摘要:

Papaya (Carica papayaL.) is an important tropical fruit tree. Thirteen different mycorrhizal fungi were screened for their symbiotic efficiency with papaya. Of the 13 fungi testedGlomus mosseae(ICRISAT) was found to be the best fungus for improving growth and nutrition of papaya resulting in a greater plant biomass, plant height, plant girth, leaf area, P and Zn content.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754763

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Varying levels of resistance to insects occur naturally in crop plants and closely related species. Historically, plant breeders have developed resistance to insects in situations where it was perceived to provide economic advantages over the use of insecticides in conventional agriculture: in field crops with low value per unit area and high acreage, and in staple food crops of developing countries. Under these circumstances, the use of resistant varieties is the principal method of control for many key insect pests. The process of identifying new sources of resistance and moving genes for resistance into commercial varieties through conventional breeding can be slow, often taking 12 years or longer.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754764

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Managing vertebrate pests has been a neglected topic of research in sustainable agriculture. Conventional approaches, often reactionary rather than preventative, have failed to provide sustainable solutions. Indeed, conventional control through density reduction often involves battling natural ecological processes. Agricultural practices may improve habitat quality for vertebrates that then become pests. Density reduction, but without a concomitant reduction in carrying capacity, may stimulate density-dependent reproduction and survival, rapid recolonization, or both; thus, vertebrate pests often show remarkable resilience in recovering from density reduction. Effective management of vertebrate pests in agricultural systems should incorporate knowledge of temporal and spatial dynamics of pest species.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754765

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In a replicated study conducted from 1990 to 1992, cover crops and a control (resident vegetation) were evaluated in an organic wine-grape vineyard (cv. ‘Chardonnay’), located at a valley floor site in Hopland, Mendocino County, California. The purpose was to assess plant phenology, stature, biomass production, competitiveness with resident vegetation, and second-year stand regeneration or persistence in an unfilled vineyard. Legumes (Fabaceae) evaluated included nine annual and two perennial types of clover (Trifoliumspp.), bell bean and three other types ofVicia, two types of coolseason annual medic (Medicagospp.), field pea (Pisum sativumssp.arvense), a mixture of biennial sweetclovers (Melilotus albaandM. officinalis), broadleaf birdsfoot trefoil (Lotus comiculatus). There were six types of cool-season annual grasses (Poaceae) including three cereal grains. Native Californian perennial grasses included one rhizomatous and five bunch types. The sole representative of Brassicaceae was black mustard (Brassica nigra). Unseeded, resident vegetation plots served as a control.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754766

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Experiments were conducted under controlled conditions to test whether the residues of cover crops or alley crops were phytotoxic to vegetable seedlings in a no-tillage cropping system. Soil and residue samples were collected from a field experiment where subterranean cloverTrifolium subterrcmeumL. var.brachycalycinumand annual ryegrassLolium rigidumGand. were grown as cover crops, and lucerneMedicago sativaL. was grown as an alley crop. Chemically inert black and white polyethylene beads were used as control treatments and provided a measure of the physical mulch effect in the absence of phytotoxic leachates from plant residues. The seedling growth of lettuceLactuca sativa, broccoliBrassica oleraceavar.italicaand tomatoLycopersicon esculentum, was reduced by ryegrass and clover cover-crops. By eliminating factors such as nutrients, soil structure and soil pathogens, we inferred that phytotoxic leachates from the cover crops were responsible for the reduced plant growth. The phytotoxic period of clover ended after 8 weeks in the field and 6 weeks in the laboratory, when conditions for the decomposition of phytotoxic compounds were favourable. The phytotoxic effect of ryegrass lasted longer, and was more severe than clover. Lucerne tops, which are used as a mulch in a vegetable alley-cropping system, caused no growth reduction. Whereas the mulches did improve plant growth by the modification of soil water and temperature regimes, some or all of these benefits were eroded by phytotoxic leachates from the cover crop residues. In contrast to cover cropping, there were no problems relating to phytotoxicity with using undecomposed lucerne shoots as a mulch in an alley-cropping system.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754767

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754768

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754769

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754762

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor