Charting a New Course in Cotton Growing with CBA’s Pioneering Research

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Charting a New Course in Cotton Growing with CBA’s Pioneering Research

Feb 5, 2024

Introduction

In Australia’s vast and sunlit cotton fields, the battle against searing heat and dwindling water is reshaping the very essence of cotton growing. Here, the relentless march of climate change is not a distant threat but a present reality, bringing with it soaring temperatures and sometimes a scarcity of water that challenge the resilience of even the hardiest cotton varieties. In often trying times, Cotton Breeding Australia (CBA), a joint venture between Cotton Seed Distributors (CSD)and CSIRO, stands as a beacon of innovation and hope. Their partnership is a testament to the industry’s commitment to not only survive but thrive amidst these environmental adversities, ensuring the sustainability of Australia’s cotton growing for generations to come.

 

Climate Challenges

Australian cotton growers are well-acquainted with the challenges brought about by an increasingly hot climate. When temperatures frequently soar above 40ºC, the stress on cotton plants increases. Intense heat can hinder key biological processes, especially photosynthesis, leading to a drastic reduction in carbohydrate production – the vital energy source for cotton’s growth and development. This shortfall manifests in various challenges that growers know all too well: smaller boll sizes, increased shedding of squares and bolls, sometimes ‘boll dangle’, and the ‘Parrot Beaking’ in bolls, a clear sign heat-stress in cotton.

Water scarcity further compounds these challenges associated with heat, an issue that certainly many rainfed growers face season after season. In this new era of unpredictability, ensuring the growth and quality of the yield with limited water becomes a critical balancing act. These situations underscore the urgency for adaptive strategies and solutions, including the development of new cotton varieties.

 

Cotton Breeding Australia Response

In response to the challenges around heat and water stress, CBA has been a trailblazer in the Australian cotton industry since 2007. CBA aims to use cutting-edge research and development to produce superior cotton varieties, characterised by enhanced yields, superior fibre quality, and efficient resource utilisation.

The heartbeat of CBA’s innovation lies in the fusion of traditional and advanced breeding. CBA’s commitment to excellence is underscored by its substantial investment of over $140 million in diverse projects, ensuring that Australian cotton remains a leader on the global stage. This strategic investment not only fortifies the current standing of Australian cotton but also gears the industry to successfully navigate future challenges such as climate change and changes in water availability.

There is focused investment through CBA in developing varieties that can withstand the rigours of higher temperatures and grow efficiently with less water is setting a new standard in cotton growing. For growers, these initiatives represent more than just the development of drought-tolerant plants; it is a comprehensive approach to ensuring that Australian cotton remains a competitive and sustainable crop in a rapidly changing world.

 

Understanding Water and Heat Challenges in Cotton

In the world of cotton farming, battling heat and water shortages is important. Highlighting this were some past investments where crop experts Drs Katie Broughton and Warren Conaty produced groundbreaking research digging into how different cotton plants deal with less water along with higher air temperatures and lower humidity, with the aim to develop tougher cotton varieties.

The project looked at two main elements in cotton plants:

  1. How they handle dry and hot air: They found that different cotton varieties react differently to dry air. Some can cut down on their water loss through their leaves much earlier as these conditions worsen for plant growth.
  2. What happens with less soil water: They also checked how different cotton varieties can deal with less water in the soil. This is key for finding out which plants can stay productive when water is scarce.

Another big focus of the initiative was on the viability of pollen and whether the genetic variation of plants responses to heat and pollen viability was an option to build resilience – viable pollen is needed for making seeds and ultimately cotton fibre. They wanted to understand how hot weather impacts negatively with the pollen and, in turn, cotton production. They found that pollen is tougher than first thought. Even if pollen viability dips a bit in the heat, cotton produces such high volumes of pollen that overall, the fertilisation of flowers is not limited by this reduction in viability. However, we all know that fruit shedding and ‘parrot beaking’ occur during heat waves, thus it is concluded that these heat stress events are more likely the result of reduced photosynthesis and carbohydrates to support fruit development. This means that pollen health might not be as big of a worry in hot conditions as previously thought.

 

Next Steps for Better Cotton Varieties

The team has not stopped there. Following the promising strides in understanding how cotton plants cope with heat and water stress in past research, the focus now shifts to integrating this work into the CSIRO breeding program by redesigning the way we breed cotton for abiotic stress resistance. Led by a team of experts including Pierce Rafter, Annelie Marquardt, Wayne Thompson, Connor Cassidy and Warren Conaty, this long-term project is forging new paths in cotton breeding for dry, rainfed environments. The CSIRO team are now looking closely at how cotton genes at a molecular level respond under these tougher conditions. Understanding how the genes respond can help develop more focused breeding strategies to deliver new cotton varieties much more quickly that are better at saving water and handling the heat, especially important for drier farming areas.

The current project encompasses four major areas of investment:

Genomic Prediction (GP): This involves developing models that can predict how cotton plants will perform based on their genes and interaction with environmental factors. Being able to identify which plants have the genes that will respond to the stress increases the chances that a plant will have a trait earlier in a breeding cycle.  One could say you are increasing the chances of finding the needle in the haystack.  This is particularly crucial for cotton grown in rainfed conditions.

New Phenotyping Methods: The team is gathering and analysing a large amount of multispectral and RGB data from various remote sensing platforms (e.g. drones) across various experiments. Improving means to identify how varieties are responding to stresses is important to identifying the plants that have the traits of interest and helps to speed up the process of breeding when larger populations are involved.

Exploring Genes and Pathways: A significant part of the project involves using metabolomics and transcriptomics to identify genes and pathways related to water conservation. Understanding these aspects at a molecular level will be key to developing cotton varieties that use water more efficiently.  As heat and water stress are complex traits (involving many genes) using technologies that identify genes the relate to specific pathways in plants (e.g. heat tolerance, photosynthesis etc.) helps to ensure that the right genes are considered when developing selection strategies to deliver these traits.

Advanced Data Management: All the above areas of investment create incredible amounts of data from diverse sources and therefore managing and integrating this information effectively is a critical aspect of the project. The team is exploring various platforms for data storage and analysis to facilitate this integration and improve efficiencies across the whole of the breeding program.

 

Looking Ahead

This is a long-term research area and advances may be slow, but success will deliver important gains to growers, especially those in areas prone to limitations to water. By harnessing the latest in genomic, phenomics, and data analytic technologies, the project aims to develop cotton varieties more quickly that are better suited to the challenges of rainfed farming. This includes plants that can thrive with less water, withstand the stresses of a changing climate, and continue to produce high-quality cotton. This project stands as a testament to the innovation to deliver resilience and adaptability to the Australian cotton industry in the face of environmental challenges.