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Seasonal changes in several forms of nitrogen were investigated in the evergreen chamaephyte Pachysandra terminalis Sieb. et Zucc. growing in temperate evergreen coniferous forest. After plants sprouted new shoots, nitrogen accumulated largely as proteins in the leaves from summer to late autumn and, additionally, during a short spring period in the following year. Proteins accumulated in the overwintered leaves decreased markedly in summer, indicating that they were used for new shoot growth. A similar change was found in Fraction 1 protein. This is consistent with the seasonal changes in photosynthetic capacity and carboxylation efficiency observed in previous studies. The allocation of nitrogen to Fraction 1 protein increased in the spring, presumably to utilize better the relatively high light intensity at the forest floor before leaf expansion of the understory deciduous plants. In contrast to protein nitrogen, soluble nitrogen was present largely in stems and rhizomes. Aspargine was the major component of the amino acid pool in all organs throughout the year. especially in stems in summer. Since asparagine has the highest N:C ratio (2N:4C), an amino acid pool dominated by asparagine is economic in the use of carbon and advantageous for the carbon-limited environment of the forest understory. [ABSTRACT FROM AUTHOR]

Considering the results of these investigations from an ecological point of view, it must be stated that the chlorophyll factor does not have much bearing on the photosynthesis in plants with foliage leaves. In most of the species the chlorophyll concentration of the fully developed leaves exceeds the optimum value for the chlorophyll factor. Only in young leaves and in leaves of aurea varieties with chlorophyll concentratration lower than this value, can the chlorophyll factor be of importance for the rate of photosynthesis, but even then, only at weak light intensities which are seldom found in nature. [ABSTRACT FROM AUTHOR]