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 The most cold‐tolerant inbreds, according to previous unpublished inbred evaluations in the cold chamber, F7 and EA2087, produced the most cold‐tolerant hybrids.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 inbreds is the cross between EA2087 and F7.

QTL studies reveal little relevance of chilling-related seedling traits for yield in maize

“…A signiWcant correlation between grain yield and dry weight of seedlings, which were exposed to low temperature, was found in a set of maize inbred lines (Mock and McNeill 1979). However, results of Revilla et al (2000) indicated that signiWcant diVerences among hybrids for early vigor under low temperature conditions were not correlated with grain yield. The comparative analysis of QTLs identiWed in seedlings grown under chilling conditions in the Weld (Jompuk et al 2005) with the QTLs found at harvest indicated that photosynthesis-related traits and morpho-physiological traits, like shoot dry weight, area of the third leaf, carbon and nitrogen concentration and C:N ratio, at seedling stage did not result in an increased biomass at harvest.…”

“…The QTLs, which were found for yield-related traits solely in 2002, were potentially involved in the late-cold tolerance. Since the genetic control of cold tolerance seems to be independent at diVerent growth stages (Revilla et al 2000) it might explain why these QTLs were not co-localized with QTLs for cold tolerance of photosynthesis at seedling stage.…”

“…Studies investigating the eVect of chilling tolerance of maize seedlings on the grain yield were conducted with individual genotypes (Mock and McNeill 1979) or hybrids (Revilla et al 2000). So far, there are no studies in term of QTL for chilling stress during seedling stage and its relation to the biomass yield at harvest.…”

QTL controlling root and shoot traits of maize seedlings under cold stress

“…The performance of the genotypes during these stages is referred to as seed vigour (Perry 1987), seedling vigour and early vigour (Revilla et al 1999), respectively. Depending on the breeding material and the environment, tolerance to cold at all three stages may be controlled by the same set of genes (Mock and Eberhart 1972) or may be inherited independently (Hodges et al 1997;Mock and Eberhart 1972;Revilla et al 2000). Ideally, a vigorous genotype will perform well during all these stages (Hodges et al 1997;Revilla et al 2000).…”

“…Depending on the breeding material and the environment, tolerance to cold at all three stages may be controlled by the same set of genes (Mock and Eberhart 1972) or may be inherited independently (Hodges et al 1997;Mock and Eberhart 1972;Revilla et al 2000). Ideally, a vigorous genotype will perform well during all these stages (Hodges et al 1997;Revilla et al 2000). While seed vigour ensures an uniform germination and plant establishment (Perry 1987), early vigour ensures successful transition to the autotrophic growth stage.…”