Sulfur deficiency of rice plants in the Lower Volta area,Ghana

Abstract

It is well known that stem nodules are formed on the aerial parts of Aeschynomene spp. and Sesbania rostrata grown in the field (Yatazawa and Yoshida 1979; Dreyfus and Dommergues 1981; Yoshida et al. 1985). We have reported that stem nodules were successfully formed by inoculation of Rhizobium isolates derived from both stem and root nodules of A. indica (Yoshida et al. 1985; Sasakawa et al. 1986). The specific activity of nitrogen fixation in stem nodules is comparable to that of root nodules (Sasakawa et al. 1986; Sasakawa 1990). A red pigment, which suggests the presence of leghemoglobin, was detected in stem nodules as well as in root nodules (Yatazawa and Yoshida 1979; Yatazawa and Susilo 1980; Sasakawa et al. 1986).     

Effect of volcanic fumes from Mt. Oyama,Miyakejima Island,on atmospheric deposition,soil solution,and soil properties in Kumagaya,central Japan

Abstract

The chemical nature of Mn in the leaves of Acanthopanax seiadophylloides, Ilex crenata var. paludosa and Kalopanax pictus was investigated.

Successive extraction of freeze-dried and fresh leaf sam pies with various solvents showed that the major portion of Mn (>90%) was extractable with water and 0.2 M HCl.

Electron probe X-ray microanalysis was performed with the fresh leaf tissues of Mn hyper accumulator A. seiadophylloides, before and after shaking with distilled water, 80% methanol and 1 M HCl. Water removed large parts of Mn in the tissue as a whole except in the region of the epidermis. A negligible amount of Mn was removed by 80% methanol; on the other hand, 1 M HCl removed almost all of the Mn in the tissues.

Paper electrophoretic experiments conducted with water and 0.2 M HCl extracts using pyridine-acetic acid buffer (pH 6.5) indicated that Mn in the extracts behaved similarly to Mn²⁺, presumably due to the labile nature of Mn components in the tissues.     

Soil and phosphorus redistribution along a steep tea plantation in the Feitsui reservoir catchment of northern Taiwan

Abstract

Feitsui reservoir, the major water supply of Taipei city, has shown declining water quality in recent years. The reservoir is located in an area famous for tea cultivation, and the question arises as to whether the hillside tea plantations have contributed to increased sediment and nutrient discharge into the reservoir. In this study, soil and phosphorus redistribution were examined along a steep tea plantation in the reservoir's catchment and the provenance of reservoir sediment was assessed. Fallout radionuclides were used as soil erosion/deposition tracers and as markers of sediment sources. Continuous fertilizer application has raised (inorganic) phosphorus levels in the studied tea plantation. The plantation's narrow bench terraces trap eroded material and slow down soil and nutrient translocation. Nevertheless, eroded soil and phosphorus have accumulated on a vegetated toeslope below the tea plantation. The reservoir sediment contained significant amounts of inorganic phosphorus and cesium-137, and application of a mixing model resulted in a surface soil contribution of approximately 30%. This points towards tea plantations as possible sediment and pollutant sources and underlines the necessity of soil conservation strategies, such as the maintenance of vegetated riparian buffer zones. However, other sources, such as landslide debris and urban wastewaters, cannot be entirely ruled out. Further research is needed to better characterize the catchment's soils and sediments and to improve sediment fingerprinting efforts. Potential point and non-point pollution sources need to be examined in detail to better understand how phosphorus enters the reservoir.     

Characterization of new soil thermophilic bacteria potentially involved in soil fertilization

Thermophilic bacteria were isolated from a soil of an olive grove in Alentejo (Portugal) and characterized morphologically, physiologically, and at the molecular level by partial sequencing of the 16S ribosomal RNA genes, followed by subsequent phylogenetic analysis. The isolates were shown to be gram‐positive rods, motile, and to belong to the Firmicutes Phylum. They were able to produce ammonium and sulfate during growth, the levels of which vary among the bacterial isolates. This ability suggests that these bacteria may have an important role in the mobilization of organic S and N in the soil and therefore in providing essential nutrients for plant growth. Tests using two isolates indicated a positive effect on initial seedling development suggesting their potential use in soil nutrient supplementation. The presence of these thermophiles in arable temperate soils might be increasingly important, particularly when the predicted global climate warming is considered, and their features are discussed in this context and considering actual strategies to improve soil fertilization.     

The effects of sediment deposits from Namibian diamond mines on intertidal and subtidal reefs and rock lobster populations

• 1. Extensive diamond mining occurs on land and in the sea on the west coasts of South Africa and Namibia, raising fears that diamond‐mining activities may impact commercial rock‐lobster fisheries and benthic communities. To explore this possibility, the effects of the diamond‐mining fines‐discharge on intertidal and subtidal rocky‐shore communities and on the population structure of the rock lobster Jasus lalandii were assessed at Elizabeth Bay.
• 2. Sampling over six years at sites covering a range of wave exposures compared impacted sites with comparable reference sites never exposed to the fines. Percentage cover and densities of benthic organisms were recorded on both intertidal and subtidal reefs. Rock‐lobster abundance was estimated from counts and catch‐per‐unit‐effort, and their length frequencies and sex ratios compared in impacted and reference areas.
• 3. The deposition of fines had no effect at wave‐exposed sites, but did impact intertidal and subtidal communities at sheltered localities where fines accumulated because wave action was insufficient to disperse them. Reductions of grazers, proliferation of algae and increased dominance by filter‐feeders were recorded at the impacted sites and persisted throughout the monitoring programme. Differences in community structure associated with different levels of wave exposure were, however, greater than those produced by depositing fines. The detected effects of fines‐deposits on the benthos were local and likely to be reversible after cessation of mining.
• 4. The fines‐deposit had no detectable effects on the sex‐ratio, size or abundance of rock lobsters, indicating that there is no conflict between the deposition of fines and the fishery for rock lobsters, although substantial inter‐site variability makes it difficult to regard the results as definitive.

Copyright © 2002 John Wiley & Sons, Ltd.     

Fat distribution in Atlantic salmon Salmo salar L. in relation to body size and feeding regime

Tissue (fillet, viscera and carcass) distributions of fat were examined in Atlantic salmon, Salmo salar L. (≈740→≈1400→≈2000 g) to test the hypothesis that the fillet becomes increasingly important as a fat depot when fish increase in size. The salmon were fed for 11 weeks on either a high‐fat feed (H: ≈39% fat) or a low‐fat feed (L: ≈28% fat), and half of the fish were then subjected to a dietary switch to create four feed treatments (HH, HL, LL and LH). Fillet fat concentration increased with the passage of time, and the fillet also represented an increasing percentage of the body mass (≈48.5→≈55→≈58.5%) as the fish increased in size. As a consequence, the fillet became increasingly important as a fat depot, containing ≈30% of the body fat in the small fish at the start of the experiment, and ≈50% in the fish sampled at the end of the trial. The proportion of fat localised in the viscera was little influenced by either fish size or feeding treatment, and was within the range of 19–25%, whereas the carcass held a decreasing percentage of the body fat stores as fish size increased. There was a highly significant negative correlation between the percentages of body fat found within the carcass (C) and fillet (F): F = 73.589–0.9285C (R² = 0.973; n = 13). Although the fillet became more important as a fat depot as fish increased in size, the percentage of the body fat reserves found within this tissue appeared to plateau at 50–55%.     

Comparison of dietary protein and energy utilization in three Asian catfishes (Pangasius bocourti, P. hypophthalmus and P. djambal)

Dietary protein and energy utilization were compared in three Pangasiid species of high economical interest for fish farming in South‐East Asia. Feeding experiments were performed during 4 weeks on Pangasius bocourti, P. djambal and P. hypophthalmus fingerlings, 6.68, 7.69 and 6.41 g mean mass, respectively. A high‐protein diet containing mostly fishmeal was designed to provide proteins without energy limitation. Growth response, variation in body composition and nutrient utilization were compared for fish receiving variable amounts of diet corresponding to increasing protein supply, 0, 5, 15, 25, 35 and 45 g kg^?1 day^?1. The highest specific growth rate was observed for P. bocourti (6.0% day^?1), followed by P. djambal (5.6) and P. hypothalamus (4.1). Pangasius djambal exhibited the highest protein deposition rate, whereas P. bocourti was characterized by a high fat deposition rate even with a low feeding rate. Lower performance was obtained with P. hypophthalmus.     

入侵植物喜旱莲子草对光、氮及其互作的表型可塑性反应

为给入侵植物喜旱莲子草的管理与防控提供一定的理论参考,对其在光照和氮沉降及光氮互作的表型可塑性反应进行了研究。结果表明:喜旱莲子草通过增加株高、节长,降低根重比,提高叶重比、叶片叶绿素含量来适应较低的光照环境,其株高、节长、总生物量对光照的表型可塑性指数较大;随着土壤氮素的增加,喜旱莲子草植株的株高、节长、茎粗、叶长、叶宽、总生物量和叶绿素都显著增加,其对氮沉降的可塑性指数在株高、生物量和叶绿素上较大;氮沉降有利于喜旱莲子草对光照反应可塑性的增加,从而补偿低光环境导致的生长不利。因此,若在持续高氮沉降的情况下,喜旱莲子草种群有向贫瘠土壤和弱光环境拓展的风险。     

硫对镉胁迫下小白菜镉富集、光合速率等生理特性的影响

以小白菜品种"七宝青"为材料,采用盆栽试验,研究外施硫(50 mg·kg^-1)对不同镉(Cd)处理水平(0、5、25、50、100 mg·kg^-1>)下小白菜生长、Cd吸收转运、光合特性及渗透调节物质含量的影响。结果显示,与单一Cd处理相比,5.25 mg·kg^-1 Cd处理水平下,外施硫显著促进了小白菜的生长,其株高分别增加了11.14%和21.16%,地上部干重分别增加了22.55%和19.90%,根部干重分别增加了27.83%和20.29%,叶绿素含量分别增加了11.81%和15.13%。外施硫降低了小白菜Cd的转运系数(TF)和地上部生物富集系数(BCF),提高了根部BCF。25 mg·kg^-1 Cd处理水平下,外施硫小白菜地上部Cd含量显著降低了24.82%,根部Cd含量显著增加了23.94%,TF值最小。5.25 mg·kg^-1 Cd处理水平下,外施硫能够明显缓解Cd胁迫对小白菜叶片光合作用的抑制,其净光合速率(Pn)分别增加了13.15%和15.22%,气孔导度(Gs)分别增加了13.81%和15.42%。25 mg·kg^-1 Cd处理水平下,外施硫小白菜叶片可溶性蛋白、可溶性糖、脯氨酸及抗坏血酸含量分别增加了20.82%、23.34%、26.79%和25.72%。研究结果表明,在25 mg·kg^-1 Cd处理水平下,外施50 mg·kg^-1硫显著减少了Cd从根部向地上部转移,降低小白菜地上部Cd含量,提高Cd胁迫下小白菜叶片的光合强度以及渗透调节物质的含量,对小白菜Cd毒害的缓解效应最为显著。     

施氮对毛竹笋营养成分的影响

  目的  探讨氮沉降对毛竹Phyllostachys edulis笋品质的影响,为竹笋品质改善和人体保健提供理论依据。  方法  通过人工喷氮模拟氮沉降方法,研究了3种不同水平的氮沉降[0 kg·hm?2·a?1(对照)、30 kg·hm?2·a?1(低氮,N₃₀)和60 kg·hm?2·a?1(高氮,N₆₀)]对毛竹笋不同氨基酸、营养成分(维生素C、粗纤维、粗蛋白质、可溶性糖)和矿质元素质量分数的影响。  结果  氮沉降对毛竹笋营养品质和矿质元素影响显著,氮沉降显著增加了总氨基酸、必需氨基酸和甜味氨基酸的质量分数(P＜0.05),高氮沉降显著提高了鲜味、苦味和芳香类氨基酸的质量分数(P＜0.05),而低氮沉降则相反;同时,氮沉降显著提高了毛竹笋中甜味氨基酸比例(P＜0.05),显著降低了必需、鲜味、苦味和芳香类氨基酸比例(P＜0.05);氮沉降显著降低了毛竹笋中维生素C质量分数(P＜0.05),但却提高了粗纤维质量分数,对粗蛋白质和可溶性糖质量分数影响不显著;氮沉降显著提高了硒、铁和钠(P＜0.05)质量分数,显著降低了铜(P＜0.05)质量分数,低氮沉降显著增加了锰、钙和镁(P＜0.05)质量分数,而高氮沉降则相反。  结论  适度的氮沉降对毛竹笋营养成分有一定的提升作用,有利于竹笋品质的改善和人体保健。图2表2参41