The analysis of factors in which the superfluous applied potassium suppresses photosynthetic rate of the leaves and sugar production of sugarcane.

本研究阐明了甘蔗根系吸收土壤中积累的过量钾素，以及高钾含量导致叶片光合速率下降的原因。在此基础上，研究了甘蔗渣炭对甘蔗糖分含量和产量的影响，结果表明，甘蔗茎鞘细胞NADP-ME和Rubisco活性降低，光合速率降低，镁的吸收受到抑制，表现为竞争性的抑制。并探讨了钾在农业可持续发展中的可能性。甘蔗渣炭钾含量丰富，研究了钾的不同投入对甘蔗生长和品质的影响。使用甘蔗渣木炭以使其成为10、30、50 g/1 Kg土壤。施肥每周一次给予改良Hoagland溶液培养基（每盆500 ml），并适当进行喷洒。种植后第5个月，测定甘蔗的茎长、茎重、出汁中的元素成分和含糖量。结果，证实了甘蔗渣炭中所含的钾被甘蔗吸收。甘蔗渣炭处理对甘蔗吸钾量的改变对甘蔗的生长和品质没有影响，因此被认为是钾肥的替代品。因此，通过甘蔗渣木炭改善土壤物理性质，有望减少甘蔗的肥料用量。

In this study, the factor that the root of sugarcane absorbed the superfluous potassium which accumulates in the soil and that the decreased photosynthetic rate of leaf due to the higher potassium content was clarified. As the process, it was clarified that the photosynthetic rate was decreased with the lowering of NADP-ME and Rubisco activities of bundle sheath cell through the lowering of magnesium of which the absorption was suppressed for rivalry like.In addition to the above-mentioned result, the effect of the bagasse charcoal on sugar content and yield of sugarcane was investigated, and the possibility of sustainable agriculture in concerned with the potassium was also examined. The potassium was abundantly included for the bagasse charcoal, and the effect of the difference of the input on growth and quality of the sugarcane was examined. The bagasse charcoal was used in order to become 10, 30, 50 g per 1 Kg soil. The fertilization gave modified Hoagland Solution culture medium once a week (500 ml per pot), and the sprinkling was properly carried out. Fifth month after planting, the stem length, stem weight, elemental component in juice extraction and sugar content of cane were measured. As the result, it was confirmed mat the potassium which is included for the bagasse charcoal was absorbed to the sugarcane. The bagasse charcoal was regarded as becoming the substitution of the potassium fertilizer, because the change of potassium uptake quantity by the bagasse charcoal treatment did not give growth and effect in the quality of the sugarcane. Therefore, it was clarified that the reduction of the fertilizer of sugarcane could be expected with the improvement on the soil physical property through the bagasse charcoal.