The aim of the project is twofold: to draw up a nitrogen budget for cotton under various conditions that are known to affect the crop's response to nitrogen; and to continue to develop the SJRATAC fruit model, in particular by refining the cotton nitrogen sub-model. The value to the industry will be to improve the efficiently of nitrogen fertilisation and pest management. Cotton growers apply between 100 and 200 kg/ha of fertiliser nitrogen to the crop, costing the industry as a whole approximately $15 million annually. At best only 50% of the nitrogen applied is taken up by the crop. Study in more detail of the fate of all nitrogen applied to the crop, and the factors affecting it, is a vital step towards improving the efficiency of nitrogen fertilisation. Incorporation of nitrogen in the SIRATAC fruit model with strengthen the application of SJRA TAC pest management to situations where nitrogen is limiting, and will be a step towards using the SIRATAC model for nitrogen management

AIMS 1. To determine the mechanical and physical consequences of land preparation and harvesting on the soils and to relate these effects to soil water content. 2. To develop and assess methods for ameliorating undesirable physical conditions in heavy clay soils. 3. To develop and assess methods for predicting and classifying clay soils with relation to susceptibility to deformation, consolidation and shear under load during cultivation and harvest.

Summary of results: This project was needed to assess the N fertiliser requirements of cotton under new tillage systems currently being adopted, particularly since the structure of cracking clay soils is prone to degradation under intensive cultivation and traffic of continuous cropping. With little chance of extreme drying and cracking to restore soil structure, the trend towards continuous cropping may force soil management towards systems that allow maintenance and natural regeneration of soil structure. Such systems are likely to be based on permanent beds with minimum disturbance. Following is a summary of results; a detailed report is appended.

Ms. McRae presented a paper titled 'Characterisation of enzymes in the spore matrix of Colletotrichum orbiculare". Attending this conference allowed the applicant to discuss her work with leading _plant pathologists in that field.

ABSTRACT: When searchinq for an ideal mass screening technique for cotton plant antibiotic resistance to Helicoverpa spp., a 48 hour feeding on squares using final instar larvae bioassay was found to be the most suitable. It correlated better, than the techniques trialed, with the Standard larval bioassay traditionally used as an antibiotic resistance measurinq tool and was more energy efficient than the 'Standard'. An ideal mass screening technique usinq the two spotted mite (Tetranychus urticae} on cotton seedlings failed to correlate with the 'Standard1 rendering it unsuitable for measuring antibiotic resistance to Helicoverpa spp . ...The widely reported finding that gossypols are very important to the antibiotic activity against the cotton bollworm (Helicoverpa arnigera was supported with highly significant correlations between gossypol content of plant material and percent larval weight gains. In contrast, condensed tannin content of 'fresh plant' diet incurred insignificant antibiotic activity against the cotton bollworm but important antibiotic activity against the two spotted mite (Tetranychus urticae).

The objective of this project was to evaluate preliminary and advanced breeding selections from the Narrabri and Biloela programs at up to five locations in Queensland. Over the period 1986/87 to 1988/89 this project played a vital role in selecting new cotton varieties for commercial production. Hundreds of lines from the Biloela and Narrabri breeding programs were evaluated in preliminary trials at Emerald, Biloela and Brookstead, while advanced material was tested in the Australian Cotton Cultivar Trials at these sites plus Theodore.

Dr Lyon travelled to the 4th Australian Cotton Conference at Surfers Paradise and presented a poster on his research into the development of a 2,4-D herbicide tolerance gene

This project is a long-running one concerned with breeding varieties adapted to Australian conditions, growing practices and markets. During the interval of this particular grant much progress occurred with the development of the original Siokras and Sicala's from a breeding program that began in 1974. The development of Siokra has been widely regarded as a noteworthy achievement since it marks the first time anywhere that an okia leaf variety has been successfully and widely grown commercially. The significance of the okra leaf has been that it has provided some tolerance to Heliothis and considerable tolerance to mites. Titls pest tolerance has resulted, where keen attention has been paid to pest management, in the savings of two or even more sprays. Very importantly both Siokra and Sicala had genes for bacterial blight resistance incorporated and had ready marketable fibre. These properties led to their readily acceptance by cotton farmers and they soon comprised between 65-75% of total Australian cotton plantings.

The overall aim of the soils research program based at Trangie has been to develop management strategies that maximise the profitability of irrigated cropping by: (i) correcting yield limiting soil physical problems; and (ii) by preventing further problemfrom developing. The work has been carried out on cracking clays and hard-setting red soil is with a strong emphasis on extension of the results to irrigation farmers. This project concentrated on evaluating the hydrological effects of deep ripping, chisel ploughing, mouldboard ploughing, minimum tillage, gypsum, and severa1 rotation crops on a furrow irrigated cracking clay. The subsequent effects upon cotton performance and farm economics were also measured and extended to cotton growers. Similar experiments were carried out on a hard-setting red soil.

Our objective was to undertake a collaborative research study to identify and investigate problems associated with the perceived "poor adoption rate of Siratac, and develop an action plan and advisory programme to significantly improve adoption