摘要:

The effects of incorporation of straw in soil, liming and genotype on N2fixation by field pea were evaluated in glasshouse experiments using the15N isotope dilution technique.

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754730

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Enhancing early crop production and yield by the use of rowcovers has achieved variable results depending on crop grown and climate. The performance of rowcovers, with or without plastic mulches, has not been evaluated in the Mediterranean region. Tomato plants (Lycopersicon esculentumMill) were grown under floating rowcover, black plastic mulch, mulch plus rowcover, or no protection i.e. control, for studying the effect on yield in terms of earliness, total yield and average fruit size. Early yield was significantly increased by the mulch treatment while the rowcover treatment yielded the least (P<0.05). Total yield was increased by the mulch and mulch plus rowcover treatments, while the rowcover and control treatments yielded the least (P<0.05). Soil temperature at 10 cm depth varied between Ioto 2°C only under the different treatments. Air temperature under the rowcover exceeded 35 to 40°C on many days, hence causing fruit setting problems and resulting in reduced early yield under the rowcover. The results of this study indicate that early production in tomato is enhanced by black plastic mulch, while the rowcover alone can have a negative effect on yield.

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754731

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A homogenate of raw garlic was chemically fractionated and the toxicity of individual fractions against the snailsLymnaea acuminataandIndoplanorbis exustuswas compared. Allicin (allyl 2-propenethiosulphinate) was tentatively identified as the active moiety causing snail death by co-migration of the active agent with extracted and synthetic allicin on TLC plates.

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754732

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Liberia's climate, with the absence of South American Leaf Blight (SALB) disease, was the major factor suiting the cultivation ofHevea brasiliensis (Hevearubber) by Firestone Plantations Company at Harbel. Notably, however, the weather was unusually hot and dry during the latter 1980's, and concerns about fires, tree survival, and economically sustainable yields surfaced. The objective was consequently set to analyze accumulated climatic data, find out if there had been significant changes in the weather at Harbel, and determine ifHevearubber cultivation at Harbel was threatened.

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754733

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Based on grower crop loss data from 1985–1987 and field and storage assessments from 1987, important pests and diseases of organic vegetables in Denmark are identified. The most important pests are cabbage root fly (Delia radicum), onion neck rot (Botrytis allii) and carrot rust fly (Psila rosae). The organic growers employ cultural plant protection methods such as placement and timing of crops, crop rotation, crop selection and field sanitation extensively, while direct control methods are rarely applied. Growers' perceptions of pest problems and crop loss due to pest and disease damage in organically grown vegetables change with marketing patterns and quality demands.

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754734

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This study was conducted to evaluate the effect of intercropping coconut lands on soil water retention, available water, porosity and their relationship with organic matter contents. The results showed that the water holding capacity and available water increased significantly at both depths (0–20 and 20–40 cm) investigated. The increase in available water was mainly due to increase in field capacity which can be attributed to better soil structural development and stability related to higher organic matter and root activity in intercropping treatments. Bulk density in coconut monoculture plots was as high as 1.72 g cm−3which is restrictive to root growth in these sandy loam soils and decreased in intercropped plots to 1.49 g cm−3facilitating better root penetration and soil aeration. The total porosity and macro-porosity increased significantly with intercropping. The intercropped treatments did not show a significantly higher organic matter content but showed an increasing trend. Clay content of this soil was as low as 8% in the top soil and increased to 17% in the sub soil. At such low clay contents, even a slight increase of organic matter will have a significant effect on soil aggregation and thereby on water retention. The coconut yields of intercropped treatments increased by 5% to 34% over monoculture indicating sustainability of such farming systems under rainfed conditions.

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754735

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

For most of this century agricultural microbiologists and microbial ecologists have been interested in the ability of some bacteria to efficiently dissolve “insoluble” calcium phosphates. This phenotype has been termed mineral phosphate solubilizing (Mps). This minireview discusses recent work suggesting that the direct oxidation pathway for glucose dissimilation forms the metabolic basis for the strongly Mps+ phenotype observed in many species of gram negative bacteria. In the past, the physiological significance of the direct oxidation pathway for a given species was often considered obscure, giving rise to the term “dissimilatory bypass” to describe the apparent inefficient utilization of reducing power. The Mps function may provide a reason for the expression of this pathway in many bacteria whose bioenergetic needs are satisfied by the Embden-Meyerhof, Entner-Doudoroff or pentose phosphate pathways. The direct oxidation of glucose results in the production of gluconic acid and (often) 2-ketogluconic acid in the periplasmic space which, in turn, results in acidification of the region adjacent to the cell or colony. Calcium phosphates in the medium (soil) are dissolved by these acidic protons. It is proposed that extracellular acidification via the direct oxidation pathway may play an ecological role in some environments including soils where calcium phosphates provide a significant pool of unavailable mineral P. Specific strategies for testing this hypothesis including the use of DNA and antibody probes are discussed.

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754736

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754737

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754738

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1995.9754739

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor