Two rice cultivars (Oryza sativa L.), Hwa-seongbyeo of Japonica type and Taebackbyeo of Indica/Japonica type, were cultivated with hydroponic culture to examine nitrogen effects on the growth responses, contents and utilizations of carbohydrates, and the ripening velocity of grains with three differ...
Two rice cultivars (Oryza sativa L.), Hwa-seongbyeo of Japonica type and Taebackbyeo of Indica/Japonica type, were cultivated with hydroponic culture to examine nitrogen effects on the growth responses, contents and utilizations of carbohydrates, and the ripening velocity of grains with three different N levels. Plant height and tiller number were clearly increased to 80 ppm N level compared to 40 ppm N level and then they were slightly decreased in N level of 120 ppm. Higher dry weights were appeared with 80 ppm N level than did with other N levels, showing statistically differences in both cultivars and N levels, while dry weight of roots was heavier with decreasing the N levels. Therefore, T/R ratios were not significantly different among N levels, although there was statistically differences between rice cultivars. After the flowering stage, higher water-soluble carbohydrate (WSC) and water-insoluble carbohydrate (WISC) were contained in stem compared with other parts, showing that WISC of sheath and stem, unlike WSC, was significantly different among N levels. Starch of grain, WISC, was remarkedly increased from 3.0% at just after the flowering to 52.0% and 75.0% at 15 and 30 day after the flowering, respectively, showing that lower N application had faster accumulation of starch in rice grains. N would affect the contents of carbohydrates of each tissue, and starch accumulation in rice grains.
Two rice cultivars (Oryza sativa L.), Hwa-seongbyeo of Japonica type and Taebackbyeo of Indica/Japonica type, were cultivated with hydroponic culture to examine nitrogen effects on the growth responses, contents and utilizations of carbohydrates, and the ripening velocity of grains with three different N levels. Plant height and tiller number were clearly increased to 80 ppm N level compared to 40 ppm N level and then they were slightly decreased in N level of 120 ppm. Higher dry weights were appeared with 80 ppm N level than did with other N levels, showing statistically differences in both cultivars and N levels, while dry weight of roots was heavier with decreasing the N levels. Therefore, T/R ratios were not significantly different among N levels, although there was statistically differences between rice cultivars. After the flowering stage, higher water-soluble carbohydrate (WSC) and water-insoluble carbohydrate (WISC) were contained in stem compared with other parts, showing that WISC of sheath and stem, unlike WSC, was significantly different among N levels. Starch of grain, WISC, was remarkedly increased from 3.0% at just after the flowering to 52.0% and 75.0% at 15 and 30 day after the flowering, respectively, showing that lower N application had faster accumulation of starch in rice grains. N would affect the contents of carbohydrates of each tissue, and starch accumulation in rice grains.
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제안 방법
This study was initiated to understand N effects on carbohydrate utilization and partitioning by evaluating the plant growth responses and determining the content of carbohydrates. The specific objectives were to examine the N effects 1) on relative rates ofleaf growth and tillering, 2) on the partitioning of dry weight to shoots and roots, 3) carbohydrate contents of plant tissues, leaves, stem, and panicle, and 4) on the velocity ofripening grain ofrice.
Growth of panicle was examined with the interval of 10 days after the flowering stage. Each plant tissue of leaf blades, leafsheaths, stem, panicles, and roots was investigated and sampled to check for the partitioning of the dry weights. T/R ratios were calculated through dividing the root dry weight to the shoot dry weight including leaves, sheaths, stems, and panicles.
성능/효과
Dry weight of roots of two rice cultivars at the flowering growth, stage was a little different in between two cultivars and among three N levels without showing the differences statistically. However, it was slightly decreased with increasing the application amount of N fertilizer in both genotypes, which Hwaseongbyeo had heavier dry weight of roots than Taebackbyeo had.
Based on these results, the dry weight ofshoot of two rice cultivars including the leaves, sheath, stem, and panicle was averagely about 47.6 and 38.8 g/hill in Hwaseongbyeo and Taebackbyeo, respectively. With three different N degrees, it of Hwasseongbyeo was about 53.
Both the WSC contents of different tissues and the changes of WSC contents with different ripening growth stages were similar tendency in between two rice cultivars. It could be assumed from this results that the sink activity, i.e. the ripening velocity of nee grain, was the highest at 15 day after the flowering compared to either that at the flowering or that at 30 day after the flowering. On the another words, it means that the photosynthates of source would be translocated to the grain very fast at 15 day after the flowering, while they would be translocated slowly from source to sink at both the flowering and 30 day after the flowering.
Number of grain per panicle was not appeared differences in between rice cultivars and among three N degrees. The rate of ripened grain was increased with decreasing the application amount ofN fertilizer; the ripening rates of grain in Hwaseongbyeo were about 84.6,75.9,72.6% with 40, 80, 120 ppm N levels, respectively. They in Taebackbyeo were about 79.
Unlike the plant height, the number of tillers of both rice cultivars at the flowering growth stage were increased with raising the application amount of nitrogen, from 40 to 120 ppm, except for it of Hwaseongbyeo with the N level from 80 to 120 ppm, showing decreasing a little number oftillers. There were no significant differences in the number oftillers between two rice cultivars, although their numbers oftillers per hill of Hwaseongbyeo and Taebackbyeo were averagely about 16.3 and 15.7, respectively, appearing slightly differences between two rice cultivars.
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