CARBON AND NUTRIENT DYNAMICS IN RELATION TO GROWTH RHYTHM IN THE GIANT BAMBOO PHYLLOSTACHYS PUBESCENS

The carbon and nutrient dynamics in relation to growth rhythm in the g iant bamboo Phyllostachys pubescens on Mount Jinyun, Chongqing, China, was studied during 1993-1996. Concentrations of TNC (total non-struct ural carbohydrates), N, P, and K all showed the same distribution patt ern among organs: leaves > branches greater than or equal to rhizomes > stems > roots. The rapid spring growth of new shoots noticeably redu ced the concentration of TNC in the rhizomes, in which a large amount of carbohydrates was stored. The N concentration of the rhizomes did n ot decrease, however. Nutrient concentration of new (Ist-year) leaves was significantly higher than that of old (2nd-year) leaves. Although the density of adult shoots was almost the same during 1994-1996, the low ratio of the number of adult shoots with new to that with old leav es from June 1994 to April 1995 resulted in a low TNC concentration in the rhizomes in early spring (April) 1995. This led to a low producti on of new shoots in the spring of 1995, their number being only ca. 10 % of that in 1994 and 1996. Before old leaves were shed, a large amoun t of nutrients was remobilized and translocated to other plant parts t o support further growth. Fertilization with NPK significantly increas ed the concentrations of N and P in leaves and subsequently increased the number of emerging new shoots.