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1.
D. L. Jennings 《Euphytica》1959,8(2):157-162
Crosses between Manihot melanobasis and cassava were very fertile and the fertility was maintained in the hybrids. The first and subsequent generations of these crosses were very high yielding. Undesirable features of the early hybrids included a straggling habit and thin stems which yielded poor planting material, a high hydrocyanic acid content in the roots, and low virus resistance: all these were rectified by further breeding. Although M. melanobasis has a high protein content in its roots it is uncertain whether this character can be transmitted to its progeny.It is concluded that M. melanobasis is a very valuable source of new genes for cassava improvement. 相似文献
2.
Histologically, the cassava pistil is trilocular with a single ovule in each locule producing a maximum of three seeds in nature. Heat stress (35°/45°C, night/day temperatures), as a physical treatment was attempted to induce useful reproductive and vegetative traits in 10 F1 hybrids derived from ‘OMR 36‐41’and ‘OMR 36‐42’crosses, and two Asian cassava cultivars,‘Rayong 60’and ‘Rayong 1′, under greenhouse and field conditions. Cytoembryological examination of the repro‐ ductive organs revealed morpho‐structural features of normal pistil in all clones except ‘Rayong 1’which exhibited reproductive variations under greenhouse culture. Genetically, an important variation was ovule dichotomy per locule of the trilocular pistil so that each pistil contained six instead of the usual three ovules and lacked any outer integument. These ovules possessed functional embryo sacs with varying nuclear number. A pair of the dichotomous ovules possessed two embryo sacs of apparent different megaspore mother cells. Vegetatively, F1 hybrids were dwarf (0.50m) in their phenotype and flowered 1 month earlier than the 1.5‐2.0m tall cultivars under greenhouse conditions. 相似文献