Screening Spring Wheat Genotypes (Triticum sp.) for Seedling Emergence under Optimal and Suboptimal Temperature Conditions

Abstract

Ninety six tetraploid spring wheat genotypes and six hexaploid wheat cultivars were allowed to germinate in four growth chambers set at temperature regimes of 5-degrees-C, 10-degrees-C, 15-degrees-C, and 20-degrees-C. Temperature had a strong effect on seedling emergence time of all genotypes. This effect was much more dramatic at the lower than at the higher temperature values. Optimum temperature conditions (15-degrees-C and 20-degrees-C) were associated with smaller genetic variances for seedling emergence time. The 15-degrees-C and 20-degrees-C did not statistically differ in their effects on emergence time. The 5-degrees-C and 10-degrees-C treatments can be successfully used to screen genotypes for their cold tolerance because of much larger genetic variances. Genotypes were classified into three categories according to their cold tolerance: tolerant, intermediate, and susceptible. Hexaploid genotypes were the most cold tolerant in this wheat population. The most cold tolerant tetraploid genotypes are 1460, Adamello, Creso, Echiopia Komugi 72-201, Kunduru 1149, Kyperounda, Latino, Mindum, and Norba. The emergence time of these 9 tetraploid genotypes was comparable to that of the hexaploid genotypes. Under low temperature conditions some spring wheat genotypes performed similarly as the winter types suggesting that cold torelance during seedling emergence is independent of varnalization requirement. There was no genotype x temperature interaction indicating that selection for cold tolerance is effective. The 10-degrees-C can be successfully used to screen genotypes for their cold tolerance during the emergence growth phase.