Effects of Root Temperature on the Nitrogen metabolism of muskmelon (Cucummis melo L.)

• Main Authors: Guo, Jain-Rong, 郭建榮
• Other Authors: Ching-Yih Chen
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/55060679165492022833

碩士 === 國立中興大學 === 植物學系 === 84 === The aim of this study was to elucidate the effects of the different root temperatures (35, 25, 15 degree )on growth and nitrogen metabolism of muskmelon (Cucummis melo L.) under the hydroponic system. Examinations on the changes of the physiological characterics under different root temperatures including biomass, photosynthetic rate, respiration rate, stomatal conductance, content of free amino acid, soluble, and the enzyme activities of NR, NiR, GS, GOGAT,GDH, and Rubisco. The results were summarized as follows: The decreasing of root temperature resulted in the decreasing of photo-synthetic rate, respiration rate, Rubisco activity and total dry weight in leaves. The lowest root temperature inhibited the absorpting of nutrition onplant growth. Undeer 15 degree root temperature treatment, the content of total solubleprotein was lowest in both roots and leaves. Furthermore, the activities ofNR and NiR were lowest in root, but highest in leaves. The reason may be an increasing in the flow rate of nitrate into leaves. Therefore, the assimilation of nitrogen increasing in leaves on low temperature. In higher plants, ammonina is mainly assimilated by GS and GOGAT pathway which produces glutamine andglutamate. The low temperature inhibited GS/GOGAT activities in roots. Thereforethat is favorable to ammonium assimilation in leaves. Our results showed that indeed asparagine was the highest content among 20amino acids in leaves and roots of all root temperature treatments. In fruit growth period, the transmitting of asparagine is very important from leaves and roots. For this reason, changes in amino acids content and composition of sink (fruit) was more important than the effect of root temperature.