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991.
A.H. Marshall T.P.T. Michaelson-Yeates M.T. Abberton A. Williams H.G. Powell 《Euphytica》2002,126(2):195-201
Interspecific hybridisation with Trifolium nigrescens Viv. is a possible strategy to improve the reproductive potential of white clover (Trifolium repens L.). Following the development of a fertile F1 hybrid, three generations of backcrossing have been carried out usingT. repens as the recurrent parent. Vegetative characteristics, stolon growth and seed yield components of the backcross (BC) 2 and
3 generations, as well as the parental species were measured on spaced plants grown in the field. Leaf size and plant spread
of the BC2 and BC3 generations were less than T. repens but there was no difference in plant fresh weight. Numbers of inflorescences per plant and florets per inflorescence of the
backcrosses were greater than T. repens however this was not reflected indifferences in seed yield per plant asT. repens had more seeds per floret and per plant than the backcrosses. Differences in stolon length, the proportion of flowering nodes
and the pattern of axillary bud development were observed between T. repens and the backcrosses. Significant variation among the BC 3 generation for vegetative and reproductive traits was observed.
Individual plants among the BC 3 generation were identified that combine high forage yield, substantial inflorescence production
and good fertility, and these will form the basis of further selection.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
992.
A yellowish brown‐seeded Brassica alboglabra was resynthesized from a (B. alboglabra×Brassica carinata) ×B. alboglabra cross, followed by self‐pollination. The resynthesized B. alboglabra lost the allele of the isozymic locus glucosephosphate isomerase‐2 (GPI‐2) from natural B. alboglabra, which was replaced by an allele from the corresponding genome in B. carinata. A simple Mendelian segregation of these two alleles was observed in the F2 population of a natural × resynthesized B. alboglabra cross. Furthermore, these two alleles segregated independently from the seed colour. 相似文献
993.
Summary An investigation was made of factors affecting the frequency of development of fertilized ovules following wheat x Hordeum bulbosum hybridizations. Seed survival, a term used here to represent the relationship between seed set and fertilization, was shown to vary between the wheat genotypes tested, but was unrelated to the crossability genes present within the wheat genotype. A high seed survival was obtained in crosses involving the variety TH3929 and the single chromosome substitution line, Chinese Spring (Hope 5B). Chinese Spring showed a poor seed survival. Some influence of the H. bulbosum genotype on seed survival was detected. The two environmental factors studied, namely the post-pollination application of gibberellic acid and the ambient temperature, were both shown to affect seed survival. The application of gibberellic acid immediately after pollination or 1 and 2 days after pollination improved seed survival, although the extent of the response was dependent upon the number and timing of the application(s). A genotype-dependent response to the ambient temperature was observed, TH3929 showing a slight but insignificant reduction and Chinese Spring a significant improvement in seed survival with an increase in temperature from 20°C to 26°C. The physiological processes which may be influenced by GA and the ambient temperature and may thereby affect seed survival are discussed. 相似文献
994.
M. O. Akoroda 《Euphytica》1990,49(1):25-32
Summary Studies during 1980–1987 relating to seed production of the fluted pumpkin (Telfairia occidentalis Hook. f.) are summarized. Essentially, the dioecious nature of the crop makes sex-ratios of plants affect the number of fruit-bearing females. Overall, about 50% of plants are female, of which some 15% are fruitless. Each fruit-bearing female has 1.5 fruits that contain 60 seeds. The mean weight of seeds is 15 g, and 74% of this total seed weight comprise the seed kernel which contains about 40% oil. Thus, a yield estimate of seed kernels reaches 1.9 t/ha; an output that is superior to that of most other oil seeds now being exploited for seed oil and cake in Nigeria. Measures to raise seed yields and the possibility of breeding work are discussed. 相似文献
995.
趋势面分析在滑坡防治工程设计中的应用 总被引:1,自引:0,他引:1
滑坡治理工程的设计主要依据滑坡面及滑体方量,滑坡的上表面一般很容易得到,而下表面则可以根据地形图中等高线来确定,但是要得到准确的滑坡面则相对较难,常用的方法是选择适当的个别点进行钻探,测得该点处滑坡厚度,再由此模拟滑坡面。以四川省古蔺县蔺双公路K1+100滑坡的滑动面(带)为例,采用多元统计的趋势面分析方法将滑坡面模拟成空间的一个曲面,求出曲面后则可计算滑坡推力、设计相应的加固方法,还可以通过滑动曲面计算滑坡的总方量。 相似文献
996.
通过分析最新的水土保持监测所获得的实地植被调查样方资料,论述了植被自然恢复在开发建设项目中的水土保持作用,并结合监测实践,探讨了植被自然恢对水土保持评价指标的影响。(1)在山西省雨量较为充沛的地区,如果重视保留表土并用之覆盖地表,就能使地面植被得到较大程度的自然恢复,其恢复面积占可绿化面积的比例约达25%。(2)在雨量较多地区的扰动地面,依靠植被自然恢复功能,可使植被盖度在1~2a内达到50%以上,形成初级植被。(3)由于对乔灌木等深根性植物的破坏较为严重,因此,在1~2a时间内,扰动地面上自然恢复所形成的植被一般为草本群落,并不能完全恢复当地的灌草植被、疏林灌草植被。 相似文献
997.
中国种业机械化现状调研与发展分析 总被引:1,自引:10,他引:1
种业机械化是种业现代化的重要基础和前提,是涵盖品种选育、品种试验、制种生产、种子加工等多环节的系统工程。为了系统梳理中国种业机械化发展成果与存在问题,有效推进种业机械化发展、促进种业现代化建设,该文从田间试验机械化、制种生产机械化、种子加工机械化等方面阐述了国内种业机械化现状调研情况和国际种业机械化发展经验,分析了中国种业机械化存在的主要问题:种业装备企业普遍规模小、装备差、科研投入少,整体水平与国外存在较大差距,装备功能有待扩展、结构设计有待优化、现代化控制水平有待提高等;提出了种业机械化研究重点:1)主要农作物品种试验机械化关键装备研究;2)主要农作物制种生产机械化关键装备研究;3)主要农作物种子低损高效精细加工技术集成研究。指出了"规模化、标准化、集约化、机械化"种子生产是现代种业持续、健康发展的重要保障和基本发展方向。 相似文献
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