Leaf area

A model of crop growth, development, and yield formation was used to compare Jerusalem artichoke and chicory — the two main agricultural sources of inulin (Meijer et al., 1993). The pattern of assimilation in the two crops was very different. Chicory is a biennial, with only vegetative growth in the first season and dry matter distributed to the storage roots during the second season. A greater fraction of total production is diverted to structural stem matter in Jerusalem artichoke. Most dry matter is allocated to the stem until the reproductive phase of Jerusalem artichoke, mainly in the form of structural stem material, but also as stored carbohydrates. 

The discrepancy between the simulations of the models and experimental data from Jerusalem artichoke grown in the field is often large, in the case of early versions of the LINTUL model, for example, due to over- or underestimation of leaf area extension, ontogenetic development, and the distribution of assimilates with time (Denoroy, 1993). The models have been improved over time, however, in the light of experimental evidence. Collectively they have provided useful insights into the development physiology and biochemistry of Jerusalem artichoke. 

The acquisition of carbon is strongly modulated by the surface area of photosynthesizing leaves hence, understanding leaf area development is germane to efforts to increase yield. In many crops, biomass is linearly related to the amount of light intercepted (Monteith, 1977). This is certainly the case for Jerusalem artichoke, where total productivity is strongly correlated with the amount of solar radiation intercepted (Denoroy, 1996 Meijer et al., 1993). Leaf area, leaf duration, and photosynthetic efficiency of the crop canopy determine how much light is intercepted and subsequently utilized (Table 10.9). 

Biology and Chemistry of Jerusalem Artichoke Helianthus tuberosus L. 

Biological Parameters, Their Descriptions, and Values for Jerusalem Artichoke 

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Test filter leaf area = 0.05 m" Vacuum applied = 0.70 bar... 

Photosynthesis and gas exchange of leaves are affected by many stresses including drought, flooding, salinity, chilling, high temperature, soil compaction and inadequate nutrition. Many, but not all, of these stresses have symptoms in common. For example, stomatal conductance and the rate of assimilation of CO2 per unit leaf area often decrease when stress occurs. Further, it is possible that several of the stresses may exert their effects, in part, by increasing the levels of the hormone abscisic acid (ABA) in the leaf epidermis. This hormone is known to close stomata when applied to leaves. 

Constitutive features of stomatal complexes which give a low stomatal conductance (e.g. sunken stomata, few stomata per unit leaf area). 

Several plant parameters are important to the design of ET landfill covers. Among the most important are parameters describing rooting depth, leaf-area-index (LAI), temperature requirements, time to maturity, and water requirements. Models that are suitable for use in design of ET covers will utilize these parameters. The quality of the plant model controls the quality of AET estimates. 

During re-entry, stratified whole-leaf sampling was conducted. Twenty-four leaves from the harvesting zone of the crop were collected in a 500-mL polyethylene bottle in duplicate. Leaf samples were stored at 4 to 7°C in the laboratory until analysis. After analysis, the leaf volume was measured by stereometric volumetry using a method described by Sherle (1970). A linear relationship between leaf volume and leaf area was determined for carnation leafs by measuring leaf area (one-sided) with a LI-COR 3100 (Ll-Cor, Inc. Nebraska). 

The theoretical initial concentration on leaves is 10 ug/cm2, based on an application rate of 1 kg/ha, no loss of spray to the ground or into the air, and a leaf area index (LAI) of only 1, which means that the total foliar surface in a treated area is equal to the ground surface. 

The results of the DFR assessment of different crop zones indicate that low-volume applications result in a more homogeneous distribution over the crop compared to high-volume applications. A recent study on the interception of high-volume applications in the cultivation of chrysanthemums revealed interception ratios from 0.2 to 1 related to the leaf area index (LAI) (Veerman et al., 1994). In our study, it was not easy to assess the LAI because of the structure of the carnation crop. Estimation of the LAI based on the results of estimation of the crop density (leaf volume index) was not reliable enough and resulted in a large variance of the calculated interception ratio (from 0.4 up to 5). 

LC50 reduced reproduction and leaf area in survivors (Correll and Wu 1982)... 

The effect of zearalenone on crop development may be connected to its influence on the status and functioning of the photosynthetic apparatus (Koscielniak et al. 2008). The after-effects of zearalenone on the growth of soybean and wheat plants, net photosynthesis and transpiration rates, stomatal conductance, photochemical efficiency of photosystem 2 and on final seeds yield were determined. Modifications in leaf area were more pronounced in soybean than in wheat, and this tendency increases in successive developmental phases. The net photosynthesis was stimulated during the juvenile phase and during that of the final one by about 13.6% (average) in soybean plants. Stimulation of transpiration was also observed after... 

The photo synthetic aquatic biomass comprises cyanobacteria (formerly called blue-green algae), planktonic, filamentous and macrophytic algae, and vascular macrophytes. The net productivity of the floodwater depends on the level of primary production by the photosynthetic biomass versus its consumption by grazing animals, particularly cladocerans, copepods, ostracods, insect larvae and molluscs. Their role will change as the canopy develops and at a leaf area index of about 6-7 there will be no more photosynthetically active radiation available to them. 

Symptoms Leaves develop a brownish-purplish tinge. A reddish band appears around leaf edges this may color the whole of the central leaf area. Growth can be patchy, individual plants becoming weak and stunted. Roots are stunted and dark brown or black in color. When the root is split open, the classic symptom is a red core running down the center. It is most noticeable in spring and fall. 

HilF reported pollutant uptake values for a number of gaseous pollutants, including ozone and PAN, with alfalfa as his test organism (Table 11-26). These values were obtained with a dynamic, but closed, exposure facility. Uptake was determined by the amount of pollutant needed to maintain a constant chamber concentration over an alfalfa bed. Uptake values, expressed on the basis of leaf area, reflect the effect of the plant canopy on the exchange of gases within the canopy and do not... 

Goudriaan, J., de Ruiter, H. E. (1983). Plant growth in responses to CO2 enriehment, at two levels of nitrogen and phosphorus supply. 1. Dry matter, leaf area and development. Neth. J. Agric. ScL, 31, 157-169. 

By June 11 all of the field load Insects had died or left the trees. Leaf damage to the test trees when measured on June 3 was relatively light. Leaves exhibiting noticeable damage averaged 27.6 i 2.1% (S.E.) for the control trees and 49.0 i 4.7% for test trees (p < 0.01, one-tailed paired t test). Estimated leaf area loss averaged 2.5 + 0.2% for controls and 11.3 i 2.1% for test trees (p < 0.005, one-tailed paired t test). Damage to control trees was due to unidentified insects other than tent caterpillars. 

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