Wheat cultivars with very early maturities appropriate for late sowings in low-rainfall (<325 mm) short-season environments are currently unavailable to wheat growers in the eastern margin of the cropping region of Western Australia. A demonstration that very early-maturing genotypes can out-perform current commercial cultivars would open new opportunities for breeding programs to select very early-maturing, high- and stable-yielding cultivars for these environments. Six field experiments were conducted over 4 seasons at 2 low-rainfall sites in Western Australia to investigate crop growth, grain yield, and water use efficiency of very early-maturing genotypes compared with current commercial cultivars when sown after 1 June. Very early-maturing genotypes reached anthesis up to 24 days (328 degree-days) earlier than the current cultivars, produced less leaves, had similar yields and dry matter, and maintained high water use efficiencies. On average across seasons and locations the very early-maturing genotypes (W87–022–511, W87–114–549, W87–410–509) yielded more than the later maturing cultivars Gamenya and Spear (190 v. 160 g/m2) but they were similar to the early-maturing commercial cultivars Kulin and Wilgoyne (191 g/m2). Very early-maturing genotypes generally had a higher harvest index and produced fewer spikelets, but heavier and more grains, than Kulin and Wilgoyne. There were only small differences in total water use between very early-maturing genotypes and commercial cultivars; however, very early-maturing genotypes used less water in the pre-anthesis period and more water in the post-anthesis period than the later maturing genotypes, and hence, experienced less water deficit during the grain-filling period. This study indicates that there is a role for very early-maturing genotypes in low-rainfall short-season environments, when the first autumn rains arrive late (after 1 June).
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