Non-Corn Belt Dent populations

The Maize Research and Development Section of Cargill, Inc. announces the release of five non-Corn Belt Dent populations derived separately and in major proportion from the Latin American racial complexes Tuxpeno, Coastal Tropical Flint-Dent, Southern Cateto, Cuzco and Coroico. Developmental procedures were appropriate that a reasonably representative sample of each race was recovered adapted to the Central Corn Belt of the USA. The principal developmental feature, the alteration from a short to a long day adaptation, has offered both an added form of preservation for such germplasm and the opportunity for its further evaluation and study under new environments.

Cargill North Temperate Zone Mexican Dent--An unimproved population having the proportionate composition:
 
Tuxpeno Inbreds   Celaya Inbred   Early USA Inbreds
T2 7.3%   Lote 829  7.3%   WD 0.5%
T10 7.3%         R181B 0.5%
T11 7.3%         W182D 1.0%
T12 7.3%   Venezuelan Inbred   MS206 0.5%
BR10 3.8%   Llera 111 3.8%   A257 0.5%
BR15 3.8%         A375 0.5%
BR20 3.8%         A427 0.5%
      Tuxpeno Populations   A509 0.5%
      Maya 3.8%   A554 0.5%
      Azteca 3.8%   A629 0.5%
      Oaxaca 84 3.8%   MS1334  0.5%
      Vera Cruz 149 3.8%      
      Vera Cruz 208  3.8%      
            Canadian Inbred
Tuxpan Inbreds         CMD5 1.0%
BR25  7.3%            
BR30 3.8%   Tuxpeno x Cateto Hybrid        
BR35 3.8%   Phoenix 1211 3.8%      

This population has the equivalent of a 94% recovery of tropical germplasm. Six of the tropical inbreds were initially adapted to the Central Corn Belt through a backcross approach incorporating two backcrosses to tropical. The early USA and Canadian inbreds were the sources of earliness. A composite of these six adapted tropical inbreds was in turn crossed with each of the other tropical entities and a new population aggregate formed through intercrossing. Adaptation to the Central Corn Belt was regained through phenotypic recurrent selection. Kernel color is predominantly white with some light yellow. Cob color is white. As could be expected, there is a strong resemblance to Corn Belt Dent and the material can be handled in like manner.

Cargill North Temperate Zone Caribbean Flint-Dent--An unimproved population having the proportionate composition:
 
Caribbean Inbreds   Caribbean Populations   Early USA Inbreds
Cuba 312-206-X 7.3%   College Yellow Flint 8.3%   Wf1 0.5%
Cuba 312-219-X 7.3%   Cuba 8.3%   B8 0.5%
Cuba 325-223-X 7.3%   Syn. Cuba Type 8.3%   B9 0.5%
BR40 7.3%   Compuesto de Cuba 8.3%   Mt42 1.0%
ETO-5C 7.3%   Comp. Yellow Var. 8.3%   Oh56 0.5%
PTR-20A 7.3%   Costeno Blanco 8.3%   W59E 0.5%
            W59M 0.5%
            MS206 0.5%
      Canadian Inbred   A251 0.5%
      CMD5 0.5%   A509 0.5%

This population has the equivalent of a 94% recovery of tropical germplasm. Each of the six tropical inbreds was initially adapted to the Central Corn Belt through a backcross approach incorporating two backcrosses to tropical. The early USA and Canadian inbreds were the sources of earliness. A composite of the six adapted tropical inbreds was in turn crossed with each of the six tropical populations and a new population aggregate formed through intercrossing. Adaptation to the Central Corn Belt was regained through phenotypic recurrent selection. Kernel hardness varies from hard dent to near-flint. Kernel color is predominantly white with some light yellow. Cob color is white. Husk coverage is heavy and often tight. There is a general resemblance to Corn Belt Dent and the material can be handled in like manner.

Cargill North Temperate Zone Cateto--An unimproved population having the proportionate composition:
 
Argentine Flint Inbreds   Argentine Cuarentin Population
Arg-1 4.70%   Cuarentin Rossi 25.00%
Arg-2 4.70%      
Arg-3 4.70%      
Arg-4 4.70%   Early USA Inbreds  
Arg-5 6.25%   WD 0.8%
Arg-6 6.25%   W37A 0.8%
Arg-7 6.25%   MS206 0.8%
Arg-8 6.25%   A509 0.8%
         
         
Brazilian Cateto Populations   Canadian Inbreds
Cateto S. Sirao 6.25%   CMV3 0.8%
Minas Gerais II 6.25%   CMD5 1.0%
Cateto Composto 6.25%   CK27 0.8%
Rio G. S. XIV 6.25%   CM37 0.8%
      KD54 0.8%

This population has the equivalent of 94% Cateto flint germplasm. All of the Argentine flint inbreds trace back to longtime open-pollinated varieties and are unadulterated by introduced germplasm. Four of these inbreds had previously been converted to earlier forms by a backcross approach where the early USA and Canadian inbreds served as sources of earliness. The other Argentine inbreds and the Cuarentin population have a late temperate zone maturity. The Brazilian populations are fully tropical. Temperate and tropic zone material were joined in a single population and this adapted to the Central Corn Belt through phenotypic recurrent selection. This fully flint material ranges in color from deep yellow to orange. Cob color is white. Husk coverage tends to be heavy. Plant type generally resembles higher-eared Corn Belt Dent and the material can be handled in like manner.

Cargill North Temperate Zone Cuzco--An unimproved population having the proportionate composition:
 
Cuzco Populations   Early Dent Population
C. Cristalino Amarillo 29.00%   Minnesota A 6.25%
C. Gigante Shaver 29.00%      
Cuzco 66 12.50%      
Cuzco Manuel 11.00%      
C. Gigante 13605 4.00%      
Cuzco 13623 4.00%      
Cuzco 13634 4.00%      

This population has the equivalent of a 94% recovery of tropical germplasm. Initially Cuzco Manuel was crossed with the source of earliness, Minnesota A. Through a series of three backcrosses to tropical, various of the seven different Cuzco populations were used at each generation to give the resulting proportions. Interpollination among the different basic sources was practiced following each backcross. An adapted population was formed through phenotypic recurrent selection out of the third backcross generation. This population differs considerably in appearance from typical Corn Belt Dent, giving an overall impression of heaviness or coarseness for many plant traits. Ears are short and blocky. Kernel row number is low, and kernels themselves range in size from typical Corn Belt Dent to 70% that of gigante. Texture ranges from dented flour to near-flint. Kernel color varies from white through medium yellow. Cob color is white and varying shades of red. Husk coverage is extremely heavy and tight. This together with a stiffly upright ear leads to extensive ear rot and lowered germination unless pollinating bags are removed early and harvest is timely. There is a strong tendency for barrenness unless plant densities are kept below 40,000 plants per hectare.

Cargill North Temperate Zone Coroico--An unimproved population having the proportionate composition:
 
Coroico Populations   Early Flint Population
Red Chavantes 27.50%   Early Russian 6.25%
Entrelacado 15.00%      
Xingu 15.00%      
Amazonas 15.00%      
White Chavantes  15.00%      
Black Chavantes  6.25%      

This population has the equivalent of a 94% recovery of tropical germplasm. Although the three Chavantes populations were presumably collected from the same Indian tribe, Chavantes, they differ considerably in maturity and gross appearance under Hawaiian growing conditions. Initially Red Chavantes was crossed with the source of earliness, Early Russian. During a series of three backcrosses to tropical, Red Chavantes was always involved and four additional representatives of this race were added at the second backcross. Black Chavantes was involved at the first backcross only. Interpollination among the different sources was practiced following each backcross. An adapted population was formed through phenotypic recurrent selection out of the third backcross generation. Appearance of this material is profoundly different from that of Corn Belt Dent. Ears are very slender with a tendency for low kernel row number towards the tip and a compounding of row numbers on enlarged butts. Ear placement is high with occasional prolificacy. Kernel texture ranges from floury to flinted-flour. Kernel color ranges from white through varying shades of yellow to occasional red. Leaves are long and slender. Tassels are very large and thin, but with profuse pollen shed. Stalks are brittle. There is a lower than average tolerance to heat, drought and high plant density. Best results are obtained where plant densities are kept below 40,000 plants per hectare.

Barring a failure in the 1979-80 and 1980 crop seasons, seed of these five adapted exotic races should be available late in 1980 from the North Central Regional Plant Introduction Station, Iowa State University, Ames, Iowa. Plant accession numbers have not yet been assigned.

E. E. Gerrish

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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