Ground Cover Supplement : GC Supplement - Tactical cereal agronomy
8 Western region Agronomy research reveals varietal differences Ongoing wheat agronomy research in Western Australia is delivering regional and local information about new and current wheat varieties By Christine Zaicou-Kunesch, Brenda Shackley and Jeremy Curry SPROUTING A variety ranking system for falling number in wheat developed by the Department of Agriculture and Food, Western Australia (DAFWA), is being used to determine the pre-harvest sprouting tendency of emerging and released varieties in WA. Wheat varieties differ in their sprouting tolerance, with grain dormancy controlling how readily individual varieties germinate in-crop following rainfall events. Dormancy traits that contribute to sprouting tolerance include seed coat dormancy and dormancy inhibitors that are released from the glumes when they become wet. Other attributes relate to the structure of the head, such as waxy, awnless or tightly adhering glumes, which influence how much water penetrates the head and into the grain. The new falling number index integrates the grain dormancy, falling number value and physical head attributes of wheat varieties to provide an indication of their in-field sprouting susceptibility following pre-harvest rain. It reflects the relative ability of wheat varieties to maintain falling number after a rain event. Presented as a one to nine scale, the higher the rating the more likely a variety is to maintain falling number. The highest rating available for WA wheat varieties is six for EGA Eagle RockA, EstocA, LongReach ScoutA and Clearfield WHT STLA (Table 1). To establish the index researchers sow pre-release and current wheat varieties at varying sowing times at Esperance Downs Research Station on the south coast of WA, where sprouting can be a significant issue for wheat growers. Hand-harvested wheat heads are hung to dry and exposed to rain treatments in a rainfall simulator ranging from no rain to 72 hours of rainfall. The varieties are then assessed for how well they maintain their falling number under the rainfall treatments. This information is then combined with falling number data from local South-East Premium Wheat Growers Association trials and germination index data from the University of Adelaide to develop the falling number index ratings for each variety. The results are presented in the Wheat Variety Guide for Western Australia and also sent to breeding companies. PHOTO: EVAN COLLIS Increasing seeding rate can have a more positive impact on wheat establishment rate than wetting agents in non-wetting soils, but in low-yielding environments high seeding rates can result in yield decline.
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