Results 221 to 230 of about 20,661 (256)

Improving Winter Wheat Yield Estimation from the CERES-Wheat Model to Assimilate Leaf Area Index with Different Assimilation Methods and Spatio-Temporal Scales [PDF]

Remote Sensing, 2017
To improve the accuracy of winter wheat yield estimation, the Crop Environment Resource Synthesis for Wheat (CERES-Wheat) model with an assimilation strategy was performed by assimilating measured or remotely-sensed leaf area index (LAI) values. The performances of the crop model for two different assimilation methods were compared by employing ...
Gaohuan Liu, Huang Chong
exaly   +3 more sources

Integrating a very fast simulated annealing optimization algorithm for crop leaf area index variational assimilation

Mathematical and Computer Modelling, 2013
Abstract Leaf area index (LAI) is a major indicator for crop growth monitoring and yield estimation. Data assimilation as an effective tool for crop LAI estimation fully considers the properties of actual observations and physical model simulations. In this work, we present a new data assimilation scheme, introducing a very fast simulated annealing ...
Chunjiang Zhao, Yingying Dong, Guijun Yang   +2 more
exaly   +2 more sources

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Investigating the Assimilation of Leaf Area Index Products at Different Temporal Resolutions in a Land Surface Model

IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
Remote sensing observations of vegetation derived from satellite retrievals provide spatially comprehensive measurements that are well-suited for data assimilation in land surface modeling over large areas. However, the temporal intervals of such satellite-based observations are usually multi-daily or monthly, which may not be frequent enough to ...
Xinxuan Zhang, Viviana Maggioni, Azbina Rahman   +2 more
openaire   +1 more source

Leaf area ratio and net assimilation rate of 24 wild species differing in relative growth rate

Oecologia, 1990
Which factors cause fast-growing plant species to achieve a higher relative growth rate than slow-growing ones? To answer this question 24 wild species were grown from seed in a growth chamber under conditions of optimal nutrient supply and a growth analysis was carried out.
Hendrik Poorter, Poorter Hendrik
exaly   +3 more sources

Model‐data assimilation of multiple phenological observations to constrain and predict leaf area index

Ecological Applications, 2015
Our limited ability to accurately simulate leaf phenology is a leading source of uncertainty in models of ecosystem carbon cycling. We evaluate if continuously updating canopy state variables with observations is beneficial for predicting phenological events. We employed ensemble adjustment Kalman filter (EAKF) to update predictions of leaf area index (
Toni, Viskari, Brady, Hardiman, Ankur R, Desai, Michael C, Dietze   +3 more
openaire   +2 more sources

LEAF AREA AND NET ASSIMILATION RATE AS DETERMINANTS OF CROP YIELD

1966
The relation of agronomic practice to crop yield is discussed in terms of photosynthetic efficiency of the crops (as measured by Leaf Area and Net Assimilation rates). The importance of a study of these factors in certain tropical crops is indicated.
Spence, J. A., Haynes, P. H., Spence, J. A., Haynes, P. H.   +3 more
openaire   +1 more source

Predicting plant leaf area production: shoot assimilate accumulation and partitioning, and leaf area ratio, are stable for a wide range of sorghum population densities [PDF]

, 2002
Predicting plant leaf area production is required for modelling carbon balance and tiller dynamics in plant canopies. Plant leaf area production can be studied using a framework based on radiation intercepted, radiation use efficiency (RUE) and leaf area ratio (LAR) (ratio of leaf area to net above-ground biomass).
Lafarge, T. A., Hammer, Graeme L.
openaire   +4 more sources

Evaluation of the observation operator Jacobian for leaf area index data assimilation with an extended Kalman filter

Journal of Geophysical Research, 2010
To quantify carbon and water fluxes between the vegetation and the atmosphere in a consistent manner, land surface models now include interactive vegetation components. These models treat the vegetation biomass as a prognostic model state, allowing the model to dynamically adapt the vegetation states to environmental conditions. However, it is expected
Jean-Christophe Calvet, Jeffrey Walker, Clement Albergel   +2 more
exaly   +3 more sources

Effects of Nitrogen on Leaf Area Index, Leaf Area Duration, Net Assimilation Rate, and Yield of Wheat¹

Agronomy Journal, 1973
AbstractThe low returns from nitrogen fertilization in central and eastern Sudan stimulated an investigation into the response of grain yields of irrigated wheat (Triticum aestivum L. em. Thell.) to two sources of nitrogen (ammonium sulfate and urea), two methods (broadcasting and sidedressing), and several times of application.
openaire   +1 more source

Retrieving crop leaf area index by assimilation of MODIS data into a crop growth model

Science China Earth Sciences, 2010
Leaf area index (LAI) is an important parameter in monitoring crop growth. One of the methods for retrieving LAI from remotely sensed observations is through inversion of canopy reflectance models. Many model inversion methods fail to account for variable LAI values at different crop growth stages.
DongWei Wang, JinDi Wang, ShunLin Liang
openaire   +1 more source