Variability in the Duration of Stem Elongation in Wheat and Barley Genotypes

Abstract

The stem elongation phase in wheat (Triticum aestivum, L.) and barley (Hordeum vulgare) is important for yield determination as it is the phase when stems and spikes grow actively. A longer duration of this phase could hypothetically increase assimilate availability, fertile florets at anthesis and final grain number. Argentine commercial wheat and barley cultivars were studied to analyse the range of genetic variability existing in the duration of the stem elongation phase, in particular, considering cultivars with similar time to anthesis. It was found that cultivars differing in time to anthesis, not only differed in the length of their early, mostly vegetative phases but also in the stem elongation phase (range 301–535 °C day for wheat and 252–404 °C day for barley), and that the partitioning of a similar time to anthesis into phases was substantially different between cultivars. Various studies with other cultivars were re‐analysed, showing that the stem elongation phase did present genetic variability as well. As a preliminary step to identifying the genetic causes behind this variability, an approximation to the possible photoperiod and/or vernalization sensitivities of this large group of Argentine cultivars was presented, by comparing behaviour in two contrasting sowing dates. This has proved useful to breeders since there have been no other previous studies including this large number of commercial cultivars.

Genetic control of pre-heading phases in the Steptoe × Morex barley population under different conditions of photoperiod and temperature

“…Gi09-Au were significant they were not consistent between studies (Appleyard et al 1982;Kitchen and Rasmusson 1983;Kernich et al 1995Kernich et al , 1997Whitechurch et al 2007;Borràs et al 2009). The lack of highly significant genetic correlations (Table 5) and the different QTLs detected for LS and SE ( Fig.…”

“…Several authors have demonstrated phenotypic variability in pre-heading phases even in varieties with similar total time to heading (Appleyard et al 1982;Kitchen and Rasmusson 1983;Kernich et al 1995Kernich et al , 1997Whitechurch et al 2007). Other authors have reported that responses to photoperiod and temperature may differ between pre-heading phases (Roberts et al 1988;Slafer and Rawson 1994;Slafer 1996;Miralles and Richards 2000;González et al 2002).…”

Monitoring the dynamics of wheat stem elongation: genotypes differ at critical stages

“…The duration of stem elongation was primarily influenced by the variation in GDD 95 while the variation in GDD 15 had little influence. This independence between SE duration and the duration of prior phases has been reported before (Whitechurch et al 2007). Our results suggest that variation in GDD 15 has an indirect effect on GDD 95 but does not affect SE duration.…”

“…It has been proposed that a prolonged SE phase would allow for more dry matter accumulation by the spike due to its longer growth phase, which would ultimately increase yield (Slafer et al 1996;Miralles and Slafer 2007;Whitechurch et al 2007).…”

Wheat physiology: a review of recent developments

“…Following Eqn 1, D s did not vary in a tall versus short isogenic comparison (see references in Fischer 2007) nor in the comparison of modern Argentine wheats (Abbate et al 1998), so apart from Serrago et al (2008) above, cultivar effects on D s have yet to be described. However, large Argentine cultivar differences in the duration of the phase (TS/SE to AN) in 8C (at least 2-fold for a given photoperiod) were reported by Whitechurch et al (2007), and these may reflect differences in D s , which falls largely within TS/SE to AN. Also, González et al (2005a) showed a highly significant relationship between SDW at flowering and solar radiation intercepted over the TS to AN phase, when its duration was varied by photoperiod extension across photoperiod-sensitive alleles in the Mercia background.…”