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 7652 IREC Farmers' Newsletter No. 195 ­ – Rice R&D 2016 As these new breeding lines are very different in maturity from the standard full season varieties, comparison in full season trials does not give a true indication of performance, so these lines have been grown in breeding trials with early, mid and late planting dates. Figure 2 compares Reiziq and YRM70 grain yield from four seasons of breeding trials at Leeton and Jerilderie by time of sowing. Earlier sowing times favour Reiziq over YRM70, while in later sowing times YRM70 performs better than Reiziq. However sowing time does not give a complete picture of varietal performance, as random weather events encountered during the growing season mean lines with differing maturity are encountering different (and unpredictable) environmental conditions even in the same field trial. Another way of comparing performance, particularly as cold tolerance plays such a large part in determining yield stability in the Riverina rice growing environment, is to compare grain yield with minimum temperatures encountered at the critical early microspore stage. Figure 3 illustrates the performance advantage of YRM70 over Reiziq at early microspore temperatures under the critical threshold of 15o C where reproductive cold damage can occur. A similar result can be seen in trials comparing YRK5 and Opus (Figure 4). Agronomic features Establishment for these lines may be easier given the warmer temperatures likely to coincide with the later sowing dates. Additionally, the speed of emergence and seedling growth at these dates means that the pre-emergent herbicide application in a drill sown situation may be sufficient for good weed control. Lodging is more pronounced in short season varieties due to rapid accumulation of biomass compared with full season varieties. However lodging potential for YRM70 and YRK5 is significantly less than Jarrah with the plant also supporting a higher yield potential than Jarrah. The lines have not been evaluated for early sowing leading to early harvest situations, however this may be an option if careful consideration is given to harvesting close to physiological maturity (at higher grain moisture). However it is anticipated that whole grain millout and other quality attributes may not be optimal with early sowing dates due to inherent warmer conditions during grain development. Shorter-season varieties present a risk management option to rice growers in an environment of uncertainty. In conjunction with the current suite of full-season varieties, they provide a much wider sowing window for rice producers when, for example, irrigation water allocations are increased in late spring. Additionally these lines provide an over-sow option for the full season varieties Reiziq and Opus in the event of establishment problems. The growth duration of both lines is short enough for them to be planted after a canola, pasture or early cereal crop without compromising yield potential, enabling rice to be grown intensively in a double- cropping rotation. The main photo on page 51 illustrates the shorter time to flowering of YRK5 compared with Opus. l Figure 1. District trial results for predicted grain yield in 2014 (full-season planting dates) and 2015 (late-season planting dates) district trials show the yield advantage of YRM70 over Reiziq in later planting dates (i.e. 2015). Barham Deniliquin Griffith Logie Brae Whitton Willbriggie Coleambally Deniliquin Moulamein Yenda C2014 C2014 C2014 C2014 C2014 C2014 C2015 C2015 C2015 C2015 n Jarrah n Reiziq n YRM70 Grain yield (t/ha)