Effects of germination and aeration treatment following segmented moisture conditioning on theγ-aminobutyric acid accumulation in germinated brown rice

Brown rice was treated by segmented moisture conditioning to reach the suitable water content and aerated with air for germination.The effects of germination and aeration treatment on theγ-aminobutyric acid(GABA)content in germinated brown rice were studied.The results showed that the germination rate,glutamic acid,glutamate decarboxylase activity and GABA content in germinated brown rice increased significantly and then decreased with the increase of germination and aeration treatment parameters.Correlation analysis also revealed that there was a significant positive correlation between GABA accumulation and glutamic acid content,glutamate decarboxylase activity.These results suggested that the aeration treatment during germination following segmented moisture conditioning could contribute to a high GABA content of germinated brown rice.

The effect of soil moisture on the response by fungi and bacteria to nitrogen additions for N_(2)O production

In addition to bacteria,the contribution of fungi to nitrous oxide(N_(2)O)production has been recognized but the responses of these two broad and unrelated groups of microorganisms to global environmental changes,atmospheric nitrogen(N)deposition,and precipitation in terms of N_(2)O production are unclear.We studied how these two microbial-mediated N_(2)O production pathways responded to soil moisture conditions and to N addition in an N-limited temperate forest.Soils from a long-term N addition experiment in Changbai Mountain,northeastern China were incubated.Varied concentrations of cycloheximide and streptomycin,both inhibitors of fungal and bacterial activity,were used to determine the contributions of both to N_(2)O production in 66%,98%and 130%water-filled pore spaces(WFPS).The results showed that N_(2)O production decreased significantly with increasing cycloheximide concentration whereas streptomycin was only inhibiting N_(2)O emissions at 98%and 130%WFPS.The bacterial pathway of N_(2)O production in N-addition(Nadd)soil was significantly more dominant than that in untreated(Namb)soil.The difference in the fungal pathway of N_(2)O production between the soil with nitrogen addition and the untreated soil was not significant.Net N_(2)O emissions increased with increasing soil moisture,especially at 130%WFPS,a completely flooded condition.Bacteria dominated carbon dioxide(CO_(2))and N_(2)O emissions in Nadd soil and at 130%WFPS regardless of N status,while fungi dominated CO_(2)and N_(2)O emissions in soil without N addition at 66%and 98%WFPS.The results suggest that flooded soil is an important source of N_(2)O emissions and that bacteria might be better adapted to compete in fertile soils under anoxic conditions.

Changes in vegetation and moisture in the northern Tianshan of China over the past 450 years

Knowledge of historical changes in moisture within semi-arid and arid regions is the basis of climatic change predictions and strategies in response to long-term drought.In this study,a multiproxy peat record with highresolution from Sichanghu in the northern Tianshan was used to document the changes in vegetation and climate over the past 450 years in the arid Central Asia.The pollen,grain size,and loss on ignition(LOI)records indicate that the productivity of local peat began to increase at^1730 AD.The vegetation in the Sichanghu area experienced several transitions,from temperate desert to dense desert,marsh meadow,and steppe desert vegetation.The climate in the study area was extremely dry during the early stages of the Little Ice Age(LIA)(before 1730 AD)and relatively wet during the late stages(1730–1880 AD).The inferred changes in the moisture conditions of the Sichanghu peatland since the LIA may have been controlled by the extent of Arctic sea ice,the North Atlantic Oscillation,and the Siberian High via the connections of large-scale atmospheric circulations such as the Westerlies.

Characteristics of In-Situ Soil Water Hysteresis Observed through Multiple-Years Monitoring

A soil water retention curve (SWRC) is an essential soil physical property for analyzing transport and retention of water in a soil layer. A SWRC is often described as a single-valued function that relates the soil water potential ψ to volumetric water content θ of the soil. However, an in-situ ψ − θ relation should show soil water hysteresis, though this fact is often neglected in analyses of field soil water regimes while long-term in-situ soil water hysteresis is not well characterized. This study aimed at probing and characterizing in-situ ψ − θ relations. The developments of large hysteresis in the in-situ ψ − θ relations were observed only a few times during the study period of 82 months. Any of the large hysteretic behaviors in the ψ − θ relations began with an unusually strong continual reduction in ψ. The completion of a hysteresis loop required a recorded maximum rainfall. Because the study field had very small chances to meet such strong rainfall events, it took multiple years to restore the fraction of soil water depleted by the unusually strong continual reduction in ψ. While wetting-drying cycles had occurred within a certain domain of ψ, hysteretic behaviors tended to be so small that the in-situ ψ − θ relation can be approximated as a single-valued function of θ(ψ). These observed patterns of the in-situ ψ − θ relations were characterized by kinds of difference in dθ/dψ between a drying process and a wetting process at a given ψ. Thus, more amounts of experimental facts about wetting SWRCs in parallel with drying SWRCs should be needed for correct modelling, analyzing, and predicting soil water regimes in fields. It is also necessary to increase our understandings about the long-term trends of occurrences of extreme weather conditions associated with possible change in climate.