The agronomics of pulses and implications of new varieties

Take home messages

• Several new varieties of lentils and a field pea have recently become available to growers. To maximise productivity and minimise risk it is important for growers to understand how agronomic traits can be best utilised.
• Due to drier conditions from July to September, disease was generally not a major issue in 2023. There were almost no symptoms of botrytis in lentil and faba bean trials and no response to fungicides.
• Faba beans showed good yield and profit stability across a sandy soil and a duplex soil in the west Wimmera compared with other pulses, showing average grain yields of 2.80t/ha. All other pulses were more variable, in particular, lentils.

Introduction

The pulse industry continues to thrive in Victoria, particularly for lentil and faba bean production and profitability. New varieties and applied agronomy continue to lift yield potential and reliability. This paper highlights some of the key recent findings from GRDC’s Grain Legume Development and Extension investment and related projects, and discusses the implications for industry. Southern Pulse Agronomy – Victoria delivers localised development trials and extension activities to close the economic yield gap and maximise farming systems benefits from grain legume (lentil, faba bean, chickpea, field pea, vetch and lupin) production. To do this, a ‘hub and spoke’ model of grower-driven validation and demonstration trials are delivered regionally through a network of state government and grower groups. Across Victoria there are three major validation ‘hub’ sites and six on-farm demonstration ‘spoke’ sites.

‘Hub’ sites focus on a combination of sub-regional grower driven D and E priorities and extension of new research learnings from aligned projects delivering a series of fully replicated trials.

‘Spoke’ sites focus on-farm, with one to two simple trials at each site which may include full scale strip trials, and/or small demonstration plot trials, driven by local grower D&E priorities.

Trials align with three broad categories:

• economic impacts of pulses on-farm profitability
• disease and integrated weed management in pulses
• flexible responses to emerging grower issues.

Research findings are delivered through flexible extension activities linked to each of the sites, including field days and crop walks and through the development of a new digital extension hub providing the latest photos, videos and results.

In 2023, good opening rain, combined with stored soil moisture from extreme rainfall in 2022, meant that pulse grain yields were generally average to above average (for example, lentils across the Wimmera and Mallee ranged from 1.0–3.5t/ha). Grain prices also remained high for lentil ($800–900/t) and faba bean ($400–500/t), resulting in pulses being very profitable.

There were, however, several challenges in different regions, which were reflected across the grain legume agronomy trial sites. In many trials, variable establishment impacted trials due to drying soil conditions throughout the sowing window. Fortunately, excellent rain from late May and throughout June ensured crops fully established. At sites in the Wimmera, there were early indications of waterlogging at the Gerang and Dooen lentil trials. Very cold and dry conditions in July slowed growth and at Dooen, there was substantial vegetative frost damage in lentils, with patches of necrosis and plant death particularly where there was heavy stubble from the previous crop. Disease was not a major issue across sites due to the dry July to September period, although Ascochyta blight did establish in early sown chickpea trials. The dry conditions also led to water stress symptoms in early October, particularly in faba beans at the Woomelang (southern Mallee) and Gerang (west Wimmera) sites. A rainfall event of 28mm on 3–4 October at Woomelang ensured crops achieved potential grain yield, however Wimmera sites continued to experience dry and cold conditions. Harvest conditions were excellent in the Mallee, however rainfall events through November, December and January affected harvest at the Dooen site, markedly affecting harvestability and grain quality.

New varieties – agronomic lessons from 2023

Within all pulses, varieties differ in agronomic traits, such as plant architecture, biomass production, reproductive duration and timing, disease resistance, herbicide tolerance and pod retention. The applied research discussed here aims to improve understanding and demonstrate how to ensure these traits are best utilised within a farming system. Below are selected key learnings from 2023.

In 2023, a lentil variety ‘ALB Terrier’ and a field pea variety ‘APB Bondi’ were released (see Victorian Crop sowing guide).  In agronomy trials, the lentil, ALB Terrier, has shown high yields across a range of sowing dates in 2022 and 2023, similar to GIA Thunder in the Wimmera and slightly lower in the Mallee (Table 1). APB Bondi (in agronomic trials,  has been the highest or equal highest yielding variety in 2023 and shown good yield stability across a range of soil types, probably due to its tolerance to boron toxicity, moderate tolerance to salinity and resistances to seed-borne mosaic and bean roll virus.

GIA Thunder is likely to become one of the most widely grown IMI varieties in coming seasons. In a range of  agronomy trials, it has performed particularly well in the Mallee (for example, Woomelang 2023; Table 1) and across a wide range of soil types, generally benefiting from earlier sowing. In addition, maintaining a proactive disease management program will be of benefit, particularly in seasons with higher disease risk. In the Wimmera, its long-term grain yields have been higher than other ‘IMI’ varieties but slightly less than the conventional PBA Jumbo2. Trials in 2023 near Dooen (Wimmera), which experience substantial frosts during winter, demonstrated a similar trend (Table 2).

Table 1: Grain yield (t/ha) of GIA Thunder compared with other lentil varieties sown 4 May and 14 June at Woomelang (southern Mallee) in 2023.

1. Each sowing date analysed as a separate trial as sown in blocks.

The novel herbicide tolerant lentil varieties GIA Metro (tolerant to metribuzin and IMI) and GIA Sire (tolerant to residual Lontrel® and IMI) have very unique flowering and growth characteristics. GIA Sire is short, very bushy and sensitive to vegetative frost. In agronomy sowing date trials in 2023, this meant that it had the lowest yields at the Wimmera trial site, with the highest levels of plant death from frost and was the most difficult variety to harvest as it had lodged and was very short (Table 2). In other trials at the site (data not shown), its harvestability was improved in standing stubble. Following harvest, the percentage of the plants not harvested due to lodging and/or short plant was assessed (‘Harvest Miss (%)’). Harvest miss was 18% in standing stubble and 37% in slashed stubble. Vegetative frost damage (assessed as the percentage % of plants that died ) showed an inverse pattern with 23% damage in standing stubble compared with 12% in slashed stubble. Conversely, at the southern Mallee site, its yield potential was close to PBA Jumbo2 where it was sown early on a sandy loam soil with a background of standing stubble, low disease risk due to dry conditions and did not experience frost.

GIA Metro has generally 20–30% lower yield than varieties like  GIA Thunder, PBA HallmarkXT and PBA Jumbo2, but has good tolerance to frost and good harvestability, as highlighted in Table 2. It appears to move slowly through the reproductive phase, limiting yield potential. To investigate this, trials in 2023 investigated different sowing dates and plant densities to maximise yield potential and minimise yield gaps to other varieties. To date, results have been variable, particularly across the sowing rates, where there have been mixed responses to an increase or decrease from the currently recommended 120 plants/m2. Trials in 2023 (Tables 1 and 2) and previous research (Brand et al. 2023) have indicated higher yield at the earliest sowing dates. A potential novel use for the metribuzin trait is highlighted below.

Table 2: Vegetative frost damage , grain yield and proportion of plot not harvested  for GIA Sire and GIA Metro compared with other varieties sown 15 May and 3 June  at Dooen (Wimmera) in 2023.

1. Each sowing date analysed as a separate trial as sown in blocks. 2. Frost damage refers to percentage of plants that died as a result of frost events primarily in July 2023 where minimum temperatures reached -5.5OC, assessed October 5.  3. Following harvest (December 21), the percentage of the plants not harvested due to lodging and/or short plant was assessed as ‘Harvest Miss (%)’. 4. PBA HallmarkXT was grown in the surrounding paddock, sown May 17 and achieved 1.40t/ha.

Soil variability and yield stability – sandy and duplex soils in the west Wimmera

A key constraint to reliability and yield stability of pulse production in some regions is soil variability. Substantial improvements in genetic adaption (for example, improved tolerance to boron and salt or sandy soils) and utilisation of soil amelioration techniques (for example, deep ripping, spading, clay spreading) has helped overcome specific constraints, improving yield and yield stability and enabling the confident expansion of pulses in these areas. In 2023 at Gerang in the West Wimmera, a range of lentil, faba bean, field pea, chickpea and lupin varieties were compared on a sandy and a duplex soil in the same paddock to demonstrate which crop and varietal options have the best fit for these variable soils with constraints related to soil texture, and boron and salinity at depth .

Faba beans had the highest grain yields and profitability consistently across both soil types. In contrast, lentils generally performed poorly, with very low yields on the duplex soil. It is hypothesised this occurred due to transient waterlogging and cold frosty conditions experienced during July (Table 4). Despite commonly held perceptions that faba beans have poor yield stability, in this trial, they had the most stable yields across individual plots in both locations when compared to other pulse options sown (Figure 2). Individual plot yields ranged from 2.1–4.6t/ha on the duplex soil and 1.7–3.4t/ha on the sand (Figure 2). In contrast, in lentil, individual plot yields ranged from 0–1.6t/ha on the duplex soil and 0.2–3.5t/ha on the sand. Yield variability was very large across very short distances in lentil, where the yield of neighbouring plots varied up to fourfold.

These results highlight the fit of faba bean in these variable soil types, with grain yields consistently higher than 1.7t/ha in these trials. In contrast, lentil were sensitive to soil type, where in some areas no yield (0t/ha) was measured due to hostile environmental or soil conditions . More detailed soil type data and individual variety responses in the sand and duplex soil will be discussed in the presentation.

Table 4: Average grain yield (t/ha) and profitability ($/ha) of pulses grown on a duplex soil compared with a sandy soil at Gerang, west Wimmera, in 2023. Estimated yield potential = 2.46t/ha (modified French/Schultz model).

¹Grain yield is an average of all varieties grown at the site on that soil type.
²Grain price is indicative of prices received in December 2023 and production costs based on advice from local agronomists for 2023.

Figure 2 . Grain yield variability of lentil and faba bean grown on a duplex soil compared with a sandy soil at Gerang, west Wimmera, in 2023. Bars indicate the number of plots in each grain yield group in the trial. Arrows  indicate the average yield across the varieties and replicates for the two soil types. Estimated yield potential = 2.46t/ha (modified French/Schultz model).

Disease management in a dry season

In 2022, botrytis was extremely difficult to control in faba beans, lentils and vetch. Complete crop failure was experienced in faba beans, particularly in the Wimmera, for the susceptible variety PBA Bendoc. Substantial yield loss in lentil and vetch was also observed, despite the use of proactive fungicide practices. Following the 2022 season, several questions have been raised from growers and agronomists asking: ‘How long until I can grow a bean, lentil or vetch crop in that paddock again without risking a botrytis outbreak?’ In 2023, there was a unique opportunity to sow pulse trials directly into highly infected faba bean stubble and observe relative responses to genetic resistance and fungicide control.

In the west Wimmera, lentil, faba bean and vetch vareties differring in resistance to botrytis were sown in 2023 into a paddock that had a failed faba bean crop in 2022, due to high levels of botrytis grey mould. In the southern Mallee, lentil and vetch were sown in 2023 into a paddock of vetch that had high levels of sclerotinia and botrytis in 2022. Both sites had fungicide strategies ranging from a nil control to a proactive approch, aiming to achieve complete control as well as a severalvarieties with a range of disease resistance ratings. Both sites experienced very low rainfall from July to September and even in susceptible varieties like PBA Bendoc (faba bean), PBA Bolt (lentil) and Morava (vetch), almost no botrytis symptoms were observed due to dry seasonal conditions. Consequently, no significant grain yield response to fungicide application was observed. Results from these trials are a reminder of the importance of conducive environmental conditions (such as a high number of rain days inducing high canopy humidity) for the development of botrytis. In drier seasons, there may be an opportunity to reduce fungicide usage and costs.

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, the authors would like to thank them for their continued support. This work would not be possible without the dedication of the various technical teams. We also gratefully acknowledge our host growers and agronomists for their generosity.

Useful resources

Brand J, Mawalagedera S, Fanning J, Moodie M, Duff G, Vague A (2023) The agronomics of pulses, implications of new varieties and herbicide tolerance. 2023 GRDC Updates, Bendigo.

2024 Victorian and Tasmanian crop sowing guide

Contact details

Jason Brand
Agriculture Victoria
Grains Innovation Park, 110 Natimuk Road, Horsham VIC 3401
0409 357 076
jason.brand@agriculture.vic.gov.au
@JasonBrand