摘要:

Three hybrid populations were obtained from 4x‐2.x, 2x‐4x, and 2x‐2x crosses by using two tetraploids (Solanum tuberosumL.) and three dip‐loid hybrids of closely related species which can produce 2n gametes. Forty‐three dihaploid plantlets were regenerated from embryoids of anthers of the three tetraploid hybrids by anther culturein vitro.Three of them could produce 2n pollen and five of them could produce 2n eggs. The morphological and agronomic characters of these dihaploids with 2n gametes were compared with those of their diploid and tetraploid parents. Two dihaploid clones with 2n gametes and improved agronomic characters were obtained. The results suggest that ploidy manipulation through sexual polyploidisation and dihaploid induction by anther culture is an effective method to obtain dihaploid clones with 2n gametes in combination with good tuber yield and tuber appearance in potato.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514116

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The behaviour and mobility of the predatory mitePhytoseiulus persimilisAthias‐Henriot (Acari: Phytoseiidae) was observed on vertically orientated leaves of carnations(Dianthus cary‐ophillus)and compared to five other greenhouse plants: cymbidium orchids (Cymbidiumspp.), roses (Rosaspp.), French beans (Phaseolus vulgaris),gypsophila (Gypsophila paniculata),and thalictrum (Thalictrum delavayi). P. persimilishad difficulty maintaining traction on carnation leaves, with only two out of 15 able to complete a vertical 25 mm test run. It was able to adhere to the remaining five plant species but the mean time to complete the prescribed distance ranged from 12.8 s on cymbidium orchid to 65.0 s on thalictrum. Scanning electron micrographs showed the waxy layer of the leaf cuticle of these plants varied from highly ornamented, dense layers of wax filaments on carnations to smooth surfaces on beans. It is suggested that the failure ofP. persimilisto control two‐spotted mite (Tetrany‐chus urticaeKoch) (Acari: Tetranychidae) on carnations is a result of its inability to maintain traction on the waxy surface of the leaves and stems.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514117

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The Obisu type ‘Delica’ buttercup squash (Cucurbita maximaDuch.) was inoculated at early, mid, and late stages of growth with zucchini yellow mosaic virus (ZYMV) and watermelon mosaic virus 2 (WMV2). The results of these field trials demonstrated that early‐ and mid‐season ZYMV infections and early‐season WMV 2 infections caused serious yield losses and adverse quality effects in comparison with yields from uninoculated plots. Total yield losses from ZYMV were 48% for early‐season and 26% for mid‐season infections. Yield losses from WMV 2 were statistically significant only after early infection (38%). Numbers of marketable fruit were similarly affected as was marketable fruit weight and incidence of fruit blistering. For example, early season single or combined infections of ZYMV or WMV 2 reduced the mean marketable yield of ‘Delica’ from 84 to 23% of the total yield of uninoculated plots. In a second trial, the effect of a mid‐season infection on three squash types showed that the Miyako type was more sensitive to losses in number and fruit weight than Obisu or Arjihei types. In both trials, mixed infections of ZYMV and WMV 2 caused yield effects that were similar to those associated with ZYMV alone. We conclude that ZYMV and WMV 2 infection either before or during the flowering period will reduce fruit size, affect marketable quality through fruit blistering, and reduce fruit numbers. It is therefore important that measures to reduce or eliminate virus infection are taken early in the growing season. Seed from infected fruits were grown and assayed for virus transmission. Incidences of up to 3.5% for ZYMV and 5% for WMV 2 were recorded, demonstrating that both ZYMV and WMV 2 can be transmitted by the seed of infectedC. maximafruit. We believe that the reintroduction and spread of ZYMV, and possibly WMV 2, into buttercup squash growing areas will continue if seed health is not addressed, in addition to practicing normal virus disease control strategies.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514118

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514119

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Calendula (Calendula officinalisL.) was drilled at 3, 6, 12, 24, 48, and 96 kg seed/ha in a trial at Lincoln, New Zealand, in November 1997. Plots were divided into five equally sized sections. Fully open flowers were harvested from Sections 2 and 4 of all plots twice or three times weekly from early February to mid March 1998, after which plant population and crop biomass were determined from the same sections and seed yield/flower determined from Sections 1, 3, and 5. Plant counts increased from 9 plants/m2at the 3 kg seed/ha rate, to 26 at 6, 46 at 12, 101 at 24, 179 at 48, and 332 plant/m2at 96 kg seed/ha. Total flower yield was not significantly different at populations over 46 plants/m2, but declined with lower plant populations. The total fresh weight (and number) of fully opened flower heads collected off each plot increased from 0.5 (164) to 1.4 kg/m2(650/m2) with increasing plant population, but did not differ at the four highest populations. Dried petals made up between 7 and 9% of flower fresh weight. Yields of dry petals/m2were 36 g at 9 plants/m2compared to an average of 89 g over the four highest plant populations. Seed weight/head was 0.78 g at 9 plants/m2compared to c. 0.5 g for the other plant populations. Seed yield increased with increasing plant population from 128 g/m2at9plants/m2to 300 g/m2at the three highest populations.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514120

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Wasabi (Wasabia japonica(Miq.) Matsum.) is a new crop to New Zealand, and nothing is known of its yield potential, growing time, or the husbandry requirements to achieve that potential. As part of an initial assessment, a wasabi crop was grown for 24 months from May 1995 in a shade house at Lincoln to determine how the yield components developed overtime. The crop was sampled monthly from September 1995 to May 1997. Plant numbers decreased from 11 to 7/m2over the time of the trial, mainly as a result of disease. Leaf area indices increased rapidly during the spring to reach full cover in summer and autumn. Stems appeared in December 1995, and increased to 4/plant by November 1996, and then trebled in number over the next three summer months. Much of this increase was the result of the growth of secondary or tertiary stems from buds on the main stems. The high value main stems weighed c. 30–40 g 8 months after planting, and c. 70 g 18 months after planting. By March 1997, only 4 of the 25 stems/m2were over 60 g each i.e., large enough for the Japanese high quality fresh market, and two of these were over 100 g. Up to 5 kg/m2of fresh material were produced in the first year after planting and 6 kg/m2in the second year, and most of this was in the petioles. The crop was hand weeded 9 times and 15 fungicide, seven insecticide, and five slug and snail bait applications were made over the 2 years of this study.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514121

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A survey of weeds and weed management practices was conducted during 1997/98 in apple orchards and vineyards of Canterbury and Nelson/Marlborough regions of New Zealand. According to growers, mallow (Malvaspp.) ranked as the most widespread weed in apple orchards of both regions. In vineyards, mallow was the most common weed in Nelson/Marlborough and the second most common weed in Canterbury. Other dominant weeds in Nelson/Marlborough included grasses, black nightshade (Solarium nigrum),fathen (Chenopodium album),and redroot (Amaranthus retroflexus). In Canterbury, grasses, clovers, fathen, and thistles were common. In almost all orchards knockdown herbicides were used but the use of residual herbicides varied. The total number of herbicide applications/year has increased in both regions over the past 10 years, but the proportional use of residual herbicides has declined. Some other weed management practices are used in orchards but a sound integration of these is commonly lacking.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514122

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Encapsulated buds excised fromin vitroproliferated shoots of the ‘Hayward’ kiwifruit (Actinidia deliciosa(A. Chev.) C. F. Liang et A. R. Ferguson) can be used for non‐embryogenic synthetic seed production. Three experiments were carried out to evaluate the aptitude of apical and axillary buds (microcuttings) towards encapsulation and synthetic seed productionJuland to find the treatments able to induce conversion of the synthetic seeds to whole plantlets. ‘Hayward’ proliferating shoots are useful sources of microcuttings for encapsulation and synseed production, since a proliferation protocol is already available. Encapsulation, although considered necessary, depressed microcuttings’ vigour and vegetative activity. Cold treatments provided to thein vitroproliferating mother shoots boosted bud vigour and subsequent conversion. Increase of concentration of sucrose in some steps of the protocol also enhanced conversion, which in some conditions reached a rate of 57.5%. Potential applications of encapsulation and the synthetic seed technology in kiwifruit germplasm exchange and commerce are also discussed.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514123

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A previously undescribed form of wood decay of kiwifruit (Actinidia deliciosa(A. Chev.) C. F. Liang et A. R. Ferguson) plants was observed in 8–10‐year‐old Emilia Romagna orchards in north‐central Italy. Symptoms appear as unspecific interveinal chlorosis of the leaf, which later may become necrotic resulting in premature leaf drop. Fruits never grow as large as on healthy plants nor do they reach full maturity. This foliage chlorosis occurred on current season's shoots developing from canes growing horizontally from the cordon. Cross‐sections of the wood show white rot areas surrounded by brown necrosis of hard consistency, preceding the white rot in the colonisation of the wood. Isolations from the zone of hard consistency onto Potato Dextrose Agar (PDA) medium yieldedPhaeoacremonium aleophilum, P. inflatipes, P. chlamydosporum, P. rubrigenum,and to a lesser extent,Phialophorasp., whereasPhellinus conchatuswas commonly isolated from white rot diseased tissue. Although pathogenicity studies on host plants are still being carried out, a strong similarity with esca disease of grapevine could clearly be noticed.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514124

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A stem canker disease of aLimoniumhybrid ‘Chorus Magenta’ was identified at several sites throughout the North Island of New Zealand. First symptoms included leaves of diseased plants turning yellow, often on one side of the leaf blades. Cankers developed blue‐black discoloration, and dark fruiting bodies of a fungus were located below the epidermis of cankers on dying plants. APhomopsissp. was consistently isolated from diseased stem tissue. Pathogenicity was confirmed by inoculating healthy plants with the fungus in the greenhouse. The pathogen was recognised as a new species and namedPhomopsis limonii.This is the first report ofPhomopsisonLimonium.

ISSN:0114-0671    

DOI:10.1080/01140671.2000.9514125

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor