FACTORS THAT AFFECT THE QUALITY OF SUGARCANE .1. CLIMATE

This is the first half of an overall survey of the factors that influe nce cane quality. The influence of management practices will be discus sed in the second part next month. The effects of climate on cane qual ity are defined from a review of the literature and through 'crop-mode ling' type analyses based on routine factory reports and agronomic exp eriments from 15 countries. Rainfall affects cane quality both long-te rm via growth rates, and shortterm through interfering with tile logis tics of harvest. The rainfall effect is influenced by factors such as the available moisture within the soil, and the degree. of harvest mec hanization, so the! slopes of the regression lines are of limited valu e. Further, a significant part of this 'ripening' effect is a change i n the degree of hydration of the cane, not a net gain or loss of sugar . Temperature is the dominant influence in medium latitude countries; the effect is remarkably consistent at around one unit of rendement pe r 4 degrees C change in temperature, averaged over the very long (2 - 3 months) effective period; the critical temperature is around 20 degr ees C. At very low latitudes, total insolation seems to become a domin ant influence; however, this conclusion is based on work at one site o nly.