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 7662 IREC Farmers' Newsletter No. 195 ­ – Rice R&D 2016 DEVELOPING COLD TOLERANT AUSTRALIAN RICE VARIETIES Kim Philpot, Mark Talbot and Peter Snell NSW Department of Primary Industries, Yanco Agricultural Institute R ICE production in southern New South Wales and northern Victoria is a challenging enterprise made more difficult by the susceptibility of rice to low temperature stress during its reproductive stage. Cool mid-season temperatures tend to coincide with the reproductive stage of rice plant development, often leading to little or no grain filling at crop maturity. Sterility causes annual yield losses of around 5–10%, which equates to more than $40 million of farm gate production. Extreme or prolonged cold snaps, which occur every 3–4 years, can lead to yield losses of around 20–40%. Currently, the only method available to reduce the effects of cold damage is to maintain deep water in fields during the most sensitive stage of reproductive development, ‘pollen microspore’. Deep water provides a thermal blanket around the developing panicle and pollen, keeping them approximately 2°C warmer on average than the surrounding air temperature. However, the extra water required to protect the developing pollen adds to financial costs for the farmer, and there is no guarantee the air temperature will not drop so low as to render the 2°C water temperature difference ineffective. Even with adequate water coverage at the threshold minimum temperature of 15°C, high levels of spikelet sterility can also occur with excessive nitrogen use. Understanding the effect of cold stress on the rice plant during its reproductive stages is the key to developing cold tolerant Australian rice varieties. QUICK TAKE l Cold-induced sterility still presents the greatest barrier to gains in production efficiency of rice in the Riverina. l  Breeding for cold tolerance at the pollen microspore stage is second only to selection for yield as a breeding objective in the rice breeding program. l Current sterility screening methods are being optimised to account for ‘blowing up’ — the combined negative effect of nitrogen and cold on successful grain set. l Understanding changes in the fertilisation process under cold temperatures is a prerequisite to developing a rice variety for future production of rice in aerobic conditions. l Rice plants growing in a temperature- controlled glasshouse, where water temperature is also controlled, using large heating elements. This enables trials to be run year round. Lights can be used to stimulate flowering in winter.