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1.
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
2.
Summary The effect of fungicides and the antagonistic fungusTrichoderma harzianum (Th) on the potato leak pathogenPythium aphanidermatum (Pa) was investigated in vitro. Rot was reduced by 73% to 89% when tubers inoculated withPa were treated by immersion in solutions (0.5% w/v) of the fungicides Ridomil MZ58. Dithane M45. Manebe 80 and Tachigaren 360.
Complete protection was achieved by dusting inoculated tubers with Ridomil MZ58 diluted in kaolin at a final concentration
of 0.1% (w/w). The biological treatments of dipping inoculated tubers in a conidial water suspension ofTh at 108 conidia/ml or of dusting with a mixture of a barley culture ofTh and kaolin to a final concentration of 2×109 conidia/g were as effective as the chemical treatments. Control was still effective when inoculated tubers were treated with
Ridomil MZ58. Tachigaren 360 or the conidial suspension ofTh after 24h incubation at 25°C. 相似文献
3.
4.
Summary The effect of adding gypsum (CaSO4) to growing media on the resistance toErwinia carotovora subsp.atroseptica (van Hall) Dye of potato (Solanum tuberosum L.) stems and mother and daughter tubers was examined in field and glasshouse experiments. The decayin situ of inoculated mother tubers from field plots treated before planting with gypsum was significantly delayed compared with
tubers sampled from non-amended plots. Blackleg development was also significantly delayed in the gypsum-amended plots; however,
for both mother tubers and stems the increased resistance associated with the application of gypsum later disappeared. Stem
resistance tended to be related to tissue calcium and magnesium concentrations which were higher in plots treated with gypsum
than in untreated plots. Daughter tubers produced in plots amended with gypsum generally contained a higher concentration
of calcium in their cortex and were more resistant to decay byE. carotovora subsp.atroseptica but the effect was not consistent. 相似文献
5.
Summary Preplant soil solarisation and mouldboard ploughing to a depth of 30 and 60 cm respectively were evaluated in two field experiments
for the control ofColletotrichum coccodes causing black dot of potato. Solarisation reduced disease incidence by 45% when tarping was done for eight weeks and temperatures
reached 56°C in the top 5 cm of soil. With a six week tarping period and lower maximum temperature (50°C) the reduction in
disease was a nori-significant 25%. Mouldboard ploughing to a depth of 30 cm reduced black dot by 34% and was twice as effective
as ploughing to a depth of 60 cm. 相似文献
6.
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
7.
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
8.
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
9.
S. H. De Boer J. D. Janse D. E. Stead J. Van Vaerenbergh A. R. McKenzie 《Potato Research》1992,35(2):207-216
Summary An indirect sandwich enzyme-linked immunosorbent assay (ELISA) was used to monitor potato stems of three cultivars for the
presence of the ring rot pathogen,Clavibacter michiganensis subsp.sepedonicus, during the growing season and in progeny tubers after harvest. The highest ELISA values were obtained with the highest concentration
of bacteria used to inoculate seed pieces in all cultivars tested. Low ELISA values were obtained for stems and progeny tubers
selected from plants grown from seed inoculated at lower bacterial concentrations. Estimates of bacterial densities in stems
and progeny tubers by immunofluorescence indicated that low ELISA values were most probably caused by low bacterial numbers.
It is suggested that the sensitivity of ELISA for detecting the ring rot pathogen in potato stems and progeny tubers is a
function of the concentration of bacteria in individual seed pieces. 相似文献
10.
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
11.
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
12.
S. H. De Boer J. Van Vaerenbergh D. E. Stead J. D. Janse A. R. McKenzie 《Potato Research》1992,35(2):217-226
Summary Potato stems and tubers grown in the field from seed tubers inoculated withClavibacter michiganensis subsp.sepedonicus, which causes bacterial ring rot, were tested by indirect, sandwich enzyme-linked immunosorbent assay (ELISA) in five laboratories.
Correlation between values for each experimental treatment from the five laboratories was greater (r=0.86) than correlation between values for individual samples (r=0.71). When three or more laboratories obtained ELISA values of ≥0.200 for a sample, that sample was presumed to be positive.
Conversely, when three or more laboratories obtained ELISA values <0.200, the consensus determination was regarded as negative.
The percentage of stem and tuber samples that were in agreement with the consensus ELISA determination varied from 65.5 to
96.7%. Indirect immunofluorescence tests, conducted on the same samples in two laboratories, were consistent with 83.4–91.9%
of the consensus ELISA determinations. Presence or absence ofC.m. sepedonicus was confirmed in some samples by an eggplant bioassay and direct isolatiion of the bacterium. The ELISA procedure was well
suited for screening large numbers of samples and this study confirms it to be a promising procedure in routine indexing of
seed potatoes forC.m. sepedonicus. 相似文献
13.
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
14.
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
15.
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
16.
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
17.
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
18.
Summary A reverse of the delaying effect of gibberellic acid (GA3) was observed in in vitro tuberization of potato plantlets when the medium contained 0.8×10−5 M jasmonic acid (JA). The promoting effect of JA seemed to be correlated with the initial absence of growing roots, probably
through direct activity of JA in microtuber-producing buds in the stoloniferous shoots. This is based on the fact that JA
did not inhibit root growth a posteriori. Endogenous gibberellins (GAs) synthesized by roots did not interfere with the previous
activity of JA in tuberization. The absence of a JA promoting-effect on tuberization of previously-rooted plantlets could
be related to the capacity of potato roots to synthesize endogenous GAs which might antagonize the JA effect on buds of stoloniferous
shoots. 相似文献
19.
Summary Over 2 years, seed tubers or stems were inoculated withFusarium sulphureum Schlecht. (F. sambucinum Fuckel f. 6 Wollenw.) and the incidence of dry rot on daughter tubers assessed by standardised wound tests. The amount of
stem and soil inoculum was also measured in one year.
Inoculating stem bases resulted in greater concentrations of spores on the stem bases, greater soil populations at harvest
and more dry rot on tubers than inoculating the seed tuber. Overall, the incidence of dry rot and the amount of stem and soil
inoculum was similar for the three methods of haulm destruction: cutting and removing the stems, applying sulphuric acid or
applying diquat dibromide to the growing plants. 相似文献
20.
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