The spring 2021 edition of CRDC's magazine, Spotlight, focuses on the capability of Australian cotton growers and our world-leading researchers, which puts Australian cotton at the cutting edge. This edition looks at the many programs that CRDC invests in to build the capacity of our industry and develop our future leaders.

It also looks at recent cotton irrigation benchmarking figures, which show that the Australian cotton industry has almost halved the amount of water required to grow a bale of cotton over the past 25 years. This is an enormous achievement, and one that has primarily been driven by growers making improvements in irrigation infrastructure and driving efficiencies in their management practices, underpinned by CRDC-supported RD&E. The research also suggests that we are well on our way to continue this trend and reach the industry’s ambitious sustainability water use efficiency target, outlined in the PLANET. PEOPLE. PADDOCK. Sustainability Framework.

This edition also features another fantastic sustainability story: a circular cotton project being led by Cotton Australia, with support from a range of partners including CRDC. This heralds the possible start of a truly circular industry.

Cotton fibre is the most important natural textile fibre, but it requires intensive scouring to disrupt the hydrophobic cuticle to allow dye to penetrate. The standard fibre qualities and amount of waxy cuticle material on cotton fibre varies across genotype. Some research has been undertaken addressing the influence of environment and management on standard fibre qualities and wax content, however no clear effect of either has been shown on cotton fibre cuticular wax despite the influence these variables have been shown to have on other standard fibre qualities and the cuticular wax content of other aerial surfaces of cotton plants. Predicted changes in climate in future will influence the ambient temperature of growing regions, likely increasing the amount of heat stress on cotton plants and may also affect water availability leading to water deficit stress. The effects of heat and water stress during flowering and early to mid fibre development period was captured for two consecutive growing seasons in a field production scenario for five upland cotton genotypes that varied in their known tolerance to both heat and water stress. It was hypothesized that stress at this time would tend to influence fibre initiation phases that might affect fibre perimeter determination and fibre lengthening, as well as wax content which is known to be deposited typically before the secondary cell wall thickening phase of fibre development. For all genotypes, water deficit increased measured cross-sectional properties with an associated increase measured in micronaire for both experiments. Increases were also seen following heat stress for fineness and maturity ratio in the second season. For fibre length, either water deficit alone or a combination of water deficit and heat stress, reduced fibre length for all but two genotypes. The exceptions were the water stress tolerant genotype which did not respond to water stress alone, and the poor water stress tolerant genotype which did not respond to either stress. Heat stress alone appeared to play the dominant role in reducing

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fibre length for the genotype included for its good water use efficiency. Either water deficit stress or a combination of both stress treatments, increased cotton fibre strength in one of the experiments, while only a combination of both stress types in the other experiment produced the same effect. Both heat and water deficit stress were shown to significantly influence fibre cuticular wax deposition, but the effect was genotype dependant with the greatest effect observed on the genotypes included for poor heat tolerance and poor water deficit tolerance. For these genotypes significant increases were measured in cuticular wax. In an attempt to replicate the effects of water stress seen the field experiment in a glasshouse setting, water deficit stress was applied to a white control genotype, a naturally coloured high wax green genotype, and the poor water stress tolerant genotype. The only effects of water stress on fibre properties were to increase fibre fineness and strength, and decrease length, for which a main effect of stress was measured. There were no significant effects on fibre cuticular wax content or other fibre cross-sectional properties. This was attributed to the possible differences in the severity of the stress between the two experiments. Following this, an investigation into the dyeability of fabrics made from three different naturally coloured upland cottons with varying wax content was undertaken. One common white cotton, and two un-common coloured cottons, one brown and one green, were used for experiments. It was hypothesised that following dyeing, fabrics that were not scoured would have inferior colour fastness following a standard fabric wash test. The effect was expected to be more prominent for fabric made from the higher wax content coloured cottons. Fabrics made from these cottons were subjected to either traditional NaOH caustic scouring or hot ETOH scouring which more specifically targets the waxes, before being dyed and washed. It was found that while NaOH scouring resulted in greater dye uptake on the brown fabric, the ethanol scouring resulted in greater dye uptake on the naturally high wax green fabric. The

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NaOH scouring adequately disrupted the hydrophobic cuticle of all experimental fabrics resulting in a dye result that was colour fast following the application of a standard wash test. Further to this a novel assessment of cotton polysaccharide content by GC-MS of three fabrics was performed. Following scouring, dyeing and washing fabrics were analysed spectroscopically to assess the ability of traditional scouring to remove polysaccharides and to assess the influence these polysaccharides may have on fabric dyeability and colour fastness. It was shown that the non-cellulosic polysaccharide content was significantly greater in naturally coloured cotton, but it did not negatively affect dyeability, and could be adequately scoured using traditional NaOH scouring method. These results further highlight the importance of carefully managing cotton growing conditions and stress to reduce any impact on fibre quality and cuticular wax component that may negatively affect the dyeability of cotton fabrics.

This project aimed to deliver a series of podcasts to inform growers and industry on the various ways FAW was having an impact and being managed in key locations internationally and locally in Australia. It also sought to pool relevant FAW information into one location.

Fall armyworm (FAW), Spodoptera frugiperda is a noctuid moth, native to the Americas. It was first reported in Australia in February 2020 and quickly established across parts of Northern Australia’s tropical and sub-tropical regions, including North Queensland, Northern Territory, and northern parts of Western Australia. Eradication has been determined to be unfeasible and it is now classified as an established pest in these areas.Given COVID-19 restrictions this year, PHA, like most national organisations, had to change the ways in which it engaged with growers, researchers and biosecurity staff.Early project discussions and planning had the project delivering a series of regional face to face forums across northern Australia, from the Burdekin , Katherine and Kununurra. While there is nothing better than standing in the paddock or at a field day and engaging growers on the challenges they face, the reality of COVID meant we weren’t able to do that.The project quickly changed tactics in light of the evolving pandemic and selected podcast as the primary delivery pathway for the information that was to be curated. This was the first attempt by PBRI and PHA to develop podcasts as the way of delivering information to industry.

The podcast series featured interviews with growers and agronomists on their first-hand experience in managing new and emerging pests, leading Australian researchers on their latest findings and observations and international experts who share their experiences and learnings. Each episode was around 30 minutes in duration (something similar to “conversations’ on the ABC, and listeners can listen in any order they want.

CRDC ID: PHA2003For Public ReleaseJuly 2020 template6 of 16 14 people were interviewed on their experiences when dealing with Fall Armyworm, the challenges they faced and any lesson that we should heed.The podcasts were hosted on the PBRI website www.pbri.com.au/pbri-podcasts and were also made available to listeners to access directly through their favourite podcast app (ie Apple podcasts, Spotify, Google56 podcasts).Throughout the series, podcast host Chris Brown delved into the biology and behaviour of fall armyworm and explored how we could best prepare ourselves to minimise its impact.

The project produced a series of 9 podcastsfrom 14 interviews on the experiences of dealing with Fall Armyworm, the challenges faced and lessons that Australia could learn from.Details of each podcast are provided in the Technical report in Part 3.

CRDC's Annual Operational Plan for 2021-22 (AOP): the fourth annual operational plan under the CRDC's Strategic RD&E Plan 2018-23.

Yarn hairiness control has become a “holy grail” of research in ring spinning. A significant amount of research effort has been devoted to the study of yarn hair generation and its control. This includes minimising the spinning triangle width and re-incorporation of protruding hairs into the yarn body. These methods led to development of different technologies, which performed the task by condensing the roving during drafting (compact spinning), untwisting-retwisting of spun yarn using swirling air jets (JetRing spinning) and splitting the drafted roving into multiple small roving strands (Solospun™ system). Of these, compact spinning is the most popular and widely used in spinning industry. However, this technology comes with significant additional cost in terms of the compacting unit (pneumatic or mechanical) and its maintenance during spinning. There is therefore still significant demand from spinning mills for new methods of hairiness reduction that require minimum investment costs.

The spinning triangle (ST) is the zone where the fibre fringe of a roving is converted into yarn and the site where hair generation occurs as a result of fibres at the edge of the drafted fibre strand not being incorporated into the yarn body. The geometrical dimensions of the ST are critical in controlling the hair formation tendency of the fibre strand. Until the concept of offset spinning came to light, the width of the ST was the only geometric parameter considered in research to reduce yarn hairiness. Offset spinning has been shown to improve hairiness in cotton yarns. However, in the absence of a mechanical support, an offset ST is prone to fibre loss, which results in high unevenness in yarn linear density.

This project focussed on detailed experimentation of offset spinning to improve the quality of ALS cotton yarns using a novel insert device. The major tasks of this project involved systematic spinning trials and design of an insert device to assist in controlled offset spinning of cotton yarns. The offset device was designed to be a simple retrofit unit which can be installed on the spinning machine with minimal installation and maintenance cost. The device demonstrated a significant improvement in yarn quality parameters, yarn hairiness in particular. The main project conclusion outlines that offset spinning is a simple geometric modification of the ST for producing yarns with reduced hairiness. However, the direction of offset plays an important role in determining this effect. A right-hand offset (RO) is effective in reducing hairiness for a Z-twist yarn while left-hand offset (LO) deteriorates hairiness results. An opposite effect is observed when the twist direction is changed. Fibres from both edges of ST undergo significant change in their wrapping behaviour depending on the direction of offset. The advantages of the insert device for Australian cotton relates to its potential ability to improve conversion of long staple Australian Upland, which typically has poorer tenacity and SFC values than SJV and Pima cotton. The ability of the device to improve yarn qualities affected by these properties means that Australian cotton value is improved. In the same way, the device could also improve the count able to be spun consistently from 100% Australian long staple Upland, e.g., from Ne 40 to Ne 50 (15 to 12 tex) and even Ne 60 (10 tex), which is a market currently limited largely to high quality SJV

Rising atmospheric CO2, warmer air temperatures, higher Vapour Pressure Deficit (VPD) and reduced water availability as a consequence of climate change is likely to affect cotton production. Previous field and glasshouse studies in Australian cotton systems have shown that warmer air temperatures may increase stomatal conductance and transpiration, resulting in reduced leaf-level water use efficiency. Increased photosynthesis and increased vegetative biomass under scenarios of projected climatic conditions will not necessarily equate to higher yields. Furthermore, elevated CO2 may potentially exacerbate the negative effects of warmer temperature in cotton, leading to large reductions in water and resource use efficiencies. Therefore, further studies were required to explore management strategies for cotton grown in high temperature, high CO2 environments, thereby enabling sustainable and efficient cotton production systems in the future.

To enhance the current understanding of cotton system adaptation to climate variability and plan for projected climate change, a combination of controlled environment glasshouse and field-based studies were conducted to assess the integrated effects of warmer temperatures and elevated atmospheric CO2 concentration on cotton growth, physiology and water use. Overarching aims were to (1) investigate the interactive effects of atmospheric vapour pressure deficit (VPD) and soil water deficit on the physiology of cotton; (2) identify potential management practices that mitigate the interactive effects of climate change; (3) improve understanding of leaf to canopy level scaling; and (4) better model and predict the impact of future climate scenarios on water use and yield of cotton.

Glasshouse studies showed that increasing VPD stimulated stomatal closure across a range of temperatures. Soil water deficit reduced stomatal conductance of cotton at all temperatures measured, particularly at lower VPD compared with well-watered plants given the same VPD. Therefore, drier climatic conditions may reduce stomatal conductance, although transpiration increases with warmer temperatures, within the range of at 50% water deficit that was tested in our study.

Glasshouse studies showed that fruit loss may greatly increase the vegetative growth rate (VGR) of cotton; however, mepiquat chloride applications were also shown to reduce the VGR of cotton that had lost fruit in warmer temperature and elevated atmospheric CO2 environments. Similarly, our field studies demonstrated that vegetative biomass was controlled by the application of mepiquat chloride in two out of the three seasons, although observations of increased difficulty in defoliating cotton plants grown at warmer temperatures and elevated CO2 suggest that understanding timing of defoliants in future climate scenarios may require further research. Therefore, this research suggests that mepiquat chloride may be a successful method of controlling excessive vegetative growth in future climates of warmer temperatures and elevated atmospheric CO2.

The climate chambers were used to measure the leaf and canopy level responses of cotton grown in warmer temperature and elevated CO2 environments; however, further research may use modelling to further link these responses. We also used a multi-faceted approach to better model and predict the impact of future climate scenarios of water use and yield of cotton. Our research indicated that climatic changes, such as an increase in the number of seasonal day degrees, have already occurred across several key locations throughout the Australian cotton industry. These findings may help define adaptation strategies by linking regions with similar past and present climatic conditions. On-going research requires a multi-faceted approach that incorporates model simulations, glasshouse and field studies to better our understanding and knowledge of system responses to projected environmental conditions for Australian cotton regions. The outcomes of the broad research into the effects of climate change on Australian cotton systems, has been summarised in our review to industry, “An overview of recent research into the effects of climate change and extreme weather events on Australian cotton systems”, published by CottonInfo.

of water from below the root zone is the most elusive component of the water balance to measure. Attention on drainage has increased because of concerns both about the efficiency with which irrigation water is used and about environmental damage caused by excess drainage through waterlogging, salinity and the movement of agrochemicals into waterways. However, most work on drainage has either used indirect measurements based on calculation of fluxes from the soil water profile measurements, chloride mass balance, or modelling to estimate its magnitude. This project attempts to directly measure drainage under an irrigated cotton system at ACRI using an equilibrium tension drainage lysimeter modified from a design of Brye et al. (1999).

The lysimeter facility has three objectives. The first is to measure drainage and better understand when it occurs during the crop rotation. The second is to act as a benchmark against which to test other, less expensive methods of measuring or estimating drainage which can be used in many more locations. Finally, data from the facility will be used to improve water balance models that can be used in conjunction with farming systems models to estimate drainage at a range of locations over long time periods (decades) and under a range of management systems. Such models can then be used to design more efficient and environmentally benign irrigation systems.