Inheritance of cold tolerance at emergence and during early season growth in maize

Abstract

Adaptation of maize (Zea mays L.) to early planting dates requires the improvement of cold tolerance, which implies high percentage emergence and vigorous seedling growth under cold temperatures. The objectives of this work were to evaluate the combining ability of elite European maize inbreds for cold tolerance and to study the inheritance of cold-tolerance. Five maize inbreds, differing in sensitivity to cold temperatures, were crossed by means of a diallel design. Hybrid seed was obtained at two production environments. Hybrids were planted on trays filled with sterilized peat in a cold chamber at four minimum temperatures, and these hybrids were also grown in field trials at two locations in northwestern Spain. The most cold-tolerant inbreds, according to previous unpublished inbred evaluations in the cold chamber, F7 and EA2087, produced the most cold- tolerant hybrids. Inbred F7 performed slightly better in hybrid combinations than EA2087 for emergence-related traits in the cold chamber, and EA2087 was superior in hybrid combinations to F7 for seedling growth. The inbred F7 may contribute cold tolerance at emergence, whereas EA2087 contributed cold-tolerance for both emergence and seedling growth. In the field, inbreds F7 and H104W were the best parent for cold-tolerant hybrids. Percentage emergence was not related to the other traits. Generally, the genetic regulation of cold- tolerance traits conformed to an additive-dominance model, and it should be possible to combine both high percent emergence and vigorous seedling growth. A promising source of new cold-tolerant rinbreds is the cross between EA2087 and F7.