Lifting barley productivity in higher rainfall zones
Author: Kenton Porker and Courtney Peirce (SARDI, New Variety Agronomy) | Date: 08 Aug 2018
Take home messages
- Higher yields are possible in new barley varieties; Rosalind and RGT Planet in the high rainfall zone (HRZ) with contrasting yield structures.
- There is opportunity to exploit variation in variety phenology of barley to maximise yields.
Overall grain crop production has rapidly increased in the higher rainfall zones of South Australia (SA) over the past decade. However, gains in the average annual farm production of barley are small compared to gains in wheat (AgSurf 2017). Barley productivity has stagnated relative to wheat because of either reduced planting area, or a slower rate in yield improvement. A number of factors could be contributing to this including market price and competition from other crops, agronomic decisions based around crop rotation, or a lack of varieties adapted to the higher rainfall zones. There is opportunity to improve barley productivity in the higher rainfall zones.
The current status of yield potential in the HRZ
Compared to wheat, barley is considered to be better adapted and offers higher yield potential in most environments. However, despite barley’s broad adaptation, recent experience in the medium to higher rainfall zones suggests this relative yield advantage is not always realised using current Australian spring barley benchmarks (Figure 1), particularly as sowing dates are moved earlier. This is an area where current spring barley profitability is limited due to reduction in yield from lodging, poor harvest index (HI, ratio of grain yield to biomass) and frost. The recent European spring barley release RGT Planet has demonstrated European material can outperform Australian spring cultivars when sown early in the medium-high rainfall zones, even when flowering at a similar time (Figure 1).
Figure 1. The relationship between the best performing wheat variety and the barley varieties; Compass and RGT Planet at co-located wheat and barley NVT trials located at Turretfield, Cummins, Wanilla and Keith in SA, and Hamilton and Streatham in Vic.
There are a number of varieties undergoing malting accreditation (RGT Planet and Banks) that have yields equivalent or greater than current accredited malting and feed barley varieties in the higher rainfall zones. The feed variety Rosalind and RGT Planet have been the highest yielding varieties on average, followed by Banks and then Compass, Fathom, LaTrobe and Spartacus CL in the higher yielding environments. RGT Planet appears better adapted and has more stable yields than previous experience with European material, however, in SA NVT trials RGT Planet has still had limited evaluation in environments <3t/ha. The limited dataset suggests the relative yield performance of RGT Planet is similar or less than Rosalind, Compass and Spartacus CL in lower yielding environments (Figure 1) but greater in environments >3t/ha (Figure 2).
Figure 2. The yield performance of selected barley varieties across South Australian GRDC NVT trials (2013 – 2017) expressed as a percentage of site mean yield relative to yield environment. (data source: GRDC NVT online long-term yield reporter).
While Banks and RGT Planet are all undergoing malt accreditation, until a decision is made growers need to make profitability comparisons with other varieties based on feed grades. Compass, and Spartacus CL are now accredited malt varieties and have outperformed both Commander and Scope CL for grain yield. Westminster lacks the yield potential of some of the new releases however remains the preferred malt variety for the higher rainfall districts in the South East. In many cases a new variety accreditation does not mean the variety will be a preferred variety until market demand is established. The preferred list of Barley Australia is updated annually on the Barley Australia website along with the timeline of malting accreditation.
Lifting barley productivity in the HRZ
The simplest way to dramatically change yield potential is to lengthen the life cycle of the crop. Early sowing of slow developing lines has the potential to improve biomass production and tillering capacity due to a longer vegetative phase. A longer vegetative phase also provides the opportunity for dual purpose use for livestock grazing. Barley is an ideal candidate for early sowing, due to its superior frost tolerance and improved early vigour compared to bread wheat. However, to date, slower developing barley genotypes with greater vernalisation and/or photoperiod have not been evaluated for early sowing (prior to April 20).
Matching phenology to sowing date
In barley, the most effective management strategy to maximise yield potential is to match variety phenology to sowing time. The control of flowering time in all of the current well adapted spring barley options are predominantly due to temperature and photoperiod (day length). Faster development has been positively correlated with grain yield, and as such, breeders have released fast developing varieties such as Compass, Rosalind, Hindmarsh, Spartacus CL, and LaTrobe that are well adapted to SA. In frost prone environments these group of varieties are less suited to pre-May sowing as they flower too early.
Fathom and Commander have a greater photoperiod sensitivity than the faster developing varieties mentioned above and will generally flower five to ten days later than Compass, Hindmarsh, Spartacus CL and Rosalind when sown in late April. However, when sowing in mid-May Fathom flowers at a time similar to the faster developing varieties, while Commander will still be later. RGT Planet and Banks have shown some flexibility across sowing dates and are capable of being sown slightly earlier than most other fast developing commercial spring genotypes. Both RGT Planet and Banks flowered similar to Commander and Westminster from a late April sowing but developed slightly quicker with later sowing dates suggesting different development controls to Commander (Figure 3).
Figure 3. Flowering time responses to sowing date of selected varieties at Kingsford SA, 2017.
Urambie is a feed winter barley available in Australia and is relatively stable in its flowering response across sowing dates due to its unique vernalisation and photoperiod response. However, it does not have the yield potential of the most adapted springs, but when sown early in frosted environments it has yielded higher than well adapted spring varieties sown too early. Oxford does not have a vernalisation requirement but can be planted in the period from April 15 – 30. Oxford was the highest yielding variety when sown early at Kingsford in 2017 similar to the best performing spring varieties; Spartacus CL and Compass sown late.
Evaluation of previous winter barley varieties in Australia concluded their performance was inferior to current spring varieties due to poor biomass production, excessive tillering, a low harvest index and low grain weights. However, current research demonstrated it was possible to achieve an improvement in harvest index (partitioning of biomass to yield) utilising new winter European introductions. Conversely, early sowing of fast maturing spring barley resulted in increased lodging, reduced harvest index, and yield loss (Figure 4). Trials conducted as part of a new SAGIT project in 2018 are investigating the potential of longer season cultivars in the higher rainfall zones.
Figure 4. Relationship between flowering date and grain yield in a selection of diverse phenology types in a trial at Kingsford SA in 2017, sowing dates included 28 April, 18 May and 15 June.
There are a number of new high yielding varieties that differ in phenology that growers can exploit to maximise grain yield and quality. This is best achieved by matching variety phenology to sowing time and environment to ensure flowering occurs at the right time to minimise exposure to frost, heat, and moisture stress. Further understanding of the varietal differences in physiology will enable further fine tuning of yield and quality using other management strategies such as sowing date, plant growth regulators, nitrogen, grazing and seeding rate.
The research undertaken is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC as part of 'Southern Barley Agronomy’ project and SAGIT for research investment in a higher rainfall barley project in 2018. The authors acknowledge the contribution from Poh Chong and the SARDI NVA team for trial management assistance.
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