Response to selection, combining ability and heritability of coleoptile length in winter wheat

Abstract

Selection of winter wheat cultivars with long coleoptiles is an important component of improving emergence, weed suppression and grain yield in low rainfall regions of the world. Seven winter wheat cultivars were hybridized in a Griffing's half-diallel mating design, method 2 (reciprocals excluded, parents included), model 1 (fixed), and the progeny analyzed for coleoptile length in the F 1 through F 4 for response to selection, general combining ability (GCA), specific combining ability (SCA) and heritability. Highly significant differences existed for GCA among progeny in each generation. SCA was highly significant in the F 1 , F 2 and F 4 , although SCA estimates were inconsistent among generations in each progeny population. The SCA/ GCA ratio was 0.15, 0.11, 0.06 and 0.04 in the F 1 through the F 4 , respectively, indicating that additive effects increased with homozygosity. Broad-sense heritability for coleoptile length was estimated at 0.86, 0.76, 0.60 and 0.78 for the F 1 through the F 4 , respectively. Realized heritabilities ranged from -0.16 to 0.85 with a mean of 0.32 in the F 3 and ranged from -0.68 to 0.68 with a mean of 0.13 in the F 4 . Spearman's rank correlation coefficients (R S ) were significant for all generation comparisons except the F 1 :F 2 , indicating that changes in rank for coleoptile length were insignificant. Cultivars with long coleoptiles and high GCA were the best parents for improving coleoptile length. Sustained selection over generations for coleoptile length was more effective than one generation of selection for genotypes both with and without reduced height genes.

The need to breed crop varieties suitable for organic farming, using wheat, tomato and broccoli as examples: A review

“…Early ground cover is one aspect vital to weed suppression [73] and this trait can be introduced into wheat varieties and was shown to provide a competitive advantage over early emerging weeds and increased resistance to mechanical weeding operations [74]. In wheat, emergence is strongly influenced by coleoptile length, a moderately heritable trait that can be effectively incorporated into modern varieties through breeding [72,75,76].…”

Response of coleoptiles to water deficit: growth, turgor maintenance and osmotic adjustment in barley plants (Hordeum vulgare L.)

“…The existence of intraspecific variability with respect to osmotic adjustment [6,16,17,19,[20][21][22] and coleoptile growth [23,24] has been demonstrated in different crops. This, along with the possibility of identifying QTLs that control drought tolerance in seedling [25], and coleoptile growth [26], renders the study of coleoptile growth of great interest in the improvement of drought tolerance.…”

Characterization for drought resistance at early stages of wheat genotypes based on survival, coleoptile length, and seedling vigor

“…Coleoptile length can also vary because of research or growth conditions. In addition, when we consider the coleoptile lengths reported as 49-119 mm by Schillinger et al (1998), 64-131 mm by Murphy et al (2008a), and 59-159 mm by Murphy et al (2008b), it can be stated that the coleoptile lengths of the bread wheat genotypes used in this study showed narrow variation. Moreover, the fact that the local cultivars and cultivars with old registration dates had longer coleoptiles than the modern and current cultivars took our attention.…”

“…Short coleoptiles in seed beds that are unsuitable with respect to moisture and sowing depth decrease yield by extending the duration of emergence, decreasing the number of emergent seedlings, and resulting in smaller leaf area indices and weak seedlings (Richards, 1992;Schillinger et al, 1998). In order to suppress weeds and increase yield, the best practice is to select winter varieties having longer coleoptiles in regions having low rainfall (Murphy et al, 2008a).…”