The effect of spacing and thinning on the yield of Cinchona ledgeriana.

Abstract

The layout of an experiment started in Indonesia in 1933 to determine the effect of spacing and thinning on yield of Cinchona ledgeriana is described. The experiment was planned to last 25 years but was interrupted in 1942 by the Japanese occupation. Data recorded during these first 9 years are tabulated and the results summarized as follows. The production of clone Tjib. 5 was about 20% higher than that of Tjin. 1. Planting of 7, 200 and 8, 600 trees per ha. produced less than the widest spaced plantings of 5, 000 per ha. and the closest spaced plantings of 12, 600 per ha. The difference in yield between plots of very different spacings was relatively small, but the plots with the densest stand gave the greatest average production of quinine sulfate. The economics of dense planting are discussed. Height of tree was found to be practically independent of spacing, in contrast to girth which was a function of it. Close spacing produced slender trees with thin bark, but expressed as a percentage of the radius such bark was not relatively thinner than that of widely spaced trees. The ring content of quinine (pure quinine in dry bark from samples cut 1 m. above the ground) showed a slight tendency to decrease with age, after reaching a maximum in the sixth year. The preliminary conclusion is reached that, with regular thinning and fertilization, close spacing of cinchona is technically desirable and gives the highest yield. (Abstract retrieved from CAB Abstracts by CABI’s permission)