this research was carried out for evaluation of competitive ability of some wheat cultivars (triticum aestivum l.) of recommended wheat in dargaz region with common weed of feral rye (secale cereale). experiment was conducted as factorial based on randomized complete block design with three replications in 2010-2011 growing season. experimental factors were included four wheat cultivars of says...

potato (solanum tuberosum l.) cultivation in two different climates causes difference in its growth process.the most frequently used indicators of growth for plants are the tuber growth rate (tgr), crop growth rate (cgr) and leaf area index (lai). shoot dry weight is the easiest, quickest and least costly component to measure the competitive features of plants.the results of some studies showed...

The amount of leaves in a plant canopy (measured as leaf area index, LAI) modulates key land–atmosphere interactions, including the exchange of energy, moisture, carbon dioxide (CO 2), and other trace gases, and is therefore an essential variable in predicting terrestrial carbon, water, and energy fluxes. The latest generation of Earth system 5 models (ESMs) simulate LAI, as well as provide pro...

Spectral vegetation indices are frequently used to estimate vegetation biophysical/biochemical characteristics. In general they have been proposed to reduce spectral effects caused by external factors such as the atmosphere and the soil background. This study evaluated narrow band vegetation indices for estimation of vegetation leaf area index. The study takes advantage of using a dataset colle...

Using an analytical model, it was shown that for a given amount of nitrogen in the canopy of a stand (N(T)), there exists an evolutionarily stable leaf area index (ES-LAI), and therefore an evolutionarily stable average leaf nitrogen content (n(ES)(av);n(ES)(av) =N(T)/ES-LAI), at which no individual plant in the stand can increase its photosynthesis by changing its leaf area. It was also shown ...