Abstract
BackgroundThere are a variety of ways of increasing crop diversity to increase agricultural sustainability and in turn having a positive influence on nearby natural ecosystems. Competitive crops may provide potent management tools against invasive plants. To elucidate the competitive mechanisms between a sweet potato crop (Ipomoea batatas) and an invasive plant, mile-a-minute (Mikania micrantha), field experiments were carried out in Longchuan County of Yunnan Province, Southwest China, utilizing a de Wit replacement series. The trial incorporated seven ratios of sweet potato and mile-a-minute plants in 25 m2 plots.ResultsIn monoculture, the total biomass, biomass of adventitious root, leafstalk length, and leaf area of sweet potato were all higher than those of mile-a-minute, and in mixed culture the plant height, branch, leaf, stem node, adventitious root, flowering and biomass of mile-a-minute were suppressed significantly (P < 0.05). The relative yield (RY) of mile-a-minute and sweet potato was less than 1.0 in mixed culture, indicating that intraspecific competition was less than interspecific competition. The competitive balance index of sweet potato demonstrated a higher competitive ability than mile-a-minute. Except pH, other soil nutrient contents of initial soil (CK) were significantly higher than those of seven treatments. The concentrations of soil organic matter, total N, total K, available N, available P, available K, exchange Ca, exchange Mg, available Mn, and available B were significantly greater (P < 0.05) in mile-a-minute monoculture soil than in sweet potato monoculture soil, and were reduced by the competition of sweet potato in the mixture.ConclusionsEvidently sweet potato has a competitive advantage in terms of plant growth characteristics and greater absorption of soil nutrients. Thus, planting sweet potato is a promising technique for reducing infestations of mile-a-minute, providing weed management benefits and economic returns from harvest of sweet potatoes. This study also shows the potential value of replacement control methods which may apply to other crop-weed systems or invaded natural ecosystems.
Highlights
There are a variety of ways of increasing crop diversity to increase agricultural sustainability and in turn having a positive influence on nearby natural ecosystems
With proportional increases in sweet potato, the main stem length of mile-a-minute was highly suppressed; for ratios of sweet potato to mile-a-minute of 3:1 and 2:1 total shoot length was much greater for sweet potato; even at a 1:3 ratio, mile-a-minute shoots were significantly shorter than in monoculture (P < 0.05)
The internode length of mile-a-minute was greater in magnitude than that of sweet potato in both mixed and monoculture (Table 1)
Summary
There are a variety of ways of increasing crop diversity to increase agricultural sustainability and in turn having a positive influence on nearby natural ecosystems. To elucidate the competitive mechanisms between a sweet potato crop (Ipomoea batatas) and an invasive plant, mile-a-minute (Mikania micrantha), field experiments were carried out in Longchuan County of Yunnan Province, Southwest China, utilizing a de Wit replacement series. In many jurisdictions more holistic agroecosystem management approaches are being implemented that incorporate crop diversity, crop rotation, and concomitant reduced inputs for weed control [3,4]. More holistic management approaches tend to increase crop diversity to improve ecosystem health. Rotating crops has been found to reduce both the economic impact and diversity of weeds [5,6]. An increase in crop diversity has numerous other benefits including improved soil properties, microbial diversity and advantages in terms of insect or fungal pest management as the more diverse agroecosystem takes on more characteristics in common with natural ecosystems [2,6]. There are several other established ways of increasing agroecosystem diversity such as cover cropping, intercropping or diversifying the soil environment through composts or manures [3]
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