NZ Institute for Crop & Food Research Ltd.

Private Bag 4704, Christchurch, New Zealand.
Tel: 64 3 325 6400, Fax: 64 3 325 2074, E-mail: griffinw@lincoln.cri.nzFONT FACE="WP TypographicSymbols"/

Wheat breeding. W.B. Griffin, D.S.C. Wright, R.J. Cross, and S.C. Shorter.
The breeding programmes are based in Lincoln and Palmerston North with the aims of improving the quality, sustainability, and productivity of wheats grown in New Zealand for the domestic and export industries. They utilise locally conserved and imported lines to generate segregating populations from which desirable new lines are identified and selected. Variations on traditional pedigree breeding systems are applied, depending upon the type of wheat involved, and selection pressure for relevant quality, disease, or agronomic characters is applied appropriately. There are separate but cooperating programmes for potential bread, biscuit, feed, snack, specialty coloured, and durum wheats. A small triticale programme is also carried out. Commercial wheat cultivars are predominantly red because of the danger from sprouting, but emphasis is being given to selection of white-grain types and white sprout-resistant materials are being developed. Both autumn and spring wheat types are selected for, with the spring bread wheat programme largely centered at Palmerston North. Depending upon maturity, there is a large exchange of materials between the autumn and spring programmes. Germplasm conservation is a vital, complementary objective to the breeding objectives. As well as being a critical repository of the germplasm produced by the breeding objectives, the Lincoln cereal gene bank holds an internationally recognised collection of early wheat land races. This is being used as a model for new proposals on the concepts of cereal conservation and distribution of useful germplasm.
Advanced materials. Recent cultivar releases include an autumn, white-grained, moderate-strength, bread wheat (Kotuku) and a very strong, spring, red-grained, bread wheat (Endeavour). Two other autumn and four other spring bread wheats, two autumn biscuit, one autumn feed, one spring feed (with relatively high metabolisable energy), one snack, one triticale, and a durum wheat are in the national Recommended List trials and semicommercial block evaluation.
Other projects. Three new cooperative projects with New Zealand universities were begun in 1994. Two PhD programmes will investigate: LMW glutenins in New Zealand wheats and their relationships to baking quality and limitations of the wheat/maize hybridisation doubled-haploid technique and its application to New Zealand wheat breeding. A third project involves an investigation of Hessian fly in New Zealand, the range of biotypes present, and the degree of resistance available within CFR breeding materials.
Publications.
Cross RJ, Wright DSC, Histen TJ, Hanson R, and Munro CA. 1993. Cultivar release of `Waitohi' high quality durum wheat. NZ J Crop Hort Sci 21:383-384.
Cross RJ, Williams WDHM, and Mujeeb-Kazi A. 1995. Evaluation of genetic resources, identification of diversity and priorities of its exploitation for wheat improvement. Proc 8th Int Wheat Genetics Symp (Li ZS and Xin ZY eds). China Agricultural Scientech Press, Beijing. Pp. 499-502.
Cross RJ, and Wallace AR. 1994. Loss of genetic diversity from heterogeneous self pollinating genebank accessions. Theor Appl Genet 88:885-890.
Griffin WB, Munro CA, and Cromey MR. 1994. The wheat disease nursery system in New Zealand. Proc 7th AWBS Assembly, Australia. Pp. 195-198.
Griffin WB and Wright DSC. 1992. Genetic constraints to improvements for wheat productivity and quality. Agron Soc (New Zealand) Special Publication. 8:33-46.
Griffin WB, and Wooding AR. 1992. The importance of work input in breeding for improved wheat bread baking quality. Proc 42nd RACI Conference, Christchurch, New Zealand. Pp. 235-244.
Wheat production.

P.D. Jamieson, R. Martin, and A.R. Wooding.
The effect of the nitrogen/sulphur balance on dough strength. In recent years, New Zealand bakeries using MDD, have found increasing difficulty in mixing doughs to optimum consistency for good bread quality, especially for the cultivar Otane. This means increased costs from higher power requirements and longer mixing times. In a recent trial funded by the New Zealand Association of Bakers, nitrogen fertilizer, with or without sulphur fertilizer, increased grain yield and protein content. It also increased loaf volume and water absorption. However, unless applied in combination with sulphur, nitrogen fertilizer increased work input by nearly 30 %. These results support the hypothesis that declining soil sulphur levels and increased use of high nitrogen and low sulphur fertilizers, have caused the increased dough work input requirements in commercial MDD bakeries. This work is being extended to other locations and wheat cultivars to determine the extent of dough quality responses to sulphur in New Zealand.
Wheat physiology. The nature and form of temperature and day length responses that determine flowering time in spring-type wheats have been described quantitatively in a cooperative research project involving Peter Jamieson of Crop & Food Research, Ian Brooking of The New Zealand Institute of Horticulture and Food Research, and John Porter, late of the AFRC, UK, and now of the Royal Veterinary and Agricultural University, Copenhagen, Denmark (Jamieson et al. 1995a; Brooking et al. 1995). These have been incorporated into a wheat simulation model, Sirius Wheat, which is being used in New Zealand and Europe to assess the impacts of global climate changes on wheat production. This project is associated with the United Nations-sponsored International Global Biosphere Programme (IGBP) in the Global Change Terrestrial Ecosystems (GCTE) project. A related project is testing the hypotheses incorporated in simulation models about the nature of response to drought, by comparing model predictions with experimental results. An analysis of the influence of drought on grain yield has been published by Jamieson et al. (1995b).
Publications.
Brooking IR, Jamieson PD, and Porter JR. 1995. The influence of daylength on final leaf number in spring wheat. Field Crops Research (In Press).
Jamieson PD, Brooking IR, Porter JR, and Wilson DR. 1995a. Prediction of leaf appearance in wheat: a question of temperature. Field Crops Research (In Press).
Jamieson PD, Martin RJ, and Francis GS. 1995b. Drought influences on grain yield of barley, wheat and maize. NZ J Crop Hort Sci 25:(In Press).
Wheat pathology.
M.R. Cromey.
Disease surveys. We carry out a disease survey in New Zealand wheat crops each year to determine any important changes to the disease spectrum, determine research and breeding priorities, and monitor the effectiveness of existing control procedures. We also collect samples of the wheat rusts for virulence analysis.
Stripe rust remains a high priority for disease control. Fungicide control is effective, but can be expensive in highly susceptible cultivars. Resistant cultivars are available, but this resistance is often eroded with the development or arrival of new pathotypes of Puccinia striiformis. A new development in the 1994-95 growing season was the identification of stripe rust on barleygrass (Hordeum murinum) for the first time. Two barley cultivars also were affected. Initial inoculations suggest that it is the wheat form of stripe rust and, therefore, could serve as a source of inoculum for wheat crops.
Head scab, mostly caused by Fusarium graminearum and F. culmorum, can be a problem in damp seasons such as 1993-94. We have observed differences between cultivars in incidence of head scab in variety trials, and may institute screening for resistance in our wheat breeding programmes. Glume blotch and Didymella leaf scorch (caused by Didymella exitialis) can be common late in the season. Current research aims to determine the yield losses associated with late-season diseases and prospects for their control with fungicides and resistant cultivars.
Rust pathotype surveys and cultivar resistance. Samples of the wheat rusts are sent to the University of Sydney Plant Breeding Institute at Cobbitty. Potential new pathotypes of stripe rust also are characterised by us at Lincoln. New pathotypes of stripe rust have been identified regularly and usually are associated with the resistance of current cultivars. The resistance genes Yr1, Yr6, Yr7, Yr9, and Yr14 have been identified in locally grown cultivars and have all been overcome individually and in several combinations. The genetic basis of resistance of some cultivars is unknown, and two probably new pathotypes have yet to be characterised fully. Although some cultivars have good levels of adult plant resistance in the absence of effective seedling resistance, many cultivars rely on seedling genes for most of their resistance.
Wheat processing quality.
T.N. Lindley.
The Grain Foods Research Unit focuses its research on the industrial processing of cereals. The main areas of work include defining the links between food composition and textural qualities, cereal protein chemistry, and improving the efficiency of cereal processing technologies. In the texture studies, Every and coworkers have studied the relationship between rate of staling in bread and the dextrins present and concluded that the proportion of small dextrins (DP3) in the crumb after baking strongly influences keeping quality. They also have studied the influence of variation in ascorbic acid oxidase levels in wheat on dough development. The protein research has been done in close collaboration with the breeding programme. In this area, Sutton and coworkers have refined the use of HPLC measurements of glutenin composition for predicting baking quality. This has included studying the effectiveness of their prediction model in improving the efficiency of selection in the wheat breeding programme. New work will place greater emphasis on understanding the formation of gluten macropolymer (GMP) during mixing. In the area of industrial processing, as well as researching new processing technologies (Wilson), Wooding is investigating the influence of genetic and edaphic factors in determining work input requirement of bread doughs. The pastry research programme seeks to better define the links between material composition, dough phase properties, and baked good quality.
Publications.
Every D, Gilpin M, and Larsen N. 1994. Ascorbic acid oxidising factors in wheat. J Cereal Sci (In press).
Every D, Mann JD, and Ross M. 1992. The relationship of dextrins in bread to staling and crumb gumminess. Proc 42nd Cereal Chemistry Division, Royal Australian Chemical Institute (RACI) Conference. Pp. 179-186.
Hay RL. 1993. The effect of flour quality characteristics on puff pastry baking performance. Cereal Chem 70(4):392-396.
Sutton K and Griffin WB. 1992. Selection for breadmaking quality: early generation screening. Proc 42nd Cereal Chemistry Division, Royal Australian Chemical Institute (RACI) Conference. Pp. 254-259.
Wilson A. 1992. Measurement of work input in industrial mixers. Proc 42nd Cereal Chemistry Division, Royal Australian Chemical Institute (RACI) Conference. Pp. 47-53.
Wooding AR, Martin RJ, and MacRitchie F. 1993. Effect of sulphur-nitrogen treatments on work input. Proc 43rd Cereal Chemistry Division, Royal Australian Chemical Institute (RACI) Conference. Pp. 45-48.