Cold Tolerance of Maize Inbred Lines Adapted to Various Latitudes in North America¹

Abstract

We evaluated cold‐tolerance responses [measured by percentage emergence (30 days after planting), emergence index (an estimate of emergence rate), and seedling dry weight (sampled 42 days after planting)] of 34 maize (Zea may L.) inbred lines adapted to various latitudes in North America. Evaluations were performed in field experiments planted in early April at Ames and Algona, Iowa, in 1974 and 1976. Objectives of our study were: i) to assess genetic variability and breeding potential for improvement of cold tolerance within maize germplasm adapted to North America, ii) to study associations of cold‐tolerance traits with other plant traits (including grain yield), and iii) to examine relationships between geographical locations of origin and cold‐tolerance responses of inbred lines adapted to North America.We observed large amounts of variability for each of the three cold‐tolerance traits. Means ranged from 27.5 to 82.9% for percentage emergence, 20.0 to 24.0 days for emergence index, and 0.33 to 1.16 dg for seedling dry weight; respective heritability estimates were 0.85 ± 0.06, 0.72± 0.06, and 0.80 ± 0.06. Genotypic correlations among the three traits were high, suggesting selection for improved cold tolerance (as an aggregate of the three traits) should be possible. Environments and genotype ✗ environments mean squares were highly significant; therefore, evaluations of cold tolerance of maize inbred lines should be conducted in more than one environment.Correlations of all three traits with juvenile plant height and leaf number (measured in early July), 50% silk emergence, mature plant height, and grain yield usually were low. Thus, seedling cold tolerance was not associated with vegetative vigor of juvenile plants, flowering date, or mature plant height. Seedling dry weight, however, was significantly correlated with grain yield (r = 0.48**), indicating good seedling vigor was related to high grain yield.Cold‐tolerance response generally was not related to geographical location of adaptation; however, 9 of the 10 best inbred lines were adapted to the central latitudes of the U.S. Corn Belt. Inbreds from the northern and southern regions ranked average or lower for cold tolerance. The three best cold‐tolerant inbreds were B73, (V3 x B14)‐2‐1 (both from Iowa), and Mo 17 (from Missouri). Breeding populations developed from the best inbreds in our study should contain gene complexes for good cold tolerance, plus variable flowering dates, plant heights, and grain yields.

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.…”

“…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

“…Maize (Zea mays L.) cultivars that show early vigour are desirable for enhancing crop establishment in areas in which low temperature retards early seedling growth (Miedema 1982) or where breeding for earliness is a strategy for avoiding the effect of drought at flowering (Mock and McNeil 1979). There are three stages of early plant development: germination, heterotrophic growth and early autotrophic growth.…”

Low temperature emergence potential of short season corn hybrids grown under controlled environment and plot conditions

“…Low temperature reduces emergence rate (Mock and McNeill 1979) and increases susceptibility to seed and seedling diseases which reduce seedling vigour (Schulz and Bateman 1968). Low temperature also reduces percent emergence (Dubetz et al 1962) (Mock and Pearce 1975), is therefore an important trait for corn in many production areas.…”