Water continues to be a major constraint for cotton production systems. There is increasing pressure to improve the water use efficiency (WUE), especially of the furrow irrigation systems used by the majority of cotton growers. Farming systems, stubble management, furrow length and slope and the flow rates are all components of the system that can be manipulated to achieve higher application and distribution efficiencies under furrow irrigation.

Previous work has shown that there is significant room for improvement in both crop water use efficiency and whole farm irrigation efficiency within the cotton production system. Crop water use efficiency (CWUE) was shown to vary between 1.8kg/ha/mm and 3.2kg/ha/mm. Whole farm irrigation efficiency was shown to vary between 20 % and 80 % with an overall average of 57 %. A key approach to improving whole farm WUE is to develop an integrated approach to water management, particularly to identify factors contributing toward high crop WUE and irrigation efficiency. In addition to irrigation, in-season rainfall and stored soil moisture contribute to meeting the crop water requirement. Strategies should be developed to maximise the use of water from in-season rainfall and stored soil moisture and to improve irrigation efficiency. This will benefit the industry by saving irrigation water and enhancing the efficiency with which water is used.

For this project the take home messages are

1. More work is required to understand extraction of water under skip row cotton.

2. HydroLOGIC includes the water use efficiency calculator and this feature will be enhanced in later versions. The capacity for HydroLOGIC so account for whole farm water use being developed.

3. Data have been collected to validate the Penman-Monteith equation and this will be completed in future.

4. Retained stubble systems offer benefits in terms of reduced loss of sediment, improved water infiltration and better early season growth. However this may be countered by the need for careful management to avoid water logging, though there are strategies to do this.

5. Investigation of the effects of vetch rotations on irrigation and water use showed slightly enhanced water holding capacity of soils following vetch rotations.

6. Resurveying the growers involved in the initial WUE Benchmarking study has been planned out and surveying will be done by Mitch Carter (NSW DPI)

The core goals of this project have now been included in CSP164C.

Options for increasing yield and water use efficiency in high retention Bollgard II cotton were identified from research that studied the growth and development of Bollgard II and conventional cotton varieties. Options include increase plant size via managing for a larger plant either at first flower or at maturity, breeding for a larger plant and avoiding water stress late in flowering. The former option would involve changes to early water management and possibly early insect management to increase early leaf area.

A further outcome of this research is changes to the OZCOT model and HydroLOGIC irrigation support tool which will assist growers with management decisions when growing the Bollgard II varieties Sicot 71BR and Sicot 289BR.

This research found that high fruit retention in the absence of early main-stem tipping combined with a lower leaf area index late in flowering were characteristics of Bollgard II. As a result, boll growth was earlier and often faster than conventional cotton. Potential yield could be less due to smaller plants in Bollgard II crop with high retention because harvest index (the ratio of boll weight to total plant weight) was the same as conventional cotton However, yield differences are likely to be confined to regions with a long growing season and full irrigation, where the later fruit set and larger plant size of conventional or lower retention crops will allow them to mature a bigger crop.

The need to monitor fruit load and avoid moisture stress late in flowering of Bollgard II varieties was identified from this research. Due to the rapid increase in boll growth, Bollgard II was more determinate than conventional cotton, hence less capable of recovering from water or other stress late in flowering.

Leaf nitrogen and photosynthesis on leaves lower in the canopy was not affected by high retention, suggesting that rapid boll growth was the major cause of growth differences due to high retention in these experiments.

Future research identified from this project includes, optimal water management of Bollgard II including options to increase early plant size, the contribution of upper leaves to yield in high retention cotton and further enhancements to OZCOT that will improve simulation of crop water use and requirements, and ultimately lead to an improved HydroLOGIC DSS.

As there was a considerable contingent of Australian delegates to this conference, this report will focus on the past harvest sessions with a particular emphasis on fibre quality and ginning. Highlights were as follows

• Major factors influencing Industry needs are;

- Consumer Demand

- Spinning Technology

- Competition with petroleum – based man – made fibres (i.e. polyester etc.)

- Competition from other growth, such as corn, wheat, soy beans, oilseeds.

- Shifts in Textile Industry

- Biotechnology

- WTO; protection of trade, subsidies.

“Severity Factors in Fusarium Wilt of Cotton” aimed to investigate the factors that affect the

severity of Fusarium wilt, and by doing so enable the development of more effective

integrated disease management (IDM) strategies. The three year project resulted in several

important outcomes with direct consequences for the industry.

Outcome 1. Cool, wet early season conditions are the single biggest factor influencing the

severity of Fusarium wilt.

Disease observed in the crop late in the season is the result of infection early in the season,

say within the first 8 weeks after sowing. Therefore, when early season conditions are

conducive to infection, disease severity will be increased. High rainfall and cool temperatures

provide the most conducive conditions for infection of plants by the pathogen. When spring

rainfall is high (say >200mm before December 31), disease severity will be high. A

prolonged period of water-logging later in the season may also induce the appearance of

external symptoms (eg. wilting, yellowing, plant death).

Therefore, the best way to reduce the impact of cool, wet early season conditions is to avoid

them by planting later (say mid-October or later). This strategy enabled us to reduce disease

severity in two out of three years. Benefits from delayed sowing are reduced when diseaseconducive

conditions are prolonged and cannot be avoided. We recommend delayed sowing

as a “best bet” strategy for minimising the impact of Fusarium wilt.

Outcome 2. Fusarium is carried in large numbers on floating trash during irrigations.

We measured over 160 million colony forming units of Fusarium oxysporum per kg of

floating trash during irrigation. Floating trash is the primary means of transport of the

Fusarium wilt fungus around the farm during irrigations. Therefore it is important to 1) stop

trash from leaving the field by using a trash-retaining drop box, and/or remove trash from

channels using trash racks. The process of passaging irrigation water back through a storage

dam or settling pond also aids in removing most of the pathogen from the water.

Outcome 3. Remove stubble, or retain slashed stubble on the surface for a month or longer

before incorporation.

Fusarium wilt will be less severe where stubble from previous crops has been raked and burnt

or slashed and retained on the surface for a month or longer prior to incorporation. These

practices are highly recommended for growers with Fusarium wilt.

Other Outcomes

• Glyphosate (RoundupTM etc) and Roundup ReadyTM technologies do NOT increase

the severity of Fusarium wilt.

• Stress from heavy boll loads does NOT increase the severity of Fusarium wilt.

• There is NO interaction between black root rot and Fusarium wilt.

• Nematodes are NOT a problem in Australian cotton.

Improved understanding of cotton plant response to water stress.

Experiments to establish the response of cotton plant to soil water stress under different soil types,

climatic conditions and fruiting loads have shown that (i) the response of cotton to water stress was

different on different soils (eg heavy clay vs. sandy-loam) (ii) these differences can be accounted for

when soil moisture content is normalised for water holding capacity, expressed as the fraction of

transpirable soil water (FTSW) (iii) that climate, especially evaporative demand, can cause plant

stress even when the crop has adequate soil moisture and (iv) there was no difference in soil water

extraction and therefore root development by crops with different levels of fruit retention.

Field experiments were run over three cotton seasons at three sites with widely different soil types

around Narrabri NSW. The response to the cotton plant to moisture stress, imposed by skipping

irrigations around flowering, was measured as leaf water potential using a pressure chamber. Cotton

plants were found to behave in the same way to moisture stress on all soil types when the soil water

holding capacity of the soil was taken in to account and expressed as a percentage or fraction of

transpirable soil water (FTSW). Over the three seasons, prevailing climatic conditions have a large

effect on the ability of the plant to cope with a given level of soil moisture deficit. Even under low

levels of soil moisture deficit, on high evaporative demand days plants often experienced stress which

would impact on yield. There are some climatic conditions under which cotton plant is unable to take

up enough moisture even from a soil profile with readily available water that the plant will become

stress no matter if more water is applied.

The results of this research will provide a basis for refined irrigation management through

understanding the effect of climate and soil type to reduce water stress and provide decision points for

future management. This information will also be included in all extension methods, especially

decision support systems through inclusion in future versions of HydroLOGIC

A separate experiment conducted over two seasons also in Narrabri showed no difference in soil

moisture extraction and therefore extent of root development between crops that had high and low

levels of fruit retention before cutout. High retention crops (such as BG II®) should be irrigated in a

similar manner to lower retention cotton. The high level of early reproductive development did not

affect root development - activity.

A preliminary experiment was also conducted to investigate partial rootzone drying in cotton. This

showed no benefit from partial rootzone drying in terms of cotton plant stomatal control, biomass

production or yield.

This project has significantly improved our understanding of basic responses of cotton to soil

moisture stress and how this is influenced by climate and soil type. This knowledge is vital in

developing improved irrigation strategies for cotton and achieving maximum water use efficiency.

Genetic engineering to confer useful agronomic and fibre traits will lower the cost and time

required for producing improved cotton varieties and will promote environmentally-friendly

farm practices. Genetic improvement of cotton fibre morphology requires both useful genes

and appropriate expression of the genes in cotton fibres. Previous CRDC-funded research in

our laboratory has aimed to address both these requisites, concentrating on genes which are

expressed in fibres but not in other cotton tissues.

We have identified six different promoters within the cotton genome which directly control

the fibre-specificity and timing of expression of genes. Fibre-specific promoters allow the

expression of any particular transgene to be targeted to the fibres only, avoiding any

detrimental effects of expression on growth and morphology elsewhere within the plant. Each

of the six promoters was fused to a reporter gene, GUS, and, in transient assays, shown to

direct reporter gene expression that was confined to the fibres. The six promoter::GUS

constructs were then used to transforrn whole cotton plants and a large number of transgenic

lines were recovered. These have been tested for presence of the transgene and T2 seed

collected. Future work involves quantitative GUS assays on fibre extracts in order to confirm

the fibre-specificity of each promoter and to determine the temporal expression pattern and

relative strength of each promoter in cotton fibres ofT2 plants.

The second aim of this project wasto identify which of our candidate genes have potential

for alteration of fibre characteristics, by preparing gene constructs designed to change their

expression and testing their effects in whole-plant transformants. The most promising of our

genes encodes an expansin, a protein thought to control plant cell growth by chemical

modification of cell wall components. Expansins could therefore play a critical role in

determination of fibre quality and yield. Four constructs were made, in which the expansin

gene was placed under the control offour different promoters, designed to alter native

expansin expression. These promoters were available from our bank of fibre-specific gene

promoters. The gene constructs were used to transform whole cotton plants and a large

number of transformed lines were recovered. These have been tested for presence of the

transgene and T2 seed collected. T2 plants will be tested for the effects of the transgene on

fibre properties such as length, strength, micronaire, uniformity and maturity.

This project has part funded field operation costs charged by DPI to CSIRO for experiments on ACRI at Narrabri in 2005/06. More than 20 projects have been supported over the three years and all field operations have been done well through collaboration within CSIRO and between CSIRO and NSW DPI.

CSIRO field research has addressed all important areas for yield and sustainability: breeding, disease resistance, soil and water management and insect management. Results of that research have substantially improved industry performance and value. Cotton breeding and decision support systems have been estimated to have added $5.2 to regional economies in the past 20 years. IPM research (by all research organisations) has been successful in substantially reducing the volume of insecticide used on cotton.

A reflection of the value of the Cotton Production course by attendee Annette Heagney.

"The Cotton Production Course has immensely assisted me in my daily working life by providing a thorough understanding of cotton and the industry. The knowledge and skill set expanded upon throughout the course has enabled me to make informed decisions within our business, from the day-to-day operations through to the strategic and Board management decisions. The education I have received through the course has allowed me to confidently contribute towards the cotton and water user committees of which I am a member. I have also been able to expand on my knowledge by attending field days, the Cotton Conference and by having more informed conversations with fellow growers. The agronomics I have learnt through the course has been invaluable when applied to all facets of our mixed farming business. The Cotton Production Course provided me with an unexpected and extensive range of knowledge and skills relating to cotton, farming and business management that will continue to serve in my working life."

In 2008 the Cotton CRC invested in an Education Officer for 5 years to promote science and agriculture in schools. The schools program was developed to enhance and expand the science and environmental management syllabus in primary and high schools by providing relevant cotton information and opportunities for practical on-farm activities. The strategy proposed by the Cotton CRC was the promotion of science and agriculture in schools to encourage school students into careers in science and agriculture, specifically the cotton industry through collaborations with school teachers, scientists, the cotton extension teams, industry, catchment and government education agencies, to encourage primary and secondary school students to develop resources and implement science and agricultural based activities that engage students and ultimately promote the cotton industry as an employee’s career of choice.

The three year project reported herein is the continuation of that initial project directly with the CRDC. As per the previous role, the Education Officer continued to be employed by CSIRO based at the Australian Cotton Research Institute, Narrabri. This facilitated continued direct connections with the industry, schools and rural communities. There was a shift in the current project to include a new initiative to better connect university graduates with potential employers in the cotton industry.

In the first two years of the project funding was allocated 60% to the project. In the third year of the project the Education Officers input increased from 60% to 100% primarily to include a new milestone that involved working with consultant, Mr Gordon Stone (Gordon Stone and Associates Pty Ltd) to establish contacts with the cotton industry agribusiness sector. Mr Stone’s CRDC funded project (GSA1501: Cotton Professional Personnel Program) was to survey agribusiness requirements for workforce development and match suitable students (undergraduates from the Horizon scholarship program, the PICSE Internship program and postgraduates) with agribusiness employers. This new initiative was an extension of the Education Officers role and involved trialing strategies for placements that vary in length and style of employment (short intensive terms, longer casual engagements, etc), and the way the employer contributes to the scheme (in-kind, financial, etc).

. The project (a) investigates soil physical and chemical measures relevant to the evaluation of the agricultural potential of cracking clay soils of the Namoi Valley; (b) provides laboratory data suited to the application of computer and geostatistical techniques to the grouping of the soils into classes for sustainable land use; and (c) relates the soil of local research stations to the soils of the neighbouring district.