A SCREEN TO DISCRIMINATE THE WATER POTENTIAL THAT LIMITS SPROUTING OF DIFFERENT SUGARCANE GENOTYPES

THE CULTIVATION OF genetically modified (GM) crops is regulated and approval is required from a relevant competent authority prior to their commercial release. Regulators are interested in the potential harms to both humans and the wider environment. Cultivars of crop plants, including sugarcane are now being developed that are designed to perform better in water-limiting environments. These plants have the potential for increased weediness as they may also perform better outside of cultivation. A simple method has been developed for assessing differences between the ability of sugarcane genotypes’ buds to sprout and grow under a range of controlled water stress levels. Buds of two cultivars with observed different rates of emergence in the field (Q242A and Q208A) were subjected to a range of water stresses generated by different concentrations of polyethylene glycol. Cultivar Q208A exhibited slower and more reduced sprouting under water stress than Q242A. There were also differences between cultivars in their responses to shoot and root length at the different levels of stress. The method developed is a good starting point to compare any GM cultivars developed in the future for potential to sprout in stressed environments and thus have potential for increased weediness. The result may also explain why Q208A was observed to sometimes emerge more slowly in the field. Under optimal conditions Q208A sprouted more slowly than Q242A, and was less able to sprout under even mild stress. Additionally, Q208A invested more in roots and less in shoot growth than Q242A.