| Summary: | 碩士 === 中興大學 === 園藝學系所 === 95 === Experiments were conducted to evaluate the effects of difference ratio of potassium to calcium on plant growth, fruit yield and quality of cucumber ‘Hsia Di’ grown in soilless medium.
Results indicated that supplement of potassium to 270 and 350 mg/l in Shan-Chi solution had significant effects on increasing nitrogen and potassium contents in cucumber. Chlorophyll content, photosynthesis rates, stomatal conductance and water potential were enhanced as the potassium concentration in solution increased. As a result of physiology behavior of plant account for plant height, leaf area, dry weight and fresh weight were also increased. The photosynthesis rates, water potential and dry matter increased significantly on plants grown in higher potassium concentration. In the mean time, the Vit C.and total soluble solids contents had the similar tendency. It is postulated that, the osmosis adjustment of cells by the supplement of potassium may led to the increase of water retention capability, which subsequently decrease the membrane disinteqration caused by chilling injury.
The supplement of potassium at 350 mg/l and calcium at 205 mg/l in Shan-Chi solution had significant effects on increase electric conductivity and approach to salt injury at 4mS/cm. Plant growth, water potential, yield and quality of fruit were adversely affected in this treatment. However, the dry matter content and fruit firmness increased. The antagonist activity between K+ and Ca+ was observed and resulted in counteraction efficacy of potassium.
In conclusion, the supplement of potassium to 270 mg/l or 350 mg/l in soilless cultural nutrition solution had dramatic effects not only on the increase of nitrogen and potassium contents in cucumber but also on the enhancement of growth, yield and quality of fruit. Especially at the highest content of 350 mg/l potassium in nutrition solution. It is worthy of further study for the commercial production of vegetables of high yield and quality.
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