Australia
April 2, 2025
- Growth stage keys have been developed to ensure pulse crops with indeterminate growth stages are measured consistently
- The keys are valuable to help understand how the environment influences crop development and in making agronomic decisions
- They have been developed via the GRDC-invested National Pulse Agronomy project
A new framework to measure pulse growth stages will help researchers, crop modellers and agronomists better align crop development to environmental influences
New ‘keys’ for recording pulse growth stages have been developed, addressing a historical focus on flowering that has hindered research and the ability to correctly understand pulse phenology.
Ensuring phenological development is measured consistently, the keys will help create confidence in how the environment influences pulse development.
CSIRO farming systems scientist Dr Jeremy Whish and CSIRO principal research scientist Dr Fernanda Dreccer built the keys through the GRDC-supported National Pulse Agronomy project. These unified pulse keys have been refined over the past three years and tested in more than 120,000 field observations.
Dr Whish says understanding phenological development is critical to matching genetics to the environment.
CSIRO farming systems scientist Dr Jeremy Whish, pictured at the Agronomy Australia Conference in 2024, has created new growth stage keys with CSIRO principal research scientist Dr Fernanda Dreccer. The keys developed via the GRDC-supported National Pulse Agronomy project create confidence in how the environment influences pulse development. Photo: Rebecca Thyer
Clear code
Dr Whish says the value of a good phenological key is often overlooked.
“The ability to understand how the environment influences the development of a crop is key to making agronomic decisions, such as when to sow and how to reduce stress in the critical period of yield formation. Without a clear code to describe when development occurs, this is not possible.”
While development keys exist, pulse crops’ indeterminate development creates a unique challenge in identifying the beginning and end of specific stages.
“Unlike many determinant crops, it is not uncommon to observe pulses producing flowers, immature pods, mature pods and leaves at the same time. Or for the primary stem to lose apical dominance.”
Dr Whish says this prevents the main stem from being the most advanced continuous measure of plant development.
GRDC sustainable cropping systems manager Dr Courtney Peirce agrees and says the team’s work has been crucial in rectifying this.
The approach taken with determinant crops – to score the main stem only – does not represent the pulse plant correctly once it becomes reproductive. Branches need to be taken into account. The message from the team is to score pulses as a whole plant once flowering begins on the branches.
Chickpea and lentil growth
The project team focused on adapting an existing key – the BBCH scale – to specifically suit chickpeas and lentils’ indeterminant nature.
The new keys consider development across the whole plant following flowering. This captures the importance of pods developing on primary branches and prevents the main stem’s development from being out of sync with the bulk of the plant.
Dr Whish says using clearly identifiable visual stages improves consistency in data recording. “This provides greater confidence in describing how the environment influences the development of chickpeas and lentils across Australia.”
Visual key
The initial key used simple line drawings and descriptions to help identify each stage.
“During development and following the key’s adoption, we passed a series of photographic explanatory slides between each other. These slides continue to be collected and have resulted in a pictorial version of the key. It has been incorporated into an app that facilitates phenology collections for the project.”
The new keys are being peer reviewed. Please contact Dr Whish for details.
More information: Dr Jeremy Whish, jeremy.whish@csiro.au
What is a growth stage key?
A key provides a common reference for describing crop development. Understanding the timing of a crop’s development is fundamental to good agronomy. One of the most well-known keys is the decile code developed for cereals.
Zadoks key uses a decimal code to match a growth stage’s appearance to 10 principal developmental stages.
The BBCH scale furthered this decimal approach, creating a unified framework that could be used to describe any crop’s development. Its initial intention was to be general and represent a population, not an individual, making the scale more useful in practical agronomy.
Crop modelling and keys
The advent of crop modelling meant keys were progressively used to describe phenological development in individual crops, not just populations.
Models use phenological stages to set the timing and arbitrate where resources (growth) are distributed to leaves, stems, flowers, grain and roots.
Each stage concludes before the next stage starts with a focus on the main stem.
Indeterminant challenge
For pulse crops, this presents a challenge. Their indeterminant nature makes their inclusion in linear frameworks difficult. Many pulses are still described using two stages – vegetative and reproductive.
Grey areas occur when trying to translate that to a modelling framework or a decimal code as a pulse crop keeps producing vegetative organs, such as leaves, after flowering or even podding (reproductive stages) have started.
The new key aims to address this by adapting the BBCH scale considering development across the whole plant.
Topics
Species
