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1.
Summary Potato plants of cvs Element and Mirka were artificially infected withV. dahliae in two greenhouse experiments. Leaf blade, petiole, aerial stem, subterranean stem, stolon and root mass were separately
harvested both when the canopy was still green and at maturity. After 4 weeks incubation, the plant tissue was air-dried and
the numbers of microsclerotia per mg tissue and per plant were determined.
The highest numbers of microsclerotia were observed in the haulm when harvest took place at maturity. Cultivar Element yielded
significantly more microsclerotia in the haulm than cv. Mirka, whilst there were no cultivar differences in the microsclerotial
production on subterranean parts. The petiole and the aerial stem contributed most to the total microsclerotial production,
whereas roots were much more important for formation of microsclerotia than stolons. 相似文献
2.
A series of field trials combining cultivars with different levels of resistance to Phythophtora infestans and different haulm killing methods was conducted in 1997, 1998 and 1999 to assess the contamination potential of the haulm.
In addition, the frequency of tubers with late blight was assessed after harvest and storage, combining effects of pretreatment
infection, infection by the haulm at harvest and the development of the disease during storage. Haulm killing was performed
by diquat (200, 400, 600 g a.i. ha-1), half cutting of the haulm in combination with diquat (100, 200, 300 g a.i. ha-1) or full cutting of the haulm. In those treatments where haulm killing was performed purely chemically the haulm remnants’
contamination potential tended to increase at reduced doses. Full mechanical destruction gave as low a contamination potential
as application of the full dose of chemical haulm killer. However, there were no consistent differences between the haulm
killing treatments in the frequency of blighted tubers after harvest and storage. This indicates that the input of chemical
haulm killers may be reduced. There was a large difference between years in tuber blight after harvest and storage, which
confirms that climatic factors are of major importance for tuber infection. The large difference found between the cultivars
in the frequency of tuber blight indicates that tuber resistance should be an important part of integrated late blight disease
management. 相似文献
3.
Summary A two year field experiment was conducted twice to assess effects of chemical soil disinfection at planting and methods of
harvesting potatoes on stem infection withRhizoctonia solani in the subsequent year. In the first year of the experiments seven methods. including one with soil disinfection at planting,
were applied in August. In the following year,R. solani stem and stolon infection (disease severity) on potato plants were assessed in June. Soil treatment at planting with pencycuron
resulted in lowest disease severity in the following year. Compared with chemical haulm killing and haulm pulling. immature-crop-harvesting
also resulted in a lower disease severity, but only when black scurf was scarce on tubers at harvest in the preceding year. 相似文献
4.
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
5.
Ulla Bång 《Potato Research》1989,32(1):101-112
Summary Various haulm treatments and harvest times differentially influenced the incidence of storage rots in potato tubers (Solanum tuberosum L.) in field experiments in Sweden performed over 4 years. The incidence of gangrene caused byPhoma foveata Foister (Phoma exigua var.foveata (Foister) Boerema) increased in cv. Bellona after spraying haulms with diquat as did the amount of infection caused byFusarium avenaceum (Corda ex. Fr.) Sacc. in all three cultivars (Bintje, Bellona, and Magnum Bonum). The lowestP. foveata infection levels occurred after pulling haulms. Late harvesting increased the frequency ofP. foveata in cvs Bintje and Bellona both at 2 and 4 wks interval between haulm treatment and harvest. Tuber and visible stem infection
caused byP. foveata were correlated for cvs Bintje and Bellona, but not for cv. Magnum Bonum. The possible relation between tuber and stem infection
is discussed. 相似文献
6.
Ulla Bång 《Potato Research》1991,34(4):429-441
Summary The incidence ofP. foveata in soil and tuber samples from field experiments often increased significantly as the harvest season progressed and temperatures
fell. Mean levels of tuber and soil infestation were significantly higher in irrigated rows compared with those artificially
sheltered from precipitation, both at normal and late harvest dates.
Soil infestation was most frequently detected within 10 cm of the parent tuber. No pycnidia were visible on the haulm, and
very few latently infected stem segments and leaves were detected using various methods.
In three out of four years, the incidence ofP. foveata in tubers after wounding was reduced by washing them gently in tap water immediately after harvest. 相似文献
7.
P. Kastelein A. Bouman A. Mulder L. J. Turkensteen J. W. L. van Vuurde 《Potato Research》1996,39(1):31-42
Summary In the Netherlands seed potato crops are harvested when still green, the haulm being destroyed before harvest. We compared
the effect on the contamination of seed potatoes byErwinia carotovora subsp.atroseptica (Eca) andE. chrysanthemi (Ech) of the common method of haulm destruction by flailing and chemically destroying remaining stems, with the recently
developed green crop lifting method.
After chenical haulm destruction the levels of contamination with both Eca and Ech surviving cold storage were found not to
differ significantly from those after green crop lifting. Losses due to watery wound rot (Pythium ultimum) were considerable in the warm and humid conditions during 1991, especially after green crop lifting. 相似文献
8.
Summary In 1983 and 1984 there were reports in Norway of more severe late blight infection than usual on tubers of cv. Pimpernel,
a cultivar without R-genes known to be somewhat resistant to both haulm and tuber infection. Results from routine tests confirmed
earlier experience that cv. Pimpernel shows stable resistance to tuber late blight, although the ranking of cultivars may
vary between years.
In experiments during three harvest seasons tubers of different cultivars were inoculated with isolates ofP. infestans obtained from stocks of cv. Pimpernel with severe tuber late blight and with other isolates. In these experiments the isolates
from cv. Pimpernel caused more rot on tubers of Pimpernel than did other isolates. 相似文献
9.
Seed tubers that are planted soon after their harvest give low yields because of dormancy and low growth vigor. In the research reported in this paper, we investigated the advancing effect of a haulm application of gibberellic acid (750 g GA/ha) 6 days before haulm pulling and its interaction with storage temperature regimes on the growth vigor of immaturely harvested seed tubers of three cultivars. The effects on tuber yield were also examined in one experiment. The storage regimes were: 18 C continuously, hot pre-treatments of different duration (different periods at 28 C and subsequently 18 C) and a cold pre-treatment (20 days at 2 C and subsequently 18 C). Both a foliar spray with GA and storage at 28 C enhanced physiological aging of the tubers and greatly advanced the growth vigor, without negative effects on the morphology of the plants. There was a clear interaction between the GA treatment and the storage temperature regime. At early planting, the effect of the treatments on tuber yield were small for Diamant (short dormancy), but strongly positive for Désirée and Draga (long dormancy). 相似文献
10.
Between 1963 and 1976 a population of South American Andigena potatoes was subjected to six cycles of recurrent selection at Ithaca, N.Y. for adaptation to North Temperate conditions. This research was undertaken to measure the changes in adaptation and earliness that have taken place in the process of selection. Field experiments with different harvest dates and a controlled daylength experiment in the greenhouse in Ithaca showed: 1) an increase in percent tuberization, tuber weight and size, and harvest index; 2) no change in total fresh weight (haulm + tuber); and 3) a decrease in fresh weight of haulm. Greatest differences among cycles of selection were observed at the early harvest date. Tuberization on cuttings was well correlated with other measures of maturity. Cycles three and four, which were started from open-pollinated seed, tended to “revert” to the form of the original population in terms of late maturity (or low tuberization and yield at the early harvest date) and low harvest index. These results are interpreted as a gain in photoperiod adaptation and earliness with possible effects of mating system and selection pressure on the rate of progress. 相似文献
11.
K. Scholte 《Potato Research》1989,32(1):65-73
Summary The effect ofStreptomyces spp. (netted scab) on the growth of potato was investigated in three pot experiments, in two of which the effect ofVerticillium dahliae was also assessed.
The netted scab organisms attacked all underground plant parts of susceptible potato cultivars early in the growing season;
the roots were especially seriously attacked, markedly reducing tuber yield and number but prolonging the duration of the
growing season. The nematicide oxamyl had little effect on the incidence of netted scab. Repeated growing of the susceptible
cv. Bintje greatly increased soil contamination with the netted scab pathogens.
V. dahliae reduced haulm growth before wilt symptoms were evident and it reduced tuber yield but not number. Oxamyl delayed infection
byV. dahliae by controlling parasiticPratylenchus nematodes (mainlyP. thornei). 相似文献
12.
The changes in dry matter (DM) yield, botanical composition and nutritive value of herbage to ruminants of two wet grasslands, Arrhenatherum elatius grassland (Experiment 1) and a Molinia caerulea fen meadow (Experiment 2), in which a range of cutting and fertilizer treatments were imposed in 1999, were assessed after 4–7 years of treatment imposition. Both experiments had a split‐plot design with four replicates. In Experiment 1 the three main‐plot cutting treatments were two cuts with a delayed first cut, three cuts and four cuts during the growing season of each year. In Experiment 2 the cutting treatments were two cuts with a traditional harvest time, two cuts with a delayed first cut and three cuts. The four sub‐plot fertilizer treatments were an unfertilized control, application of a phosphorus and potassium (PK) fertilizer, application of a nitrogen (N) and PK fertilizer to the first cut only (N1PK) and application of PK plus N applied to each of two, three or four cuts (Nc PK). Application of fertilizer influenced yield and botanical composition of herbage more than the cutting treatments while the opposite occurred for nutritive value of the herbage. Application of fertilizer increased the proportion of tall grasses in Experiment 1 and forbs in Experiment 2. The proportion of Equisetum palustre, present only in Experiment 1, was reduced from 0·33 to less than 0·01 by increased cutting frequency together with the NPK fertilizer treatments. In Experiment 1 diversity of vascular plants was negatively affected only by the four‐cuts treatment while on both wet grasslands other cutting and fertilizer application treatments had no effect. Changes in DM yield of herbage caused by the cutting and fertilizer application treatments were similar for both vegetation types with DM yield increased significantly by fertilizer application but only slightly or not reduced by increasing the cutting frequency. Nutritive value of herbage was positively correlated with cutting frequency and was most influenced at the first cut. 相似文献
13.
L. E. R. Dawson R. M. Kirkland C. P. Ferris R. W. J. Steen†‡ D. J. Kilpatrick†‡ F. J. Gordon†‡ 《Grass and Forage Science》2002,57(3):255-267
Abstract Two experiments were carried out in consecutive years to examine the influence of cutting date and restricting fermentation by carboxylic acid treatment on the nutrient intake from grass silage by beef cattle. In year 1, four cutting dates during July and August after a primary growth harvest and, in year 2, five cutting dates of primary growth between mid‐May and early July were examined. Herbage was ensiled either untreated or treated with high levels of acid additive (‘Maxgrass’, mean 8·6 l t?1). Ninety‐six (year 1) or forty‐eight (year 2) continental cross steers were used in partially balanced changeover design experiments with each silage type either unsupplemented or supplemented with 4·5 (year 1) or 5·5 (year 2) kg concentrates head?1 d?1. Silage digestibility declined significantly between initial and final harvest dates (P < 0·001), whereas silage dry‐matter (DM) and digestible energy (DE) intakes were significantly higher in the initial compared with final harvest dates in both years of the study (P < 0·01). Similarly, silage DM and DE intakes, and total DM intakes, of acid‐treated and unsupplemented silages were greater than those of untreated and concentrate supplemented silages, respectively (P < 0·001). The results indicate that earlier cutting dates, and addition of acid to herbage before ensiling, can increase silage DM intake by beef cattle. 相似文献
14.
Six experiments were carried out in two climatically different regions in south‐east Norway in order to compare different procedures for autumn management and use of regrowth in seed crops of timothy (Phleum pratense L.) cv. Grindstad. The experiments were laid out after seed harvest in mid‐August in crops with a stubble height of 5 cm (two experiments) or 12–15 cm (four experiments). Cutting to 5 cm on 15 September or 15 October, with or without an application of 50 kg N ha?1 immediately after seed harvest, and with or without an additional application of 30 kg N ha?1 after cutting, were compared with an uncut and unfertilized control treatment. As a main effect,autumn cutting increased seed yield in the subsequent year in only one experiment; this was laid out in a 13 cm stubble on a fertile soil near the coast. In the remaining five experiments seed yields were unaffected byautumn management regardless of climate or stubble height. Autumn cutting and N application increased the number of seedheads in two experiments, but this was offset by a drop in other seed yield components. On average for two cutting dates and for plots receiving an application of 50 kg N ha?1 after seed harvest, the dry matter (DM) was 1430 kg ha?1 on an inland site with 12–15 cm stubble, 1400 kg ha?1 on a coastal site with 5 cm stubble and 2460 kg ha?1 for two coastal sites with 12–15 cm stubble. Whereas forage yield and quality were fairly stable from the first to the second cut at the inland site, the yield of DM increased, but the crude protein and energy concentrations decreased from 15 September to 15 October at the coastal sites. It is concluded that the stubble and regrowth in seed crops of timothy cv. Grindstad can be harvested for forage without any effect on seed yield in the next year. 相似文献
15.
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
16.
The nutritive value of berseem clover (Trifolium alexandrinum L.) may be influenced by changes in the nutrient concentrations of morphological fractions as a consequence of cutting treatment. The aim of this study was to evaluate the effects of different cutting treatments on the nutritive value of herbage and leaf and stem components in two Mediterranean berseem genotypes during growth in order to develop management approaches for harvesting forage with a high nutritive value. Spring growth of genotypes of Egyptian (cv. Giza 10) and Italian (cv. Sacromonte) origins was harvested in each of 2 years beginning 196 days after sowing and thereafter every 6 days (twelve harvests in total) to measure dry matter (DM) yield and nutritive value. Cutting treatments were initiated at sixth internode elongation (A) and early flowering (B) and there was an uncut control treatment (C). In vitro digestibility of organic matter (IVOMD) and crude protein (CP) concentration were determined for leaf, stem and total forage of each cultivar at each harvest. For both cultivars, in the uncut treatment (C), DM yield increased linearly to a maximum of 14 800 kg ha?1, on average, by 250 days after planting, the same time at which stem DM accumulation peaked, whereas the nutritive value, in terms of IVOMD and CP concentration, declined with age, coinciding with a reduction in leaf:stem ratio (LSR) from 1·00 to 0·30. Plant parts differed (P < 0·01) in nutritive value with stems being of lower nutritive value than leaves, in the two cutting treatments. There were strong positive correlations between LSR and herbage IVOMD and CP concentration, in both cutting treatments, indicating that, during growth, part of the changes in IVOMD and CP concentration of berseem clover plants was due primarily to the changes in the LSR. Defoliation induced a considerable reduction in DM yield, but an increase in the LSR and a small increase in nutritive value. Plants cut at the sixth internode elongation (A) showed a small proportional decrease (0·19) in total DM yield, but higher LSR values and similar or higher IVOMD and CP concentration than initiating cutting at early flower (B). Delaying defoliation to the early flowering stage (B) increased the proportion of stems and, therefore, decreased nutritive value. Therefore, harvest management in which cuts are applied at the stage of sixth internode elongation appears to be the most favourable for obtaining relatively high yields of forage with high nutritive value in berseem clover grown in Mediterranean regions. 相似文献
17.
Summary In a glasshouse experiment three potato cultivars were grown to maturity in wet or dry compost. The number of lenticels per
tuber was greater with larger tubers but was unaffected by the cultivar or soil moisture regime. The frequency of lenticel
penetration by a water soluble stain, safranin O, remained high as tubers developed to maturity in wet soil. In dry soil penetration
declined markedly as the tubers matured. When tubers, harvested just before the onset of haulm senescence, were inoculated
withErwinia carotovora ssp.atroseptica, the frequency of lenticel rotting was less than the rate of stain penetration, indicating that additional factors were involved
in the bacterial infection process. Inoculating mature tubers with bacteria and incubating them in anaerobic conditions frequently
resulted in rotting of the lenticels. Comparable tubers incubated in aerobic conditions showed no rotting or invasion by bacteria.
The results are discussed in relation to the biological control of blackleg. 相似文献
18.
《Crop Protection》1988,7(5):327-331
The effects of solarization, metham-sodium (12·5 or 25 ml/m2) and combined action of the two treatments (soil solarization plus metham-sodium) on the viability of Verticillium dahliae (VD) and Fusarium oxysporum f. sp. vasinfectum (FOV) added to field soil were compared in two successive field experiments. In both experiments solarization combined with metham-sodium was more effective in destroying both pathogens as compared with solarization or metham-sodium alone. In the earlier experiment, when soil temperatures were higher, soil solarization and combined treatments were more effective in controlling VD and FOV than in the later experiment. The effect of metham-sodium on V. dahliae microsclerotia was studied in open and sealed containers incubated at 25° and 35°C. The fumigant dose required to kill 50% of the microsclerotia at 25°C was four times higher at 25°C than at 35°C. Toxicity of the chemical was similar in open and sealed containers. This and field experiment results suggest that the higher toxicity observed under plastic cover in the field is due to synergistic interaction between solarization and metham-sodium. Combined solarization and metham-sodium killed more propagules more quickly than solarization alone; these results suggested that the period over which effective solarization can be used is longer than previously thought and that the time needed to solarize the soil for control of these pathogens is less. 相似文献
19.
Verticillium wilt, caused by the soil-borne fungus Verticillium dahliae, is one of the most important diseases of potato in North America. Soil incorporation of alfalfa residues prior to planting potato could be a nonchemical Verticillium wilt management tactic by reducing the number of viable microsclerotia in field soil. Verticillium dahliae microsclerotia were quantified in field soils where organic material from alfalfa was incorporated, and numbers of microsclerotia were compared to fields where alfalfa residue was not incorporated. In addition, bacterial metagenomics was utilized to characterize soils where organic material from alfalfa was or was not incorporated to determine if alfalfa residue incorporation facilitates the formation of soils that suppress or kill V. dahliae microsclerotia. The number of V. dahliae microsclerotia in soil was greater (P = 0.0003) in fields where crop residue was incorporated than fields without incorporation when chloropicrin was used as a fumigant. Conversely, the number of V. dahliae microsclerotia observed in potato plants did not differ (P = 0.4020) between fields where residues were or were not incorporated if chloropicrin was used. Alfalfa residue incorporation did not significantly alter the soil bacterial metagenome compared to fields not subject to residue incorporation in both years of study. Despite these conclusions, the method can be employed to analyze the effect of grower practices with the intent of linking a field practice to increasing soil bacterial diversity and decreasing Verticillium wilt severity on potato. 相似文献
20.
刈割后施氮对冬小麦再生植株干物质积累、氮素吸收及产量的调控效应 总被引：1，自引：0，他引：1
为了解冬小麦刈割后的氮素调控作用,在温室控制条件下,以冬小麦品种陇育2号为材料,在分蘖期刈割后施氮0、0.1、0.2、0.3、0.4 g·kg-1土（分别用N0、N1、N2、N3、N4表示）,探究了冬小麦刈割后干物质积累、氮素吸收和产量对不同施氮水平的响应。结果表明,与N0处理相比,刈割后施氮使小麦拔节期和开花期的叶面积指数提高90%~155%（P<0.05）。施氮处理延长了小麦生长旺盛期3~6 d,促进了干物质积累,其中N2处理干物质积累量增加129%（P<0.05）,并且提高了穗部干物质的分配比例。施氮提高了开花期茎部可溶性碳水化合物含量,其中N2处理的增幅达到39%（P<0.05）。冬小麦各器官氮素含量均随施氮量的增加而增加,刈割后施氮使氮素转运效率提高6%左右（P>0.05）,氮素收获指数提高10%~15%（P<0.05）。施氮处理的籽粒产量、穗粒数、有效穗数和收获指数较N0处理增加显著（P<0.05）,且以N2处理效果最好,说明0.2 g N·kg-1土是冬小麦刈割后良好生长发育、高产、稳产、氮素高效利用的最佳施氮水平。[JP] 相似文献