ECOLOGICAL STUDY ON WEED FLORA GROWING IN THE ORCHARDS OF NEW DAMIETTA

Abstract

A survey was made to record the most of common weeds in the study area as well as the dominant, associated and rare species. Five sites were selected for this survey, random sample of weeds, fixing and making herbarium sheets for these weeds and deposited them in Herbarium of Botany Department, Faculty of Science, DamiettaUniversity. Furthermore, the characteristics of the soil were these weeds growing in the orchards of new Damietta were analyzed. The most habitat types in the study area were namely, orchards, sandy fertile cultivated lands, banks of irrigation canals, reclaimed lands and waste lands. 60 wed species related to 23 families most of them are annuals, some hemicrytophytes and few perennials. The recorded species were formed monocots and dicots, with Poaceae(13 species) was the most represented family followed by Asteraceae(10 species). Chorological analysis of the recorded species indicated that the Mediterranean weed species extending into the Euro-Siberian territory attained higher occurrence in the study area as compared to those species with Saharo indian extension. Shannon and Simpson diversity index of site П was the most diverse site while the least diverse was site Ш. It's mean that there variety of species in site П compared with the rest of sites so, thus means that this site is a suitable field for growing a high no. of species. The most important soil variables controlling the distribution and richness of weed species were: soil texture, porosity, water-holding capacity, organic carbon, conductivity, calcium carbonates, chlorides and potassium, sodium and calcium cat ions. Soil pH, water holding capacity, calcium carbonates and soil bicarbonates as the best set of predict or variables of the weed species distribution in the study area. The obtained results will be useful for the determination of weeds of national significance. This approach was used to focus on the key species and make an extensive research on them. Most of these weeds remain significant problem at orchards and field crops. Results will be useful for optimum management of the noxious weeds in orchards.