摘要:

Methods and progress in breeding all-male hybrids of asparagus at Lincoln, Canterbury, New Zealand are reviewed. The effect of andromonoecism (hermaphroditism) is considered and yield data presented from breeders' trials. The disadvantages and advantages of all-male hybrids are discussed, and modifications to the current approach are suggested.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428091

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Azinphosmethyl-resistant first instarEpiphyas postvittanafrom Mariri, Nelson, New Zealand possessed a similar level of resistance to another methyl organophosphate phosmet, but only low resistance to the ethyl organophosphates chlorpyrifos and triazophos, and to a methyl carbamate, carbaryl, by a direct spray technique. There was no evidence of resistance to pyrethroids. Concentration-mortality responses of larvae from azinphos-methyl resistant or susceptible strains were established after 3 weeks exposure to artificial diet containing azinphos-methyl, chlorpyrifos, or carbaryl. The resistance factor of a mildly azinphos-methyl resistant strain was increased significantly following one generation of selection with the LC99of azinphos-methyl. Selection of the same mildly resistant strain with chlorpyrifos raised the level of chlorpyrifos tolerance, but did not affect the response to azinphos-methyl compared to the unselected parent strain. Similarly, selection with the LC99of carbaryl did not affect azinphos-methyl resistance, although resistance to carbaryl was increased 6-fold in two generations (compared to tiie maximum recorded of 25-fold in a reference resistant strain). Resistance was also investigated in field-collected strains. Sixteen lines of progeny were established from field collection of single females. Offspring from each female were split into two groups and exposed to diagnostic concentrations of azinphos-methyl or carbaryl. Progeny of survivors of azinphos-methyl were exposed to diagnostic concentrations of chlorpyrifos. The distribution of carbaryl resistance and chlorpyrifos tolerance was consistent with the distribution of azinphos-methyl resistance, suggesting a common detoxication mechanism or close genetic linkage. Field application of carbaryl would therefore not be expected to provide control of azinphos-methyl-resistantE. postvittana.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428092

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The time required for potato late blight lesions, caused byPhytophthora infestans(Mont.) de Bary, to produce sporangia during periods of continuous leaf wetness, and for inoculations to produce lesions bearing sporangia, was determined over a temperature range of 5–24°C. Equations were derived relating time to sporulate with temperature. A 2-h break in leaf wetness, initiated at any time within the first 3 h of incubation after inoculation, markedly reduced lesion numbers. When the break was initiated later it had less effect, except at the lowest temperature tested (9°C).

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428093

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Various parameters were monitored during growth and storage of fruit of buttercup squash (Cucurbita maximaD. hybrid ‘Delica’) in an attempt to identify a physiological basis for the marked influence of maturity at harvest on the susceptibility of fruit to rot in storage. Protease inhibitor levels in the exudate from artificial wounds were consistently higher in the more resistant fruit, harvested within 14 days after completion of expansion, than in the less resistant fruit, harvested about 21 days later. Enzymes capable of cleaving the agluconic bond in the artificial substratesp-nitrophenyl-N-acetyl-β-D-glucosamide andp-nitrophenyl-β-D-N, N'- diacetylchitobiose, possibly functioning as exochitinases in vivo, were found in the juice of the fruit tissue, but not in the wound exudate. The late-harvested, less resistant fruit consistently exhibited higher levels of these activities than did the early-harvested fruit. Other distinguishing factors which were also higher in late-harvested than in early-harvested fruit, both at harvest and throughout storage, included total (free) titratable acids, tissue water potential, and total soluble solid concentration. Factors which were higher in the late- than in the early-harvested fruit when freshly harvested, but which did not continue to differ significantly during storage, included sucrose and citric acid contents, and capacity of seed to germinate.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428094

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effect of postharvest fumigation and controlled atmosphere (CA) storage on fruit quality of two nectarine (Prunus persica(L.) Batsch var.nectarina(Ait.) Maxim.) cultivars was investigated. ‘Redgold’ and ‘Fantasia’ nectarines were either not fumigated or fumigated with 64 g/m3methyl bromide for 2 h at 12°C, and then cool-stored for up to 6 weeks in air or CA. The main effects of CA storage on non-fumigated ‘Redgold’ and ‘Fantasia’ nectarines were to retard softening and loss of green colour, to maintain soluble solids concentration (SSC), and to delay onset of storage disorders such as mealiness and internal breakdown. Fumigation retarded fruit softening, lowered SSC, and increased the severity of mealiness and internal breakdown in nectarines stored for more than 3 weeks. It did not significantly affect flesh colour development CA storage did not alleviate the effect of fumigation on SSC or the severity of internal disorders. Fumigated ‘Redgold’ nectarines, stored in either air or CA, showed signs of skin damage after 2 weeks of storage; damage increased in severity with length of time in storage. With ‘Fantasia’ nectarines, skin damage was found only in fruit that had been forced-air-cooled and CA-stored immediately after fumigation.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428095

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Fifteen sequences of sunlight exposure and exclusion were imposed on fruit of ‘Granny Smith’ apple (Malus domesticaBorkh.) by covering individual fruit with opaque paper bags. Fruit were harvested at commercial maturity and fruit background colour, blush, soluble solids concentration, flesh firmness, and starch pattern index were measured. The following year, seven of the same sequences were repeated and fruit colour was measured at 10-day intervals beginning from fruit drop until commercial harvest. A strong linear relationship between fruit colour lightness and hue (visually perceived colour) was evident in both years. Fruit became lighter as greenness decreased while an increasing yellowness only slightly increased lightness. Longer durations of light exclusion resulted in lighter coloured fruit, but for a given duration of shading, fruit exposed 1 month before harvest were lighter than fruit which remained shaded until harvest. All fruit became lighter in colour with time, although the rate at which fruit became paler was increased by profound shading. The incidence and severity of blush was highest on fruit from which light had been excluded for more than 2 months and then re-exposed 1 to 2 months before harvest. Exclusion of light depressed the soluble solids concentration slightly, although flesh firmness and starch index were unaffected.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428096

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effect of calcium (Ca) concentration on the firmness of kiwifruit during cool-storage was investigated by (a) postharvest dipping of fruit in CaCl2, and (b) comparing endogenous Ca and firmness of fruit which differed in one of the following orchard or fruit variables: fruit size; crop load; position of the fruit on the vine; exposure to sunlight during growth; and irrigation treatments. Postharvest dipping of kiwifruit in 2,3,4, or 5% CaCl2reduced the rate of fruit softening early in storage, resulting in fruit which were firmer after storage than control fruit. However, severe pitting of the fruit skin developed during storage as a result of dipping in 5% CaCl2. Total endogenous Ca levels in kiwifruit from several orchard sources ranged from 1.7 to 2.7 mg/g dry weight, but were not correlated with fruit firmness during storage. Furthermore, lines of kiwifruit which became particularly soft during storage had Ca concentrations similar to or even higher than lines of fruit which had remained firmer. These results are discussed in relation to the prediction of fruit firmness during storage, and the potential of developing commercial postharvest treatments for maintaining firmness of kiwifruit.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428097

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Five trials were conducted over 2 years to investigate the effects on growth of the nematicide Nemacur (400 g/litre fenamiphos) applied as a bareroot dip on four species of deciduous fruit trees, including nectarines, apricots, apples, and cherries. Nemacur concentrations of 0.1, 1.0, and 5.0% in solution (400, 4000, and 20 000 ppm a.i. respectively) were used in combination with dipping times of 10, 15, and 30 min. No change in growth was observed in apples or apricots bare-root dipped at any of these concentrations. However, growth retardation was observed in cherries at the 1.0% concentration, and in nectarines at all concentrations.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428098

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Individual replacement canes on kiwifruit vines were trained upwards on a Y-trellis (60° above horizontal), while control canes on the same vines were trained downwards on a T-bar (45° below horizontal). Training canes upwards during summer reduced the percentage of shoots which produced flowers in the following spring by 20%, whereas training canes upwards during winter or spring reduced the percentage budburst by 21%. Training all of the canes on a vine onto a Y-trellis reduced budburst, the number of flowers per cane, and the proportion of large fruit. In the following year, when all vines had been retrained onto T-bars, vines which had previously been on a Y-trellis flowered poorly. Budburst, the percentage of shoots with flowers, and the number of flowers per flowering shoot were all reduced. This resulted in a 58% decrease in the number of flowers per cane.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428099

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Some biological characteristics of seven pistillate and three staminate New Zealand cultivars of kiwifruit (Actinidia deliciosa(A. Chev.) C.-F. Liang et A.R. Ferguson var.deliciosa) are described. Cultivars considered include the pistillate types ‘Allison’, ‘Bruno’, ‘Constricted’, ‘Elmwood’, ‘Gracie’, ‘Hayward’, and ‘Monty’, and the staminate types ‘Matua’, ‘Tomuri’, and ‘M51’. Characteristics described are: phenological phases; fruit yield and ‘commercial yield’; fruit maturity on the vine and during storage; vitamin C content, total acidity, dry weight, and sensory qualities of the fruit. Results show that ‘Hayward’, the commercially preferred cultivar, has a more acceptable flavour, a longer storage life, and a higher commercial yield than the other pistillate cultivars studied.

ISSN:0114-0671    

DOI:10.1080/01140671.1990.10428100

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor