摘要:

Armoured scale insect (Hemiptera: Diaspididae) leaf infestations were monitored from rows of kiwifruit (Actinidia deliciosa(A.Chev.) C.F. Liang et A.R. Ferguson var.deliciosa) vines in three blocks at each of 11 sites, at 3–8 times from December until May. The relationship of scale leaf infestation with distance across kiwifruit blocks (scale distribution) was analysed using different regression models. Scale distributions were best described using linear models for 26 kiwifruit blocks and for seven blocks using quadratic models. Scale distributions derived using live scale followed similar patterns to those derived from total scale. Overall 53% of sites or blocks had significant linear or quadratic scale distributions. Kiwifruit blocks with high scale infestations invariably had significant scale distributions whereas those with low infestations had non‐significant distributions. The finding of significant relationships using regression models with parallel lines or curves for different sampling times at some sites, showed scale distributions hold throughout the season. In the simplest situation scale infestations were highest in kiwifruit rows adjacent to alternative host plants and declined linearly away from the scale source. These findings were consistent with the hypothesis that scale distributions were caused by the aerial dispersal of crawlers from alternative host plants.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514074

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Genetic variation of the fungal plant pathogenSclerotinia sclerotiorum(Lib.) de Bary was examined using DNA fingerprinting. Seventy‐five isolates ofS. sclerotiorumwere collected from four populations in the South Island of New Zealand. DNA fingerprints were generated for each isolate by Southern blotting using a cloned repetitive sequence, pLK44.20, as a probe. The 47 different fingerprints produced revealed a high level of variation both within and between populations. Comparison of fingerprint similarities indicated substantial local movement of isolates but gave little evidence for long‐range dispersal. A subset of the isolates was tested for mycelial compatibility. Pairs with identical or highly similar DNA fingerprints gave compatible reactions, whereas isolates whose fingerprints were dissimilar were incompatible. The high level of variation observed in New Zealand populations ofS. sclerotiorumhas relevance for control of diseases caused by this pathogen, as any method of disease control must be effective across the range of pathogen variation.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514075

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Potted kiwifruit (Actinidia deliciosa(A. Chev.) C.F. Liang et A.R. Ferguson) plants were transferred to a controlled environment at monthly intervals throughout the growing season (October‐May). Daily time‐courses of net photosynthesis and respiration were measured on vegetative and fruit‐subtending leaves that emerged in October, November, December, and February. Net carbon acquisition of each leaf was determined from daily and seasonal changes in gas exchange. Maximal rates of photosynthesis were coincident with or shortly after leaves became fully expanded and photosynthetic development was dependent on the environmental history of leaves. Photosynthesis declined during the day by 10–40% in vegetative leaves and 20–50% in leaves subtending fruit. Carbon acquisition of leaves subtending fruit was 60% lower than vegetative leaves. Results imply that competition between fruit and vegetative sinks has a regulatory role on carbon acquisition of leaves but further elucidation to understand how this affects variation in fruit size is required.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514076

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The influence of temperature (1–25°C) and maturity on organ abscission promoted by a range of ethylene concentrations (0.3–100 μl litre‐1) was examined on stem explants of twoCamelliacultivars ('Anticipation’ and ‘Donation';C. salue‐nensis × C. japonica). Time to abscission of 50% of leaf and floral buds was measured. Leaves were most responsive during stem elongation following vegetative budbreak. In contrast, ethylene‐responsiveness of floral buds gradually increased with maturity. Low temperatures (1–5°C) reduced the rate of abscission response to ethylene at all concentrations, but with greatest effect at low concentrations (<2 μl litre‐1). Floral buds of bothCamelliacultivars were more sensitive to ethylene than leaves. Application of a high ethylene concentration correctly determined relative abscission differences for maturity effects, but inter‐organ differences required a range of ethylene concentrations. It is proposed that “responsiveness” be defined as differences in abscission response to a high ethylene concentration (e.g. 10 μl litre‐1), whereas differences in abscission response to low ethylene concentrations (<1 μl litre‐1) be defined as “sensitivity” differences.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514077

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A field experiment was conducted to study the effects of soil type (sandy loam and silt loam) and soil depth (5, 10, 15, 20 cm) over the crown during harvest on the yield and quality of asparagus (Asparagus officinalisL.) spears. It was found that covering the crowns with sandy loam produced significantly higher spear yield, spear number, and better spearhead quality than covering with a heavier soil (silt loam). The increase in spear yield was because of an increase in spear numbers. Spear‐head quality decreased with soil depth.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514078

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Following unusually high temperatures during the 1997/98 growing season, a significant incidence of watercore was observed in the New Zealand ‘Braeburn’ crop (Mains domestica) for the first time. Serial proton magnetic resonance imaging was subsequently used to monitor the characteristics of disorder amelioration in individual fruit during 3‐week and 15‐week storage trials (0–0.5°C). Symptoms (water‐soaked appearance of flesh around the locule area and extending into the cortex) in “slightly” affected fruit (>0.5 cm2affected or <25% of the equatorial cross‐section area affected) gradually dissipated in 3–5 weeks leaving fruit with normal appearance and taste. Extracellular fluid in fruit classified as “severely” affected (>25% of the equatorial cross‐section area affected) also dispersed completely, but over a longer time—6–8 weeks. However, the internal appearance of some severely affected fruit was unacceptable after 15 weeks of coolstorage. It is not clear whether the presence of cavities and brown mealy flesh was attributable to watercore or other factors associated with the anomalous seasonal conditions. Lines of ‘Braeburn’ in which a high incidence of severe watercore is present at harvest thus represent high risk for long‐term storage.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514079

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Partitioning patterns of13C‐labelled assimilate were studied in mature field‐grown plants of three asparagus (Asparagus officinalisL.) cultivars. Plants were labelled in January and destructively harvested at different stages of the summer fern growth phase and in early spring. There was very little new fern establishment after January, so the majority of the assimilated label was translocated from the labelled fern to the storage roots, and in smaller amounts to buds on the rhizome, from where it was later remobilised into new spear growth in the spring. The label was confined to a physiological unit composed of the labelled fern, the rhizome from which it grew, and buds, roots, and new shoot material associated with that rhizome. Similar patterns of13C distribution within the physiological unit were observed in three cultivars differing in spear yield.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514080

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effect of staminate kiwifruit (Actinidia deliciosa) vine distributions and flower numbers on pollination was investigated. There was no significant difference in seed numbers or fruit weight from orchards with 1:3 to 1:8 staminate: pistillate vines distributions. There was, however, a significant decline in seed numbers with increasing distances between staminate rows in orchards with strip or overhead staminate vines. Decreasing the number of staminate flowers on vines by 25, 50, and 90% had no significant effect on fruit size.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514081

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effects of ethanol on carnation (Di‐anthus caryophyllusL.) cut flowers were studied by treating five cultivars ('Yellow Candy’, ‘Sandrosa’, ‘Francisco’, ‘White Candy’, and ‘Iury') with up to 8% ethanol solution and measuring vase life, solution uptake, delay in bud opening of flowers, and ethylene production. Treatment with 4 or 6% ethanol increased the vase life of ‘Yellow Candy’, ‘White Candy’, and ‘Iury’, but not of ‘Sandrosa’ or ‘Francisco’. Cultivars showed variable response to ethanol treatment with regards to uptake of solution, vase life increment, and delay in bud opening. The highest increment in vase life after flower opening with 4% ethanol was for ‘Yellow Candy’, where the vase life doubled. Total ethylene production in untreated flowers varied according to cultivars; treatment with 4% ethanol inhibited ethylene production as well as sensitivity to ethylene. ‘Yellow Candy’ was the most sensitive to ethylene and most responsive to ethanol; ‘Sandrosa’ was the least sensitive to ethylene and least responsive to ethanol treatment. The effectiveness of ethanol in extending vase life correlated closely with the longevity, ethylene production, and ethylene sensitivity of each cultivar.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514082

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Chlorophylla, b, a:b,carotenoid, carbohydrates, sugar, protein, and polyphenol content were estimated and their association with rhizome yield compared in 10 cultivars of ginger (Zingiber officinaleRose). The analyses indicated significant differences amongst the cultivars for all the studied parameters. The highest fresh rhizome yield (462.6 g/plant) was recorded in ‘Gorubathaney’ and the lowest (234.5 g/plant) in ‘Suprava’. Higher rhizome yields were highly associated with grater chlorophyllaand carbohydrate (r= 0.52 and 0.60 respectively) and lower polyphenol (r =‐0.15) levels in the leaf. The protein content in the leaves of ginger showed significant correlation with carbohydrates and chlorophylla:bratio (r = 0.55 andr =0.76 respectively). The chlorophylla:bratio also showed highly positive correlation with carbohydrate content (r = 0.92) of leaf. However, polyphenols showed a significant positive correlation with chlorophyllband carotenoids and carotenoids with chlorophyllaand chlorophyllb.

ISSN:0114-0671    

DOI:10.1080/01140671.1999.9514083

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor