Evidencing the contribution of yearly climatic factors to rubber annual yields over a 23-year period (1990-2012) in the coastal zone of Cameroon with the use of simple and multiple linear regression equations

摘要

This study was aimed at determining the contribution of yearly climatic factors on the variation of the tonnage of rubber annual yields in the coastal zone of Cameroon. Climatic and yield data were gathered in three locations (Tiko, Dizangué and Niété), within the rubber estates of three agro-industrial corporations. Yearly climatic variables were recorded for a period of 23 consecutive years (1990-2012). Rubber annual yields of four clones (GT1, PB217, PB235 and PB260) were also recorded in five field plots per clone in each location for the same period. Buildups in annual yields (in metric-tons of dry rubber per hectare) were significantly influenced by years of production. Only a few yearly climatic variables were significantly correlated with some rubber annual yields (minimum relative humidity, mean relative humidity and minimum temperature in Tiko; none of the climatic variables in Dizangué; maximum temperature, mean temperature, and minimum relative humidity in Niété). Low but significant simple and multiple linear regressions relationships were established that contributed to explain 17.90 to 55.50% of rubber annual yields. Covering more locations where rubber cropping is conducted in Cameroon with this kind of study must be encouraged. Other mathematical relationships for more accurate predictions must be built, as for example curvilinear regressions; for linear regressions may not be sufficient to explain yield variations in their completeness.