Growth and yield of sugarcane genotypes are strongly correlated across irrigated and rainfed environments

Sugarcane is a high biomass crop grown mostly in rain-fed environments. Water is a key determinant of sugarcane productivity, and in most production regions, varying and sometimes severe water stress occurs. Understanding the extent of genetic variation in response to water stress may allow for better targeted breeding programs. In this study a set of field experiments evaluating 31 sugarcane clones under rain-fed and irrigated conditions was conducted in two sugarcane production areas in Yunnan province, South China. While the water treatments had a large impact on mean cane yield there were little or no genotype × water treatment interactions for cane yield or sugar content at harvest, or for dry biomass sampled about five months (early biomass) after the start of crop growth. The high genetic correlation between well-watered and water stress treatments is consistent with the hypothesis that clone performance under water stress is mostly associated with general vigour rather than traits acting specifically under water stress. From a practical breeding program perspective the results suggest that choice or management of water stress level in selection trials is not a critical consideration for sugarcane breeding programs, and that selection under reasonably well watered conditions will be effective for attaining satisfactory selection gains under at least moderate levels of water stress. Early biomass was positively correlated with yield at final harvest for all water treatments. Resolution of the physiological basis of the high genetic correlations between growth under well-watered and water limited conditions may assist in future breeding efforts.