Basic Development Rate in Spring Wheat¹

Abstract

There have been a number of reports indicating that, in the absence of vernalization and photoperiod influences, there is a factor(s) which acts to exert control over the rate of development in bread wheat (Triticum aestivumL. em. Thell.). In an attempt to characterize this phenomenon more fully, three sets of wheat genotypes were examined for their rate of development in the absence of vernalization and/or photoperiod influences. Seventeen spring wheats, prevernalized and grown with an 18‐h photoperiod in an outdoor pot experiment were found to differ in development rate, indicating that it may be of significance to adaptability and yield, at least in this type of wheat. In a set of near‐isogenic lines of ‘Triple Dirk’ (differing for the vernalization response genes vrn 1 and vrn 2) their development rates were similar, indicating that it is not a manifestation of the action of genes for vernalization response. Additionally, the absence of a close correlation between the level of vernalization response and basic development rate in the 17 spring wheats indicates physiological independence between the two processes. Using growth apex dissection the various phases of floral development were followed in two Australian spring wheat cvs., Pinnacle and Falcon, at four times of sowing in an outdoor situation and grown under an 18‐h photoperiod. The cv. Falcon was much faster than Pinnacle from sowing to floral initiation, terminal spikelet, and ear emergence at the four times of sowing. While the vegetative phase in Pinnacle was generally longer than in Falcon, the spikelet initiation and stem elongation phases did not show the same relative prolongation. ‘Chinese Spring’/‘Thatcher’ chromosome substitution lines 7B and SD, pre‐vernalized for weekly periods from 0 to 8 weeks and grown with an 18‐h photoperiod in an outdoor pot experiment were used to investigate the chromosomal control of development rate in wheat. Chromosome 7B of Thatcher substituted in Chinese Spring reduced its vernalization requirement and increased its rate of development. Chromosome 5D of Thatcher did not alter either vernalization response or rate of development of Chinese Spring. In view of these data and earlier reports, the term “basic development rate” is proposed to denote differences between wheats in the rate of development in the absence of vernalization and photoperiod influences. Recognition of the phenomenon of basic development rate prompts a re‐evaluation of the developmental basis of flowering in wheat and other temperate plants.

Differential reaction of wheat cultivars to hot environments

“…A most remarkable example is given in the work of BAGGA & RAW~ON (1977), where Kalyansona, compared with Condor showed excellent stability in grain number per spike at increasing temperatures. This and their own data led FLOOD & HALLORAN (1984) to propose that wheat genotypes have a basic development rate, irrespective of their vernalization and photoperiod requirements, and that this basic rate may be used in breeding for a wider environmental adaptation.…”

Impact of Growth Habit and Architecture Genes on Adaptation and Performance of Bread Wheat

“…Bread wheat is generally classified as spring or winter types according to its response to low temperatures during the vegetative phase [22][23][24]. Exposure to low temperatures (0-10°C) for several weeks (usually 6-8 weeks) is necessary for the development of tillers and the induction of flowering in winter wheat, whereas tillering and flowering of spring wheat occur regardless of temperature [22,25].…”

“…Exposure to low temperatures (0-10°C) for several weeks (usually 6-8 weeks) is necessary for the development of tillers and the induction of flowering in winter wheat, whereas tillering and flowering of spring wheat occur regardless of temperature [22,25]. The flowering models of the temperate cereals indicate that before vernalization, Vrn-3 series is repressed by Vrn-2 and long exposure to low temperatures is necessary for the upregulation of Vrn-1 series and downregulation of Vrn-2 in the leaves.…”

Development of Near Isogenic Lines of Wheat Carrying Different Spike Branching Genes and Their Agronomic and Spike Characters

“…The duration of the development stages depends on genotype and environment. Different genotypes have different photoperiod sensitivity, vernalisation properties which regulating the time from sowing to anthesis (Flood et al, 1984). Many tillage methods, such as crop rotation (Verhulst et al, 2011), early sowing (Gbmez-Macpherson et al, 1997), plant growth regulators (Biesaga-Koscielniak et al, 2010), and fertilizer (Oscarson et al, 1995) also had effects on the development stages.…”