The two-year scoping study aimed to achieve the following objectives to investigate various aspects of long coleoptile wheat relative to WA farming systems for eventual grower integration:
• Extend long coleoptile findings and discussions to growers across agricultural regions of Western Australia
• Quantify differences in emergence from deep and shallow sown varieties with varying coleoptile lengths.
• Investigate emergence through furrow fill from wind and rain events.
• Investigate emergence from uneven soil platforms, such as from deep-ripping
• Investigate emergence through both low and high soil temperatures.
• Explore biomass and vigour differences between varieties with and without the Rht18 gene.
• Quantify differences in annual ryegrass competition and wheat vigour interactions with grass weeds.
• Explore herbicide interactions across depths of sowing to investigate crop safety and ways of adjusting/changing IBS and EPE herbicides.
• Explore rhizoctonia wheat root infection between depths of sowing.
• Analyse grain yield of various varieties and coleoptile lengths, including Rht18 wheat.

Overall, there was a positive relationship with coleoptile length and wheat emergence in both 2021 and 2022 trials, where Halberd, Rht13 variety Magenta-13, and Rht18 varieties Mace-18 and Yitpi-18 consistently had 95-100% emergence when sown at depth. Shorter coleoptile varieties had significantly less plants emerge by comparison, such as Scepter (60-75% emergence from depth), and Mace (50-70% emergence from depth). Emergence was significantly faster for Mace-18 compared to varieties such as Scepter and Calibre when sown at depth (120 mm) into soil temperatures below 10 degrees Celsius. Mace-18’s coleoptile elongated twice as much as Calibre’s at 8 DAS.
The 2022 Muntadgin trial exhibited how longer coleoptile wheat had significantly more plants emerged and emergence at faster rates than shorter coleoptile varieties (100mm+ sowing) across uneven soil platforms following soil amelioration.
Rhizoctonia was prevalent in most shallow-sown plant samples (sown 35 mm dry) compared to deep sown wheat (100 mm into moisture) which exhibited very few spear-tipping symptoms in various 2021 trials, and at Ballidu in 2022.
More vigorous Rht18 varieties such as Mace-18 had significantly less annual ryegrass weeds in deep sown plots compared to Mace sown deep across three assessed locations (2022). Shallow-sown Mace-18 was more vigorous than Mace, also leading to weed out competition in conventional sowing situations. In Ballidu, deep-sown mace had significantly higher weed infestation (nearly three times the weed counts) than Mace-18 sown deep.
Overall, there was the same yield result (100-200 kg/ha difference) between shallow sown Mace and Mace-18 at 5 locations. At three of the five locations, Mace-18 yielded better than Mace when sown deep in 2022.
There were few differences in emergence and yield where various IBS and EPE herbicides were applied to shallow and deep sown wheat. Long coleoptile wheat was shown to improve crop safety where trifluralin was applied IBS, with 90 mm sown wheat, demonstrating reduced coleoptile thickening and greater seedling vigour across multiple treatments compared to 35 mm sown plots. Field walk discussions were made around exploiting the absence of nodal roots with pre-emergent herbicides when sowing deep, as mobile pre-emergent herbicides (Sakura, Luximax and Overwatch) may cause greater crop damage when washed into the root zone of shallow sown crops.