Pulse physiology, phenology, and productivity
Pulse physiology, phenology, and productivity
Author: Victor Sadras, Lachlan Lake, Mariano Cossani, James Manson, Raul Gimenez (South Australian Research and Development Institute), Nicole Dron (NSW DPI) | Date: 04 Feb 2025
Take home messages
- After a lag and slow start in the 1980s, national acreage of pulses increased rapidly reaching a peak in 2016–2017: 1.1 Mha in chickpea, 0.7 Mha in lentil and 0.35 Mha in faba bean. Acreage has retracted in the last few years.
- Production tracked harvested area. The contribution of yield improvement in growers’ fields to total production has been largest in faba bean, for which national average yield increased at a substantial 21 kg/ha per year. Actual yield gains have been smallest in chickpea and intermediate in lentil.
- The increase in yield of faba bean is attributable to agronomic improvement and breeding that has enhanced crop standability and disease tolerance. However, breeding has not increased yield potential.
- Genetic gain in lentil has been substantial, at an average 1.2% per year. Gains have been particularly high in drier environments. Genetic gains are associated with shifts in phenology – newer varieties have a shorter time to flowering, and slightly earlier maturity, with an increase in the flowering-to-maturity period. Across Australia, lentil yield associates with earlier flowering.
- Genetic gains in lentil have not been fully captured in growers’ fields. In high-yielding environments, high biomass crops fail to yield due to low harvest index. This decoupling of growth and yield needs attention of agronomists and breeders.
- Genetic gain in yield of chickpea has been very low. In common with faba bean, this partially relates to markets driving bigger seed and a trade-off between seed size and seed number. Also in common with faba bean, disease tolerance is a high priority in breeding programs.
Context: area harvested, production and yield
Figure 1 shows the trajectories of harvested area for faba bean, chickpea, and lentil in Australia. Faba bean cropping was incipient in the 1960s and started a rapid increase in harvested area in the late 1970s. Chickpea and lentil followed with a substantial increase after a lag phase in the early 1980s. Chickpea harvested area peaked at 1.1 Mha in 2016 and retracted to 0.6 Mha in the last few years. Lentil harvested area peaked at 0.7Mha in 2017. Faba bean harvested area peaked at 0.35 Mha in 2016. Production largely tracked harvested area (Figure 1, mid row). National average yield increased at a substantial 21 kg/ha per year in faba bean, with little improvement in chickpea and intermediate rate for lentil (Figure 1, bottom row). Three factors drive yield: better varieties, better agronomy, and the synergy between breeding and agronomy, and these need particular attention where yield progress has been slow.
Figure 1. Harvested area, production, and yield of chickpea, faba bean and lentil. National data from FAO.
A bit of pulse yield physiology
In common to all annual crops, seed number accounts for most of the variation in the yield of pulses in the range from failed crop to potential. Seed number is determined in a critical period centred at podding. This is in contrast to cereals, for which the critical period is centred at flowering (Figure 2). In faba bean and lentil, for which the podding-to-flowering period is often short and varies little between cultivars, flowering is a useful reference. In chickpea, for which podding varies strongly between cultivars and can be substantially delayed under unfavourable conditions, flowering time has little agronomic meaning.
The flowering-to-podding interval in chickpea can vary 3-fold between varieties. The flowering-to-podding interval has been attributed to low temperature, but our current thinking is that it is more of a syndrome, where the flowering-to-podding intervals shortens with high radiation, and warm and dry air. With warm temperature (mean above 17 oC), low radiation and high humidity can still compromise podding (Gimenezet al. 2024). Delayed podding reduces chickpea harvest index (Gimenezet al. 2024).
Figure 2. The critical period for grain set and yield in cereals and pulses. Source: Sadras and Dreccer (2015).
Genetic gains in yield
GRDC has made specific investments to quantify the rate of genetic gains in pulses. Experiments compare historic collections of commercial varieties, and genetic gain is calculated as the slope of the relationship between yield and year of release. Rates are similarly calculated for other traits, such as time to flowering, biomass, and harvest index.
Genetic gain in lentil yield has been large, about 1.2% per year, and this compares well with wheat. Considering the modest investment in pulse research and development, lentil genetic gains per dollar invested are possibly higher than in wheat. Improvement in yield of lentil has been associated with shorter time to flowering and podding (-0.72 % per year), and a slight shortening in time to maturity (-0.22 % year) resulting in a substantial increase in podding-to-maturity (+0.56 % per year): newer varieties spend more time setting pods (Sadraset al. 2021). Genetic gains in yield are larger than actual change in yield in growers’ fields (Figure 1), hence, investments in lentil agronomy are needed to close the increasing gap between potential and actual yield. There is an opportunity for agronomic and breeding solutions to increase lentil yield in high yielding environments, where crops produce high biomass with low harvest index.
Genetic gain in yield of faba bean and chickpea has been negligible. This relates to physiological and breeding trade-offs. Physiologically, heavier seed, driven by market demand, has been achieved at the expense of seed number, and this has probably halted yield improvement. Genetic yield gains in both faba bean and chickpea need to account for this trade-off. In faba bean, there is a trade-off between adaptation to low and high yielding environments (Figure 3). Note yield is shown as a percent of average trial yield and data are scattered in Figure 3. If PBA Zahra outyields PBA Marne by 1% in a 7 t/ha environment, the gain is a substantial 0.7 t/ha, but if PBA Marne outyields PBA Zahra in a 1 t/ha environment, the gain is 0.1 t/ha.
Figure 3. Trade-off between yield in high and low yielding environments for varieties adapted to northern (left) and southern (right) Australia. Yield is per cent of trial. Source: Manson et al. (2024)
In comparison with wheat, nationwide investments in pulse breeding are modest. Furthermore, disease tolerance is critical in pulses and this trait ranks high in breeding programs. Figure 4 illustrates the breakdown of resistance to Ascochyta blight in Fiesta and Farah, and breeder’s rapid reaction restoring resistance in subsequent varieties.
Figure 4. Mean Ascochyta blight scores of faba bean southern varieties released since 1980. Two pathogen strains representing pathogenicity groups 1 and 2 (PG-1 and PG-2, colours) were tested. Asterisks indicate treatments that significantly differ from the most resistant treatments near zero (Tukey’s Honest Significant Difference for the Variety: PG interaction, p<0.05). The red circle highlights the lack of genetic resistance in Fiesta and Farah to the PG-2 pathogen strain which was identified in the mid-2010s. Source: Manson et al. (2024).
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. We also thank pulse breeders for plant material and insights – Kristy Hobson, Garry Rosewarne, Arun Shunmugam, Sam Catt, Kedar Adhikari.
References
Gimenez R, Lake L, Cossani MC, Ortega Martinez R, Hayes JE, Dreccer MF, French R, Weller JL, Sadras VO (2024) Linking phenology, harvest index and genetics to improve chickpea grain yield. Journal of Experimental Botany 2024 Nov 29:erae487. doi: 10.1093/jxb/erae487. Epub ahead of print. PMID: 39626055.
Manson JB, Adhikari KN, Blake SN, Catt SC, Denton MD, Lake L, Brand J, Walker C, Taylor J, Sadras VO (2024) Genetic gain in yield of Australian faba bean since 1980 and associated shifts in the phenotype: Growth, partitioning, phenology, and resistance to lodging and disease. Field Crops Research 318, 109575.
Sadras VO, Dreccer MF (2015) Adaptation of wheat, barley, canola, field pea and chickpea to the thermal environments of Australia. Crop and Pasture Science 66, 1137-1150.
Sadras VO, Rosewarne GM, Lake L (2021) Australian lentil breeding between 1988 and 2019 has delivered greater yield gain under stress than under high-yield conditions. Frontiers in Plant Science 12, 674327.
Contact details
Victor Sadras
South Australian Research and Development Institute
victor.sadras@sa.gov.au
GRDC Project Code: UOT1909-002RTX, UOA2204-004RTX, DPI2205-022RTX, UOA2202-006RSX,