Search results for "use efficiency"
showing 10 items of 54 documents
Linking photosynthesis and sun-induced fluorescence at sub-daily to seasonal scales
2018
Abstract Due to its close link to the photosynthetic process, sun-induced chlorophyll fluorescence (F) opens new possibilities to study dynamics of photosynthetic light reactions and to quantify CO2 assimilation rates. Although recent studies show that F is linearly related to gross primary production (GPP) on coarse spatial and temporal scales, it is argued that this relationship may be mainly driven by seasonal changes in absorbed photochemical active radiation (APAR) and less by the plant light use efficiency (LUE). In this work a high-resolution spectrometer was used to continuously measure red and far-red fluorescence and different reflectance indices within a sugar beet field during t…
Retrieval of daily gross primary production over Europe and Africa from an ensemble of SEVIRI/MSG products
2018
The main goal of this paper is to derive a method for a daily gross primary production (GPP) product over Europe and Africa taking the full advantage of the SEVIRI/MSG satellite products from the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) sensors delivered from the Satellite Application Facility for Land Surface Analysis (LSA SAF) system. Special attention is paid to model the daily GPP response from an optimized Montheith's light use efficiency model under dry conditions by controlling water shortage limitations from the actual evapotranspiration and the potential evapotranspiration (PET). The PET was parameterized using the mean daily air temperatur…
Modelling nonlinear dynamics of Crassulacean acid metabolism productivity and water use for global predictions
2021
Crassulacean acid metabolism (CAM) crops are important agricultural commodities in water-limited environments across the globe, yet modeling of CAM productivity lacks the sophistication of widely used C3 and C4 crop models, in part due to the complex responses of the CAM cycle to environmental conditions. This work builds on recent advances in CAM modeling to provide a framework for estimating CAM biomass yield and water use efficiency from basic principles. These advances, which integrate the CAM circadian rhythm with established models of carbon fixation, stomatal conductance, and the soil-plant-atmosphere continuum, are coupled to models of light attenuation, plant respiration, and bioma…
Environment-sensitivity functions for gross primary productivity in light use efficiency models
2022
International audience; The sensitivity of photosynthesis to environmental changes is essential for understanding carbon cycle responses to global climate change and for the development of modeling approaches that explains its spatial and temporal variability. We collected a large variety of published sensitivity functions of gross primary productivity (GPP) to different forcing variables to assess the response of GPP to environmental factors. These include the responses of GPP to temperature; vapor pressure deficit, some of which include the response to atmospheric CO2 concentrations; soil water availability (W); light intensity; and cloudiness. These functions were combined in a full fact…
A physiology-based Earth observation model indicates stagnation in the global gross primary production during recent decades
2020
Abstract Earth observation‐based estimates of global gross primary production (GPP) are essential for understanding the response of the terrestrial biosphere to climatic change and other anthropogenic forcing. In this study, we attempt an ecosystem‐level physiological approach of estimating GPP using an asymptotic light response function (LRF) between GPP and incoming photosynthetically active radiation (PAR) that better represents the response observed at high spatiotemporal resolutions than the conventional light use efficiency approach. Modelled GPP is thereafter constrained with meteorological and hydrological variables. The variability in field‐observed GPP, net primary productivity an…
Water Status and Yield Response to Deficit Irrigation and Fertilization of Three Olive Oil Cultivars under the Semi-Arid Conditions of Tunisia
2019
Sustainability of olive production is possible by adopting the modern techniques of irrigation and fertilization. In Tunisia, olive trees are usually cultivated in poor soils, under semi-arid conditions characterized by water scarcity. This study investigated the effects of different water supply and fertilization on leaf water status and crop yield of three different olive oil varieties cultivated in central Tunisia, during four experimental seasons (2014&ndash
Effect of Bacterial Inoculum and Fertigation Management on Nursery and Field Production of Lettuce Plants
2020
Plant growth-promoting rhizobacteria have been applied to different vegetable crops but there is still no information on the effect of bacterial biostimulant application under variable nutritional level on lettuce seedlings and their performance after transplanting in the field. This study aimed to evaluate the efficacy of a bacterial biostimulant to enhance growth and quality of lettuce seedlings fertigated with increasing nutrient rates and to assess the efficacy of these treatments on lettuce head production. Lettuce seedlings were inoculated with 1.5 g L&minus
Response of grapevine (Cabernet Sauvignon cv) to above ground and subsurface drip irrigation under arid conditions
2018
Abstract The response of wine grapes to irrigation systems was investigated in a Cabernet Sauvignon/140 Ru vineyard in sandy loam soil in Sicily during a two-year study. Two different drip irrigation systems were evaluated: one surface drip and two subsurface drip irrigation systems, with the trickle line located at different distances from vine trunks. Vegetative and quantitative parameters, must quality and root distribution were compared among irrigation treatments. During the two study years, irrigation of grapevines via a subsurface drip system resulted in greater water use efficiency without affecting must composition. Establishing the trickle line near the trunk positively influenced…
Effects of Three Irrigation Strategies on Gas Exchange Relationships, Plant Water Status, Yield Components and Water Productivity on Grafted Carménèr…
2018
In the Chilean viticultural industry, Carménère is considered an emblematic cultivar that is cultivated mainly in arid and semi-arid zones. For this reason, it is necessary to use precise irrigation scheduling for improving water use efficiency (WUE), water productivity (WP), yield and wine quality. This study evaluated the effects of three deficit irrigation strategies on gas exchange variables, WUE, WP and yield components in a drip-irrigated Carménère vineyard growing under semi-arid climatic conditions during two consecutive seasons (2011/12 and 2012/13). The irrigation strategies were applied in completely randomized design from fruit set (S) to harvest (H). The first irrigation strate…
Use of biochar as peat substitute for growing substrates of Euphorbia × lomi potted plants
2016
Biochar from conifers wood was used in soilless culture as growing substrate alternative to peat for ornamental crops. Potted plants of Euphorbia × lomi Rauh cv. ‘Ilaria’ were grown with different mixtures (v:v) of brown peat and biochar in order to evaluate main physical and chemical characteristics of this biomaterial as well as its effect on plant growth, ornamental characteristics and nutrients uptake. Biochar addition to peat increased pH, EC and K content of the growing substrates, as well as air content and bulk density. Biochar content of substrates significantly affected plant growth and biomass partitioning: higher number of shoots and leaves, leaf area and leaf dry weight were re…