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KMID : 0380119820050000089
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Korean Journal of Ecology
1982 Volume.5 No. 0 p.89 ~ p.99
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Characteristics of CAM and Seasonal Dimorphism in the Succulent C_4 Dicot, Portulaca grandiflora Hook
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Abstract
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Morphology, anatomy and diurnal acid fluctuations were investigated monthly for the succulent C_4 dicot Porlulaca grandiflora Hook. growing under natural environmental conditions.
Modified Kranz-Type sturcture and typical CAM-like cells were shown in leaves and stems, respectively. Values of indices of mesophyll succulence in leaves and stems were 5.62 and 16.68, respectively. The number of stomata were 1476㎝^-2 in leaves while the stomata in stems were not observed through growing seasons from spring to summer. However, on Sep. 16, 1981 in defoliate autumn season, stomata were begun to be produced for the first time in stems and the number were increased gradually to 216㎝^-2 on Oct, 29. This feature can be interpreted as a seasonal plant dimorphism. P. grandiflora exhibited a diurnal fluctuation of titratable acidity in leaves and stems. Seasonal amplitudes of acid fluctuation in stems were as follows: 27 μeq./g.f.wt. on Sep. 21; 57 μeq/g.f.wt. on Oct. 3; 80μeq./g.f.wt. on Oct. 21. Such the results in seasonal amplitude were able to consider due to decrease of light period and cool night air temperature according to change of season. Also, the naturally defoliated stems which had already stomata exhibited usual diurnal acid fluctuation, on the other hand the treated stems which possessed artificially closed stomata showed a few of acid fluctuation. Especially, stomata in stems are developed by seasonal dimorphism and activated stomata participate in CAM behavior of stems.
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