leaf area index Articles
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Nondestructive measurement of grapevine leaf area by ground normalized difference vegetation index
Vine leaf area index has a great impact on berry quality. This study was conducted to determine whether vine leaf area index could be estimated, and mapped through normalized difference vegetation index (NDVI) ground-based measurements. The NDVI measurements were performed using a Greenseeker (N-Tech Industires, Ukiah, CA and Oklahoma State Univ., Stillwater), pointed sideways at the vertical ...
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Comparison of three methods for estimating leaf area index of upland rice cultivars
Nondestructive estimation of leaf area index (LAI) using two canopy analyzers (LAI-2000 and SunScan) was compared with destructively measured LAI for four upland rice (Oryza spp.) cultivars with various types of canopy development during the period from 21 to 56 d after sowing (DAS). For the LAI-2000, LAI was estimated with or without the wide angle reading (Ring 5). When data from 50 and 56 DAS, ...
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A study on crown interception with four dominant tree species: a direct measurement
An experiment was conducted to concentrate on the rainfall interception process of individual trees for four common species in Beijing, China, which included needle species (Platycladus orientalis and Pinus tabulaeformis) and broadleaf species (Quercus variabilis and Acer truncatum). Two types of interception storages, the maximum (Cmax) and the minimum interception storage (Cmin), were ...
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Growth analysis of biomass production in sole-crop and double-crop corn systems
Increased biomass productivity could be achieved through double-cropping if extended growth duration could be realized with minimal reductions in growth efficiency relative to sole-cropping. To test this hypothesis, functional growth analysis was used to assess the relative importance of photosynthetic duration and efficiency in determining biomass production by sole-crop corn (Zea mays L.; SC) ...
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Monitoring Forest Phenology and Leaf Area Index with the Autonomous, Low-Cost Transmittance Sensor PASTiS-57
Abstract : Land Surface Phenology (LSP) and Leaf Area Index (LAI) are important variables that describe the photosynthetically active phase and capacity of vegetation. Both are derived on the global scale from optical satellite sensors and require robust validation based on in situ sensors at high temporal resolution. This study assesses the PAI Autonomous System from Transmittance Sensors at 57 ...
By Hiphen
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The Importance of Leaf Area Index (LAI) in Environmental and Crop Research
Leaf Area Index (LAI), which is used as a measure in hundreds of studies on forests, crops, climate and the environment, is calculated as half the area of all leaves per unit area of ground. It is measured as the leaf area (m2 ) per ground area (m–2) and is unit-less. So, a plant with a LAI of 2 has an amount of leaves that can cover a given area two times. LAI is calculated for a plant or ...
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The importance of Leaf Area Index (LAI) in environmental and crop research
Leaf Area Index (LAI), which is used as a measure in hundreds of studies on forests, crops, climate and the environment, is calculated as half the area of all leaves per unit area of ground. It is measured as the leaf area (m2 ) per ground area (m–2) and is unit-less. So, a plant with a LAI of 2 has an amount of leaves that can cover a given area two times. LAI is calculated for a plant or ...
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Response of yield heterosis to increasing plant density in maize
Genetic yield improvement in maize (Zea mays L.) has been associated with heterosis and increased tolerance to high plant densities, but the physiological processes underlying heterosis for tolerance to plant density stress have not been identified. The objective of this study was to quantify the response of heterosis for grain yield to increasing plant density, and to examine the processes ...
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Variability in Leaf Area and Stemwood Increment Along a 300-year Lodgepole Pine Chronosequence
Large disturbances such as the 1988 Yellowstone fires produce considerable spatial heterogeneity in ecosystem processes across landscapes, in part by affecting vegetation structure. However, the persistence of this heterogeneity with time since disturbance, and thus the role of large disturbances in shaping the heterogeneity of ecosystem processes over large spatial and temporal scales, remains ...
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Effects of treated municipal wastewater on fluctuation trend of leaf area index and quality of maize (
Zea mays )The effect of primary-treated municipal wastewater (TMWW) on the leaf area index (LAI) and quality of maize (Zea mays) was studied in comparison to the clean irrigation water (control). The experiment was based on a randomized block design with four replicates, and it was conducted in a field experiment in Aligoudarz (Iran). Irrigation was applied with five different methods as treatments: T1: ...
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Estimation of maize evapotranspiration using extreme learning machine and generalized regression neural network on the China Loess Plateau
Accurately estimating crop evapotranspiration (ET) is essential for agricultural water management in arid and semiarid croplands. This study developed extreme learning machine (ELM) and generalized regression neural network (GRNN) models for maize ET estimation on the China Loess Plateau. Maize ET, meteorological variables, leaf area index (LAI), and plant height (hc) were continuously ...
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Simulating switchgrass growth and development under potential and water-limiting conditions
Anticipating a demand for switchgrass (Panicum virgatum L.) as a source for biofuel production, a crop simulation model of this crop can be a component of a biofuel decision support system. The objective of this effort was to develop and test a model for switchgrass, based on robust empirical relationships between plant behavior and the environment. The model simulates date of annual growth ...
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The ratio of transpiration to evapotranspiration in a rainfed maize field on the Loess Plateau of China
Maize (Zea mays L.) is a major crop on the Loess Plateau, and calculating the ratio of transpiration to evapotranspiration (T/ET) of maize is important for estimating field water balance. In this study, the sap flow method was adopted to measure transpiration (T) characteristics of maize. In order to calibrate the sap flow gauge, the sap flow rate was compared to the leaf T determined by the ...
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Breeding effects on grain filling, biomass partitioning, and remobilization in mediterranean durum wheat
This work assesses the changes resulting from durum wheat (Triticum turgidum L. var. durum) breeding in Italy and Spain during the 20th century on grain filling, biomass production, and allocation at anthesis, and the remobilization of preanthesis photosynthates to the grain of main stems. Field experiments, involving 12 Italian and 12 Spanish cultivars released at different periods, were ...
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Effect of height on the competitive ability of wheat with oats
Competitive ability of wheat is influenced by a range of attributes such as plant height, tiller number, and light interception. This study focused on the effect of plant height on weed competitiveness of a set of near-isogenic wheat lines (NILs). The set included seven bread wheat (Triticum aestivium L.) and six durum wheat (T. turgidum L.) cultivars, each having a semidwarf and tall ...
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Comparative plant growth and development in two cotton rotations under irrigated and non-irrigated conditions
Incorporating perennial grasses such as bahiagrass (Paspalum notatum Fluegge) to diversify the conventional two-crop rotation of peanut (Arachis hypogaea L.) and cotton (Gossypium hirsutum L.) prevalent in the U.S. Southeast (SE) is advocated. However, little is reported on growth and development for cotton grown in rotation with perennial grasses. Our objectives were to compare plant ...
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Variation in photosynthetic photon flux density within a tropical seasonal rain forest of Xishuangbanna, south-western China
The effects of canopy development, solar angle, and weather conditions on temporal variation in photosynthetic photon flux density (PPFD) at three heights within a tropical rain forest canopy in Xishuangbanna, China, were examined. PPFD was measured every second and stored as 10-min averages from 1 December 2002 to 30 November 2003. PPFD variability was examined at three different tempcral ...
By IOS Press
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Projection of future climate change impacts on nonpoint source pollution loads for a forest dominant dam watershed by reflecting future vegetation canopy in a Soil and Water Assessment Tool model
This study is to assess the future impact of climate change on hydrological behavior considering future vegetation canopy prediction and its propagation to nonpoint source pollution (NPS) loads. The SWAT (Soil and Water Assessment Tool) model was used for the assessment. For a forest dominant ChungjuDam watershed of South Korea, the MIROC3.2hires climate data of SRES A1B and B1 scenarios were ...
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Growth, yield, and yield component changes among old and new soybean cultivars
Soybean [Glycine max (L.) Merr.] yield has increased at a rate of 25 to 30 kg ha–1 yr–1 due in part to improved genetic gain, and has been further advanced by the addition of resistance to soybean cyst nematode (Heterodera glycines Ichinohe; SCN) in new cultivars. The objective was to determine specific growth changes that explain the yield improvement from old to new cultivars and the further ...
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Observations and snow model simulations of winter energy balance terms within and between different coniferous forests in southern boreal Finland
Variation of canopy properties between different forest types is seldom taken into account in hydrological and climate models, and consideration of variation inside a forest is normally omitted. In this work, three data sets on near surface energy balance terms (incoming shortwave and longwave radiation; air and snow–soil interface temperatures) were collected in the southern boreal ...
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