Tham khảo tài liệu 'water stress part 16', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Sugarcane Responses at Water Deficit Conditions 259 Christin et al. 2007 Ghannoum 2009 . Despite mechanisms that facilitate reactions of CO2 fixation sugarcane as any given plant species is subject to water deficit. Longer periods of drought on sugarcane crops can significantly decrease growth productivity and quality of product Wiedenfeld 2000 . In C4plants some evidences demonstrate that photosynthesis is highly sensitive to water deficit Ghannoum 2009 . Moreover these plants present low recovery capacity mainly when water deficit exceeds the plant recovery capacity limiting the photosynthesis metabolic pathways Ripley et al. 2010 . In Brazilian sugarcane cultivars the capacity to recover the physiological responses was compromised from the tenth day of stress and damaged the photosynthetic apparatus as can be observed through the low photosynthetic rate stomatal conductance and transpiration rate Grace et al. 2010 . Plants under water deficit conditions show modifications in their metabolism to tolerate water loss. Concerning these changes the root system is the first part to detect the stress and signal to other tissues. The hydraulic perturbation Buckley 2005 stimulates plants to send chemical signals through roots to trigger changes on stomata during the water deficit. Therefore the abscisic acid ABA Kholová et al. 2010 the pH Schachtman Goodger 2008 and the ionic distribution Bahrun et al. 2002 seem to play an important role on signaling throughout the plant under water stress. Molecular studies have identified a wide range of genes expressed by sugarcane plants under water stress conditions Iskandar et al. 2011 Prabu et al. 2010 Rodrigues et al. 2011 . Regarding the responses to stress signaling pathways regulated by hormones are highly drought-responsive mainly those associated with the increased ABA synthesis Pinheiro Chaves 2011 . Under drought stress condition the level of endogenous ABA was increased and its function upon the stomatal closure can .
