ITEMS FROM NEW ZEALAND

CROP & FOOD RESEARCH LTD.

P.B. 4704, Christchurch, New Zealand.

Wheat breeding.

W.B. Griffin, D.S.C. Wright, R.J. Cross, and S.C. Shorter.

The New Zealand wheat crop in 1995 continued the trends of recent years, with a slightly increased area planted and a move from spring to autumn planting. With the total deregulation of the wheat industry in the late 1980s, there was a rapid switch to spring cultivars, which could provide the high-quality wheat the processing industries could now specify. New high-quality autumn cultivars have allowed farmers to move back to the higher potential productivity of autumn planting. At the same time, the processing industries are demanding increasingly specialized wheats for each particular end product, meaning that the breeding programs also are diverging for end product specifications. Over the past year, contacts between C&FR and these industries have strengthened, with new wheats being released or evaluated in almost all areas of interest.

A developing area of interest in New Zealand agriculture is specialized cereal feed/forage production, for an increasing dairy industry and an emerging beef feedlot industry. Increasingly sophisticated feed grains are being demanded, and different cereals and cereal-legume mixes are being evaluated as forage/hay crops. The breeding program, which has concentrated upon grain production, now also is evaluating its germplasm for forage potential, and C&FR is developing new projects with suitable industry partners, both to determine quality parameters and to implement them within the selection process.

A major new development early in the year was ratification of a farmers' arable-production levy and the consequent establishment of a Foundation for Arable Research (FAR) to determine research directions for the levy funds. Their largest commitment is to the national Recommended List testing system, which also has gone through significant changes during the year and is now called the Arable Cultivar Evaluation (ACE) system, with separate trials for bread and feed/biscuit wheats and barleys. Oats are being considered for inclusion. Fungicide responses also are included in some of the trials. Other work funded by FAR includes specialized disease and sprouting resistance nurseries for breeding materials. FAR will provide a valuable link between the C&FR breeding projects and the production sector. Such linkages are now essential in New Zealand, if crown funding is to be maintained.

The season of 1995 was conductive to high yields, with little extreme weather or disease pressure. Conditions for early autumn planting in May were good, although rains in late May meant that many autumn crops were delayed significantly. Conditions through spring (August-September) remained favorable for growth, but cooler temperatures meant only low disease pressure. Intermittent rain allowed irrigation scheduling to be maintained into early summer (December), and yield potential remained high. A period of dull weather just before harvest (January) allowed some head diseases to develop. Harvest started in hot, dry conditions, and early crops and trials were high-yielding and of good seed quality. However, subsequent widespread rain made finishing the harvest difficult and lowered quality. Sprouting will be a factor in these later harvested crops and trials.

Advanced materials. Two new C&FR wheats were both grown on significant areas in 1995. `Kotuku', an autumn white-grained moderate strength bread wheat showed excellent potential during the season, but may have suffered during the poor weather unless harvested early. `Endeavour', an over-strong, specialized-product spring wheat, showed a widespread susceptibility to stripe rust and required fungicide protection. Another moderate-strength autumn bread wheat was named `Rata', and two other high-quality spring bread wheats named `Kohika' and `Morahi'. Final industry evaluation of these three cultivars will be made following this harvest. A new autumn biscuit wheat, `Devoy', and a new high-yielding autumn feed wheat, `Impact', were both accepted for the first time into industry contracts for the 1995 season. Other advanced lines are in semi-commercial block trials for bread, biscuit, feed, snack, weetbix, colored, and durum wheats.

Other projects. A Ph.D. investigation of wheat-maize hybridization has made steady progress in developing a successful protocol for New Zealand genotypes. It is now investigating in more detail aspects of the system to determine limiting factors relative to the maize pollen used and the physical conditions under which the process is carried out. A final aspect of the investigation will be a comparison of variability in DH and conventional F2 populations. Another Ph.D. project investigating LMW glutenins in NZ wheats is making slower progress. The HMW glutenins of all parental lines are determined and used to help decide particular crosses. A consideration of both HMW and LMW glutenins may allow an earlier generation screen for quality. Funding was requested for a molecular marker study of some bread wheat quality characters in DH populations developed by the Queensland Wheat Research Institute, Toowoomba, Australia. This project will be part of an Australian-wide study using these DH populations to find molecular markers for agronomic, disease, and quality characteristics.

Publications.

Griffin WB. 1994. The Crop & Food Research wheat breeding programme. Crop & Food Res CropSeed Rep No. 5.

Griffin WB, Penno DJ, Bates R, McCloy BL, and Lindley TN. 1995. Quality assurance in the New Zealand milling wheat crop. Proc APAIC Conf, Brisbane (Proc Agron Soc NZ) (In Press).

Griffin WB. 1995. Types of wheat produced in New Zealand. Proc AACC Frozen Dough Course, Christchurch.

Wright DSC and Arthurs S. 1994. Using the Hunterlab colorimeter to measure colour intensity of cereal grains and grain products. Crop & Food Res CropSeed Confid Rep No 160.

Wheat pathology.

M.G. Cromey.

A major focus of wheat pathology in New Zealand recently has been the importance and control of late-season diseases. Glume blotch is surprisingly uncommon in the main wheat-growing areas of New Zealand. Didymella exitialis has become, in recent years, the most common plant pathogen found on flag leaves in wheat crops throughout New Zealand. This fungus is associated with a leaf scorch symptom, but also exists endophytically within wheat leaves, often sporulating only when the leaf has senesced. Because it sporulates readily on any dead leaf tissue (such as that caused by herbicide damage), it is difficult to distinguish Didymella-scorch from scorch-with-Didymella.

I am often asked why D. exitialis has become so common in recent years. What we have found is that levels of D. exitialis are greater when certain DMI fungicides are used than when no fungicides are applied. Use of DMI fungicides has become widespread in New Zealand wheat. Our working hypothesis is that most DMI fungicides have little effect on D. exitialis itself, but that they reduce the populations of saprophytes that normally provide a degree of biological control. We have identified one fungicide that provides effective control of D. exitialis and are using this and other fungicides to determine whether D. exitialis is largely a benign endophyte or whether it is yield-reducing pathogen.

Apart from black-point, ear diseases are seldom of major importance in Canterbury, the main wheat-growing area of New Zealand. However, in other regions, head scab, caused by Fusarium spp., is of increasing concern. New Zealand cultivars were shown to differ in resistance to head scab, and disease resistance is likely to provide a suitable means for the cnntrol of the disease in the future.

Publications.

Cromey MG, Ganev S, Braithwaite M, and Boddington HJ. 1994. Didymella exitialis on wheat in New Zealand. J Crop Hort Sci 22:139-144.

Cromey MG, Boddington HJ, and Mace MA. 1994. Plant pathogens on flag leaves and spikes in Canterbury wheat crops in 1993/94. Proc 47th Plant Protection Soc. Conf. Pp. 17-21.

Griffin WB, Munro CA, and Cromey MG. 1994. The wheat disease nursery system in New Zealand. Proc 7th Assemb, Wheat Breed Soc Aus. Pp. 195-198.

Ghannadha MR, Gordon IL, Cromey MG, and McEwan JM. 1995. Diallel analysis of the latent period of stripe rust in wheat. Theor Appl Genet 90:471-476.

Cromey MG and Mace MA. 1995. Development, yield effects, and control of Didymella exitialis on wheat in Canterbury in 1994/95. Proc 1995 Plant Protection Soc Conf. Pp. 161-164.

Wheat processing quality.

T.N. Lindley, M.P. Morgenstern, M.P. Newberry, and R.L. Hay.

The Grain Foods Research Unit focuses its research on 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 co-workers studied the influence of variation in ascorbic acid oxidase levels in wheat on dough development, factors that cause stickiness in preharvest sprouted wheat, and enzyme activity tightly associated with industrial gluten. The protein research program has a close collaboration with the breeding program. In this area, Sutton and co-workers have refined the use of HPLC measurements of glutenin composition for predicting baking quality. This study includes the effectiveness of their prediction model in improving the efficiency of selection in the wheat breeding program and comparison of HPLC and immunoassay techniques for screening wheat properties. In the areas of industrial processing and research of new processing technologies (Wilson), Wooding is investigating the influence of genetic and edaphic factors in determining work input requirement of bread doughs. The pastry and biscuit research programs seek to improve efficiency and product quality in cereal-based foods with high butter content (important exports for New Zealand). This research has led to enhanced understanding of dough-phase rheological properties in these products, new solutions to industrial processing problems, and development of a test to aid better milling of pastry flour.

Publications.

Every D, Gerrard JA, and Gilpin MJ. 1995. ß-amylase activity in commercial gluten. J Sci Food Agric 69:257-263.

Every D, Gilpin M, and Larsen NG. 1995. Ascorbate oxidase levels in wheat and their relationship to baking quality. J Cereal Sci 22:(in press).

Every D and Ross M. 1996. The role of dextrins in stickiness of bread crumb made from pre-harvest sprouted wheat or flour containing exogenous alpha-amylase. J Cereal Sci 23:(In press).

Andrews JL, Hay RL, Skeritt JH, and Sutton KH. 1992. HPLC and immunoassay-based glutenin subunit analysis: screening for dough properties in wheats grown under different environmental conditions. J Cereal Sci 20:203-215.

Wilson A. 1993. Measurement of work input in industrial mixers. Proc 42nd Cereal Chem Div, Royal Aus Chem Inst (RACI) Conf. Pp. 47-53.

Wooding AR, Martin RJ, and MacRitchie F. 1993. Effect of sulphur-nitrogen treatments on work input. Proc 42nd Cereal Chem Div, Royal Aus Chem Inst (RACI) Conf. Pp. 45-48.

Morgenstern MP, Newberry MP, and Holst SE. 1993. Biaxial extension of dough sheets. Proc 42nd Cereal Chem Div, Royal Aus Chem Inst (RACI) Conf. Pp. 372-375.

Busch JM, Hay RL, Holst SE, Lake R, Lindley TN, and Newberry MP. 1993. A rapid test for propensity of pastry doughs to develop dark specks. Proc 42nd Cereal Chem Div, Royal Aus Chem Inst (RACI) Conf. Pp. 303-306.

Newberry MP, Humphrey-Taylor VJ, and Larsen NG. 1993. To check or not to check - a biscuit making phenomenon investigated. Proc 42nd Cereal Chem Div, Royal Aus Chem Inst (RACI) Conf. Pp. 299-302.