Leaf Layers Research Articles

Spring air temperature accounts for the bimodal temporal distribution of Septoria tritici epidemics in the winter wheat stands of Luxembourg

Septoria tritici is the causal agent of leaf blotch in wheat and among the most damaging fungal cereal pathogens in the humid regions of central Europe. The percentage of the leaf area colonized by S. tritici was recorded weekly between April and July every season between 2004 and 2010. A total of 11 cultivars with moderate susceptibility [ratings of 4–6 on a 1 (resistant) to 9 (susceptible) scale] were included. The disease level was assessed on the upper three leaf layers at 2 locations between 2004 and 2006 and at 3 locations between 2007 and 2010. The period between sowing and the point of time, when 50% of the leaf area was necrotized due to colonization by S. tritici (T50) was estimated for each year, site, cultivar and leaf layer by non-linear regression. T50 values followed a bimodal distribution with one maximum at 245 days after sowing (DAS; early epidemics) and one maximum at 270 DAS (late epidemics). Early epidemics were preceded by almost constant daily average temperatures of 13.2 ± 0.8 °C between 181 and 210 DAS. Late epidemics were preceded by an approximately linear increase in temperature from 8.7 ± 0.9 to 12.1 ± 0.9 °C during the same period of time. Based on these differences, it seems possible to predict whether an early or a late epidemic can be expected at least 35 days before the epidemic outbreak. Temperature sums calculated with a base temperature of 6.6 °C starting at sowing and ending when T50 was reached were not significantly different between early and late epidemics (P = 0.73) and averaged 1721 ± 49°days. Fungicide applications, which resulted into a delay of the epidemic development similar to the difference between early and late epidemics, resulted in a yield increase between 11.7 and 12.6%.

Mechanical Canopy and Crop-Load Management of Pinot gris in a Warm Climate

The interactive effects of mechanical canopy management on the optimum cropping level and Ravaz index of Pinot gris in a warm growing region were determined. The study examined two pruning methods, three shoot thinning treatments, and two leaf removal treatments arranged factorially in a randomized complete block design with four replications. The pruning methods were applied by either hand pruning to 23 nodes/m or mechanically hedging and retaining a 100 mm spur height. The shoot thinning treatments were applied mechanically at modified E-L stage 17 to retain 23 (low), 33 (medium), or 45 (high, not thinned) shoots/m of row. The leaf removal treatments removed leaves on the east side of the canopy in a 450 mm zone in the fruiting zone, 20 days postbloom with a mechanical deleafer or no leaf removal was done. The interaction of mechanical hedging and medium shoot thinning treatments reduced the contribution of noncount shoots to total shoots. Percent canopy gaps and photosynthetically active radiation increased, while canopy leaf layers decreased with the application of leaf removal regardless of pruning or shoot thinning regime in both years. Yield increased and berry and cluster weight decreased in both years with the application of mechanical hedging and medium shoot thinning compared to hand-pruned vines without any detrimental effects on fruit composition. To achieve the economic crop level threshold of 8.15 kg/m, a Ravaz index of 10.2 to 12.0 kg/kg was needed. This Ravaz index corresponded to a pruning weight of 0.82 to 0.92 kg/m. The study identified a mechanical hedging and shoot thinning method where a 100 mm spur height was retained during the dormant season and 35 shoots/m of row was retained at E-L stage 17 to optimize crop load without adversely affecting pruning weight or fruit composition in a warm climate. The identified method provided 79% labor operations cost savings compared to hand pruning alone.

Training System Effects on Sunlight Penetration, Canopy Structure, Yield, and Fruit Characteristics of ‘Frontenac’ Grapevine (Vitis spp.)

Trellis or training systems influence many aspects of grapevine growth and production. This study investigated the effects of four trellis styles (Geneva double curtain, high cordon, Smart-Dyson, and vertical shoot positioned) on the fruit-zone light environment, fruit chemical composition, and yield of ‘Frontenac’ grapevines (Vitis spp.) grown on a fertile site near Crete, Nebraska over two growing seasons. Photosynthetically active radiation was measured above the canopy and within the fruiting zone at berry set, veraison, and harvest. At all sampling dates in 2008, vines grown on Geneva double curtain and high cordon had higher mid-day transmittances than vines grown on Smart-Dyson and vertical shoot positioned. In 2009, transmittance relationships among training systems were similar. In both years, leaf layer number was lower for Geneva double curtain and high cordon than for Smart-Dyson and vertical shoot positioned. In 2008, Geneva double curtain vines had higher fruit yield than vertical shoot positioned, Smart-Dyson, and high cordon. In 2009, Geneva double curtain yielded more than vertical shoot positioned and high cordon. In 2008, Geneva double curtain had higher pH and °Brix than other trellises; titratable acidity was lower in Geneva double curtain and high cordon than in Smart-Dyson and vertical shoot positioned. In 2009, fruit composition results were not related to transmittance. We propose Geneva double curtain training as a viable choice for Midwestern growers.

How deep does a remote sensor sense? Expression of chlorophyll content in a maize canopy

Remote sensing offers a unique perspective of plant vigor based on reflectance of the crops' canopy. The goal of this study was to determine how deep into the maize canopy red-edge chlorophyll index, CIred edge, was affected by foliar chlorophyll (Chl) content and leaf area. Reflectance in the range 400 to 900nm was measured at both the leaf and canopy levels and was used to determine foliar Chl and total canopy Chl content using CIred edge. Statistical techniques, a hierarchical regression and three Aikaike Information Criteria, were used to determine how many leaf layers are sensed by the CIred edge. All statistical techniques showed that the CIred edge senses the chlorophyll content of the upper 7 to 9 leaf layers in a maize canopy and that remote sensing technique is able to accurately estimate maize canopy Chl content.

The modification of a slip resistance meter for measurement of railhead adhesion

The aim of this work was to find a quick, flexible and localised method for determining railhead adhesion. The proposed method is a pendulum rig, which has a rubber pad at the base of a swinging arm. The arm is released and as the rubber pad slides across the contact surface, energy is lost. This loss can be translated into a friction coefficient. Tests have been performed under dry and contaminated conditions, including water, oil and leaf layers both in the laboratory on extracted rail and in the field on live rail. Friction modifiers were also tested. The results of these tests are compared with data obtained using a hand-pushed tribometer. The performed study shows that the pendulum is a viable way to test adhesion levels in the field.

Effects of Balanced Pruning Severity on Traminette (Vitisspp.) in a Warm Climate

Canopy architecture, yield components, fruit composition, vine size, Ravaz index, and midwinter primary bud cold hardiness of Traminette grapevines were measured in response to balanced pruning treatments of 20, 30, or 40 nodes retained for the first 454 g of dormant pruning weight and an additional 10 nodes for each additional 454 g in 2006 and 2007. As pruning severity increased from 40 + 10 to 20 + 10, shoots per hectare decreased and the distance between shoots increased. Leaf area per vine and leaf layer number showed a linear increase as pruning severity decreased. As the pruning severity decreased, the number of clusters harvested per vine and yield increased. Fruit composition was not affected by pruning severity. Vine size and leaf area per unit of fruit weight were not affected by the treatments, but Ravaz index (weight of fruit per weight of pruned wood) increased linearly as pruning severity decreased in 2007. In 2007, as pruning severity increased, more nodes were mature by late fall and buds were more cold hardy in midwinter. Results suggest that in the absence of any measurable effects of disease incidence or adverse effects on fruit composition, the 40 + 10 treatment should be used in the lower Midwest of the United States, as it optimized yield with only a slight decrease in primary bud cold hardiness.

RESPONSE OF RHAMNUS ALATERNUS TO FIVE SHADING LEVELS

ISHS XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Greenhouse 2010 and Soilless Cultivation RESPONSE OF RHAMNUS ALATERNUS TO FIVE SHADING LEVELS

A Computational Approach for Balancing Competing Objectives in Winegrape Production

Operational field targets, such as leaf layer numbers or leaf-area-to-fruit-weight ratios, are often used to guide cultural practices to achieve particular production objectives, including reduced disease pressure, increased yield, and improved fruit composition. However, these targets are not customized to individual producers nor do they account for the need to balance potentially conflicting objectives, such as simultaneously increasing fruit-zone sunlight exposure to reduce disease pressure while minimizing fruit exposure to avoid sunburn or the development of undesirable aroma compounds. The approach here balances multiple production objectives by adapting a multiobjective optimization method known as nondominated sorting genetic algorithm. The method was demonstrated in a hypothetical situation where a grower has competing objectives of reducing 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) precursors in Riesling while concurrently minimizing the amount of active ingredient used in an existing spray program. The demonstration model used two previously quantified responses for cluster exposure flux availability (CEFA) versus TDN precursor concentrations, and one previously quantified response for CEFA versus fruit spray residue. Optimal targets for CEFA and fruit spray inputs were computed that balance minimal TDN potential versus minimal spray active ingredient. A second analysis demonstrated how evolving knowledge of field responses can be used to update vineyard targets to maintain an optimal balance among production objectives.

Image‐Assisted Gap Estimation, a Simple Method for Measuring Grapevine Leaf Canopy Density

ABSTRACTThis study compared an image analysis method of leaf canopy density measurement, image‐assisted gap estimation (ImAGE), with the commonly used point quadrat (PQ) analysis. For ImAGE, a blue background (plastic tarpaulin) was placed behind the grapevine (Vitis vinifera L.) row and digitally photographed and the image was analyzed using application‐specific software to calculate the area ratio of background to vine canopy. This was used as an estimate of the percentage area of gaps in the leaf canopy. Relationships among PQ leaf layer number (LLN), ImAGE gap area percentage (GAP), and fruit exposure were investigated in New Zealand vineyards during the 2008–2009 season in Hawke's Bay and in the 2008–2009 and 2009–2010 seasons at Pukekohe (Auckland region).. Gap area percentage was closely related (R2 = 0.87) to LLN. Significant relationships (p < 0.01) were also found between canopy density (measured by either method) and percentage severity of botrytis bunch rot at harvest. Image‐assisted gap estimation provides an alternative method to PQ analysis for measuring canopy density that is quicker, less subjective, and nondamaging. Image‐assisted gap estimation would primarily be useful as a low‐cost research tool as it could provide practical and rapid assessments without a significant investment in equipment. It may also help viticulturists achieve target leaf canopy densities for management of disease risk.

Leaf thickness and structure of <em>Vitis vinifera</em> L. cv. Albariño clones and its possible relation with susceptibility to downy mildew (<em>Plasmopara viticola</em>) infection

<p style="text-align: justify;"><strong>Aims</strong>: The grapevine (<em>Vitis vinifera</em> L.) cultivar Albariño is currently the most economically important in Galicia (northwestern Spain). Earlier works assessing the natural susceptibility to downy mildew leaf infection (both in the laboratory and in the field), carried out in the collection of Albariño clones at the Misión Biológica de Galicia (CSIC), showed great differences among the clones (Boso <em>et al.</em>, 2004b, 2005b, 2006; Boso and Kassemeyer, 2008). The aim of the present work is to highlight the histological differences in leaves, in particular thickness and structure, among the 11 different Albariño clones and to find out their possible relation with their natural susceptibility to <em>Plasmopara viticola</em>.</p><p style="text-align: justify;"><strong>Methods and Results</strong>: Transverse sections of adult leaves where prepared and observed under light microscope. The area corresponding to the different leaf layers was measured. The results showed significant differences between the clones regarding the thickness of the spongy mesophyll. The clones CSIC-4 and CSIC-1 had the thickest spongy mesophyll (average mean = 14316.8 μm<sup>2</sup>) whereas CSIC-3 showed the thinnest one (11548.1 μm<sup>2</sup>).</p><p style="text-align: justify;"><strong>Conclusion</strong>: The CSIC-3 clone, one of the least susceptible clones to <em>P. viticola</em> in previous studies, showed the thinnest and most compact spongy mesophyll. On the contrary, the CSIC-1 clone had the thickest spongy mesophyll and was also one of the most susceptible to this pathogen. Therefore, it could be possible to relate their histological leaf characteristics with their different levels of natural susceptibility to <em>P. viticola</em>.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This work contributes to the understanding of the link between histological characteristics of leaf layers and mesophyll cells and the different natural susceptibility of grapevines to downy mildew. This may become in the future a valid tool to be used during clonal selections in grapevine breeding programs.</p>

Achieving Vine Balance of Syrah with Mechanical Canopy Management and Regulated Deficit Irrigation

Canopy architecture, yield components, fruit composition, and vigor of Syrah were measured in response to four canopy management and three regulated deficit irrigation (RDI) treatments. The control consisted of dormant hand pruning to 22, two-node spurs (HP) with no further manipulation. Other treatments consisted of mechanically box pruning vines to 10 cm hedges and mechanically thinning the canopy to a density of 5 (CLL) or 7 (CLM) count shoots per 30 cm of row or mechanically box pruning to a 10 cm hedge with no shoot thinning (CLH). Control vines were irrigated to 70% of evapotranspiration (ET_o) from fruit set until harvest (RDIC). Other vines either received 70% of full vine ET_o until veraison and 50% of ET_o (RDIL) thereafter or received 50% of ET_o between fruit set and veraison (RDIE) and 70% thereafter. Mechanical shoot thinning (CLM) removed 25% of the total shoots, exposing 70,600 shoots·ha⁻¹ with a distance of 4.6 cm between count shoots on the cordon, which translated to four leaf layers and 12.6 m² leaf area. The combination of the CLM and RDIE decreased berry weight at harvest by 12% without decreasing yield compared to HP, resulting in 21.5 tons·ha⁻¹ yield. A combination of CLM and RDIE was needed to achieve vine balance with a crop load of 9.9 kg yield/kg pruning weight and a leaf area to fruit ratio of 0.75 m²·kg⁻¹. The study identified a canopy management method that can be used in combination with regulated deficit irrigation that reduces input costs through mechanization and enhances berry composition with a vine balance that provides sustainable production.

Weed discrimination using ultrasonic sensors

Andújar D, Escolà A, Dorado J & Fernández‐Quintanilla C (2011). Weed discrimination using ultrasonic sensors. Weed Research51, 543–547.SummaryA new approach is described for automatic discrimination between grasses and broad‐leaved weeds, based on their heights. An ultrasonic sensor was mounted on the front of a tractor, pointing vertically down in the inter‐row area, with a control system georeferencing and registering the echoes reflected by the ground or by the various leaf layers. Static measurements were taken at locations with different densities of grasses (Sorghum halepense) and broad‐leaved weeds (Xanthium strumarium and Datura spp.). The sensor readings permitted the discrimination of pure stands of grasses (up to 81% success) and pure stands of broad‐leaved weeds (up to 99% success). Moreover, canonical discriminant analysis revealed that the ultrasonic data could separate three groups of assemblages: pure stands of broad‐leaved weeds (lower height), pure stands of grasses (higher height) and mixed stands of broad‐leaved and grass weeds (medium height). Dynamic measurements confirmed the potential of this system to detect weed infestations. This technique offers significant promise for the development of real‐time spatially selective weed control techniques, either as the sole weed detection system or in combination with other detection tools.

Distribution pattern of antioxidants in white cabbage heads (Brassica oleracea L. var. capitata f. alba)

The aim of this paper has been to investigate the occurrence of health-promoting antioxidants, such as vitamins C and E as well as antioxidative enzymes, e.g. superoxide dismutase, catalase and peroxidase in different parts of the cabbage head (the outer one green leaves, the central leaf layer and the inner layer young, etiolated leaves). Vitamin C content in both the central (209 mg/dm3) and inner (202 mg/dm3) layers of cabbage heads was higher in comparison to the outer one (163 mg/dm3), while vitamin E content (α-tocopherol) in the outer layer (4 μg/g FW) was higher by about 26 and 34% in comparison to the central and inner layers, respectively. The cooperation between vitamins and enzymatic antioxidants led to the highest H2O2 level in the outer layer, while the O 2 ·− level was the highest in the inner part of the cabbage head. We conclude that leaf layers in cabbage heads reflect the different potential of bioactive compounds accumulation, related to the stage of tissue development, as well as tissue-specific stress response.

Quercetin and Isorhamnetin Glycosides in Onion (Allium cepa L.): Varietal Comparison, Physical Distribution, Coproduct Evaluation, and Long-Term Storage Stability

During onion processing, the outer dried protective layer (outer paper layer) and first two fleshy leaf layers are removed. This coproduct material is a potential commercial source of flavonoids especially quercetin. In the following study, the flavonoid composition was determined in coproduct materials and the press cake (material generated after juice extraction) in several commercially important onion varieties grown in California. Flavonoids were characterized and quantified using LC-(ESI)MS/MS and HPLC. The long-term stability of quercetin glycosides was assessed in dried coproduct materials stored at 4 and 22 °C over a 12 month period. In all varieties, the predominant forms of quercetin were the quercetin 3,4'-O-glucoside and 4'-O-glucoside. The first layer had significantly higher levels of flavonoids than the outer paper, second, and inner flesh layers on a DW basis (p < 0.05). Allium cepa "Milestone" contained the highest levels (p < 0.05) of flavonoids (1703 mg/100 g on a dry weight basis (DW). Onion press cake had significantly higher levels of total quercetin as compared with fresh onions (p < 0.05). The levels of 4'-O-glucoside significantly decreased during the first month of storage and remained stable for 12 months of storage at either 4 or 22 °C (p < 0.05).

Plant Type and Its Effects on Canopy Structure at Heading Stage in Various Ecological Areas for a Two-line Hybrid Rice Combination, Liangyoupeijiu

A two-line hybrid rice combination, Liangyoupeijiu, was used to estimate several factors of plant type, and environmental models for these factors at the heading stage were established using the data of eight ecological experimental sites in 2006 and 2007. According to climatic data from 1951 to 2005, the differences in those factors and their effects on plant canopy were analyzed for four rice cropping areas in China, including South China, the middle-lower reaches of the Yangtze River, Sichuan Basin, and river valley in Yunnan, China. The thickness of leaf layer (the distance from pulvinus of the third leaf from the top to the tip of flag leaf) and distribution of leaf area could be used as candidate indices for the plant type of a rice canopy.

Direct somatic embryogenesis and plant regeneration from leaf explants of Limoniumsinensis (Girard) Kuntze

The potentialities of direct somatic embryogenesis and plant regeneration from leaf explants of Limonium sinensis var. Golden Diamond in vitro were investigated. Young whole leaf and cut leaf explants when cultured on MS basal medium supplemented with each of the growth regulators N 6-benzyladenine (BA) (0.44–2.2 μM) or thidiazuron (TDZ) (4.54 μM) alone or in combination with a fixed concentration of α-naphthalene acetic acid (NAA) (1.07 μM) produced somatic embryos directly. More than 90% of the leaf explants produced white, globular somatic embryos on BA (2.2 μM) and NAA (1.07 μM) supplemented MS basal medium within 1 week of inoculation. Most of the embryos matured further and converted after 8 weeks of culture on the same medium. Histological observation showed that the somatic embryos originated from single cells of epidermal layer of leaf. Histological evidence of formation of shoot and root poles during conversion of the embryos confirmed that these structures were true somatic embryos. After conversion the plantlets were further placed on MS medium containing 0.44 μM BA and 4.5 μM IBA for better shoot and root growth. About 90% of the plantlets transferred to the mixture of soil:perlite:vermiculite (1:1:1) in small plastic pots acclimatized successfully. Of these 85.5% plants survived after transferring into earthen pots containing a mixture of soil, coarse sand and cattle manure (1:1:1) under greenhouse or shady open condition.

GOLD IS EARNED FROM THE PRODUCTION OF THAI GOLD LEAF

Thai people like to cover sacred objects or things dear to them with gold leaf.. Statues of Buddha are sometimes covered with so many layers of gold leaf that they become formless figures, that can hardly be recognized. Portraits of beloved ancestors, statues of elephants and grave tombs are often covered with gold leaf. If one considers the number of Thai people and the popularity of the habit, the amount of gold involved could be considerable.

Effects of Sunlight Exposure on Berry and Wine Monoterpenes and Sensory Characteristics of Traminette

Traminette is a cold-hardy interspecific Gewürztraminer hybrid winegrape cultivar grown in the eastern United States. A study from 2003 through 2005 investigated impacts of canopy management on aromatic qualities of fruit and wine. Cluster-shading treatments under leaf layers (0, 1, 2, and &gt;3) and synthetic coverings (greenhouse shade cloth and light-excluding apple bags) were implemented in field trials, and fruit composition and wine sensory analyses were conducted. Fruit from fully exposed clusters had 30% higher concentrations of potentially volatile terpenes compared with heavily shaded fruit (&gt;3 leaf layers). Descriptive analyses showed higher ratings for color, linalool, rose, and spice aromas with exposed wines in 2004. There were no differences in wine aroma intensities in 2005. Berry skin color at harvest correlated with potentially volatile terpenes concentration and may be used as a field guide to estimate monoterpene concentration at harvest.

A review of light interception in plant stands from leaf to canopy in different plant functional types and in species with varying shade tolerance

AbstractChanges in the efficiency of light interception and in the costs for light harvesting along the light gradients from the top of the plant canopy to the bottom are the major means by which efficient light harvesting is achieved in ecosystems. In the current review analysis, leaf, shoot and canopy level determinants of plant light harvesting, the light‐driven plasticity in key traits altering light harvesting, and variations among different plant functional types and between species of different shade tolerance are analyzed. In addition, plant age‐ and size‐dependent alterations in light harvesting efficiency are also examined. At the leaf level, the variations in light harvesting are driven by alterations in leaf chlorophyll content modifies the fraction of incident light harvested by given leaf area, and in leaf dry mass per unit area (MA) that determines the amount of leaf area formed with certain fraction of plant biomass in the leaves. In needle‐leaved species with complex foliage cross‐section, the degree of foliage surface exposure also depends on the leaf total‐to‐projected surface area ratio. At the shoot scale, foliage inclination angle distribution and foliage spatial aggregation are the major determinants of light harvesting, while at the canopy scale, branching frequency, foliage distribution and biomass allocation to leaves (FL) modify light harvesting significantly. FL decreases with increasing plant size from herbs to shrubs to trees due to progressively larger support costs in plant functional types with greater stature. Among trees, FL and stand leaf area index scale positively with foliage longevity. Plant traits altering light harvesting have a large potential to adjust to light availability. Chlorophyll per mass increases, while MA, foliage inclination from the horizontal and degree of spatial aggregation decrease with decreasing light availability. In addition, branching frequency decreases and canopies become flatter in lower light. All these plastic modifications greatly enhance light harvesting in low light. Species with greater shade tolerance typically form a more extensive canopy by having lower MA in deciduous species and enhanced leaf longevity in evergreens. In addition, young plants of shade tolerators commonly have less strongly aggregated foliage and flatter canopies, while in adult plants partly exposed to high light, higher shade tolerance of foliage allows the shade tolerators to maintain more leaf layers, resulting in extended crowns. Within a given plant functional type, increases in plant age and size result in increases in MA, reductions in FL and increases in foliage aggregation, thereby reducing plant leaf area index and the efficiency of light harvesting. Such dynamic modifications in plant light harvesting play a key role in stand development and productivity. Overall, the current review analysis demonstrates that a suite of chemical and architectural traits at various scales and their plasticity drive plant light harvesting efficiency. Enhanced light harvesting can be achieved by various combinations of traits, and these suites of traits vary during plant ontogeny.

Utilizing in situ directional hyperspectral measurements to validate bio-indicator simulations for a corn crop canopy

Two radiative transfer canopy models, SAIL and the two-layer Markov-Chain Canopy Reflectance Model (MCRM), were coupled with in situ leaf optical properties to simulate canopy-level spectral band ratio vegetation indices with the focus on the photochemical reflectance index in a cornfield. In situ hyperspectral measurements were made at both leaf and canopy levels. Leaf optical properties were obtained from both sunlit and shaded leaves. Canopy reflectance was acquired for eight different relative azimuth angles ( ψ) at three different view zenith angles ( θ v), and later used to validate model outputs. Field observations of PRI for sunlit leaves exhibited lower values than shaded leaves, indicating higher light stress. Canopy PRI expressed obvious sensitivity to viewing geometry, as a function of both θ v and ψ. Overall, simulations from MCRM exhibited better agreements with in situ values than SAIL. When using only sunlit leaves as input, the MCRM-simulated PRI values showed satisfactory correlation and RMSE, as compared to in situ values. However, the performance of the MCRM model was significantly improved after defining a lower canopy layer comprised of shaded leaves beneath the upper sunlit leaf layer. Four other widely used band ratio vegetation indices were also studied and compared with the PRI results. MCRM simulations were able to generate satisfactory simulations for these other four indices when using only sunlit leaves as input; but unlike PRI, adding shaded leaves did not improve the performance of MCRM. These results support the hypothesis that the PRI is sensitive to physiological dynamics while the others detect static factors related to canopy structure. Sensitivity analysis was performed on MCRM in order to better understand the effects of structure related parameters on the PRI simulations. LAI showed the most significant impact on MCRM-simulated PRI among the parameters studied. This research shows the importance of hyperspectral and narrow band sensor studies, and especially the necessity of including the green wavelengths (e.g., 531 nm) on satellites proposing to monitor carbon dynamics of terrestrial ecosystems.