because plant density is often measured by using plots and also in most cases are done by the method of estimation and counting the individuals, so one of the important cases that we have to decide on is the size and shape of plot. in this research, the density of astragalus verus that it's one of the dominate species in the area and has separate and recognizable individuals plant from eac...

An analysis is introduced, based on the decomposition of relative growth rates, to examine the mode of competition (i.e. whether competition is symmetric or asymmetric), the size-dependence of growth, and their interdependence. In particular, the basis for two commonly held views is examined: (1) that the type of resource limitation determines the mode of competition, and (2) that asymmetric co...

The activities of plants and plant/microbial associations may offer a viable means of accomplishing the in situ remediation of contaminated soils. Two uses of plants for phytoremediation are reported here. In one set of studies, the ability of plants to foster degradative microorganisms was investigated. Results indicated that the degradation of several chlorinated pesticides increased in rhizo...

Plants load sugars from photosynthesizing leaves into the phloem of exporting veins either "apoplastically" (by using H+/sucrose symporters) or "symplastically" (through plasmodesmata). The ability to regulate photosynthesis in response to the light environment was compared among apoplastic loaders (pea and spinach) and symplastic loaders (pumpkin and Verbascum phoeniceum). Plants were grown un...

It is often assumed that planted wastewater treatment systems outperform unplanted ones, mainly because plants stimulate belowground microbial population. Yet, fundamental interactions between plants and associated microorganisms remain only partly understood. The aim of our project was to evaluate microbial density and activity associated to the rhizosphere of three plant species. Experimental...

Plant-insect interactions often are important for plant reproduction, but the outcome of these interactions may vary with environmental context. Pollinating seed predators have positive and negative effects on host plant reproduction, and the interaction outcome is predicted to vary with density or abundance of the partners. We studied the interaction between Silene stellata, an herbaceous pere...

Predators of herbivorous animals can affect plant populations by altering herbivore density, behavior, or both. To test whether the indirect effect of predators on plants arises from density or behavioral responses in a herbivore population, we experimentally examined the dynamics of terrestrial food chains comprised of old field plants, leaf-chewing grasshoppers, and spider predators in Northe...

Morphological defense traits of plants such as trichomes potentially compromise biological control in agroecosystems because they may hinder predation by natural enemies. To investigate whether plant trichomes hinder red imported Wre ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), as biological control agents in soybean, Weld and greenhouse experiments were conducted in which we manip...

The density at which a crop is grown is known to affect its growth and quality, but little is known about how plant density affects the growth of native perennial forage grasses. The objectives were to investigate the effects of plant population density on the forage yield, forage quality, and plant canopy structure of two native bluestem species. Big bluestem (Andropogon gerardii Vitman) and s...

Linseed, one of the oldest cultivated crops, is again gaining in importance, mainly due to its nutritional benefi ts and biomedical applications. Th erefore, it is expected that herbivores will also exist in greater abundance. Among them the fl ea beetle, Aphthona euphorbiae Schrank and Longitarsus parvulus Paykull are considered to be serious pests of fl ax grown for fi bre and seeds in Europe...