Soil nutrients in arid systems are supplied to plants in brief pulses following precipitation inputs. While these resource dynamics have been well documented, little is known about how this temporal heterogeneity inXuences competitive interactions. We examined the impacts of the temporal pattern of N supply on competitive intensity and ability in an N-limited desert shrub community. At our Weld...

The Cecidomyiidae (Diptera: Bibionomorpha) fauna of Egypt is poorly known. Investigations in northern Egypt in 2013 revealed the presence of seven species of gall midges on three host plant species: Atriplex halimus L., Arthrocnemum macrostachyum (Moric.) and Suaeda pruniosa Lange (all Chenopodiaceae). Among the gall midges, Baldratia salicorniae  Kieffer and Stefaniella trinacriae De Stefani a...

This work addresses the issue of Zn, Cu, Pb, Cd, Ni and Cr accumulation in wildgrown plants in the context of their possible use for the sanitation of sludge and waste substrates. The highest contents of heavy metals were noted in Lactuca serriola, Chenopodium album, Artemisia vulgaris and Atriplex nitens. Assuming maximum crop production which is to be obtained from sludge and waste substrates...

Enzymes which are affected by the addition of inorganic salts during in vitro assay were extracted from salt-sensitive Phaseolus vulgaris, salt-tolerant Atriplex spongiosa, and Salicornia australis and tested for sensitivity to NaCl. In each case malate dehydrogenase, aspartate transaminase, glucose 6-phosphate dehydrogenase, and isocitrate dehydrogenase showed NaCl responses similar to those f...

This is the third article in a series of four articles dealing with the P vs. NP question. The purpose of this work is to demonstrate that although the oracle relativizations of the NP complexity class eliminate some methods as possible routes to a solution, the methods used in the first two articles of this series are not affected by oracle relativizations. Furthermore, the solution to the P v...

Competition, Evolution and Optimisation: Comparisons of Models in Economics and Ecology

Abstract One basic method of improving rangelands in a country is the use of native as well as exotic species of plants adaptable. Among the but introduced species, Atriplex canescens has been introduced in many rangelands, but it is important and necessary to consider it’s effects on native species. In the current study the effect of chemical competition (allelopathy) of Atriplex canescens o...