Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Page 48 Page 49 Page 50 Page 51 Page 52 Page 53 Page 54 Page 55 Page 56 Page 57 Page 58 Page 59 Page 60 Page 61 Page 62 Page 63 Page 64 Page 65 Page 66 Page 67 Page 68 Page 69 Page 70 Page 71 Page 72 Page 73 Page 74 Page 75 Page 7643 IREC Farmers' Newsletter No. 195 ­ – Rice R&D 2016 Growing system Rice growing under aerobic conditions is the most suitable system for the high rainfall areas of northern Australia, as it better fits existing crop rotations, requires less irrigation water and minimises bird pests, compared with flooded systems. A split fertiliser application strategy was tested, with different rates of basal fertiliser (several nutrients) at seeding followed by different rates of nitrogen at different growth stages. High rates of basal fertiliser did not achieve significant yield increases over low basal rates. Grain yield data indicated significant differences between the top-dressed nitrogen rates but the response to was not specific for varieties or irrigation systems. The highest grain yield was achieved when nitrogen was applied at the panicle initiation stage. Minimising cold damage Minimum air temperatures of less than 15°C had the biggest impact on varietal performance. Potential cold damage during the months of June and July warrants selection of varieties with cold tolerance for this environment, especially for production in an aerobic rice system. Ponded water provides a 4–8°C temperature buffer against ambient air temperature, thus providing some protection against cold. In the project, this resulted in higher yields under the flooded system. Planting dates, varying from late February to late May, were found to play a crucial role for plants to avoid low temperature damage at critical growth stages. The results also indicated that late planting ensured high yields (Figure 1), but the grain quality suffered due to extreme weather conditions prior to harvest. The maturing grain experienced high fluctuations in diurnal temperatures which caused cracking of the grains, and hence low whole grain millout and high chalk content in grains. High percentage whole grain millout was achieved by harvesting at high grain moisture levels, for example, greater than 19.4, 19.5 and 20.0 per cent, for varieties NTR 426, NTR 587, and Yunlu 29, respectively. However, high chalk in harvested grains remained an issue. Best varieties Seven temperate and 20 tropical rice varieties, sourced from nine countries (Australia, USA, Korea, Indonesia, Japan, India, Philippines, China and Vietnam), were evaluated in field trials for their yield performance in the Ord River Irrigation Area, during the dry seasons between 2009 and 2014. A similar set of varieties was also tested l There is a need for more information about tropical rice growing in northern Australia. l Figure 2. Rates of evaporation, transpiration and deep percolation under flooded system. l Figure 1. Grain yield of five varieties planted on 22 April (1st planting), 8 May (2nd planting) and 21 May (3rd planting) in 2013 Doongara NTR 426 NTR 587 Pandan Wangi 7 Viet 1 Grain yield (t/ha) Water loss (mm/day) n 1st planting n 2nd planting n 3rd planting ◆ Evaporation n Transpiration ▲ Deep percolation