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Yield Characteristics of Ancient Races of Maize Compared to a Modern Hybrid

Agron. Dep., Univ. of Florida, Gainesville, FL 32611

Raul Valle

CEPEC/CEPLAC, Itabuna, Bahia 45600, Brazil

^* Corresponding author

Open-pollinated races of maize (Zea mays L.) have been cultivated in the Americas since antiquity although their performance is poor compared to modern hybrids. However, morphological-physiological characteristics that contribute to the yield superiority of modern hybrids over ancient lines have not been well documented and such information should be useful in the selection of improved open-pollinated lines and management strategies. Therefore, a study was conducted in Gainesville, FL (29 °38'N lat) to identify and quantify morphological-physiological traits that are responsible for yield differences between ancient and modern hybrid maize cultivars. The characteristics assessed included photosynthetic capacity, grain-filling rate and duration, and photosynthate partitioning. Three Central American ancient lines (Chapalote, Nal-Tel, and Maiz Criollo) and a hybrid (Coker 77) widely adapted to the Southeast USA, were sequentially harvested at 10-d intervals until physiological maturity for growth analysis. Leaf area index (LAI) and vegetative crop growth rate (CGR_v) were similar for all genotypes except for Nal- Tel, which had lower values. The hybrid had greater LAI, leaf area duration (LAD), ear and kernel growth rates, as well as kernel number and size. Additionally, the hybrid redistributed more stalkstored photosynthate to the grain, and its grain-filling period was longer. We conclude that the primary weaknesses of these ancient races compared to hybrids were low LAI and LAD, short grainfilling duration, and low photosynthate redistribution and sink capacity due to fewer and smaller kernels.

Received for publication June 12, 1989.