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Summary Ulluco (Ullucus tuberosus) is a vegetatively propagated crop plant that flowers abundantly but sets only few seeds. We examined if the low seed/ovule ratio can be explained by morphological abnormalities in ovules, embryo sacs or embryos. In 35 clones growing in the actual area of cultivation in Ecuador and in 5 clones grown in Finland flowers were analysed by clearing technique. About half of all analysed clones contained ovules and embryo sacs whose development was arrested, in two clones there were embryo sacs whose cell patterns were abnormal and in four clones there were double embryo sacs. There were both normal and abnormal ovules and embryo sacs in the same plant. Genetic load is suggested to be one of the causes for the low sexual fertility found in ulluco. It may be incapable of maintaining homeostasis of development of the ovule and embryo sac in a varying environment. The occurrence of developmental abnormalities should be studied in each clone intended for inclusion in traditional breeding programmes. 相似文献
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Severe rot of stem bases caused by Pythium aphanidermatum was found on ulluco (Ullucus tuberosus) grown in Kagawa Prefecture, Japan, in September 1999. The name “foot rot of ulluco” is proposed for this new disease.
Received 14 November 2001/ Accepted in revised form 7 January 2002 相似文献
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Leena Pietilä 《Euphytica》1995,84(2):127-131
Summary Pollination experiments were carried out on ulluco (Ullucus tuberosus), known as a very poor seed producer. All the clones used were diploids. The effect of self-vs. cross-pollination was studied in Experiment 1. Caged selfpollinated flowers produced no seeds. Different clones produced seeds in 0–8% of caged cross-pollinated flowers and in 5–19% of cross-pollinated non-caged flowers. Ulluco is thus basically an outbreeder.Experiment 2 studied whether seed set is limited by pollen availability. Total seed number per inflorescence number did not differ between plants treated with supplemental pollen and control plants; pollen availability thus did not limit seed set. The treated plants, however, produced more seeds in cross-pollinated than in other flowers on the plant, and the control flowers on treated plants produced fewer seeds than those on the control plants. In the treated plants, resources may have been allocated to artificially cross-pollinated flowers at the expense of other flowers. In some clones, seed set after artificial cross-pollination was at a level practicable for breeding work. 相似文献
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Summary The paper deals with variations in enzyme pattern in the seeds of ulluco, Ullucus tuberosus. Six seeds per clone, four clones and three enzyme systems (malate dehydrogenase, glutamate oxaloacetate transaminase and 6-fosfoglucose dehydrogenase) were examined. There was variation in enzyme pattern between the seeds of a single clone. It is concluded that ulluco is not an apomictic species but a truly sexual one. Consequences of these findings for breeding programmes of ulluco are pointed out. 相似文献
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Summary Ulluco, Ullucus tuberosus, is a tuber crop plant with a reduced ability to produce botanical seed. This paper discusses problems related to the botanical seed set of ulluco. Ten clones of this species were studied, and the number of seeds per plant was recorded. Enhancement of seed production was attempted by the application of three growth regulators; gibberellic acid, CCC, and a synthetic cytokinin, 6-benzylamine purine. Seed set ability was shown to vary between the clones, and the application of plant growth regulators did not enhance seed production. Variation in fruit weight was observed. Because of genetic variation between clones in their ability to set seed, it is proposed that there is a possibility of breeding ulluco using botanical seeds. However, methods for improving the yield of botanical seed need to be developed. 相似文献
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