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A field study was carried out in two-year-old bambusetum established at main campus, Kerala Agricultural University, Thrissur, Kerala to evaluate the growth performance of selected six bamboo species of potential relevance to the humid tracts of Kerala, India. The selected bamboos included are Dendrocalamus longispathus Kurz; D. brandisii (Munro) Kurz; D. asper (Schult.f.) Back.ex Heyne\ Bambusa balcooa Roxb; B. vulgaris Schrad and B. tulda Roxb. Growth parameters such as clump height, clump circumference (at 1.37 m), culm girth (at 1.37 m), internodal length and number of culms were observed in the field at periodic intervals of four months. The field result showed considerable variation in growth and productivity among the six bamboo species under study. Overall growth performance was better for B. vulgaris, D. brandisii and D. longispathus. For instance, B. vulgaris and D. brandisii were the toppers in terms of clump height, clump circumference and culm girth while B. tulda showed relatively poor growth for these parameters. Among the species, the highest internodal length was observed for D. brandisii and D. longispathus while B. tulda recorded the shortest internodal length. Number of culms per clump was highest for D. asper while it was the lowest for B. balcooa. Faster growth rendered by all the species except for B. tulda suggest their vast potential for integration in the farm lands of Kerala for enhancing the economic and ecological benefits to the farmers. [ABSTRACT FROM AUTHOR]

Initial spacing and pruning are silvicultural strategies that influence the resource acquisition capabilities of trees. A field study was conducted in the humid tropics of peninsular India to test the assumptions that: (1) high stand density of Acacia mangium induces greater root uptake capacity close to the stem and from the subsoil; and (2) crown pruning stimulates greater root uptake capacity at proximal points. Root activity pattern of two-year-old A. mangium was evaluated as a function of three population densities (1,250, 2,500 and 5,000 stems ha−1), with, and without 50% crown pruning, using 32P soil injection. The label was placed at 25, 50 and 75 cm lateral distances and at 30 and 60 cm depth. Low density stands (1,250 stems ha−1) generally showed higher 32P recovery ( P < 0.01), which was exaggerated by pruning. Pruned low density stands had 34% root activity at 25 cm, as against 23% for unpruned. The low density stands also showed higher root activity at 75 cm, signifying greater root spread. We suggest that high stem densities favour restricted spread of absorbing roots and may facilitate competitive downward displacement of roots. Pruning the lateral shoots at low stem densities may simulate this to some extent. The net outcome of interactions, however, will depend on trade-offs between stem density and tree management over time. [ABSTRACT FROM AUTHOR]