摘要:

The micropropagation ofGentiana cerinaandG. corymbiferawas investigated. Cultures were initiated from axillary shoots or seed. Seeds ofG. corymbiferagerminated on a Murashige & Skoog (MS) medium containing 100 mg/litre gibberellic acid (GA3) with 54% of the seed germinating within 70 days. In the absence of GA3germination did not exceed 5%. Both species proliferated shoots on MS medium supplemented with 6‐benzylaminopurine (BAP). ForG. cerinathere was no significant difference in proliferation rates for BAP concentrations between 0.05 and 0.5 mg/litre. In contrastG. corymbiferagave highest multiplication rates on 0.2 mg/litre BAP. Addition of 1 mg/litre GA3to the medium gave improved proliferation compared to treatments in which GA3was absent. The best treatment forG. cerinaresulted in a shoot multiplication rate in excess of 7‐fold after 50 days whereas forG. corymbiferathis increase was more than 3‐fold. Root initiation occurred on MS medium supplemented with indole‐3‐butyric acid (IBA). In both species the frequency of explants with roots increased with increasing IBA concentration, but at IBA ≥ 1 mg/litre and 3 mg/ litre forG. cerinaandG. corymbiferarespectively a high proportion of the plants developed a basal callus. Survival of theG. cerinaplants during acclimatisation was related to IBA concentration but survival was unrelated to IBA concentration forG. corymbifera. G. cerinasurvival rates decreased from 80% with up to 0.3 mg/litre IBA to c. 5% at the highest rate of IBA. ForG. corymbiferaaverage survival of plants after acclimatisation was just over 20%. Thus root initiation with 0.3 mg/litre IBA can be recommended for both species.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513981

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Phytophthora cactorumcauses significant mortality of mature trees in New Zealand pipfruit orchards. Replants of infected sites often succumb to this pathogen within 3 years.Enterobacter aerogenes,strain B8 was reported to controlP. cactoruminfection of apples in nursery soils in British Columbia. This strain was imported to New Zealand in 1991 and compared with indigenous isolates ofE. aerogenes.The Canadian isolate differed from New Zealand isolates in utilisation of tartrate, tolerance of NaCl (5 cf. 7%), and inhibition ofP. cactorumin vitro. Strain B8 was fungicidal whereas New Zealand isolates were fungistatic. Electron microscopy of mycelium exposed to strain B8 on agar revealed extensive disruption of cell membranes, intermixing and aggregation of organelles, necrosis, vacuolation, breakdown of the cell wall, and hyphal death. Hyphae exposed to New Zealand isolates ofE. aerogenesexhibited vacuolation of the outer cytoplasm and degradation of the cell wall and plasmalemma but not cell degradation and death.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513982

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Twenty‐five wound dressing compounds were screened for control ofChondrostereum purpureuminfection of pruning wounds on willows (Salixspp.), apples (Malus domestica), and golden queen peaches (Prunus persica). None were completely effective but products giving best control were: Garrison; Shell pruning grease; and cyproconazole + iodocarb.C. purpureuminfection with Nectec Liquid and copper oxychloride treatments was significantly (P >0.05) greater than the control indicating a reduced host resistance either directly or by elimination of antagonists. Application of the biocontrol fungusTrichoderma virideto wounds failed to give significant (P >0.05) control ofC. purpureuminfection in willows and peaches. Scanning electron microscopy of field exposed wound dressings revealed considerable differences in film integrity with fissures, pores, and fungal hyphae evident.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513983

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The concentrations of fructose, glucose, sucrose, and maltose in sweetpotato (Ipomoea batatas(L.) Lam.) roots, following an 8‐month storage period, were assessed by high performance liquid chromatography (HPLC). Imported cultivars and breeding lines were compared in both the raw and cooked state against New Zealand standards. Strong linear relationships were demonstrated between concentrations of the sugars (fructose, glucose, and sucrose) in cooked roots, and the corresponding sugars in raw roots (R2of 93.5, 93.8, and 88.8% respectively). The relative proportion of fructose to glucose 0.44: 0.56 was very stable across all cultivars, and independent of the total concentration of the three sugars—fructose, glucose, and sucrose. The negative relationship between sucrose and the levels of fructose + glucose was significant (P< 0.001) excluding cultivars ‘Jewel’ and “Toka Toka Gold’. All of the clones produced considerable amounts of maltose during cooking, which was significantly (P <0.001) related to % dry weight. Using canonical variates to group the clones, ‘Owairaka Red’, the New Zealand standard cultivar, was shown to cluster with the Japanese cultivar, ‘Beniazuma’, and the Taiwanese breeding line, ‘93N12/1’, on the basis of high dry matter and low fructose + glucose levels. The minor New Zealand cultivar, ‘Toka Toka Gold’, clustered near the North American cultivar, ‘Jewel’, on the basis of low maltose, high sucrose, and medium dry weight. ‘Toka Toka Gold’ had a higher fructose + glucose than its sucrose concentration would predict, as well as a lower maltose level than estimated from its dry matter content.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513984

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

In a field trial, the effect of soaking three cultivars of mustard (Brassica junceaL. Czern &Coss.) namely ‘RK‐8203’,’PR‐18’, and ‘Varuna’ for 4 h in 0.0125, 0.025, 0.05, and 0.10% aqueous pyridoxine solution was studied on growth and yield characteristics. In addition to pyridoxine treatment, two controls (unsoaked and water‐soaked) were also maintained for comparison. The parameters studied included root length, leaf number, dry weight/plant, and leaf N, P, and K content at 70 days after sowing (DAS). Pods/plant, seeds/pod, 1000 seed weight, oil content, seed yield, and oil yield were measured at harvest. The pyridoxine requirement for optimum performance of ‘RK‐8203 ‘ was 0.05% and for ‘Varuna’ it was 0.0125%, whereas ‘PR‐18’ showed inhibitory effect to pyridoxine treatment. This variation in pyridoxine requirement of mustard cultivars for optimum performance seems to be the result of the difference in the native pyridoxine content in the seed. The results suggest that the performance of cultivarsof Brassica junceahaving low seed pyridoxine content could be improved by soaking the seeds in aqueous pyridoxine solution so that pyridoxine in seeds reaches the optimum level.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513985

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Five‐year‐old ‘Braeburn'/MM.106 (Malus domesticaBorkh.) trees growing under a high‐density (10 000 trees/ha) planting system were treated with paclobutrazol (PBZ) as a soil drench at 250 mg(a.i.) per tree in August 1993. Gibberellin (GA), GA, or GA4, was sprayed on vegetative buds at 0, 10, or 100 μg per bud at three times between 22 November and 22 December 1992 (before PBZ treatment), or in 1993 (after PBZ treatment). Data on yield and yield components and vegetative growth were collected for 2 years. Time of GA application did not affect vegetative and reproductive growth components. The total shoot number, total shoot length, and total bud number were consistently reduced with PBZ application for 2 years of application. GA caused a decrease in shoot number across 2 years whereas total shoot length and total bud number were increased with GA treatment across 2 years. Fruit yield was decreased with PBZ application by 42 and 23% across 2 years in Trial A and by 27 and 12% across 2 years in trial B. Total fruit number per tree were decreased with PBZ application and varied from year‐to‐year showing biennial bearing (BI) patterns in both trials. PBZ plus GA reversed the PBZ effects on fruit yield and total fruit number and reduced bienniality in trees for 2 years. GA application to the trees which had previously received PBZ was most effective in reducing BI values. Mean fruit weight was not affected with PBZ treatment. The deleterious effects of these two plant growth regulators were reversed by the combined use of PBZ and GA, which provided a balanced yield and vegetative growth and prevented the trees from going into biennial bearing. No consistent, significant effects of GA types or G A levels or their combination with PBZ on vegetative and reproductive growth were found. It is suggested that PBZ and GA can be used to manipulate apple tree growth in a high‐density apple production system and their use in a cultural management system for high‐density apple orchards should be explored.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513986

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Five‐year‐old ‘Braeburn/MM.106’ apple (Malus domesticaBorkh.) trees growing under a high‐density (10 000 trees/ha) planting system were treated with paclobutrazol (PBZ) as a soil drench at 250 mg(a.i.) per tree in August 1993. Gibberellin (GA), GA3or GA4, was sprayed on vegetative buds at 0, 10, or 100 |jg per bud at three times between 22 November and 22 December 1992 (before PBZ treatment), or on the same dates in 1993 (after PBZ treatment). Apples harvested from the experimental trees in 1994 and 1995 were evaluated for fruit quality at harvest and during 90 days of storage at 10°C. Time of GA3or GA4application did not affect fruit quality at harvest. PBZ generally increased mean fruit weight the year after and then decreased 2 years after PBZ application. Fruit L/D ratio was decreased, °Brix values and fruit flesh firmness were generally increased with PBZ application to the trees. However, the effects were minor. The addition of GA to PBZ treated trees generally reversed the effects of PBZ. GA4was more effective than GA, in increasing fresh weight and L/D ratio. After 90 days of storage duration flesh firmness was reduced as an average from 8.4 to 5.2 units, °Brix values were increased as an average from 12.9 to 13.2, and average weight loss reached 13 g/fruit. Time of G A application, PBZ, or GA did not modify the effects of storage at 10°C.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513987

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Sandersonia (Sandersonia aurantiacaHook) tuber growth and secondary tuber development were assessed in two growing environments (a greenhouse and outdoors), at three planting dates (1 October, 1 December, and 1 February) and with six stem pruning treatments. Tubers of c. 1 g were used. The pruning treatments consisted of cutting the stem just above the second flower when 50% of the stems had the second flower open, or 2, 4, 6, and 8 weeks later. In another experiment the effect of stem tipping, stem pruning, flower removal, and an auxin transport inhibitor (2,3,5‐triiodobenzoic acid (TIBA)) applied 3 weeks after the second flower opened were assessed. Tuber growth and secondary tuber development were affected by the date of planting, with both tuber weight and incidence of secondary tubers declining significantly in the later planting dates. Environmental factors including temperature, radiation, and day length may have influenced the rate and type of tuber growth. Stem pruning, removal of the growing tip plus flowers, or applying TIBA reduced secondary tuber numbers and had little effect on tuber size. This study suggests that it is possible to reduce the presence of undesirable secondary tubers by manipulating the growing environment or by developing appropriate cultural practices.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513988

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The effects of three plant densities (128, 256, and 384 tubers/m2), three stem pruning treatments, and shading on tuber weight and incidence of secondary tuber production inSandersonia aurantiaca(Hook.) were assessed in a factorial experiment. Pruning treatments were an unpruned control, a single cut just below the lowest flower at early flowering, and a multiple cut treatment (as per single cut treatment plus 25% more stem removed every 2 weeks). Tuber weight and secondary tuber formation were significantly affected by both plant density and stem pruning treatments, but not by shading. Averaged across all pruning treatments secondary tuber formation was reduced from 25.7 to 0.6% with increasing plant densities. Mean daughter tuber weight, including the weight of tubers with attached secondary tubers, was also reduced with increasing plant density (11.4, 7.9, 6.5 g) and with increasing severity of pruning treatments (11.1, 8.4, 6.2 g). However, the effect of stem pruning on secondary tuber formation was much less than that of plant density. Only at the lowest density of 128 tubers/m2were there significant responses, with secondary tuber formation declining from 33.7 to 15.5% with increasing severity of pruning. Increasing the plant density from 128 to 256 tubers/m2reduced secondary tuber formation to a low level (3.2 cf. with 33.7%) on unpruned stems, without affecting the daughter tuber weight (10.5 versus 10.7 g). Such cultural practices show great promise for controlling secondary tuber formation during commercial tuber production.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513989

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A study was made of three New Zealand grown tamarillo varieties—two red and one yellow. Fruit were analysed by high performance liquid chromatography for their sugar (sucrose, fructose, and glucose) and organic acid (citric and malic) content. The sweeter red variety, as assessed by the growers, ‘Andys Sweet Red’, had significantly higher sugar levels and sugar to acid ratio than the more astringent tasting ‘Secombes Red’, in agreement with the measured soluble solids and titratable acidity results. The yellow variety ('Goldmine') had high sugar and acid levels resulting in a sugar to acid ratio between that of the two red varieties.

ISSN:0114-0671    

DOI:10.1080/01140671.1997.9513990

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor