| Summary: | 碩士 === 國立嘉義大學 === 園藝學系研究所 === 105 === In the cultivation condition of high relative humidity (RH) and low ventilation, the specific cultivars of Phalaenopsis (P.) are easy to perform the guttation, subsequently leading to sooty mold disease and other diseases. This study investigated the guttation of virus-infected P. cultivars from various physiological indexs and observed the histological changes on guttation site between virus-infected and healthy plant. To establish the protocol of off-guttation for P. cultivars, the different relative humidity (RH) and density treatment were used and the cell membrane thermostability (CMT) were analyzed. The plant of Doritaenopsis (Dtps.) I-Hsin Ice Coke and P. Sogo Yukidian ‘V3’ in 10.5 cm pot were used as materials for virus inoculation experiment, inoculation of Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) through tissue leaf disc and top irrigation inoculation methods, and then cultivated in high temperature (31℃) and high RH (90%-95%). Two inoculation treatments showed similar pattern on the guttation fluid during 10 weeks. The volume of guttation fluid became stable on P. Sogo Yukidian ‘V3’ at 4th week, and showed the bell-shaped curve on Dtps. I-Hsin Ice Coke which gradually decrease after 6th week, respectively. Especially, the tissue leaf disc treatment caused serious guttation on P. cultivars. To investigate the effect of different virus, such as CymMV, ORSV, and the combination of both, infected through tissue leaf disc on P. cultivars, the plantlet of P. Big Chili and P. Sogo Yukidian ‘V3’ in 7.5 cm pot were used as materials. With the time after inoculation increased, the volume of guttation fluid also increased on P. cultivars. The treatment of CymMV-only on P. Big Chili, and ORSV-only on P. Sogo Yukidian ‘V3’, not only demonstrated the highest fluid volume at 10th week, but also had 3.87 mg and 6.08 mg weekly secretion amount per plant, respectively. From circadian rhythm of P. to realize secretion volume after inoculated 10 weeks, ORSV-only P. Sogo Yukidian ‘V3’ and CymMV-only P. Big Chili, both of them has the highest volume (3.87 mg and 5.1 mg volume per plant) at 10 a.m., and also has its (4.3 mg and 4.25 mg volume per plant) at 10 p.m., respectively. The effect of guttation on SPAD value of P. cultivars was also evaluated. The SPAD value of P. cultivars decrease with the time after inoculation. The SPAD value of virus-free plant was maintained between 70 and 80, and the virus-infected plant was reduced to between 55 and 68. The SPAD value of the 1st and 2nd expand leaf and the guttation fluid volume at 10th week has a significant negative correlation. It means that the lower SPAD value of the leaves may be accompanied by the more serious guttation fluid of the P. cultivars. The result of RT-PCR reveal the high positive correlation between circadian rhythm guttation fluid and the CymMV virus quantity of the P. Big Chili. The result of soft material slice of light microscopy (LM), cryo-scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal the difference between stomata of the virus-free and virus-infected plants was that the chloroplast of the virus-infected plants was disappeared and the deformation of the guard cells and its subsidiary. It is presumed to cause the changes osmotic pressure of the stomata, so that the stomata can not be closed properly and forms the guttation of Phalaenopsis. The method to improvement of the guttation of Phalaenopsis (planted in 7.5 cm pot) was suggested to improve the environment as relative humidity of 60%-70% RH and 80 plant·m-2 that not only reduce the guttation fluid secretion of Phalaenopsis effectively but also keep the higher fresh weight relative growth rate and enhance the cell membrane stability of the leaves to same as virus-free plants.
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