Studies on microörganisms and their activities in soil Part. 2. Virgin and cultivated soil of the same origin

The nature of soil is modified differently depending upon the artificial condition such as its utilization or management. It is therefore expected that the microbiological characteristic of soil is changed also. Greaves¹⁾ and Williams²⁾ reported that the reclamation of virgin soil brought about a change of bacterial count. Suzuki et al³⁾ observed that the kind of fungi differed between a virgin and a cultivated soil and that the vegetative mycelium was numerous in the former than in the latter. On the other hand, according to W aksman and Starkey⁴⁾, the bacterial count differed depending upon the fertility of soil. Singh⁵⁾ reported also that the number of fungi and actinomycetes was higher in a fertile than in an infertile soil. Lochhead⁶⁾, and Lochhead and Chasen studied the bacterial flora of a fertile (long-continued application of manure) and an infertile (no fertilizer for many years) soil and found that a certain difference could be observed when morphological, physiological and nutritional classification are tried.     

Studies on microbial population in the rhizosphere of higher plants with special reference to the method of study

Introduction

Many previous investigations, beginning with the observations of Hiltner¹⁹, have established the fact that soil in the rhizosphere contains a higher quantity of microorganisms than soil which is not within the influence of the plant root. It has been shown also that the balance between certain physiological groups^4,21,43,45, as well as that between morphological types of bacteria or fungi^30,50 is changed in the rhizosphere. In addition, Canadian investigators^23,34,62) have reported a change in the balance of certain nutritional groups of soil bacteria in the rhizosphere. Two excellent reviews^6,22) covering these papers have recently appeared. Since then a number of papers^{2,7,9,11,13,15-18,25,26,33,36,38-40,48,54,57-60,63)} concerning various aspects of the microbial population of the rhizosphere have been published.     

Methods for estimating Pg content in P type humic acid and for calculating Δlog K of its Pb fraction

Based on the assumption that P type humic acid is composed of green fraction (Pg) and brown fraction (Pb),. methods for estimating Pg content and calculatlng Δlog K of Pb by analyzing the absorption curve of P type humic acid were presented. A green fraction of P type humic acid obtained from an alpine meadow soil by gel filtration was used as the Pg standard (λmax 450, 575, and 615 nm, E 1% 290, 126, and 168).

Alkaline solutions of standard Pg obeyed the Beer-Lambert law within the concentration range of 1.6 to 31 ppm. To verify the methods, Pg content in the mixed solutions of Pg and A, B, or Rp type humic acid was estimated. It was found that the recovery of Pg would be 95±14 (2S) per cent with a probability of 0.99. Also, the calculation of Δlog K of humic acid in the mixed solutions gave satisfactory results.

It was distinctly shown that the shape of absorption spectra of P type humic acid did not only depend on Pg content, but also on Δlog K of Pb.     

Amino acid metabolism in plant leaf

Recent studies have shown that the incorporation of ammonium nitrogen into amino acids in the leaves is strictly dependent on light (1-4). It is speculated that the effect of light on ammonium assimilation may be through the synthesis of the precursors of amino acids, or by the supply of the energy required for amination and amidation with organic acids. In the Vicia faba chloroplasts Givan et al. (1) exhibited that the synthesis of glutamic acid from a-ketoglutarate was linked with the generation of reduced pyridin nucleotide by photosynthetic electron transport. Mitchell and Stocking (2) suggested the direct coupling of glutamine formation with photophosphorylation in the pea chloroplasts. On the other hand. the processes of nitrate assimilation are more indebted to light than those of ammonium assimilation, because the former ones involve the reduction of nitrate to ammonium which is believed to be light-dependent (5). Canvin and Atkins (6). and Atkins and Canvin (7) reported that the incorporation of ¹⁵N-labeled ammonium and nitrate into amino acid fractiom was depressed by the dark treatment and by photosystem inhibitors; 3-(3′,4′-dichlrophenyl)-1-1-dimethylurea (DCMU) and carbonyl-cyanide-m-chlorophenyl-hydrazone(CCCP).     

Incorporation of 14CO2 and 15NH4 into amino acids of the two subunits of fraction 1 protein in spinach leaves

In the investigation of nitrogen metabolism in plants, it is important to deal with proteins, which are the end-products of nitrogen metabolism.     

Characterization of plasma membrane-bound Fe3+-chelate reductase from Fe-deficient and Fe-sufficient cucumber roots

Abstract

One of the authors analyzed the brown spot symptoms developed on plant leaves caused by nutritional disorders using an X-ray Micro-Analyser (Sasaki et al. 1980). The use of an X-ray Fluorescence Element Mapping Spectrometer (XEMS) revealed that external and internal stresses such as X-ray irradiation and manganese excess induced the transport of manganese, and excess of manganese concentration as cationic Mn²⁺ was related to the formation of the abnormal brown spots (Watanabe and Kobayashi 1986; Watanabe et al. 1988). Since, the mechanism of the transport of manganese remains to be elucidated the analysis of the chemical state of manganese in plant is important. Since the valency of manganese readily changes depending on the redox potential, non-destructiye analysis may be effective. In fact, few studies have been carried out on the non-destructive determination of the manganese state in plant tissues. We studied the state of manganese in rice leaf in performing Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) analyses by X-ray Absorption Spectrometry with syncrotron radiation as the analytical source. X-ray absorption spectrometry provides structural information about the local surroundings of a metal ion, the binding configuration, etc. The concept and method of analysis were reviewed in detail by Teo (1981). The advantage of these methods over the previous methods is reported and the state and transport of manganese in leaf are discussed.     

Seedling characteristics and retention of current photosynthates in leaves in relation to initial growth in pigeonpea (Cajanus cajan L. Millsp.) and cowpea (Vigna sinensis Endl.)

Improved varieties of pigeonpea (Cajanus cajan L. Millsp.) still retain some growth characteristics of perennial types of wild species such as slow seedling growth and rato on ability which are considered to be major yield-restricting characteristics when the growth period is shortened. Studies on the physiological background of slow initial growth may help improve the potential productivity of short-duration pigeonpea. It was found that the low seedling vigor of pigeonpea could be ascribed to the small seed size (Narayanan et al. 1981; Brakke and Gardner 1987), low rate of photosynthetic CO₂ fixation (Rawson and Constable 1981), and low rates of metabolic processes (Huber and Hanson 1992; Ito et al. 1996). However, few authors have related the slow growth to the retention of current photosynthates and leaf respiration during the night. In contrast, seedling growth of cowpea (Vigna sinensis Endl.) was reported to be vigorous (Brakke and Gardner 1987).

The objectives of this study were to characterize the initial growth of pigeonpea in comparison with cowpea. Two experiments were carried out, one dealing with growth analysis and the other with O2 uptake of leaf and retention of current photosynthates during the night.     

Humus composition of mountain soils in Central Japan with special reference to the distribution of P type humic acid

The central districts of Japan are mountainous areas rising to 3,000 metres which are predominantly covered with forest vegetation. A comprehensive and systematic classification of the soils in this region has not yet been made, but the following soil types have been reported to occur: - 1. 1. Brown forest soils, podzolic soils, black soils and red soils. [Described by OHMASA (14)]

2. 2. Alpine grassland soils and alpine meadow soils. [Described by KUMADA et al. (9)]

3. 3. A series of randzina-like soils with a very restricted distribution. These are derived mainly from limestone and show various degrees of maturity. [Described by KUMADA et al. (8)]

4. 4. Red-yellow soils. These sometimes show a close resemblance to OHMASA's red soils and are found on diluvial plateaux and hills. [Described by KANNO (1)]

5. 5. Paddy soils.

     

Effect of nitrogen deposition on CH4 uptake in forest soils in Hokkaido,Japan

Abstract

It has been well documented by short-term artificial experiments that the CH⁴ uptake is inhibited by N input, especially NH^{4 p+}-N input. To investigate the effect of the natural N input by throughfall and other factors on the CH⁴ uptake in forest soils, we measured the CH⁴ uptake rates for 6 months during the snow-free period of the year and N input by throughfall throughout the year at 10 sites in Hokkaido, Japan, from 1997 to 2002. Water filled pore space (WFPS) and pH values in the soils varied widely among the sites (38-93% and 3.9-6.2, respectively). The rates of NH^{4 p+}-N and NH^{3 p-}-N inputs ranged from 1.3 to 6.9 kg N ha^p-1 year^p-1 and from 0.8 to 2.9 kg N ha^p-1 year^p-1, respectively. The NH^{4 p+}-N input was generally higher than the NH^{3 p-}-N input. Total N input by throughfall amounted to 2.3-9.4 kg N ha^p-1 year^p-1. The highest CH⁴ uptake rate occurred within the period from July to September (41-215 μg CH⁴ m^p-2 h^p-1) each year at most sites. CH⁴ uptake rate was relatively low (~50 μg CH⁴ M-2 h^p-1) at northern sites, while a high CH⁴ uptake rate was observed throughout the year 100 (? CH⁴ m^p-2 h^p-1) at southern sites. The mean CH⁴ uptake rates were significantly different among the sites. Cumulative CH⁴ uptake ranged from 1.4 to 6.6 kg CH⁴ ha^p-1 [184 d]^p-1 with a mean values of 3.22 ± 1.36 kg CH⁴ ha^p-1 [184 d]^p-1. Cumulative CH⁴ uptake increased with increasing temperature and decreased with an increase in precipitation (Rain), NH^{4 p+}-N input (TF^NH4) WFPS, soil total C (TC), and total N (TN). There was a quadratic relationship between the CH⁴ uptake and NH^{3 p-}-N input (TF^NO3), soil pH, and C / N ratio in soil. A regression equation was obtained as follows to predict the CH⁴ uptake in forest soils: Cumulative CH⁴ uptake = 0.47 / Rain + 0.38 / TF^NH4 + 0.34 / TC - 0.30 / TF^N03 (R ^p2 = 0.74, p = 0.0001). This equation indicates that atmospheric N input into forest soils is one of the main factors that control cumulative CH⁴ uptake with precipitation, total carbon content in soil in Hokkaido, Japan.     

A Japanese Black breeding herd exhibiting low blood urea nitrogen: A metabolic profile study examining the effect on reproductive performance

Ten reared cows of a Japanese Black cattle herd in Kagoshima prefecture, Japan, exhibited extremely low blood urea nitrogen (BUN) concentration (2.6 ± 0.6 mg/dL). Examination of dietary feed nutrition and relevant pastureland soil content suggested a correlation with crude protein (CP) deficiency or unbalanced nutritional dietary feeds. Thirteen months after the introduction of a dietary remedial measure (bean cake supplementation), BUN, total cholesterol and albumin concentration from five of the original 10 cows increased significantly compared with their values of before the dietary remedy. The postpartum day open period was significantly lower after the dietary remedial measure than that before it. The abnormally low BUN levels of the cattle herd may be due to inadequate dietary nutritional content, primarily from the imbalance of total digestible nutrient and CP of the feed and far lower han average CP value. In conclusion, routine examination of serum biochemical parameters in Japanese Black breeding cattle may be a useful strategy for determining subclinical metabolic failure of cattle herds, and consequently, its effect on reproductive performance of the herd.