Measuring ecological preference for growth of the most influential weeds in weed community structure associated with agronomic and horticultural crops in Nile Delta, Egypt

Abstract

The studying of the performance of weeds and weed assemblages associated with different crops through phytosociological researches derives its importance mainly from weeds adverse impact on crop productivity. Hopefully, the current study is beneficial for developing a sustainable long term weed control and soil management strategy. The objective of the present work is to measure three ecological preferences: crop diversification, soil type and crop seasonality. A sample area was selected comprising farmland of Nile Delta and its adjoining east and west territories, Egypt. Sixty-four sites in 12 governorates comprising 30 agroecosystems were monitored. 150 species were designated as most influential weed-species out of 555 species recorded. Ecological preference for species for crop seasonality was evident through the results of Agglomerative hierarchical clustering (AHC). Three weed communities or weed assemblages’ groups (WAG) were identified. Their diversity evaluated and their linear correlation strength was determined. The fidelity measurements showed that 60-species have fidelity to WAG A; 46 to WAG B; 44 to WAG C. Measuring the ecological preference of species for crop diversification and soil type indicated that the growth activity of 36-species was more affected by crop diversification; 63-species preferential for growth in fine grained soil (FGS) and 87-species in coarse grained soil (CGS). By employing Redundancy analysis (RDA) with variation partitioning (VP), the variability in species frequency in WAG that can be explained by ecological preference of species for the three ecological preferences was determined and variation was partialized out to estimate their partial, linear effect. In fact, weed control is a recalcitrant issue and the current study revealed that a portion of the solution is in a successful crop diversification plan. The successful selection for a competitive crop that can be taken seriously as an adequate weed controlling mechanism in a crop rotation technique will cause the strongest population reduction of harmful weeds on infested farmland, especially in relevance for crops grown for organic certification.