Abstract
This study were conducted to investigate the influence of chilling on photosynthetic rate, root activity, contents of total sugars and fatty acids of cucumber seedlings grown in a greenhouse. Even though photosynthetic activity of seedlings exposed to $0^{\circ}C$ for 5 hours was little or insignificantly influenced, it was reduced by 52.8% and 67.7% in seedlings exposed to the same temperature for an extended 10 and 24 hours, respectively. Photosynthetic rate decreased significantly when seedlings were illuminated, as compared to continuously held under darkness, during 15 hours of chilling treatment at 3$^{\circ}C$. Recovery of photosynthetic ability was also retarded by illumination during a recovery period after chilling treatment. Root activity, as measured by the oxidation power of $\alpha$-naphtylamine, was significantly reduced by chilling treatment at 0 to 6$^{\circ}C$, but amount of bleeding xylem sap collected at 40 days after chilling treatment was not significantly different among treatments. Total sugar content increased by 12 and 23% as compared to the control in seedlings chilled for 24 hours, respectively, at 3$^{\circ}C$. Contents of unsaturated linolenic and oleic acids increased, while content of saturated palmitic acid decreased with chilling treatment.
겨울철 시설내에서 정전 등으로 인하여 수시간 동안 작물체가 생육한계 온도로 경과시 이오묘에 나타나는 피해와 피해발생의 생리적 요인 및 경감대책을 구명하기 위하여 저온 스트레스가 이이묘의 광합성 및 생리반응에 미치는 영향을 연구한 결과는 다음과 같다. 냉온처리($0^{\circ}C$)는 무처리에 비한 오이묘의 광합성량이 10시간 처리는 52.8%, 24시간 처리에서는 67.6% 감소시켰으나, 5시간처리는 무처리와 큰 차이가 없었다. 냉온처리 기간중의(3$^{\circ}C$, 15시간)광조사는 암상태에서 보다 광합성을 크게 저해시켰다. 냉온처리 후 회복기간 중에 암조건을 주면 광합성량이 다소 회복되었으나 광조사시에는 회복되지 못하였다. 0~6$^{\circ}C$ 범위내의 냉온처리는 무처리에 비해 뿌리활력을 유의하게 감소시켰고, 냉온처리 40일후 채취된 오이줄기의 일비액량은 처리간 유의차를 보이지 않았다. 냉온처리(3$^{\circ}C$)시 전당 함량은 무처리에 비해 24시간 처리에서는 12%, 48시간 처리에서는 23% 증가되었다. 한편 냉온처리에 의하여, 불포화지방산인 linolenic acid와 oleic acid는 증가되었으나, 포화지방산인 palmitic acid는 감소되었다.