摘要:

SUMMARYThe tolerance of plants produced from reciprocal grafts between cv. Cara and cv. Pentland Dell were compared in field plots containing different initial population densities ofGlobodera rostochiensis.Both stock and scion contributed to the greater tolerance of cv. Cara as compared with cv. Pentland Dell. Ground cover measurements, made by a novel photographic method, showed that a heavy infestation ofG. rostochiensisdecreased the top growth of all plants: more for those with scions of Pentland Dell than those with scions of Cara. The stock did not initially affect the extent to which top growth was reduced in the heavily infested plots but later measurements showed a progressively increased effect on top growth for plants with stocks of Pentland Dell and a decreased effect for those with Cara. In a destructive harvest 13 wk after planting the relatively small effect ofG. rostochiensison the top growth of plants with Cara scions was not reflected in the tuber yields which were markedly decreased. However, plants with Cara stocks were considerably more tolerant (i.e. tuber yields were affected less) than those with stocks of Pentland Dell. Overall, plants of Pentland Dell scions on Cara root stocks were most tolerant at this stage. Between 13 and 16 wk, when a second destructive harvest was made, plants with Pentland Dell scions were senescent and their yield increased little. In contrast, plants with Cara scions were still growing and their yield increased markedly so that by 16 wk the most tolerant combination was Cara on Cara.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03236.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYcAMP levels in eggs ofG. rostochiensisand the diameter of the nucleolus of the nucleus within the dorsal pharyngeal gland cell of the second stage juvenile have been measured as indicators of the response of the nematode to the hatching stimulus in potato root diffusate. The nucleolus increased from 2.72 ± 0.103 μm for unhatched individuals to 3.28 ± 0.14 μm and 3.88 ± 0.15 μm after soaking eggs in potato root diffusate for 3 and 4 days respectively. Juveniles expressed from unstimulated eggs in water to potato root diffusate for 4–5 days showed a similar increase in size of the nucleolus to 3.94 ±0.15 μm but those released into water for this time had smaller nucleoli of 3.20 ± 0.98 μm. The change in diameter of the nucleolus is probably related to the accumulation of secretions in this gland cell before hatching.Preliminary results with dibutyryl analogues of CAMP and cGMP showed some inhibition of hatch in 10% potato root diffusate. Theophylline had a similar effect but NaF was dissimilar in that the effect of this inhibitor was not reversible. A standard radioimmunoassay showed that significant changes in cAMP levels occurred in the unhatched juveniles within cysts after treatment with potato root diffusate for 2.5 or 8 h compared with values for cysts kept in water. This change occurs before other known responses of the juveniles to potato root diffusate and it defines the period of interest for future work on the initial action of hatc

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03237.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYThe potential of several chromatographic methods for isolating hatching factors for potato cyst nematodes from potato root diffusate was investigated using a bioassay based on emergence of juveniles from cysts. Gel filtration provided an overall estimate of molecular weight of 437 Da for the hatching activity and ion exchange chromatography indicated that at least 60% of the recovered activity was anionic in nature.Material less polar than the hatching activity could be removed by passing potato root diffusate through a reversed‐phase Sep‐Pak C18cartridge and the elutant showed 83.3 ± 4.4% (mean of 32 cysts) of the initial hatching activity. High performance liquid chromatography (HPLC) with a reversed phase, C18column and gradient elution (0–80% CH3OH in water) confirmed that much of the hatching activity was polar and that it was not retained by this method of separation. A weak anion exchange resin achieved slight retention of much of the hatching activity and an ion pairing reagent lowered the polarity sufficiently to allow some retention in subsequent reversed phase HPLC on a CIScolumn. Both ion exchange and ion pairing HPLC suggested that hatching activity was not chromatographed as a single compound and indicated that fractions able to influence the nucleolus of the nucleus within the dorsal pharyngeal gland cell did not always show hatching ac

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03238.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYAs little as 0.8 kg aldicarb ha‐1applied to bands of soil 15 cm wide × 15 cm deep, in which sugar beet seeds were sown, increased beet yields as much as did 2.6 or 5.0 kg ha‐1rotary cultivated into the top 15 cm of soil lightly or moderately infested with beet cyst‐nematode,Heterodera schachtii.In a very heavily infested soil, 1.7 kg ha‐1applied to the bands of soil increased beet yields as much as 2.6 kg ha‐1rotavated into the top 15 cm of the soil; yields were further increased by 5.0 and 9.9 kg ha‐1rotavated in but not by 3.5 kg ha‐1in the bands of soil. Soil populations of the nematode increased little or not at all whether the soil was treated with aldicarb or not. The band treatment was achieved by a vertical band‐ reciprocating harrow technique, which is described. The advantages of this new technique for the control of beet cyst‐nematode and other soil pests of widely spaced row crops are safer application of less pesticide, thereby minimising cost of treatment and any risk to the environment, faster seedbed preparation and adequate control of pest population increase on the susceptible crop, especially if coupled with

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03239.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYTwo carrot cultivars which represented contrasting levels of resistance to carrot fly,Psila rosae, were grown in a replicated field experiment at Wellesbourne in 1984–85. Seed was sown on five occasions between April and August 1984 and the crop harvested after a minimum growth in the field of 16 wk on seven occasions between August 1984 and February 1985. A highly significant correlation (r = ‐0.78;P>0.001) between the levels of carrot fly damage and the concentration of chlorogenic acid in the roots enabled a model to be formulated to predict the relative predisposition to carrot fly larval damage; high levels of chlorogenic acid early in the season predisposed roots to severe attack when they were ol

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03240.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYBananas (MusaAAA Group, Cavendish Subgroup) were ripened over a range of temperatures from 15 to 35°C. The rate of ripening in both pulp and peel was accelerated with an increase in storage temperature up to about 24°C. Above this temperature the pulp softened and sweetened without the development of a fully yellow peel due to a decrease in the rate of chlorophyll breakdown. Peel carotenoid content was higher at 35°C than at 20

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03241.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYAn investigation was undertaken to examine the roles of ethylene, oxygen and carbon dioxide in the failure of bananas to degreen at high temperature. Also a comparison was made of the response of bananas and plantains to storage at high temperature.Bananas produced more ethylene at temperatures where they failed to degreen than at those where they turned fully yellow, and supplying high levels of exogenous ethylene to bananas ripening at high temperature did not induce the development of a yellow peel. Isolated peel tissue held, in the presence of ethylene, at 20 or 35°C failed to develop a yellow colouration at 35°C in air or 80% oxygen, while all detached peel tissue held at 20°C degreened. However, when atmospheres were enriched with carbon dioxide degreening of detached peel was suppressed at both 20 and 35°C. In contrast to bananas, plantain fruit degreened more rapidly at 35°C than at 20°C. The way in which high temperatures may inhibit degreening in bananas is disc

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03242.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYThe seed attacking mothCarposina autologawas released in South Africa for control of the weedHakea sericeabut established poorly. Altering the release method such that it corresponded more closely to natural infestation and better training and supervision of field workers resulted in a 111 % increase in success of a subsequent release.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03243.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYOne‐month‐old fruits ofAcer ginnalawith winged pericarp attached gave 44% germination and this was not increased by cold treatment at 4°C for 0, 10, 20, or 30 days, gibberellic acid treatment at 0, 1, 10, 100 or 1000 mg litre‐1, or ethephon treatment at 0, 2, 20, 200 or 2000 mg litre‐1.After 6 months of storage at 20–25 °C, germination of untreated fruits fell to 5% but could be restored to that of 1‐month‐old fruits by incubation at 4 °C for 30 days.After 9 months storage, no germination occurred in untreated fruits. Cold treatment (30 days at 4 °C partially restored germination (26%). Treatment with either gibberellic acid (1000 mg litre‐1) and 30 days at 4 °C (40%) or ethephon (100 mg litre‐]and 30 days at 4 °C improved germination (69%). The combination of all three treatments, i.e. 100 mg litre‐1gibberellic acid, 100 mg litre‐1ethephon and 30 days at 4 °C, optimised germination (86%).Thus, dormancy ofA. ginnaladeveloped during storage but could be reversed by a combination of treatment with low temperature and growth regulators. The highest germination (86%) was achieved after low temperature and growth regulat

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03244.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYThe effects of cutting and the herbicide asulam for the control of a dense uniform stand of brackenPreridium aquilinumwere investigated experimentally over a 6 —yr period in Norfolk, England. Bracken is a particularly difficult species to control by either mechanical or herbicidal means because of its extensive and complex rhizome network, containing large reserves of dry matter and a large number of frond buds. Cutting bracken in the summer removed dry matter from the system and reduced frond vigour but did not reduce the number of frond buds to a critical level. Whereas the first few cuts substantially reduced the standing crop of fronds, relatively stable standing crops of fronds were observed in future years despite continued cutting. Asulam caused a 99% reduction in the standing crop of fronds in the year after spraying, but in the absence of further treatment, fronds recovered to pre‐spray levels after 6 yr. Asulam caused severe localised damage to frond buds and rhizome apices, but otherwise the rhizome network remained intact. New sections of frond bearing rhizome (short shoots) developed on storage rhizome (long shoots) deep in the soil of both the asulam plots and those

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1987.tb03245.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY