weed's behaviors differ in a multiweed-crop competition system compare to a mono weed-crop competition system. the present investigation was carried out in mashhad, iran, to study the effect of weeds, which emerged naturally in a multi species community along side with melon, on quantitative and qualitative characteristics of the crop during 2007. thirty five plots were selected randomly in a g...

Twelve diverse strains of Drosophila melanogaster have been examined with respect to their individual fitness components and with respect to their relative performance under competitive and noncompetitive conditions. Individual fitness components included estimates of time until successful copulation (t), fecundity (f) and egg-to-adult viability (v), and a composite index of overall fitness of ...

In this paper, we develop an empirical model of an agro-pastoral system subject to high climatic risk to test the impact of rainfall variability on livestock densities, land allocation patterns and herd mobility observed at the community level. Also, because grazing land is a common-pool resource, we determine the impact of cooperation on these decision variables. To capture different abilities...

We studied the relationships among 5-year radial (diameter and basal area) growth of red oak (genus Quercus, subgenus Erythrobalanus) crop trees and predictor variables representing individual tree vigor, distance-dependant competition measures, and distance-independent competition measures. The red oaks we examined are representative of the commercially and ecologically important oak species o...

The effect of some weed control treatments (Bifonex, Tribenuron-methyl, hand weeding and unweeded check), five wheat cultivars (Sakha 69, Sids 6, Sids 7, Sids 8 and Sids 9) and their interaction on the productivity of wheat plants and associated weeds were examined under the sandy soil conditions. The obtained data indicated that total dry weight/m2 recorded at 60 days from wheat sowing signifi...

Understanding the likelihood and extent of introgression of novel alleles in hybrid zones requires comparison of lifetime fitness of parents and hybrid progeny. However, fitness differences among cross types can vary depending on biotic conditions, thereby influencing introgression patterns. Based on past work, we predicted that increased competition would enhance introgression between cultivat...

concluded that the intercropping system needed to be optimized with respect to crop quality and weed supIntercropping leek (Allium porrum L.) with celery (Apium graveopression for successful implementation and suggested lens L.) is an option to reduce growth and reproductive potential of weeds while maintaining productivity. In this study, a combined applying ecophysiological simulation models ...

a greenhouse study was conducted to investigate the effects of nitrogen (n) on wild barley (hordeum spontaneum koch) interference with winter wheat (triticum aestivum var. pishtaz) by an additive series experiment. the experiment was conducted in a split plot design with 3 replications. wheat plant height losses were on average 30, 10, and 10% in a wild barley density of 16 plants per pot with ...