Acta Botanica Croatica, Vol. 46 No. 1, 1987.
Izvorni znanstveni članak
Seasonal Changes in Chloroplasts of Blackberry Leaves
Zora Modrušan
; Hrvatska
Mercedes Wrischer
; Hrvatska
Sažetak
The ultrastructure, pigment content and photosynthetic activity of chloroplasts in blackberry (Rubus fruticosus L. s. 1.) leaves were investigated during spring, summer, autumn and winter. The fine structure of young spring leaves shows all characteristics of the young leaf tissue with the maximum value of photosynthetic activity. Their ultrastructure changes parallelly with the development and maturation of these leaves through summer and autumn. Chloroplasts of the summer leaves have a well developed thylakoid system with big grana, and starch is always present in the stroma. The content of pigments reaches its maximum in the summer leaves but the photosynthetic activity slowly falls. A reduction in the thylakoid system and enlargement of plastoglobules are the features of chloroplasts in the autumn leaves. Their photosynthetic activity and content of pigments are low, so these leaves gradually decay. New leaves which grow up in the late summer and early autumn, remain on the shrubs throughout winter, and end their lifespan in the late spring. Chloroplasts of the winter leaves have a well developed thylakoid system and numerous plastoglobules in the abundant stroma. It is significant that these leaves are exposed to low temperatures and short days throughout the period from autumn to winter and thus they are adapted to low temperatures. The winter leaves have large chloroplasts and a high content of pigments, but their photosynthetic activity is relatively low. The fine structure of the winter leaves frozen to subzero temperatures (up to —12°C), was also examined. Cells of these leaves have a dense cytoplasm pushed among cell organelles, many small vacuoles and numerous vesicles.
Ključne riječi
Hrčak ID:
159297
URI
Datum izdavanja:
31.12.1987.
Posjeta: 840 *