Ecological adaptation of weed biodiversity to the allelopathic rank of the stubble of different wheat genotypes in a maize field

摘要

The objective of this study was to integrate allelopathic bioassay and point sampling methods to investigate the allelopathic rank of the stubble of different wheat genotypes and its effect on weed biodiversity in a maize field. The study consisted of 17 wheat stubble treatments derived from ten wheat genotypes planted individually (monoculture) or in pairs (mixed culture). The maize was planted in the plots immediately following the wheat harvest and the number of weed species, total weed number, weed density, weed height, and weed cover were determined 50 days later. The results indicate a significant rank effect of allelopathic potential in the stubble of the different wheat genotypes. There was a stronger allelopathic effect from the straw in the mixed-culture treatments compared to the monoculture treatments. Acalypha australis and Setaria viridis were the dominant weed species in the maize fields. The regression analysis shows that the weed biodiversity indices were significantly related to the allelopathic rank. The allelopathic potential exhibited spatial heterogeneity in all the scales, which would trigger resource heterogeneity and change the microhabitat conditions. Therefore, weed biodiversity would respond spatially and biologically to the heterogeneous distribution of allelochemicals from the wheat stubble. The allelopathic rank of the wheat stubble would lead to changes in weed biodiversity by regulating the ecological niche of the weed population. The weeds showed resistance or an adaptive response to exterior pressure, including allelopathic pressure. This study on the effect of allelopathic potential on weed biodiversity provides a solid theoretical basis for sustainable weed management of agro-ecosystems.