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991.
992.
In Colombia, Streptomyces scabiei (syn. S. scabies) is commonly believed to be the causal organism of scab disease in local potato crops. However, very little is known about this organism and about the diversity and pathogenicity of the Streptomyces species associated with potato crops in Colombia. This study, therefore, aimed to elucidate aspects regarding the diversity of these bacteria associated with potato crops in a particular region of Colombia and evaluate their pathogenicity. We obtained 33 isolates of Streptomyces from netted, superficial and deep-pitted potato scab lesions from two main potato-producing regions in Colombia. Of these, 17 were pathogenic based on in vitro and in planta assays. None of these isolates carried the txtA, txtB, or nec1 genes, commonly associated with pathogenicity in Streptomyces, and characteristic of the pathogenicity island (PAI). We also characterized all isolates based on phenotypic characteristics and analysed their phylogenetic relationships using the 16S rRNA, atpD, recA, rpoB, and trpB genes. The isolates were highly diverse, placed in nine clades with 15 different phenotypes. The 17 pathogenic isolates were placed into three clades, namely S. pratensis, S. xiamenensis, and unknown species. This study is a preliminary investigation towards understanding scab disease in Colombia through the study of both pathogenic and nonpathogenic species present in scab disease lesions in potatoes. Also, this is the first report of Streptomyces species associated with potato tubers in Colombia. 相似文献
993.
Stephen L. Love Timothy J. Herrman Asunta Thompsonjohns Timothy P. Baker 《Potato Research》1994,37(1):77-85
Summary Potato tuber glycoalkaloid content was measured in response to nitrogen fertilizer rate, storage temperature, length of storage
period and cultivar. Cvs Gemchip, Norchip and Russet Burbank were grown with applied nitrogen fertilizer rates of 0, 168 or
336 kg/ha and then stored at either 4.4 or 10°C. Total glycoalkaloid content was determined one month before harvest, at harvest,
after three months of storage and after nine months of storage. Higher rates of nitrogen, higher storage temperature and a
period of storage all resulted in significantly (P<0.05) higher concentration of glycoalkaloids. The cv Norchip had higher glycoalkaloids than cvs Gemchip or Russet Burbank.
Only the storage period had more influence than the environment (difference between years). Significant (P<0.05) two-way interactions were detected for year x cultivar, year x nitrogen, storage period x cultivar and nitrogen x cultivar.
Most interactions were due to the unique responses of cultivars. 相似文献
994.
对转Aclnv反义基因马铃薯品系的相对电导率、丙二醛含量(MDA)和超氧化物歧化酶(SOD)活性进行检测.结果表明:转基因"大西洋"品系的相对电导率显著低于受体品种,且C2代的MDA含量显著低于受体水平;转基因"台湾红皮"品系相对电导率和MDA含量与受体品种无显著差异;Aclnv反义基因的导入对"大西洋"和"台湾红皮"两个马铃薯品系的SOD含量影响不大.对转Aclnv反义基因马铃薯品系过氧化物酶同工酶谱带分析表明,转Aclnv反义基因马铃薯品系与受体亲本存在明显的变异. 相似文献
995.
Summary Sprouts of cvs Arran Chief, Pentland Kappa and Golden Wonder were inoculated with fresh wart tissue using the Glynne-Lemmerzahl
(GL) method and results of tests carried out using five different incubation regimes were compared. When tubers of Arran Chief
and Pentland Kappa were incubated uncovered in the light. rotting of sprouts was reduced and there was more extensive development
of summer sporangia. Similar results were obtained on a range of cultivars when inoculations were done using summer or winter
spores. Winter spores, which germinate freely in distilled water, can readily be extracted from dried rotted wart tissue to
provide a reliable and continuous supply of inoculum. At the Scottish Agricultural Science Agency, wart susceptibility testing
using the GL method has been done with winter spores since 1987. 相似文献
996.
Antje Moll 《Potato Research》1994,37(1):11-20
Zusammenfassung Die Wachstumskapazit?t (GC=g Spross- plus Wurzelmasse pro Knolle nach 20 Tagen bei 22°C) beschreibt im Verlauf der physiologischen
Alterung eine Optimumskurve. Das Maximum der Wurzelmasse wurde in der Regel früher durchlaufen als das Maximum der Spross-
bzw. Gesamtmasse. In 2 Jahren konnten Sortenunterschiede für die Alterungsrate in der Lage des Optimums der GC auf der physiologischen
Zeitachse, in der Breite des optimalen Bereiches der GC und in der H?he der GC direkt nach der Beendigung der Dormanz festgestellt
werden.
Summary The following test was carried out in two years: during physiological ageing, samples of 15 tubers of each of eight cultivars were desprouted, planted into a mixture of compost and peat, and placed in darkness at a temperature of 22°C. Averaged over cultivars, the number and length of sprouts increased with increasing physiological age of the seed tubers until a maximum was reached. Beyond this, a slight decline in the number of sprouts was observed (Fig. 1a,b). With advanced physiological age, the diameter (Fig. 1c) and dry-matter content (Fig. 1d) of the sprouts decreased. However, these characteristics could not be used to monitor differences in the rate of physiological ageing between the potato cultivars. The growth capacity (GC=sprout and root mass) (g) per tuber after 20 days at 22°C) showed an optimum in the course of physiological ageing (Fig. 3). Root mass reached optimum levels earlier than sprout mass (Fig. 2) and in most cases also earlier than the total mass (Fig. 3). Despite year-to-year variation cultivar differences in the rate of ageing could be noted from the timing of the GC optima (based on temperature sum), from the maximum values of GC and from the GC values immediately after the end of dormancy. For three pairs of cultivars the differences in rate of physiological ageing—as observed in field trials—were confirmed by differences in growth capacity in the laboratory tests (Figs. 2, 3a, 3c). For one pair of cultivars the laboratory test did not predict the different behaviour in the field (Fig. 3b).相似文献
997.
Summary The effect of environmental conditions on seed tuber production from true potato seed (TPS) in nurseries was evaluated in
different growing periods during two seasons in Egypt. In the autumn season, high soil and air temperatures reduced emergence
and initial foliage development of early-sown seedlings, and decreased tuber yields. In late-sown seedlings low night temperatures
and short daylengths caused early tuberization, poor foliage development and low tuber yields. In the spring season, low temperatures
and short daylengths resulted in a slow initial foliage development and early haulm-tuber competition for assimilates in early-sown
seedlings. However, tuber yields were higher than for late-sown seedlings, presumably because net assimilation and assimilate
partitioning to the tubers were impaired by above optimum air and soil temperatures in May and June. Slow development of true
seed-sown plants caused a high sensitivity towards adverse environmental conditions and would limit yielding ability in Egypt. 相似文献
998.
P. C. Struik M. F. Askew A. Sonnino D. K. L. Mackerron U. Bång E. Ritter O. J. H. Statham M. A. Kirkman V. Umaerus 《Potato Research》1997,40(1):5-18
Summary The highlights and achievements of 40 years of potato research in agronomy; genetics, breeding and varietal assessment; physiology;
pathology (including nematology); virology; engineering; and utilization are reviewed and the prospects for new developments
are analysed. In all disciplines progress has been impressive and has changed the potato industry dramatically. Yet, some
old problems remain unsolved (Phytophthora infestans, blackspot) or are returning (cyst and other nematodes) and new problems have arisen (e. g. volunteer potatoes, new strains
of PVY, virulent cold-resistant strains ofPseudomonas solanacearum). The potato industry faces new challenges from society (environmentally safe production) and the consumers (improved quality).
Farmers, researchers and processors have access to many new exciting techniques, tools and opportunities, such as precision
farming, genetic engineering, molecular detection and analytical techniques, integrated chain management, novel preservation
and processing methods. The problems and opportunities both warrant a continued effort in potato research. 相似文献
999.
D. C. E. Wurr C. C. Hole Jane R. Fellows Jane Milling J. R. Lynn P. J. O'Brien 《Potato Research》1997,40(3):297-306
Summary Five experiments studied the effects of shading, temperature and stolon growth medium on stolon and tuber formation. The lowest
numbers of stolons and tubers were produced at the higher and lower nodes. Numbers of primary stolons and tubers were relatively
stable across nodes and treatments and variation in total numbers was largely due to changes in numbers of lateral and branch
stolons. In the field, 70% shading reduced numbers of stolons and tubers by reducing lateral and branch stolons, while in
hydroponics, 45% shading and temperatures at initiation had no effect on tuber numbers. In both environments later planting
tended to reduce numbers of stolons and tubers. There were large effects of the physical environment, with compost producing
three times as many tubers as dry vermiculite. The potential number of tubers may be determined by the number of stolons and
the environmental conditions affecting stolon formation and development. 相似文献
1000.
Summary Field-grown tubers of 22 progenies ofSolanum tuberosum L. generated in a crossing programme involving seven parents differing in resistance toFusarium coeruleum Lib. ex Sacc. andF. sulphureum Schlect. (=F. sambucinum Fuckel, teleomorphGibberella pulicaris (Fr.) Sacc.) were wound-inoculated with a cornmeal + sand culture of each pathogen. Parental genotypes were also included.
The mean lesion size of each progeny was compared in 2 years of tests, as well as with published data on glasshouse-grown
tubers. ForF. coeruleum there was a high correlation between years as well as with the glasshouse data, but no such correlations were apparent withG. pulicaris. Furthermore, parental and GCA values, as well as progeny means and mid-parent scores, also correlated highly forF. coeruleum but not forG. pulicaris.
Glasshouse-grown tubers of 11 wildSolanum spp. were also inoculated with both pathogens. Some resistance to one or other, or both, was apparent, particularly inS. chacoense. 相似文献