| Abstract | Water stress is the major constraint to productivity in the Australian sugar industry, with an estimated cost of $260 million/annum (CSE014 Milestone Report 3.5). In 2003 and 2004, the losses exceeded $140 million in Mackay alone. This impact may increase with climate change. About 40% of the Australian sugarcane production is rain-fed with or without supplementary irrigation. With the erratic rainfall and the increasing cost and restrictions on water use, efficient use of available water is an increasingly important priority in irrigated production systems as well.Varieties that adapt well to drought and use water efficiently are becoming increasingly important for sustainable sugarcane production. Australian sugarcane breeding programs, however, do not explicitly address selection for response to dry conditions. To effectively address this issue there is a need to understand the main physiological mechanisms underlying genetic variation in response to different types of water stress environments in sugarcane. Hence, this project was initiated to determine the potential of Australian sugarcane germplasm for developing water use-efficient and drought tolerant commercial cultivars.In this project the phenotypic and genetic variations of traits that confer or linked to drought tolerance and water use efficiency (WUE) and their contribution towards productivity were studied in a genetically diverse sugarcane population. Field experiments were conducted for 3 years under rainfed, fully irrigated and managed drought conditions at three locations in the Northern Queensland. The experiment sites were in Home Hill in the Burdekin shire, Crystal Creek in the Herbert Shire and Dalbeg in the upper Burdekin. All trials were conducted in commercial sugarcane farms and followed the best crop management practices. A genetically diverse population (131 genotypes) comprising S. officinarum crosses with wild relatives, commercial cultivars including foreign clones, advanced lines in the selection program and some parental clones in the BSES breeding program was used as test clones. Clone performance was evaluated under rainfed, irrigated and managed drought conditions adopting most appropriate statistical field designs for the respective sites. The agronomic and cane yield characteristics, fibre, sugar and sugar quality characteristics and physiological traits related to drought tolerance were collected during the crop growth period and at harvest. Appropriate statistical methodologies were used to analyse and interpret the results at the end of the project. |
