摘要:

A field experiment was conducted to evaluate the benefit to growth ofAllium cepaL. of inoculation with a mixed culture of indigenous arbuscular mycorrhizal (AM) fungi. Four locally adapted onion cvs., Pusa White Flat (PWF), Pusa White Round (PWR), Early Grano (EG) and Pusa Madhvi (PM) were grown at two phosphorus levels (25 and 50 kg P ha−1) in a P deficient alfisol. Inoculation significantly increased mycorrhiza formation over that caused by the level of native AM fungi present at the site. At harvest, all inoculated onion varieties showed higher values of bulb diameter, fresh weight, shoot dry matter, shoot p content and bulb yield than uninoculated plants. However, the magnitude of AM response for yield in a given onion variety was found to be different at different levels of P. This holds true in all the varieties tested. Inoculated plants tended to have greater bulb yield for varieties PM and PWR grown at 25 kg P ha−1. On the other hand, PWF and EG plants showed similar response at 50 kg P ha−1. The percent root length colonized by AM fungi between both the P levels of inoculated plants did not differ significantly. However, the extent of colonization varied among the varieties. The dependence of plants on mycorrhizal fungi for bulb production varied among the varieties grown at a particular P. EG and PWF plants showed maximum dependence on AM at 50 kg P ha where as PM and PWR plants exhibited a maximum MD at 25 kg P ha−1.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754860

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In a replicated field plot study conducted during 1994 and 1995 in the Sacramento Valley, California, U.S.A., combinations of three levels each of soil-applied organic fertilizing materials and foliar-applied seaweed and fish powder were tested on processing tomato (Lycopersicon esculentumMill.), cv. Orsetti's Halley 3155 to determine effects on crop yield, fruit quality and economics. The experimental design was a factorial split plot arranged in a randomized complete block with four replicates. Main plot treatments consisted of three soil fertility levels: (1) control, (2) woolypod vetch (Vicia villosaRoth ssp.varia[Host] Corbiere), cv. Lana and (3) Lana vetch and poultry manure compost. Subplot treatments consisted of three foliar spray levels: (1) control, (2) seaweed and fish powder applied at label rate, and (3) seaweed and fish powder applied at twice the label rate. The study was designed to simulate practices used by growers of organic processing tomatoes in the area. No significant differences were found for yield or quality of marketable fruit in any soil and foliar treatment combination in either year. Because no significant differences for yield or fruit quality were detected, no economic benefit for seaweed and fish powder can be inferred under the experimental conditions.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754861

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The response of pepper to various mixtures of organic manures was studied with and without supplementary addition of mineral fertilizer under field conditions. Application of farmyard manure + poultry manure at 5 t ha−1each, supplemented with 50 kg N ha−1resulted in significantly higher fruit yield compared with other treatments in 1995. Farmyard manure at 10 t ha−1+ poultry manure at 5 t ha−1out-yielded other treatments in 1996. High rates of combined organic and mineral fertilizers significantly reduced crop establishment in 1996 and caused excessive vegetative growth in both years of study. Poultry manure had higher concentration of nutrients in both years. Mineral nitrogen fertilization resulted in higher concentrations of N, P and K in pepper fruits.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754862

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Results from experimental trials and on-farm surveys have suggested that organic farm management is associated with positively enhanced soil physical, chemical and biological characteristics. To test this hypothesis more rigorously, 30 paired organic and conventional farms were assessed across a range of soil types and management regimes in the south of England. The 60 paired farms ranged from grassland to horticultural/arable and purely arable. The soils of all chosen farms were measured for a wide range of physical and chemical characteristics. The data were subjected to a multivariate analysis and the results interpreted so as to identify the management factors deemed beneficial for topsoil physical and nutritional conditions.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754863

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In organic farming, nitrogen is supplied to the nutrient cycle of farms primarily through biological nitrogen fixation. In Finland, the most common way of doing this is cropping of perennial red clover-timothy leys. The clover content is an important factor in organic grassland management in utilizing nitrogen from the atmosphere for the field and the farm. The aim of this study was to determine the variation of the yield level and clover content of one-, two- and three-year-old leys. This was done by taking ley samples from experimental plots and organic farms. The yields were highest in the two- and three-year-old leys and lowest in the one-year-old leys in the experimental plots in 1994–1996. The yields ranged from 5300 to 7500 kg ha~' dm (dry matter). The year also had a statistically significant effect on the ley yields; in one location having a greater effect on the yields than the age of the ley. On the farms, the yields decreased from two-year-old (6500 kg ha−1dm) to three-year-old (4900 kg ha−1dm) leys in 1998, with no significant change between one- and two-year-old leys. The clover content (20–80% of dm) and total nitrogen content (1.5–4% of dm) of the yields varied so much in the experimental plots that no clear conclusion could be drawn. In the farm samples the clover content diminished in the same order as the yields. On farms there may be problems in maintaining the clover content and yield level high enough for three years which is economically favourable.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754864

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

During four consecutive years of experiments with carrots in monocrop and undersown with subterranean clover (Trifolium subterraneum), it was shown that intercropping significantly reduced root damage by the carrot rust fly (Psila rosae) and by cavity spot (Pythiumspp.). Differences between a standard variety and a carrot rust fly ‘tolerant’ variety were found. Good yields in quality and quantity could be obtained. Possible causal mechanisms of the observed intercropping effects are discussed.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754865

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Two alternatives to chemical control ofBotrytisin strawberries were assessed, post-harvest defoliation and finger harrowing, the latter being used primarily in weed control but also claimed to affect the occurrence ofBotrytis.Post-harvest defoliation, though having some positive effect on marketable yield, did not reduce the incidence ofBotrytissignificantly. This was the case regardless of whether or not cut leaf material was removed from the plots. Finger harrowing, though in some instances having a negative effect on yield, did not controlBotrytissignificantly either. However, it was clearly demonstrated that, in organic strawberry growing, the incidence ofBotrytisincreases with plant age. Therefore, a short-term cropping system may be more important in controllingBotrytisthan either post-harvest defoliation or finger harrowing. In conclusion, the combined use of several cultural methods may be needed when controllingBotrytisin organically grown strawberries.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754866

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754867

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754868

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754869

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor