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1.
M. K. Van Ittersum 《Potato Research》1992,35(3):261-269
Summary The variation in duration of dormancy within a seed tuber lot was studied over three years by harvesting individual plants
of cvs Diamant and Désirée from field plots and by storing the tubers at 18°C. The variation in dormancy within a tuber lot
was large (especially for cv. Diamant) and was mainly caused by variation within plants.
For cv. Diamant there was a close negative relation between dormancy and the cube root of tuber weight, whereas for cv. Désirée
a relation with tuber weight was almost absent.
The duration of dormancy of a seed lot comprising tubers with a narrow range in weight can be well described by two parameters.
It is proposed to maintain the moment of 80% sprouting as the criterion for the end of dormancy of a tuber lot and to characterize
the spread in dormancy duration by the time lapse between 10% and 90% sprouting. 相似文献
2.
Summary A heat balance method for measuring sap flow in actively growing plants was tested on three potato (Solanum tuberosum L.) cultivars Monona, Norchip and Atlantic. The method is based on applying a known heat source to the stem of an intact
plant: by measuring the axial and radial heat dissipation the magnitude of sap flow can be quantified. The technique shows
promise as 24 h accumulated sap flow measurements were highly correlated (r2=0.935, n=36) with gravimetric measurements of transpiration and produced an average root mean square error (RMSE) of 20 g
d−1. The accuracy of the method improved as daily accumulated flow increased. Under low daily flow rates overall RMSE increased,
supporting the need for a heat storage term in the heat balance equation. Short term flow rates were less significantly correlated
(r2=0.764, n=1572) and produced an average RMSE of 2.89 g h−1. Identification of these short term flow rates during high flow periods may be difficult. The presence of water potential
gradients and the likelihood of re-hydration during high flow events may have also affected the short term performance of
the method. At low flow rates, many different errors may be introduced. 相似文献
3.
Effect of inorganic nitrogen nutrition on cytokinin-induced potato microtuber production in vitro 总被引:1,自引:1,他引:0
Summary The effect of inorganic nitrogen nutrition on the induction and development of microtubers by cytokinin-induced tuberization
was studied in four potato genotypes belonging to different maturity groups. The objective of this study was to investigate
whether a reduction in total nitrogen level in the Murashige & Skoog medium would improve cytokinin-induced tuberization rate.
The effect of three levels of total nitrogen (15, 30 and 45 meq) on tuberization was studied at constant (20 meq K) and varying
potassium levels approximating to 5, 10 and 15 meq. Reducing the total nitrogen supply increased the number but decreased
the size of nitrogen level on the rate of assimilate partitioning (harvest index) during cytokinin-induced microtuberization. 相似文献
4.
Summary The relationships between the number of initial sprouts, the number of main stems, stolons and tubers per plant are depicted
in 4-quadrant figures. The number of sprouts per seed tuber varied because of different pre-sprouting conditions and/or because
of the use of different cultivars. Good linear relationships are shown between the numbers of sprouts and stems, stolons and
tubers, and sprouts and tubers, but especially between stolons and tubers within each trial with the one cultivar. When comparing
different experiments with the one cultivar the linear relationship between the numbers of stems and stolons disappeared.
When comparing different cultivars, no relation was found between the numbers of sprouts and stems. These two cases also led
to a statistically less significant relation between the number of sprouts planted and the number of tubers harvested. 相似文献
5.
C. M. Menzel 《Potato Research》1985,28(2):263-266
Summary In potato (Solanum tuberosum L., cv. Sebago), benzyladenine (BA) promoted tuberization at high day/night temperatures (32°/18°C), while gibberrellic acid
(GA) and chlorethylphosphonic acid (CEPA) reduced tuberization at low day/night temperatures (22°/18°C). These results are
consistent with the hypothesis that temperature exerts its influence on tuber formation by altering the balance between endogenous
gibberellins, cytokinins and inhibitors, but not ethylene. 相似文献
6.
Summary TwoPythium spp. were isolated from diseased tubers exhibiting rots at harvest, in summer stores and also in refrigerated storage. Symptoms
shared features described for both pink rot caused byPhytophthora erythroseptica and leak caused byPythium spp.
The causal agents were identified asPythium aphanidermatum andP. ultimum by morphological and physiological observations and by fingerprinting using oomycete specific primers to amplify the internal
transcribed spacer (ITS1) within ribosomal DNAs. The optimum temperatures for infection were 30°C forP. aphanidermatum and 25°C forP. ultimum, corresponding to the optimum temperatures for growth in vitro. The optimum concentration for infection of tubers inoculated
by dipping in a suspension of oospores or hyphal swellings after wounding was found to be 103 reproductive organs/ml, whereas the infection threshold was 10 reproductive organs/ml. 相似文献
7.
Assessing progenies of potato for resistance to skin spot (Polyscytalum pustulans) in the glasshouse
Summary Crosses were made between six parents differing in susceptibility to skin spot and glasshouse-grown tubers from true seedlings
of the nine resulting progenies assessed for resistance to the disease. The assessment was evaluated by a two-year comparison
with the behaviour of field-grown tubers of the progenies and their parents. The correlations between progenies in the glasshouse
and field were r=0.911 and 0.753 and those between the mid-parental values and the progeny means were high (r>0.864), indicating
that parental differences were heritable. It is concluded that correlations were sufficient for glasshouse-grown tubers to
be used for assessing large numbers of progenies in genetical studies and for eliminating highly susceptible progenies at
an early stage in a breeding programme.
R.L. Wastie died 16.01.96. 相似文献
8.
Summary Tests for resistance toPhytophthora infestans were done twice in each of 2 years on field- and glasshouse-grown tubers of ten cultivars. The cultivar rankings, were almost
identical for the means of the four glasshouse tests and the means of the four field tests. However, for the field tests but
not for the glasshouse tests there were cultivar x harvest date and cultivar x year interactions. It is concluded that resistance
can be assessed on glasshouse-grown tubers and that such assessments should prove more consistent over years than those done
on field-grown tubers.
R.L. Wastie died 16.1.96 相似文献
9.
Summary Potatoes were stored in three insulated bins having ventilation rates of 0.0190, 0.0306 and 0.0417 m3/s·t. The results showed that in the climate of northern Italy potatoes can be stored successfully at ventilation rates of
not less than 0.0306 m3/s·t resulting in product weight loss of less than 2.0% after 100 days' storage. The incidence of diseases and of sprouting
was very low at rates of 0.0306 and 0.0417 m3/s·t, but greater at 0.019 m3/s·t because of the higher tuber temperature. Laboratory tests simulating ambient conditions confirmed the validity of a thermodynamic
model simulating air-potato heat exchange. 相似文献
10.
Summary The susceptibility of 21 potato cultivars to leak (watery wound rot) caused byPythium aphanidermatum was compared. Whole tubers were inoculated after wounding by dipping into a water suspension of 103 oospores/ml and incubated for 3 days at 25°C. The mean penetration of tissue calculated from the recording of lesion width
and depth and the qualitative assessment of rot extension were highly correlated. For 10 of 12 cultivars tested at least twice,
consistent reactions were obtained: cvs Korrigane. Superstar, Safrane and Yesmina were moderately susceptible, whereas Atlas,
Diamant, Mondial, Obélix, Spunta and Timate were susceptible to highly susceptible. Tubers originated from two locations and/or
two cropping seasons: thus, the performance of these cultivars under different production conditions reveals a satisfactory
level of agreement with the test. Moreover, ratings assigned are supported by field or store observations. 相似文献
11.
Helen E. Stewart J. E. Bradshaw R. L. Wastie G. R. Mackay Orly Erlich L. Livescu A. Nachmias 《Potato Research》1994,37(3):257-269
Summary Progenies from crosses between cultivars varying widely in resistance to early blight (Alternaria solani Sor.), were assessed for resistance as true seedlings in a glasshouse in Scotland. The resistance of a representative sample
of surviving genotypes from each progeny was compared with samples of the same progenies not previously exposed to the fungus,
both in the glasshouse in Scotland and in the field in Israel. The exposed population was more resistant. Resistance was identified
more effectively in adult plants from tubers in the glasshouse than in true seedlings and agreement between glasshouse and
field assessment was better when progenies were compared rather than individual genotypes. The mid parent and progeny mean
scores of the unexposed population were correlated at both sites, thus confirming that the resistance is heritable. Selecting
resistant individuals at the seedling stage is suggested as a useful tool for resistance breeding, having first chosen the
best parents for crossing. 相似文献
12.
Summary Potato cultivars Chieftain and Kennebec were prewarmed at 70°C for 15 min. prior to heating at 100°C for 18 min. in a water
bath. Chieftain exhibited a large increase in fracturability upon treatment while Kennebec showed a smaller increase. Pectic
substances of the two cultivars were sequentially extracted in water, sodium hexametaphosphate (0.5%), hydrochloric acid (0.05M, 50°C), and sodium hydroxide (0.05M, 5°C). The largest fraction isolated from both cultivars consisted of hydroxide-soluble pectic substances, and was followed
by the acid-soluble fraction. Chieftain contained significantly greater amounts of the hydroxide-soluble fraction than Kennebec.
Ion exchange chromatography revealed that the extracted pectic substances from the two major fractions consisted of a charged
pectin chain with attached neutral sugars. Gel filtration chromatography revealed wide molecular size distributions for the
isolated pectic substances. Pectic neutral sugar content for the hydroxide-soluble fraction (50% of total pectic substances)
was greater for Chieftain than for Kennebec. 相似文献
13.
D. Levy 《Potato Research》1986,29(1):95-107
Summary The effects of high temperatures and water deficit on potatoes were investigated under field conditions. Nine cultivars and
one un-named seedling were grown in the spring and in the summer under high temperatures. In both seasons the cultivars were
grown under 3 water regimes: adequate water supply, moderate water deficit, and severe water deficit that were achieved by
a modification of the single line source sprinkler irrigation system. Severe drought reduced tuber yields in both seasons.
Moderate tolerance to a moderate water deficit in the spring season was exhibited by Draga, Désirée, and Monalisa. Late and
intermediate cultivars produced high tuber yields in the spring season, and early cultivars had relatively smaller yield losses
in the summer. The extent of tuber disorders, sprouting, rotting and malformation, varied considerably. High temperatures
enhanced sprouting, rotting and malformation and drought may enhance sprouting and malformation.
This investigation was supported by a grant from the Ministry of Foreign Affairs, Technical Assistance Department, Netherlands. 相似文献
14.
K. Scholte 《Potato Research》1989,32(3):367-376
Summary The effects of soil-borneRhizoctonia solani on yield and quality of potato were studied by an extensive individual plant sampling procedure. From 1983 to 1986, stem
canker and stolon pruning were examined in 10 768 plants growing on a sandy soil. Tuber yield and quality and haulm yield
per plant were also recorded.
The degree of attack byR. solani depended on the cropping frequency of potato. Severe and very severe stem and stolon attacks decreased fresh yield, dry matter
yield and dry matter content of tubers and increased the number of deformed and small tubers, whereas the effect on haulm
yield and stem number was small.
Potato cultivars differed in susceptibility toR. solani, but yield response did not differ significantly between cultivars at the same levels of stem and stolon infection. 相似文献
15.
Changes in potato starch quality during growth 总被引:2,自引:0,他引:2
Summary Potato starch quality parameters (amylose concentration, glucose-6-phosphate content and granule size) were analyzed in relation
to the harvesting date and tuber size of four cultivars. A significant increase in the glucose-6-phosphate content and granule
size of starch was observed during tuber growth, whereas the amylose concentration was constant. Granule size increased markedly,
whereas glucose-6-phosphate content showed slightly increasing values with increasing tuber size. Amylose concentration showed
no correlation with tuber size. We conclude that the changes in the granule size, glucose-6-phosphate and amylose content
of potato starch during growth are independent of each other. 相似文献
16.
Barbara J. Christ 《Potato Research》1989,32(4):419-424
Summary Powdery scab incidence and severity was examined on six potato cultivars planted at two different dates in a naturally infested
field. There were two sub-plots; one where seed was exposed prior to planting to spores ofSpongospora subterranea from scabby peels, which were then added to the furrow at planting, and another where seed was exposed only to natural inoculum
within the field. The later planting data reduced incidence and severity, but there were no differences between sub-plots.
All cultivars became infected, but ‘Rosa’ was the most susceptible and ‘Katahdin’ the most resistant.
Contribution No. 1720, Department of Plant Pathology, The Pennsylvania Agricultural Experiment Station. Authorized for publication
September 22, 1988 as Journal Series Paper No. 8007. 相似文献
17.
Effect of haulm treatments on the formation of microsclerotia ofVerticillium dahliae Kleb. on potato
Summary In four pot experiments, potato plants of cv. Element were artificially infected withV. dahliae. At an early and a late harvest haulms were killed chemically, by burning or by various other treatments, including cutting
them into pieces of different lengths and keeping the debris on the soil surface or covering with soil. After 4 weeks the
plant material was air-dried and the number of microsclerotia per mg was determined.
At the early harvest, in two experiments, the chemical treatment yielded more microsclerotia than the cutting treatments.
Covering colonised haulm tissue with non-sterilised soil was effective in inhibiting microsclerotia formation. Shorter haulm
pieces led to fewer microsclerotia at the later harvest if the material was kept on the soil surface. The variation in microsclerotial
yield and in treatment effects among the different experiments was large. 相似文献
18.
Summary Factors affecting the volume expansion of potato cubes during puffing in a fluidised bed were examined. It was found that
puffing temperature, initial size, pre-drying time and puffing time influenced the degree of expansion of the cube during
the puffing step. Blanching alone was found not to influence expansion, but in conjunction with the other factors it was found
that blanched samples showed greater volume expansion than unblanched samples. The optimum conditions for maximum volume expansion
were found to be; blanching for 80 s, cube size between 7.5–12.5 mm, pre-drying time of 90 min. at 90°C and a puffing time
of 270s at 130°C. 相似文献
19.
Summary Potato crops in subtropical climates are often subjected to water stress, resulting in low yields and poor tuber quality.
The yield response of potato genotypes to water supply was investigated in six trials, three each in spring and autumn plantings.
Trials were conducted under automated rain shelters, using an irrigation boom to impose five soil water regimes.
The negative effect of water stress on tuber yield was more detrimental in spring than in autumn, because of higher atmospheric
evaporative demand and higher temperatures in spring. An average yield reduction of 68% was recorded for the most severely
stressed regime in spring plantings, while the mean reduction for the same treatment in autumn was only 42%. Genotypic differences
in yield response to drought were clearly illustrated in spring, but not in autumn. This suggests that the choice of genotypes
is only influenced by the availability of water in spring, when more drought tolerant genotypes should be used. 相似文献
20.
Summary The severity of late blight tuber rot in five potato cultivars (Green Mountain, Sebago, Dorita, AC Brador and Island Sunshine)
resulting from inoculation with US-1/US-8 combinations of Canadian isolates ofPhytophthora infestans was evaluated. In addition, the potential for mixed (A1∶A2) inoculations to result in oospore formation was examined. In
studies conducted in 1996 and 1997, cv. Dorita (and Island Sunshine in 1997) developed the least amount of surface or internal
necrosis relative to the other cultivars following co-inoculation with US-1 and US-8 isolates ofP. infestans. Differences also were revealed among isolate combinations used for inoculation. The combination of a US-1 isolate from Prince
Edward Island with a US-8 isolate from New Brunswick consistently produced the least amount of necrosis in tubers of the various
cultivars. There was no evidence of oospore production in any of the tubers examined.
AAFC Contribution No. 919 相似文献