Abstract
Evidence indicates that Allium and Brassica species which release bioactive compounds are widely used in bio-fumigation to suppress soil-borne diseases. However, the active molecules of such plant residues are easily volatilized. In this study, we conducted mixed cropping of the apple tree with Allium fistulosum or Brassica juncea; the results demonstrated that such mixed cropping significantly improved the growth of the grafted apple seedlings and alleviated apple replant disease (ARD) for two years. The terminal-restriction fragment length polymorphism profile results showed that the soil fungal community demonstrated distinct variation and diversity in terms of composition. A. fistulosum and B. juncea significantly improved the Margalef, Pielou, and Shannon indices. In addition, the analyses of clone libraries showed that A. fistulosum and B. juncea promoted the proliferation of antagonistic fungi such as Mortierella, Trichoderma, and Penicillium, and inhibited the proliferation of pathogens such as Fusarium. Fusarium. Proliferatum(F. proliferatum) was abundant in replanted soil and proved to be an aggressive pathogen of apple seedlings. Our findings thus indicate that apple tree mixed cropping with A. fistulosum and B. juncea was an effective long-term method for modifying the resident fungal community and alleviating ARD.
Highlights
The analyses of variance showed that the soil fumigated by methyl bromide resulted in the greatest growth, followed by that with mixed cropping treatments (Table 1)
Our results showed that mixed cropping with A. fistulosum and B. juncea could alleviate Apple replant disease (ARD) in replanted apple seedlings and lead to more growth (Table 1)
This study evaluated the effects of mixed cropping of apple trees with B. juncea and
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Apple replant disease (ARD) occurs in all major apple-growing regions worldwide [1]. Necrosis of fine feeder roots stunted tree growth both above and below ground, and drought and nutrient stress leading to yield reduction, are considered to be the main symptoms of ARD [2]. This disease affects apple yield and quality for the entirety of the orchard’s lifetime. Due to limited land resources, ARD is expected to dramatically restrict the development of the modern apple industry in China
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