ナタネ子実の油脂生成に関する生態的研究
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概要
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In the cultivation of rape, the oil content of seed must be regarded as a important factor as well as the seed yield. This studies aimed to research the basic materials in relation to cultivating technic and breeding for the increase of oil production, and were concerned with the ecological changes of the oil formation in rape seed under various conditions during seed development. I. Relation of oil formation to the morphological development of seed under several condition (1) In autumn seeded rape, oil formation was accelerated especially in later half period during seed development, and continued untill 55 days after flowering when dry weight of seed reached maximum. Iodine value and refractive index of oil decreased as seed matured. (2) The flowering period continued for about a month in autumn seeded rape, and therefore, as flowering was later, the rate of development of pod, seed and embryo and of oil formation became more rapidly. But oil content of seed was lower in later flowering. It was confirmed that iodine value of oil decreased as seed matured. (3) In spring seeded rape at the high land, the rate of seed development and oil formation was extremly promoted because of high temperature even at the early stage of seed development. But the seed harvested had very low oil. Iodine value of oil, which was very low at the earliest stage of the oil formation, increased rapidly until the middle stage, and then decreased gradually. (4) It was clarified that oil formation in rape seed was closely combined with the development of seed, especially of embryo or cotyledon in which oil was synthesized and accumulated. The difference in the change of iodine value between autumn and spring seeded rapes was discussed. It was suggested that percent constitution of each fatty acid during oil formation was both influenced by the environmental and hereditable factors. II. Influence of natural environmental conditions on the oil formation of seed (1) It was confirmed experimentally that high temperature during seed development decreased the yield and oil content of seed. (2) When 50% of the natural sun light was shaded during seed development, oil content of seed decreased about 10%. Shading from 30 to 15 days before maturation most profoundly effected on the oil content and yield of seed. (3) Excessive soil moisture decreased both the oil content and yield of seed. Under dry condition of soil, oil content was not lower than under moderate condition, but seed yield decreaced remarkably. (4) Year variation of oil content in rape seed was evident in similar variety at similar station. Relationship between this variation and weather condition of each year was discussed. Relatively low temperature, much sunshine and moderate precipitation during seed development may be favourable both for the high yield and the high oil content of seed. III. Influence of cultivating conditions on the oil formation of seed (1) Oil content of seed was low on the area of high soil productivity, and was high on the area of low soil productivity. There was no significant difference in oil content between areas where soil productivity was shown to be uniform. It was considerable that available nitrogen was rich in such high productive soil. (2) With the increase of nitrogen application, seed yield increased and oil content of seed decreased. In this case, increased application of potassium fertilizer with nitrogen did not decreased the oil content. (3) The oil content of seed tended to behigher in direct sowing cultivation than in transplanting. Effect of delay in sowing time on the oil content of seed seemed to be variable owing to the weather conditions during growing season and the varieties. Early type may be preferable in oil content to the later type under various conditions. Density of sowing had a little effect on the oil content of seed.
- 1963-03-31