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 trends and changes within the breeding projects signalled in last year's report have developed over the past 12 months. The original C&FR Cereal Grains Breeding Program, described in the 1995 report, is being split into cereals for human foods, cereals for animal feeds, and cereal forages, to allow better focus upon their respective industry sectors. Farmer research levies, controlled through the Foundation for Arable Research (FAR), are now an integral part of arable research funding. The breeding programs continue to be largely based on field pedigree systems, with some generations handled in the glasshouse. However, the above changes will mean some re-examination of breeding methodology. New techniques, such as wheat-maize doubled haploids and molecular marker-assisted selection, are being investigated but are not yet part of the routine breeding programs.

The overall industry continues good, with domestic production slowly increasing. The rapid movement in international prices has focused attention upon internal contracts and pricing schemes, and most farmers will benefit from contract prices fixed in mid 1996. Prices for the 1997-98 season are expected to drop, with possible pressure on maintaining production levels.

The 1996 planting began under good conditions, but deteriorated rapidly towards the end of May. A significant area of the autumn crop could not be planted until early spring. A number of NZ cultivars are facultative types, and planting of this type resumed in early spring, together with an increased area of true spring wheat. Periodic rain through spring and early summer ensued continued crop growth with little moisture stress and high potential yields. Conditions also were favorable for high foliar-disease incidence, and severe epidemics of stripe rust, powdery mildew, speckled leaf blotch, and leaf rust were recorded. However, these will cause little overall commercial crop loss, because of a combination of resistant cultivars and fungicide applications. A weekly crop health monitoring system funded by the FAR was extremely effective in keeping farmers fully informed of the latest disease developments. Midsummer weather was wetter than normal, allowing some development of head diseases and slightly delaying the harvest. However, most crops were harvested in good condition with high yields.

Advanced materials. All the new cultivars presented in last year's report were grown as commercial crops this season. Kotuku, a medium-strength white autumn bread wheat, and Endeavour, a very high-strength spring bread wheat, each account for almost 10 % of total production. Smaller volumes of the others (the autumn bread wheat Rata (red chaff), the spring bread wheats Morahi and Kohika, the autumn biscuit wheat Devoy, and the autumn feed wheat Impact) were all grown. The increased disease pressure seen this season caused some problems for all these new cultivars except Kotuku, which continues to show very high levels of resistance, particularly to stripe rust. No other new lines were tested semicommercially this season, although advanced lines of all wheat types (bread, biscuit, feed, colored, snack, weetbix, and durum) are under evaluation in regional trials. Some of these will be advanced to semicommercial testing in 1997-98, with the collaboration of appropriate industry sectors.

Other projects. A Hessian fly problem in one region of New Zealand has been investigated over the past two seasons, but the intermittent nature of the infestations has made it difficult to determine its real significance. Hessian fly-resistance in New Zealand cereals is generally low, and crosses are being made to increase the background resistance. The wheat-maize project has investigated the effects of temperature and light upon the system over the past year and is currently extending this work under more controlled climate and laboratory conditions. DH lines already generated were field planted last spring and have been monitored over their growing season for within line variation compared to the parent cultivars. A postdoctoral student began work on a molecular-marker project for quality using two DH populations developed by the Queensland Wheat Research Institute. This project has funding for 2 years initially, and will be managed in collaboration with the Australian molecular-marker project through their Wheat Quality CRC and the new proposed Molecular Marker CRC. The DH lines in New Zealand have just been harvested. Agronomic observations on them were made and grain quality evaluation will now begin, with particular emphasis upon HPLC tests. Green leaf samples for DNA extraction were made on all lines, and molecular probes are being gathered from suitable sources.

Publications.

Campbell AW, Griffin WB, Conner AJ, Rowarth JS, and Burritt DJ. 1996. A system for wheat-maize doubled haploid production in New Zealand wheats. Proc 8th Assemb Wheat Breed Soc Austr, Canberra. pp. 90-92.

Cross RJ and Hay RL. 1995. Characterisation of 20 novel Glu-1 high molecular weight glutenin alleles by SDS-PAGE and RP-HPLC. In: Proc Inter Workshop Gluten Proteins, Viterbo, Italy.

Cross RJ and Guo B. 1996. Novel allelic glutenin variation in a diverse world wheat landrace collection. In preparation.

Cross RJ. 1996. Genetic shifts over time in the worldwide distribution of Glu-1 alleles in bread wheat. In preparation.

Griffin WB, Wright DSC, and Shorter SC. 1996. Wheat breeding systems at Crop & Food Research, New Zealand. Proc 8th Assemb Wheat Breed Soc Austr, Canberra. pp. 45-47.

Griffin WB. 1996. Ten years of the Australian Interstate Wheat Variety Trials in New Zealand. Proc 8th Assemb Wheat Breed Soc Austr, Canberra. pp. 222-225.

Harris MO, Dando JL, Madje C, and Griffin WB. 1995. Relationships between New Zealand populations of Hessian flies and various cultivated and wild grasses. NZ J Crop Hort Sci (submitted).

Harris MO, Dando JL, and Griffin WB. 1996. Susceptibility of cereal and non-cereal grasses to attack by Hessian fly. NZ J Crop Hort Sci (in press).

Wheat pathology.

M.G. Cromey.

Late-season foliar diseases were particularly prevalent in Canterbury in the 1996-97 season, largely because of frequent rain over late spring and summer. Glume blotch, not usually a problem in Canterbury, was common. Didymella leaf scorch also was common. Most years, the fungus D. exitialis is largely endophytic, causing few obvious symptoms, although possibly contributing to early flag leaf senescence. By way of contrast, during 1996-97, leaf scorch disease symptoms were obvious in many crops from ear emergence onwards. We have shown in fungicide trials that the DMI fungicides, which are commonly used on wheat in New Zealand, result in increased levels of D. exitialis, probably through eliminating many of the fungi that provide a degree of natural biological resistance to this pathogen. Fungicides in the new strobularin group, such as azoxystrobin, reduce the levels of D. exitialis and result in a delay in flag leaf senescence with consequent yield increases.

Head scab was common in North Island wheat crops this season. Currently, we are examining the species of Fusarium associated with head scab in New Zealand and differences in resistance among wheat cultivars.

Several previously resistant wheat cultivars have recently succumbed to new races of stripe rust. We have received additional funding from the public good science fund to try to improve the durability of stripe rust resistance in future New Zealand wheat cultivars. As a first step, we are examining New Zealand and overseas cultivars that may have useful levels of durable resistance to stripe rust.

Publications.

Mace MA and Cromey MG. 1996. Presence, development, yield effects and control of late season diseases of wheat in Canterbury in 1995/96. Proc 1996 New Zealand Plant Protection Soc Conf. pp. 296-299.

Wheat processing quality.

T.N. Lindley.

The Grain Foods Research Unit seeks new understanding in three general areas: composition of cereal grains needed for good processing and product quality, behavior of cereal materials as they pass through processing, and behavior of cereal based foods after processing. In the first two areas, we have placed particular emphasis on elucidating the mechanism for the ascorbic acid improver effect in bread making, the impact of protein composition, and making better use of rheological measurements on doughs. Every and coworkers developed new analytical procedures for following ascorbic acid oxidation in flour and concentrations of dehydroascorbic acid during processing and currently are applying these in mechanistic studies. Gerrard and Fayle have found evidence that dehydroascorbic acid can cross link gluten proteins by mechanisms other than disulphide bond formation, and Larsen and Wilson have shown that considerable savings could be made in bread production costs if ascorbic acid levels were lowered to 50-75 ppm in well-controlled processing plants. In protein chemistry, Sutton used a new technique for directly measuring the size of gluten macro polymers. Morgenstern and Newberry used biaxial deformation techniques on an Instron testing machine to follow stress relaxation in pastry doughs and applied these extension measurements to improve lamination and rest cycles in pastry making. In addition to research, the unit handles an extensive range of technology transfer activities (distance learning programs, a phone-in information center, baking technology newsletters, and specialist seminars) aimed at increasing intelligent application of technology in the New Zealand baking industry.

Publications.

Every D and Ross M. 1996. The role of dextrins in the stickiness of bread crumb made from pre-harvest sprouted wheat or flour containing exogenous alpha-amylase. J Cereal Sci 23:247-256.

Every D, Gilpin MJ, and Larsen NG. 1995. Continuous spectrophotometric assay and properties of ascorbic acid oxidising factors in wheat. J Cereal Sci 21:231-239.

Every D. 1996. Enzymatic method to determine dehydroascorbic acid in biological samples and in bread dough at various stages of mixing. Analytical Biochem 242:234-239.

Every D, Farrel JA, and Stufkens MW. 1996. Cultivar susceptibility to wheat-bug damage in New Zealand. Proc 46th Austr Cereal Chem Conf and the 6th Inter Gluten Workshop, Sydney, September 1996. Pp 283-286.

Fayle SE and Gerrard JA. 1996. Investigation into dehydroascorbic acid mediated cross-linking of model proteins. Proc 46th Austr Cereal Chem Conf and the 6th Inter Gluten Workshop, Sydney, September 1996.

Morgenstern MP, Newberry MP, and Holst SE. 1996. Extensional properties of dough sheets. Cereal Chem 73:478-482.

Larsen N and Wilson A. 1996. The effects of ascorbic acid oxidation on the properties of dough and bread. Proc 46th Austr Cereal Chem Conf. pp. 302-305.

Newberry MP, Morgenstern MP, and Ross M. 1996. Dough relaxation during and after puff pastry processing. Proc 46th Austr Cereal Chem Conf. pp. 311-314.

Sutton KH. 1996. Analysis of wheat glutenin protein aggregate size using photon correlation spectroscopy. Proc 6th Intern Gluten Workshop. pp. 317-320.

Lindley TN and Larsen NG. 1996. Cereal processing in New Zealand - inversion, diversification, innovation, management. Proc: Cereals: novel uses and processes. UMIST, Manchester. In press.

Wheat physiology and modeling.

P.D. Jamieson.

Modeling of wheat physiology continues at Crop & Food Research, Lincoln, led by Peter Jamieson, with cooperation from Ian Brooking (HortResearch), John Porter (Royal Veterinary and Agricultural University, Denmark); and Mikhail Semenov (Long Ashton Research Station, BBSRC, U.K.). Recent progress was the development of a mechanistic approach that explains how phenological development in wheat varies with exposure to vernalizing temperatures and day length. The major mechanism is the variation in final main stem leaf number caused by these factors, and also the effect of temperature on rate of leaf appearance (Jamieson et al. 1997a). Sirius, the Crop & Food Research wheat simulation model, uses this approach in its phenological description (Jamieson et al. 1997b). Sirius also is one of five wheat models whose performance was tested against data from an experiment where exposure to drought was varied. There was substantial variation among the models in their predictions of leaf area development and biomass accumulation, but much less variation among them in the prediction of grain yield. In most cases, grain yield predictions matched observations well. We conclude that all of the models integrate the effects of drought well, even though they vary in their prediction of intermediate steps (Jamieson et al. 1997c).

Publications.

Jamieson PD, Brooking IR, Semenov MA, and Porter JR. 1997a. Making sense of wheat development. Field Crops Res (submitted).

Jamieson PD, Semenov MA, Brooking IR, and Francis GS. 1997b. Sirius, a mechanistic model of wheat response to environmental variation. Field Crops Res (submitted).

Jamieson PD, Porter JR, Goudriaan J, Ritchie JT, van Keulen H, and Stohl W. 1997c. A comparison of the models AFRCWHEAT2, CERES-Wheat, Sirius, SUCROS2 and SWHEAT with measurements from

wheat grown under drought. Field Crops Res (submitted).

ITEMS FROM ROMANIA

I.C.C.P.T. - RESEARCH INSTITUTE FOR CEREALS AND INDUSTRIAL CROPS

Fundulea, 8264, jud. Calarasi, Romania.

Environmental and genotypic effects on test weight in wheat

Nicolae N. Saulescu, Gheorghe Ittu, and P. Mustatea.

A study was conducted on test weight variation in 12 cultivars grown in yield trials in 40 to 113 environments. Variation caused by environment was larger than differences among cultivars. The highest average test weights were found in cultivars Dropia, Flamura 85, and Fundulea 29. The lowest average test weights were found in the large-grained cultivar Transilvania 1 and in the late cultivar Delia.

The frequency of test weight values lower than 75 kg/hl (the lower limit required by present standards for breadmaking wheat) varied from 22-25 % in Dropia, Flamura 85, and Lovrin 34; to 35-37 % in Transilvania 1, Turda 81, and Lovrin 41. Low test weights were associated with long periods of high temperature (higher than 30 C) during grain filling, preharvest rains, and/or high incidence of disease.

Changes in HMW-glutenin subunit composition of wheat grown in Romania from 1980 to 1995.

Ioana Hagima, Nicolae N. Saulescu, and Gheorghe Ittu.

The HMW-glutenin subunit composition of 26 of the main winter wheat cultivars grown in Romania during the last 15 years was established by SDS-PAGE. Alleles known to have a favorable effect on breadmaking quality were more frequent among recently released cultivars. The percentage of total wheat area covered by various glutenin alleles was computed for each of the last 15 years, taking into account the area grown with each cultivar and the corresponding HMW-glutenin subunit composition. Significant changes took place in the areas covered by alleles of all glutenin loci. The area covered by alleles Glu-A1b and Glu-A1a (controlling fractions 2* and 1) increased from 10 to more than 50 %, whereas that covered by Glu-D1d (fractions 5+10) increased from 60 % to more than 90 %. These changes suggest that the breadmaking quality potential of Rumanian wheat has significantly improved.

Results in triticale breeding for breadmaking quality.

Gheorghe Ittu, Nicolae N. Saulescu, Mihaela Tianu, and Ioana Hagima.

Improvement of the breadmaking quality of triticale is one of the main ways of increasing the value of this crop. In the Rumanian triticale-breeding program, selection pressure for breadmaking quality has been applied for the last 10 years.

Germplasm with improved SDS sedimentation value was first obtained by crossing a Rumanian early short-straw line 5735TW3-3 (selected from a `triticale/bread wheat' hybrid) and the Polish cultivar Presto. Two lines selected from this hybrid population (91053T2-42 and 91053T2-52) had significantly higher sedimentation values than the commercial triticale cultivars (Plai and Colina ) and both parents in 3 years of tests. Their SDS-sedimentation values were nearly 90 % of that of the medium-quality bread wheat Fundulea 4, and nearly 70 % that of the high-quality bread wheat Flamura 85.

Mixogram characteristics of these lines are still lower than those of bread wheat. These lines do not contain the 5+10 glutenins of wheat chromosome 1D. Therefore, further progress is expected from crosses with a T1DS-1RL translocation line provided by A. Lukaszewski, University of California, Riverside.

Variation in Fusarium sp. pathogenicity to wheat.

Mariana Ittu and Steluta Raranciuc.

The success of breeding wheat with resistance to FHB is dependent on understanding variation in pathogen virulence and cultivar resistance Pathogenicity monitoring of Rumanian Fusarium populations of several origins (host cultivars varying in resistance and locations) is a permanent goal in our breeding strategy in order to manipulate the existing natural variability with accuracy.

A study of some cultural characteristics (growth rate of colony, pigment production, and type and size of conidia) on different growth media and of the aggressiveness in a collection of over 60 Fusarium isolates was performed in 1995 and 1996. These isolates were sampled from cultivars differing in their reaction to scab in six locations from the south (Fundulea and Valu lui Traian), central (Turda), and north (Podu-Iloaiei, Secuieni, and Suceava) of Romania

A large variability of inoculum aggressiveness was discovered depending on the host and geographic origin. Mean values of relative coleoptile length in inoculated seedlings of three cultivars ranged between 5.3-87.0 in 1995 to 24.4-79.4 in 1996. These results allow us to speculate that a higher amplitude of variation for pathogenicity was registered in Fusarium cultures sampled from moderately resistant cultivars compared with susceptible ones. Geographic differences in both pathogenicity and cultural characteristics also occurred. The most virulent strains were identified in locations where significant epidemics frequently are recorded.

S.C.A. - AGRICULTURAL RESEARCH STATION

Turda, jud. Cluj, Romania.

Maria Moldovan, V. Botezan, and V. Moldovan.

Sources of winter wheat resistance to Fusarium head blight.

During 1993, 1994, and 1995, 46 winter wheat genotypes (cultivars and lines) with different reaction to FHB were tested in conditions of artificial inoculation in the field to determine the factors influencing this reaction and to identify the sources of partial resistance or tolerance to this disease.

We inoculated at anthesis with a local isolate of F. graminearum. The two central spikelets of each of 10 ears of each entry were inoculated. The inoculum was a drop of a liquid Czapek-Dox medium containing a suspension of mycelium and conidia. The reaction to FHB was evaluated as the percentage of total diseased area of the ear at 10 and 20 days after inoculation. Equal numbers of inoculated and noninoculated ears were harvested. Decreases in ear weight (g), grain weight per ear (g), and 1,000-kernel weight (g) were determined for 36 genotypes.

The influence of environmental conditions (years) and genotype (cultivars and lines) on the degree of infection (20 days after inoculation) and the degree of infection on the ear weight were determined using a split-plot design. We also determined the correlation and the regression coefficients between the degree of FHB infection and other criteria (decrease in ear weight, grain weight/spike, and 1,000-kernel weight).

Environmental conditions (years), genotype, and the `G x E' interaction significantly influenced the degree of FHB infection: year, F = 227.50 (3.55; 6.01); genotype, F = 25.61 (1.39; 1.59); and `year x genotype', F = 9.88 (1.24; 1.36).

The ear weight is significantly influenced by the year: F = 62.650 (4.41; 8.28); genotype, F = 24.24 (1.46; 1.70); degree of infection, F = 4,202.315 (3.84; 6.63); and their interaction.

The mean degree of infection by the FHB fungus in the 3 years was 44 %. The mean in 1993 (73 %) and in 1995 (71 %) were very high, with statistically significant differences.

The correlation coefficient between the degree of infection (%) and the decrease in ear weight were statistically significant (1993, r = 0.83217; 1994, r = 0.61984; and 1995, r = 0.77080). A similar situation was found for the correlation coefficient between the degree of infection and the decrease in grain weight per spike (1993, r = 0.86037; 1994, r = 0.646; and 1995, r = 0.83582) and between the degree of infection and the decrease in the 1,000-kernel weight (1993, r = 0.92874; 1994, r = 0.6955; 1995, r = 0.86118).

Wheat genotypes with good and stable reaction to FHB are difficult to detect. No genotype with total resistance to scab was discovered, only genotypes with partial resistance and/or tolerance. For example, different degrees of statistical significance were compared to the mean of the experiment (56.9 %) and also with different degrees in reaction stability. The genotypes are noted in Table 1.

Table 1. Mean degree of infection and coefficient of variation for 14 Rumanian wheat cultivars for reaction to Fusarium head blight. Results are compared to the mean of the experiment, 56.9 %.

Turda 45-85, T2317-90, Bizel-Zenith 53-4, and Turda 95 had small losses in ear weight and a low degree of infection during the 3 years. Some genotypes, such as Fundulea 29, Transilvania, and Br 918, had small losses in ear weight, but a high degree of infection. These genotypes could prove to be tolerant to the FHB pathogen.

We tested 113 genotypes (cultivars and lines of winter wheat) in 1996 using the same inoculation methods. The reaction to FHB was determined by the following two criteria: the dynamics of the disease noted by AUDPC, and the decrease of the ear weight compared to the uninoculated control. We observed great variation in the AUDPC, between 288.5 and 1,475.0, and for ear weight, between 85.7 % and 19.3%, compared to the control. There is a significant negative correlation (r = -0.53714) between these two criteria.

Genotypes tested in 1996 that could be possible sources of resistance (with low values for AUDPC and little loss in ear weight) are F201 R2-121, T45-85, F637 U2-2, T107-93, F201R, F11793-91, F4549 W2, F12653-91, T2362-93, F199 19-11, and Br918. Other genotypes, T2-93, T7-93, 74-2(Sz), T12-93, T51-90, 76-1-146(Sz), T4-4-93, T20-90, and T21-91 could be tolerant, because of small losses in ear weight at high AUDPC levels.


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