Composition and Function of Weed Communities Associated with Cereal Crops in Menofia Province, Egypt

Abstract

The main objectives of this study are to study the floristic and vegetation analyses of wheat and maize crops and their associated weeds and the environmental variables affect them. It also evaluates the weed-crop interaction, in terms of density and biomass, and its impact on the crop yield, in addition to the impact of nutrients and trace metals captured by weeds on the nutrient absorption and production of the study crops. Moreover, the impact of weeds on the functional traits of wheat and maize plants was also investigated. The weed flora associated with wheat and maize crops were surveyed through randomly selecting a number of stands (each 10 × 10 m) in Menofia Province. A visual estimate of the total cover and the cover of each species (%) of weeds was assessed; in addition to life forms and global geographical distribution. Two-way indicator species analysis (TWINSPAN) and Detrended Correspondence Analysis (DCA), as classification and ordination techniques, were applied to determine the different communities associated with the crops. Four crop cultivated farms were selected during winter for wheat and summer for maize. Farm I was not subjected to weed management practices, but supplied with fertilizers, while farms II, III and IV were subjected to chemical weed control with herbicides and application of fertilizers. For wheat farms I and II were sown by drilling (pitting), while farm III by broadcasting (dispersion); and farm IV by furrowing (striation) methods. On the other hand, all maize farms were sown by pitting. At each farm, five quadrats (0.5 x 0.5 m) were randomly selected for determining the number of cereal shoots (tillers for wheat) as well as the number of individuals of each of the common associated weeds, the shoot height; stem diameter; leaf length, width and area; and spike (cob for maize) length and diameter for cereals and their common grasses. Then the shoots of cereal plants and their common associated weeds were oven dried for estimating their biomass.