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81.
Phytophthora root rot, caused byPhytophthora cinnamomi Rands, is the most important disease of avocado (Persea americana Miller). In an attempt to identify root rot-resistant rootstocks that could ultimately be used under conditions in southern
Florida, we screened open-pollinated progeny of avocado from the National Germplasm Repository in Miami. From 1996 to 1998,
a total of 2,355 seedlings from 51 accessions were examined in potting mix artificially infested withP. cinnamomi. Most seedlings developed severe root rot, but tolerance was observed in some families (i.e., progeny of certain accessions). Although the most susceptible families developed mean disease ratings of up to 97% root
necrosis, mean ratings for the most tolerant families were less than 60%. There was also a strong relationship between the
racial background of the female parent and the tolerance of seedlings. Seedlings of the West Indian race and hybrids between
it and the Guatemalan race were significantly more tolerant than those from other parents (P< 0.05). Individuals in several
families developed < 50% root necrosis, the arbitrary standard of tolerance in this study. Twelve families accounted for 82%
(188 of 229) of the tolerant seedlings, and only two of these did not have a West Indian or Guatemalan × West Indian pedigree.
Broad-sense heritability for PRR tolerance was 0.45. This is the first report on the inheritance of PRR tolerance in avocado
and on the influence of genotype and racial pedigree under controlled conditions. 相似文献
82.
油料向日葵根系生态与生理特性分析 总被引:2,自引:0,他引:2
长期以来对作物地上部分的结构功能和叶光系统进行了大量研究,对向日葵的根系发育规律的研究相对较少,盐渍化地区向日葵根系发育规律的研究就更少。为了有效地研究油料向日葵根系吸水过程和根系分布的关系,本文对向日葵根系生长发育规律和根系密度分布进行研究。 相似文献
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Armillaria species on tea in Kenya identified using isozyme and DNA sequence comparisons 总被引:1,自引:0,他引:1
E. Mwenje B. D. Wingfield M. P. A. Coetzee H. Nemato M. J. Wingfield 《Plant pathology》2006,55(3):343-350
The aim of this study was to identify seven Armillaria isolates obtained from diseased tea bushes in Kenya using pectic enzyme profiles, PCR-RFLP and IGS-I DNA sequence data. The combination of these identification methods confirmed the presence of three distinct Armillaria groups. One of these groups resembled Zimbabwean group I ( A. fuscipes ). The second group was phylogenetically closely related to A. mellea ssp. nipponica . The third group was different from all other African isolates examined, but had isozyme patterns, especially of pectin methylesterases (PMEs), similar to those of isolates related to A. mellea ssp. nipponica. Analyses of sequence data suggested that this group is phylogenetically closely related to A. hinnulea from Australia and New Zealand. 相似文献
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白头翁药理作用研究进展 总被引:7,自引:0,他引:7
综述了白头翁抗肿瘤、增强免疫功能、抗炎、抗病原微生物、抗寄生虫、保肝及毒性等方面的药理作用。 相似文献
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Current year shoot cuttings were collected in October and August from three growth habits of peach (Compact, Pillar, and Standard) and treated with one of four concentrations of indole butyric acid (0, 250, 1250, and 2500 mg L−1 IBA). Rooting response was measured after 5 weeks in the greenhouse. Little or no rooting occurred with cuttings from any growth habit that was collected in October or in August when treated with 0 and 2500 mg L−1 IBA. In August, the number of shoots that rooted was greater in cuttings from Pillar (79 and 45%) than Compact (13 and 3%) treated with 250 and 1250 mg L−1 IBA, respectively. Cuttings from Standard trees had intermediate rooting of 56 and 6% at 250 and 1250 mg L−1 IBA, respectively. Pillar trees consistently grew more roots with greater root length per cutting than the other growth habits. It is proposed that differences in rooting response among the growth habits may be associated with differences in endogenous auxin concentration that had been found in previous studies. Within peach and possibly other fruit trees, the capacity of shoot cuttings to develop adventitious roots can vary by cultivar and successful root induction with exogenous plant growth regulators may depend, in part, on endogenous hormone levels. 相似文献
90.