The effects of Sika deer (Cervus nippon) browsing on the regeneration of pioneer species were studied in relation to canopy gaps in a warm temperate evergreen oak forest in Kasugayama, Nara City. Four study sites, three in canopy gaps and one under a closed canopy, were selected and each divided into fenced and unfenced plots. Under the closed canopy, seedlings of a!l the pioneer species died irrespective of browsing pressure. However, in the canopy gap sites, seedlings of the pioneer species could establish and grow well. The seedling survival ratio in the fenced plots in the canopy gaps was > 60% 1 year after germination. However, in the unfenced plots, only < 20% of the seedlings survived I year, with all dying within 3 years after germination. Thus, the regeneration of pioneer trees in this forest was strongly inhibited by deer browsing. Successful regeneration of a pioneer, Zanthoxylum ailanthoides, occurred for several years even after two major wind disturbances during the past 90 years. This may be due to less browsing pressure from the deer.
Miscanthus sinensis is a moderately invasive ornamental grass species being considered as a bioenergy species in the USA and elsewhere. In this study, we show the range of environmental conditions tolerated by this species in wild populations in the USA and in Japan. Six naturalized populations in the USA and five native populations in Japan were sampled in summer 2009. In each population, environmental factors (canopy cover and soil fertility) were measured, along with measurements of size and morphology for 30 plants. Relationships between M. sinensis size and environmental variables in the two countries were determined using linear mixed effects models. Results indicated that M. sinensis can tolerate extremely wide variation in soil and climate conditions in the populations we sampled across both ranges, suggesting that it could be successfully grown across a wide distribution in the USA, both intentionally as a bioenergy crop and unintentionally as an escaped invader. Plant size generally responded to different environmental conditions in both ranges, with USA plants being negatively influenced by canopy cover and Japanese plants being positively influenced by soil fertility measures. We recommend caution in growing M. sinensis for bioenergy or ornamental purposes to minimize escape outside of its native range.
Effects of an agropastoral system on the production of soybean and wheat were investigated by comparing, from 2003 to 2007, agropastoral plots that had been converted from 7-year pasture (guinea grass: Panicum maximum; 1996 to 2003) to crop cultivation, with control plots that had been continuously cropped over 10 years with soybean at the Japan International Cooperation Agency's Paraguay Agricultural Technology Center (CETAPAR-JICA). Soybean productivity in this area increased from 1979 until 1993, when yield peaked at 3.39 t/ha and then declined. In this study, soybean yields ranged from 1.48 to 3.56 t/ha in agropastoral plots and from 0.63 to 2.47 t/ha in control plots. In each year, the yield in the agropastoral plots was 1.1 to 2.4 times more than in the control plots. Wheat yields were also higher in agropastoral plots (1.59 to 3.17 t/ha) than in control plots (1.18 to 2.31 t/ha). In each year, yield in the agropastoral plots was 1.2 to 1.8 times more than in the control plots. Thus, soybean and wheat yields were sustained by introducing an agropastoral system. We also examined the chemical and physical properties of the soil under initial conditions in both plot types. The concentrations of phosphate, potassium and magnesium in surface soil in agropastoral plots were significantly lower than in control plots. The content of organic matter at soil depths of 0 to 60 cm in the agropastoral plots was significantly higher than in the control plots, and the physical properties of the agropastoral plot soil (gaseous phase, bulk density, and soil aggregates) were improved. We conclude that the agropastoral system positively affected all these properties.
Brachiariagrass is an important tropical forage grass cultivated around the world. Despite its global importance, the development of brachiariagrass breeding programs was delayed by the complications of recombining aposporous apomictic genotypes until the late 1980s. 'Mulato' is the first apomictic hybrid cultivar of brachiariagrass with the development of synthetic sexual tetraploid lines. An amplified fragment-length polymorphism (AFLP) linkage map of the apomictic pollen donor 'Mulato' was developed to identify molecular markers for apospory. The map contained 29 linkage groups with 272 markers. Twelve tightly clustered AFLP markers related to apospory were identified in linkage group 2. Furthermore, we identified quantitative trait loci (QTLs) for leaf width, leaf shape ratio (width/length), stem diameter and percentage of filled seeds using simple interval mapping and composite interval mapping. The AFLP markers tightly linked to apospory and QTLs associated with important agronomical traits will be valuable tools for marker-assisted selection in brachiariagrass improvement programs.
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