for complete cellulose hydrolysis. It is especially important to have sufficient quantities of β-glucosidase in order to prevent inhibition of cellobiohydrolases by cellobiose. In order to optimize the produced cocktail, a more efficient β-glucosidase was cloned into T. reesei Cl847 strain. The new strain, called Cl847 TR3002, secretes the evolved β-glucosidase and was tested for cellulase production in laboratory-scale reactors. Its growth kinetics and cellulase production were characterized using fed-batch and chemostat modes under various culture conditions. The cellulase activities of the evolved strain were compared with activities of the parent strain. In addition, hydrolysis of a steam exploded wheat straw was performed at three different enzyme-loading levels （5 mg/g, 10 mg/g and 20 mg/g of dry matter） and a new kinetic model was developed.

关键词： Trichoderma reesei cellulases fed-batch bioreactor kinetics.

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汉诺坝幔源单斜辉石巨晶氢同位素组成的离子探针分析:微尺度不均一性

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岩石学报 2001年第1期17卷 7-10页

作者：夏群科潘尤杰陈道公 DElOUlEetienne 支霞臣程昊吴元保中国科技大学地球和空间科学系合肥230026 合肥市城市排水监测站合肥230061 CRPG-CNRS

运用离子探针技术测定了河北汉诺坝新生代玄武岩中 3个单斜辉石巨晶的氢同位素组成 ,结果显示同一颗粒内部表现出微尺度的不均一性 ,2 mm范围内 δD的变化达到 6 0‰。δD和氢含量之间不存在同步的变化 ,巨晶内部的化学成分均一 ,因此... 详细信息

运用离子探针技术测定了河北汉诺坝新生代玄武岩中 3个单斜辉石巨晶的氢同位素组成 ,结果显示同一颗粒内部表现出微尺度的不均一性 ,2 mm范围内 δD的变化达到 6 0‰。δD和氢含量之间不存在同步的变化 ,巨晶内部的化学成分均一 ,因此我们认为巨晶的氢同位素不均一性继承自母岩浆。母岩浆的氢同位素变化可能是去气过程中气相与熔体之间的分馏引起的。单斜辉石巨晶形成后很短的时间内即被寄主岩浆带至地表并经历了快速淬火。

关键词：离子探针氢同位素单斜辉石微尺度不均一性母岩浆去气作用

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