摘要:

The introduced Mexican beetle,Zygogramma bicolorataPallister (Chrysomelidae), has brought about large scale defoliation of the noxious weedParthenium hysterophorusL. (Asteraceae) in Bangalore and surrounding areas. Studies carried out over a period of two years in two uncultivated parthenium infested horticultural fields showed that defoliation by the beetle can cause up to 99.5% decline in weed density, provided the soil is left undisturbed. Forty different species of plants, formerly suppressed by the weed, were noticed to grow in the areas vacated by parthenium. The studies also indicated that the rate of decline of parthenium and the degree of diversity of succeeding plant species in fallow lands, after defoliation by Z.bicolorata, may vary depending on the duration of weed occupation and the history of land utilisation.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754753

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The molluscicidal activity of water extracts of pre- and post-harvested garlic (Allium sativum) was studied against the snailsLymnaea acuminataandIndoplanorbis exustus.The increase in 24-h toxicity of garlic bulbs from the 2nd to the 11th month after sowing, againstLymnaea acuminatawas 48.33 times, whereas againstI. exustusit was 24 times. The increase in toxicity of pre- and post- harvest garlic bulbs is discussed in relation to the synthesis of a chemical in the pre-harvested bulb and changes in the chemical composition of garlic after harvesting.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754754

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Jackbean (Canavalia ensiformis(L.) DC.), is considered one of the few pulses that grow really well on the highly leached, nutrient-depleted lowland tropical soils. Natural pollination with its close relative, the swordbean (Canavalia gladiata(Jacq.), offers exploitable opportunities for gene introgression and varietal improvement without the necessities of artificial pollination. This paper reports the growth, biomass yield, nodulation and seed quality of advanced generation lines derived from the natural crossing of jackbean with swordbean.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754755

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Conventional strawberry (Fragaria ananassaDuch. cv. Chandler) production was compared with production undergoing conversion to certified organic management in a three-year, replicated, on- farm study. Plant vegetative development, measured as leaf number, leaf area, and vegetative biomass, decreased in the organic production system compared to the conventional system. Developmental differences were less significant in the third year of the study. Reproductive development, measured as number of flower buds, open flowers, and immature fruit, as well as total reproductive biomass, was also lower in the organic system. The timing and degree of difference in responses studied varied over the course of the study. The percent of total berries produced which were not marketable was larger in the conventional system in the second and third years of the study. Marketable fruit yield was consistently lower in the organic plots, but the margin of difference decreased over the course of the study from 39% to 28%. However, market conditions resulted in greater returns per hectare in the organic production system.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754756

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The burning of crop residues and trash is a common practice in the groundnut cropping areas in Congo. In order to study the effect of this farming system, soil rhizobia and yields in groundnut crops were compared with those obtained at different levels of phosphorus and potassium fertilization. In the first experiment, the burning farming system with and without liming was tested on the nodulation and yields of threeA. hypogaeacultivars. In the second one, a combination of four levels of phosphorus (0, 40, 80 and 120 kg P/ha) with three levels of potassium (0, 50 and 100 kg K/ha) were tested. In the third one, the four levels of P (0, 40, 80 and 120 kg P/ha) and Kat a rate of 50 kg K/ha were also tested. Results showed that burning increased the nodulation in groundnut crops by up to 91% and yields by up to 47–56%. Increasing the rate of phosphorus from 0 to 40 kg P/ha failed to enhance nodulation and pod yield. However, at a rate of 50 kg K/ha, phosphorus application at rates ranging from 40 to 120 kg P/ha increased the nodulation and yields in the groundnut crop by up to 57–176% and 17–54%, for nodulation and yields, respectively. Average increases ranging from 52–256% and 80–105% could be reached depending on field conditions.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754757

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In a long-term comparison of agricultural systems, bio-dynamic, organic and conventional farming have been compared since 1978. The treatments differ mainly in plant protection management and fertilization (organic vs. mineral, and intensity). The experimental field is situated on a Luvisol from loess in Therwil (Switzerland). Here, the fauna of beneficial epigaeic arthropods (carabids, staphylinids and spiders) in differently cultivated winter wheat plots was investigated with pitfall traps (live catches) in 1988, 1990 and 1991. Compared with the conventional plots (= 100%), the bio-dynamic plots contained 193% of epigaeic arthropods, the organic plots 188%. The activity- density of carabids, staphylinids and spiders was higher in the bio-dynamic and the organic than in the conventional plots in all three years. In two out of three years, the difference between the conventional and the biodynamic, organic plots was significant. For carabids, the differences between treatments were most pronounced in spring. In the biological plots, the species number of carabids was higher in each year than in the conventional ones: On average bio-dynamic plots contained 18–24 species, organic plots 19–22 species and the conventional ones 13–16 species. The frequency distribution of the carabid species was also more even in the bio-dynamic and the organic plots. The influences of plant protection and fertilization on epigaeic arthropod populations are discussed.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754758

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754759

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754760

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754761

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754752

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor