Biodiv Sci ›› 2018, Vol. 26 ›› Issue (11): 1158-1167.DOI: 10.17520/biods.2018213

• Original Papers • Previous Articles     Next Articles

Effects of annual precipitation pattern variation and different cultivation modes on the growth of Amaranthus retroflexus and Glycine max

Baiwen Jiang1, Jing Li1, Rui Chen1, Ping Lu1,*(), Qi Li1, Tongyu Xiao1, Yamei Bai1, Xianfeng Zhang2, Yiqi Li1   

  1. 1 College of Resources and Environment, Northeast Agricultural University, Harbin 150030
    2 Experiment Practice and Demonstration Center, Northeast Agricultural University, Harbin 150030
  • Received:2018-08-03 Accepted:2018-10-27 Online:2018-11-20 Published:2019-01-08
  • Contact: Lu Ping
  • About author:# Co-first authors

Abstract:

Global climate change will alter temporal and spatial distributions of precipitation patterns. The effects of precipitation changes on crop seed germination and growth have been previously investigated, however, there has been limited research on effects of precipitation changes on how invasive weeds compete with crops. Exploring competition between exotic weeds and native crops under different annual precipitation patterns and cultivation modes will provide a theoretical basis to control alien weeds with impending changes to the global climate. In this study, we assessed how precipitation alters competitive dynamics between two plants, Amaranthus retroflexus, a widespread invasive weed in agricultural ecosystem in Northeastern China, and Glycine max, one of the most important native crops in China. We conducted pot experiments under three patterns of annual precipitation: the average annual precipitation pattern (the average total precipitation amount of growing season of the recent 30 years), the deficient annual precipitation pattern (20% lower than the average value), and the plentiful annual precipitation pattern (20% higher than the average value). The pots were placed underneath a rainout shelter, and the two plants were seeded as two plants of the same species per pot (sole species) or two plants of different species per pot (mixed species). We found that the plant height and total biomass of A. retroflexus and G. max in the average precipitation annual pattern were higher than those of deficient precipitation annual pattern, but lower than those of the abundance precipitation annual pattern. The root to shoot ratio of the two plants at the early growing season were all highest in the deficient precipitation annual pattern, indicating that both plants could adapt to the arid environment by increasing the root biomass allocation and decreasing the shoot biomass allocation. Under all the annual precipitation patterns, plant height, relative growth rate and total biomass of mixture G. max were significantly less than sole planted G. max, while A. retroflexus showed the opposite trend. These results indicate that interspecific competition significantly inhibited the growth of G. max, but promoted the growth of A. retroflexus, suggesting asymmetric competition between the species. In general, the competitive ability of G. max increased with higher precipitation, while that of A. retroflexus increased when precipitation declined. The results indicated that A. retroflexus can successfully invade G. max cropland under all three precipitation scenarios, and maintain a high plant height, relative growth rate, and biomass over a wide range of annual precipitation variation. These biological characters of A. retroflexus may allow it to become a successfully globally invasive weed, and drought may favor its invasion of G. max cropland.

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Key words: exotic weed, native crop, annual precipitation pattern, cultivation mode, growth