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Contrasting infection frequencies of Neotyphodium endophyte in naturalized Italian ryegrass populations in Japanese farmlands
Author(s) -
Yamashita Masayuki,
Iwamoto Miyuki,
Maruyama Keisuke,
Ichihara Minoru,
Sawada Hitoshi
Publication year - 2010
Publication title -
grassland science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.388
H-Index - 19
eISSN - 1744-697X
pISSN - 1744-6961
DOI - 10.1111/j.1744-697x.2010.00177.x
Subject(s) - biology , agronomy , weed , endophyte , oryza sativa , paddy field , lolium multiflorum , neotyphodium , population , crop , poaceae , lolium perenne , botany , demography , sociology , gene , biochemistry
Neotyphodium endophytes often confer benefits to their host grasses and may enhance invasiveness of some grasses. The knowledge of infection frequencies of endophytes among invading weed populations is necessary to understand the relationships between endophyte infection and invasiveness. Here we present data on infection frequencies of Italian ryegrass ( Lolium multiflorum Lam.), an important weed in some farmlands in Japan, persisting in contrasting farmlands: a terraced paddy field and a wheat‐soybean double‐cropped field in the western region of Shizuoka prefecture, Japan. The terraced paddy site is a mosaic of several landscape elements such as paddy fields, levees, fallow and abandoned fields, with a high percentage of non‐crop area. Rice ( Oryza sativa L.) has been cultivated for more than a decade with no application of chemical fertilizers, pesticides and fungicides. The wheat‐soybean field is characterized by the aggregation of large‐scaled fields that were originally reconstructed paddy fields, showing a low percentage of non‐crop area. Wheat and soybean have been grown as winter and summer crops, respectively, using chemical fertilizers and herbicides. We examined the presence or absence of endophytes in a total of 1200 seeds sampled from the two Italian ryegrass populations. The terraced paddy population exhibited a markedly high infection frequency (91.0%), due possibly to selective feeding of non‐infected seeds by insects. In contrast, the wheat‐soybean farmland population showed almost no infection (1.1%), whereas the putative source of the invasion in the proximity exhibited a relatively high infection rate (64.4%). Such a micro‐scale variation in infection frequencies may be attributable to a loss in endophyte viability within the wheat‐soybean field. The findings suggest that endophyte infection frequency may markedly differ among the Italian ryegrass populations even within the same region, presumably depending on the abundance of the seed‐eating insects, farmland management regimes and/or environmental conditions such as soil humidity.