Leaf size and venation show remarkable diversity across dicotyledons, and are key determinants of plant adaptation in ecosystems past and present. Here we present global scaling relationships of venation traits with leaf size. Across a new database for 485 globally distributed species, larger leaves had major veins of larger diameter, but lower length per leaf area, whereas minor vein traits we...

two-spotted spider mite, tetranychus urticae koch. is one of the most harmful pest of common bean in most areas of iran, including lorestan province. the appropriate unit and universe sampling of mite population were investigated in common bean fields in borujerd, dorud and azna in 2008. the results showed that samples should be taken from top, middle and bottom of the plant height. in addition...

A study was conducted at the National Agriculture Research Center, Islamabad during summer 2001 on 27 genotypes of soybean to determine the correlation and path analyses of yield and its components. Significant differences among genotypes for characters viz., leaf area, chlorophyll content, first pod height, days to 50% flowering, days to flowering completion, days to pod initiation, days to 50...

To assess the variability of net photosynthetic CO(2) exchange per unit leaf area and to construct budgets for stands of field-grown tobacco (Nicotiana tabacum, Connecticut Broadleaf), a number of short-time measurements were made on all available leaf positions on two varieties using a hand-held transparent chamber for conducting gas exchange measurements on leaves. Measurements of net CO(2) e...

Fractionation of carbon isotopes by plants during CO(2) uptake and fixation (Delta(leaf)) varies with environmental conditions, but quantitative patterns of Delta(leaf) across environmental gradients at the global scale are lacking. This impedes interpretation of variability in ancient terrestrial organic matter, which encodes climatic and ecological signals. To address this problem, we convert...

in order to study of some effective phenologic and physiologic characteristics on 18 sunflower hybrids yield under optimum conditions, an experiment was conducted as randomized complete block design with three replications at the research field of seed and plant improvement institute-karaj in 2006-2007. the result indicated that the hybrids showed significant difference in phonologic characteri...

Background: Biostimulants are amino acids and organic components, which can play main role in the plant growth and dry matter accumulation. Objective: Determine the influence of foliar application of active amino acids on quality and quantity yield of Melissa officinalis L. Methods: This study was conducted in a research farm at the institute of medicinal plants on the base of randomized ...