EFFECT OF COMPETITION ON THE INTERACTION BETWEEN MAIZE AND WEED EXPOSED TO WATER DEFICIENCY

ABSTRACT The ability of plants to adapt to water deficient conditions in soil is directly related to the competitive ability of each species. The objective of the present study was to evaluate the effects of water deficiency and interspecific competition on the growth components of maize (Zea mays), brachiaria (Urochloa decumbens), and hairy beggarticks (Bidens pilosa L). The experimental design was in randomized blocks, with eight replications. The treatments were arranged in a 5 × 2 factorial design, with the first factor corresponding to the different competitive arrangements among species (maize + U. decumbens, maize + B. pilosa, maize without competition, U. decumbens without competition, and B. pilosa without competition). The second factor constituted two water regimes (daily irrigation and water deficit). The soil water deficient condition strongly decreased maize plant growth; however, it had little or no effect on the growth of weeds U. decumbens and B. pilosa. Interspecific competition decreased the growth of maize plants and U. decumbens, and intensified the negative effects of water deficiency on these species. Interspecific competition and water deficiency also decreased the N, P, and K content in maize plants, which contributed to the effects on plant growth. U. decumbens was more competitive with maize compared to B. pilosa.

摘要 植物适应土壤水分亏缺环境的能力，与各物种的竞争能力直接相关。本研究旨在评估水分亏缺与种间竞争对玉米（Zea mays）、臂形草（Urochloa decumbens）及毛鬼针草（Bidens pilosa L.）生长指标的影响。本试验采用随机区组设计，设置8次重复。试验处理采用5×2因子组合设计：第一因子为物种间不同竞争配置，具体包括玉米+臂形草、玉米+毛鬼针草、无竞争玉米、无竞争臂形草、无竞争毛鬼针草5种处理；第二因子为两种水分管理模式，即每日灌溉与水分亏缺处理。土壤水分亏缺显著抑制玉米生长，但对杂草臂形草与毛鬼针草的生长几乎无影响。种间竞争会抑制玉米与臂形草的生长，并加剧水分亏缺对这两个物种的负面影响。种间竞争与水分亏缺还会降低玉米植株的氮（N）、磷（P）、钾（K）含量，进而对植株生长产生不利影响。相较于毛鬼针草，臂形草与玉米的竞争能力更强。