Crop yield response to water - Cra

to produce energy (electricity from burning stalk fibre and ethanol from fermenting sugars) ona large scale in several countries and this is gaining momentum because it is a renewable source.In Brazil about 40 percent of the cane is used to produce alcohol as auto fuel.Growth and developmentThe stalk cuttings to establish a plant crop are termed setts and are several internodes long.One primary shoot and many sett roots are produced from each viable node of the sett. Theseare later followed by roots that grow rapidly (up to 22 mm/day) from shoot nodes and enablesdeep (up to 4.7 m) exploration of soil profiles (Carr and Knox, 2011). The rate of bud sproutingand primary shoot emergence depends on planting depth, temperature and soil water status(van Dillewijn, 1952). The number of shoots that emerge and the subsequent rate of tillering,depends on the amount of viable buds that were planted (typically 10 to 30 buds/m 2 ) and rowconfiguration. Sugarcane tillers profusely from the time shortly after primary shoot emergenceto canopy closure. At canopy closure, peak tiller population (up to 40/m 2 ) is reached and theyoungest tillers start to senesce, leaving between 4 to 18 tillers/m 2 to develop into stalks thatelongate, thicken and accumulate sucrose (Singels et al., 2005; Bell and Garside, 2005). Unlessflowering is initiated, stalks will continue to grow and add nodes and internodes as long aswater and nutrients are available and temperature is not limiting. Leaves will appear on eachnew node, expand and senesce at given GGD intervals (Inman-Bamber 1994b).Table 1Range in duration of different development stages (in calendar days).Development stagePlanting/ratooning toemergencePlanting/ratooning tostart of yield formation(coincides roughly withachieving maximumcanopy)Plant cropRatoon cropTropical 1 Subtropical 1 Tropical Subtropical21-40 28-70 5-10 7 - 21110-130 135-175 85-105 105-145Planting/ratooning to startof maturation 2 335-395 335-700 335-395 335-700Planting/ratooning toharvest 3 365-425 365-730 365-425 365-730Building harvest index 225-275 200-544 250-300 230-5851Assumed annual range in daily mean temperature: Tropical – 20-28 o C; Subtropical 17 -26 o C2Assumed 30 days before harvest3Harvest at 12 to 14 months in tropical areas, 12 to 24 months in subtropical areas176crop yield response to water