In this study, a model for estimating crop gross primary production (GPP) using the product of a chlorophyll-related vegetation index (VI) and incident photosynthetically active radiation (PARin) was developed and tested. This model, which may be based entirely on satellite data, was tested using Landsat and MODIS data for GPP estimation in both maize and soybean, crop types that differ in leaf...

BACKGROUND AND AIMS Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species. However, it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. The objective of this study was to investigate the responses of leaf hydraulic conductance (Kleaf) in Glycine max (soybean) to growth at elevated [CO2] and increased te...

Current background ozone (O(3)) concentrations over the northern hemisphere's midlatitudes are high enough to damage crops and are projected to increase. Soybean (Glycine max) is particularly sensitive to O(3); therefore, establishing an O(3) exposure threshold for damage is critical to understanding the current and future impact of this pollutant. This study aims to determine the exposure resp...

[1] The oxygen isotopes of CO2 and H2O ( O-CO2 and O-H2O) provide unique information regarding the contribution of terrestrial vegetation to the global CO2 and H2O cycles. In this paper, a simple isotopic land surface model was used to investigate processes controlling the isotopic exchange of O-H2O and O-CO2 between a soybean ecosystem and the atmosphere. We included in a standard land surface...

The objectives of this work were to determine the effect ofsink sBtngth (presce or absence of pods) ad nitrogen source (nodulatng nw nnoting pnnts) on enymk activ chlorophyll co tion, and sescence of soybean (GIycl max [L.] Merr. cv Harosoy) isolnes. A 2-year (1981-1962) feld sdy was ducted. For both nodlatesd ando lated p ts, ribe bisphosphate carboxybse (RuBPCe) acivity of upper-canopy leaves...

In a previous study by the same authors, a new modified Jarvis model (NMJ-model) was developed, calibrated, and validated to estimate stomatal resistance (rs) for maize canopy on an hourly time step. The NMJ-model’s unique subfunctions, different from the original Jarvis model (J-model), include a photosynthetic photon flux density (PPFD)-rs response subfunction developed from field measurement...

[1] Accurate estimation of spatially distributed chlorophyll content (Chl) in crops is of great importance for regional and global studies of carbon balance and responses to fertilizer (e.g., nitrogen) application. In this paper a recently developed conceptual model was applied for remotely estimating Chl in maize and soybean canopies. We tuned the spectral regions to be included in the model, ...

Carotenoids are organic pigments that are produced predominantly by photosynthetic organisms and provide antioxidant activity to a wide variety of plants, animals, bacteria, and fungi. The carotenoid biosynthetic pathway is highly conserved in plants and occurs mostly in chromoplasts and chloroplasts. Leaf carotenoids play important photoprotective roles and targeted selection for leaf caroteno...

One of the main factors affecting vegetation productivity is absorbed light, which is largely governed by chlorophyll. In this paper, we introduce the concept of chlorophyll efficiency, representing the amount of gross primary production per unit of canopy chlorophyll content (Chl) and incident PAR. We analyzed chlorophyll efficiency in two contrasting crops (soybean and maize). Given that they...

Photosynthetic rate, ribulose 1,5-bisphosphate carboxylase activity, specific leaf weight, and leaf concentrations of carbohydrates, proteins, chlorophyll, and inorganic phosphate were determined periodically from midbloom until maturity in leaves of soybean plants (Glycine max L., var. Hodgson) from which reproductive and vegetative sinks had been removed 32 hours before measurement, or contin...