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 7656 IREC Farmers' Newsletter No. 195 ­ – Rice R&D 2016 will assist the greater goal of increasing the low-temperature threshold of new commercial rice varieties. A new screening process The phenotyping system screens advanced and promising genotypes that have been progressed by the rice breeding program to the F5 or F6 stage. Plants are exposed to low temperature (21°C/15°C) for 14 days/nights at the early booting stage (Set 2) and at the flowering stage (Set 1), both conducted in a controlled-temperature glasshouse facility at UQ. Genotypes in Set 1 (i.e. exposed to cold at the flowering stage) are sown 17 days prior to genotypes in Set 2 (i.e. exposed to cold at early booting). Both sets are managed the same way in terms of water and nutrient supply; and glasshouse conditions are managed for ideal day length. There are three replications of each line (genotype) in each set. For Set 1 (exposed to cold at the flowering stage), each pot is moved into the cold room when the individual plant reaches the heading stage. When two out of three replications of each line in Set 1 have reached the heading stage, all three replications of the same line in Set 2 (exposed to cold at the early booting stage) are also moved into the cold room — noting that Set 2 was planted 17 days after Set 1. All genotypes in both sets remain in the low temperature room for 14 days and then are transferred back to the warm room until maturity, when they are harvested. At maturity, spikelet sterility is determined, and in turn, tolerance to low temperature is determined for both development stages. Results to date Results from the phenotyping system have identified genetic variation for cold tolerance within populations of genotypes in development, in advanced genotypes and within previous and current commercial varieties. For example, there was a very wide variation in spikelet sterility which ranged from 4–99% in the early booting stage among genotypes that were derived from a population (KKN) based on Kyeema crossed to a Japanese cold tolerant donor (NorinPL8). Several cold tolerant genotypes were identified from a population that used Reiziq and Chinese cold tolerant donor Lijiangheigu , and there is work now focused on phenotyping a population that uses Millin and Lijiangheigu. Table 1 shows the spikelet sterility, as an indicator of cold tolerance, measured by the phenotyping system for a range of current and previous commercial rice varieties. The screening process was applied to genotypes from a Japonica diversity set of l Undergraduate Science student Ella Wherritt (left) working with PhD student Chris Proud at UQ to investigate early vigour in relation to aerobic rice production and cold tolerance in rice.