ITEMS FROM MEXICO

CIMMYT / Mexico

International Maize and Wheat Improvement Center, Lisboa 27, Colonia Juarez, Apdo.

Postal 6-641, D.F., Mexico.

Developments in CIMMYT wheat program in 1994.

R.A. Fischer and G. Varughese.

Staff changes. The last year (1994) will be remembered for the difficulties caused by the reduction in core funds. However, through cuts in operations (there was no crop improvement training in 1994 and the second breeding cycle in summer was curtailed), and the arrival of new Special Project funds, disruptions to staffing were reduced.

With the appointment of Osman Abdalla to a regional breeder pathologist position in Eastern Africa, Wolfgang Pfeiffer took over leadership of our global durum wheat breeding effort; triticale breeding continues, but at a reduced level. Tom Payne moved to a regional wheat/maize position in Zimbabwe, and Alexei Morgunov replaced him in Ankara. Edmundo Acevedo, who lead Crop Management and Physiology for 4 years, returned to Chile in mid year and has not been replaced. Similarly our BYDV pathologist, Lukas Bertschinger, returned to Switzerland, and bread wheat breeder, Gurdev Singh, returned to Punjab Agricultural University. Jesse Dubin came back to base after many years in outreach in order to head up Crop Protection, being replaced in Nepal by Gene Saari. Jesse also will be in charge of Seed Health, because Larry Butler left in 1994. Our team in Paraguay has dispersed, with Mohan Kohli going to Montevideo, Uruguay, and Pat Wall joining a bilateral project in Santa Cruz, Bolivia. On new Special Projects, Gunther Manske (Germany) joined us to work on selection for phosphorus use efficiency and Arne Hede (Denmark) will be doing a thesis on molecular-aided transfer of traits from rye to wheat, as well as assisting Bent Skovmand in all aspects of Wheat Genetic Resources.

Other, new Special Projects brought short-term support for research on heat tolerance (Matthew Reynolds), nonspecific foliar pathogens (Etienne Duveiller), nitrogen use efficiency (Ivan Ortiz-Monasterio), and continuing our efforts to develop an International Wheat Information System (Paul Fox). Sylvie Lewicki, who was working on osmotic adjustment, returned to France. Jim Quick, from Colorado State University, joined us as a visiting scientist for 1 year. Our tireless editor of 8 years, Gene Hettel, went to IRRI and has been replaced by Alma McNab.

Internally managed, external review of Wheat Genetic Improvement. A team headed by John Axtell and comprising Ron Rasmusson, Don Marshall, M.V. Rao, and Don Duvick spent 1 week at CIANO in late March reviewing the above Subprogram. Following much praise of our wheat breeding achievements, many challenging recommendations were made, relating more to Program organization and communication, priorities in the face of a shrinking budget, and closer collaboration with NARS, rather than questions of breeding strategies and methods. Program restructuring and a series of CIMMYT-NARS meetings for 1995 have been visible responses to this.

Program restructuring. With changes in the CG System in 1994, and in order to improve communication within the Program, the Wheat Program adopted a matrix structure. We still maintain a disciplinary dimension that now comprises five units (heads in parentheses), namely Bread Wheat Breeding (S. Rajaram), Durum Wheat and Triticale Breeding (W. Pfeiffer), Genetic Resources and International Nurseries (B. Skovmand), Crop Protection (J. Dubin), and Crop Management and Physiology (R.A. Fischer). These units exist for management of people and shared resources.

In the second dimension, we now have outputs that are identifiable products of our research and other activities. There are, in fact, 23 outputs each with a leader. The output structure exists for better scientific communication on

issues, for monitoring of research progress, and for greater transparency in research priorities. As part of the restructuring, our major activities in the area of Natural Resource Management Research were grouped together across commodities; Peter Hobbs in Nepal hence left Wheat to join the NRMR group. It is too soon to say whether these changes have been successful.

Northwest Mexico in 1993-94. After mid November, the 1993-94 cropping season in northwest Mexico was rainless with radiation and temperature levels close to normal, except for one period of hot weather in mid

April. Yaqui Valley yields were high (mean 5.4 t/ha, some 20 % above 1992-93) as were irrigated plot yields (up to 9 t/ha); it was the best season for yield since 1989-90. Severe stress was imposed on unirrigated

simulated-drought plots and on late planted simulated-heat plots. There was practically no Karnal bunt (KB) infection in the Yaqui Valley in 1993-94 (99 % of the farmer's samples were free of KB), apart from the artificially inoculated sprinkler irrigated KB-screening area. All international nursery seed is now produced in the KB-free Mexicali area, adjacent to the California border.

Research activities. Wheat research projects for 1994 are documented in terms of descriptions and updates and organized by outputs (Fischer 1995). There were just over 200 ongoing projects at the end of 1994. Highlights included the very exciting progeny coming from utilization of the many new synthetic wheats developed by our wide crossing program. Not only are we seeing resistance to KB and spot blotch coming from this source, some derivatives have given promising yields (see contribution from Villareal et al.). Chinese sources have produced improved levels of spot blotch resistance, as well as better resistance to Fusarium head scab. The ITMI molecular-mapping population, also derived from a new synthetic crossed to a modern bread wheat, was yield-tested for the first time in 1993-94 and was screened for KB and leaf rust resistance. Advances were made in understanding the genetics of KB resistance (Morgunov et al. 1994). Our physiologists, working with scientists from advanced institutions have confirmed the association seen between recent yield progress in bread wheats, increased stomatal conductance, and reduced canopy temperature. In durum wheats, recent progress is associated more clearly with increased leaf chlorophyll content. Important publications include the research report on Russian Wheat Aphid (Robinson 1994) and the proceedings of the final meetings held with support of the now terminated UNDP Warmer Area Wheat Project (Saunders and Hettel 1994).

References.

Fischer RA. 1995. Wheat project documentation for 1992-93. Internal publication, CIMMYT.

Morgunov A, Montoya A, and Rajaram S. 1994. Genetic analysis of resistance to Karnal bunt (Tilletia indica (Mitra)) in bread wheat. Euphytica 74:41-46.

Robinson J. 1994. Identification and characterization of resistance to the Russian Wheat Aphid in small-grain cereals: Investigations at CIMMYT, 1990-92. CIMMYT Research Report No. 3, Mexico, D.F.: CIMMYT.

Saunders DA and Hettel GP eds. 1994. Wheat in heat-stressed environments: irrigated dry areas and rice-wheat farming systems. Mexico, D.F.: CIMMYT.

Yield potential of some bread wheat derivatives from durum and synthetic hexaploid crosses.

R.L. Villareal, G. Singh, and S. Rajaram.

The CIMMYT Bread Wheat Breeding Program continues to study and use genetic diversity to increase stability in its germplasm, and to meet its objective in assisting NARSs in increasing the reliability of food production. In this context, many avenues are being explored to broaden the genetic yield base of its bread wheat germplasm. Some of the

new strategies employed were use of durum (Triticum turgidum) and synthetic hexaploids (T. turgidum x T. tauschii) in crosses with available high yielding improved bread wheat germplasm in the program. Through this route, we attempt to move some yield components (e.g., large seed size) from durums and synthetics into bread wheats resulting in improved yields.

Some of the highest yielding entries of the 14 replicated yield tests involving synthetic-derived advanced bread wheats are shown in Table 1. The mean yield of all the entries during the 1993-94 wheat season was 5.75 t/ha, as compared to 6.61 t/ha of the high yielding bread wheat check cultivar, Baviacora. The highest yielding entry was derived from the `Duergand/T. tauschii// Weaver' cross with 7.28 t/ha. Some of the outstanding durum-derived, advanced derivatives are also presented (Table 1). The highest yielding genotype was the `Esmeralda/Shearwater//Bacanora' derived line with 7.63 t/ha (7 % better than Baviacora). Yield performance of these lines, during the 1992-93 season, is also shown. Because several hundred T. tauschii accessions and improved durums are available that remain to be exploited, these sources of diversity for yield promise to be rewarding. These materials are now being seed increased for distribution to cooperators in September 1995

Agronomic performance of advanced bread wheat derivatives from Thinopyrum distichum.

R.L. Villareal and A. Mujeeb-Kazi.

The original `Inia/Thinopyrum distichum//Inia' (2n = 8x = 56, AABBDDX1X2) germplasm was obtained from Dr. R.V. Pienaar's program in South Africa during the early 1980s. CIMMYT's Wide Crosses Program modified the germplasm to improve its plant type by backcrosses to the Mexican bread wheat cultivars, Ciano 79 and Genaro 81. The objective of the study was to evaluate the agronomic performance of some advanced derivatives from Th. distichum developed through this breeding effort.

Two yield trials were conducted at Sonora, Mexico, during the 1991-92 and 1992-93 wheat seasons. Twenty-four test entries were arranged in a randomized complete block design with three replicates. Each plot consisted of 8 rows, 20 cm apart and 5 m long, and was machine-sown at a seeding rate of 100 kg/ha. One hundred fifty kg N/ha (in ammonium sulfate) and 40 kg P/ha (in tri-superphosphate) were applied prior to seeding of the trials.

Agronomic performance of the 10 best yielding Th. distichum derivatives, compared to that of the bread wheat cultivar checks, Ciano 79 and Genaro 81, are summarized in Table 2. The highest yielding genotype was a derivative of `Inia/Th. distichum//Inia/3/2*Ciano 79' with 7.32 t/ha as compared to Ciano 79 (6.53 t/ha) and Genaro 81 (6.75 t/ha). Mean grain yield of all the derived lines was 6.56 t/ha, ranging from 6.18 to 7.32 t/ha. None of the derivatives yielded better aboveground biomass than the check cultivars. All entries, except one, are shorter than the checks. On 1,000 grain weight, 18 lines possessed heavier grains than Ciano 79, whereas three were heavier than Genaro 81.

Consequently, these lines showed better test weight than Ciano 79 and Genaro 81. No analysis has been done to detect the incorporation of the alien chromosomal material.

Agronomic and yield evaluation of salt-tolerant bread wheats under optimum growing conditions.

R.L. Villareal and A. Mujeeb-Kazi.

Eight salt-tolerant bread wheat cultivars from Egypt, India, and Pakistan and a high-yielding local check cultivar, Seri 82, were grown at the Mexican Institute of Forestry, Agriculture and Livestock in the Yaqui Valley, Sonora, Mexico, during the 1991-92 and 1992-93 wheat production seasons. The study was designed to evaluate the yielding ability and agronomic characteristics of some selected salt-tolerant bread wheats under optimum growing conditions for better utilization as progenitors in our breeding program. A randomized complete block design was used with three replications. Each plot consisted of 8 rows, with each row 5 m long and 20 cm apart. The experiment was machine-sown at a seeding rate of 100 kg/ha. The trials received high levels of agronomic inputs and management regarding fertilizer (150 kg N/ha and 40 kg P/ha), irrigation (as required until the latest maturing genotype reached

physiological maturity), weed control (selective herbicide), and Folicur for control of leaf and stem rusts. Insect control was not required at any time during the season.

The mean grain yield and other agronomic characteristics of the test entries as compared to the bread wheat cultivar check, Seri 82, over 2 years of experiment are presented in Table 3. The highest mean grain yield among the test cultivars was 7.15 t/ha for WH 533 from India; however, this was not significantly different from Seri 82 (6.91 t/ha). The mean yield of the eight salt lines was 5.65 t/ha. All of the test lines flowered earlier than the check cultivar. Kharchia 65 was the tallest (106 cm) genotype among the entries and was the only lodging entry at harvest. LU 26 (50.0 g) and WH 157 (45.6 g) had heavier 1,000 grain weights than the check (40.5 g). Test weight was better for Raj-307 and LU 26 with 81.5 and 81.0 kg/hl, respectively, as compared to Seri 82 (80.1 kg/hl). In conclusion, better understanding of the variation among these materials will aid in utilization of these valuable germplasm resources as recipient pools for alien genetic diversity introgression from other Triticeae species.

Winter-spring crossing strategy for bread wheat breeding.

In 1988, we started this research, within the Breeding Methodology Project, in order to learn how winter germplasm (W) impacts the mean yield and genetic variance when used to breed spring wheat (S). We selected as parents five high-yielding (H) and five low-yielding (L) lines derived from `S x S' crosses. Crosses were made among lines of different yield levels, within each seasonal type, following the `crossed' or `North Carolina II' design. Evaluation of F₁ progenies indicated no effect of winter germplasm on yield mean of crosses between seasonal types or of crosses made among lines with different yield level aptitude. However, the highest-yielding crosses were

`H x H' in `S x W', and `L x H' in `S x S' (Table 1).

An analysis of variance revealed an additive variance broadening of about five times in `S x W' crosses by using winter germplasm (Table 2), with `H x L' crosses being the broadest, combining seasonal crosses. Within seasonal crosses, the broadest were `L x L' in both `S x W' and `S x S' (Table 2).

Results suggest that winter germplasm can be used to breed spring wheat without decreasing mean yield and with a broadening of genetic additive variance.

In the next step, we will test several random, true breeding lines from each cross between different yield levels within seasonal types, in order to verify these preliminary conclusions.

Publications.

Butron-Rodriguez J. 1986. Comparacion de lineas de trigo (T. aestivum L.) derivadas de cruzas entre tipos estacionales bajo riego y temporal. Tesis de Maestria en Fitomejoramiento, Univ. Aut. Agraria A. Narro.

Carranza-Bazini HE. 1989. Potencial genetico de progenies segregantes de trigo (T. aestivum L.) entre progenitores de diverso origen estacional de alto y bajo rendimiento. Tesis de Maestria en Fitomejoramiento, Univ. Aut. Agraria A. Narro.

Martinez-Zambrano G, and Carranza-Bazini HE. 1994. Uso de progenitores contrastantes en rendimiento y tipo estacional en el mejoramiento del trigo primaveral. Memoria del XI Congr. Latinoamericano de Genitica y XV Congr Nal de Fitogenitica, Monterrey, Mexico. p. 114.