Skip to main content Accessibility help

Differences in phasic development rate amongst wheat cultivars independent of responses to photoperiod and vernalization. A viewpoint of the intrinsic earliness hypothesis

  • G. A. Slafer (a1)


Differences amongst wheat cultivars in the rate of reproductive development are largely dependent on differences in their sensitivity to photoperiod and vernalization. However, when these responses are accounted for, by growing vernalized seedlings under long photoperiods, cultivars can still differ markedly in time to ear emergence. Control of rate of development by this ‘third factor’ has been poorly understood and is variously referred to as intrinsic earliness, earliness in the narrow sense, basic vegetative period, earliness per se, and basic development rate. Certain assumptions are made in the concept of intrinsic earliness. They are that differences in intrinsic earliness (i) are independent of the responses of the cultivars to photoperiod and vernalization, (ii) apply only to the length of the vegetative period up to floral initiation (as suggested by several authors), (iii) are maintained under different temperatures, measured either in days or degree days. As a consequence of this, the ranking of cultivars (from intrinsically early to intrinsically late) must be maintained at different temperatures. This paper, by the re-analysis of published data, examines the extent to which these assumptions can be supported.

Although it is shown that intrinsic earliness operates independently of photoperiod and vernalization responses, the other assumptions were not supported. The differences amongst genotypes in time to ear emergence, grown under above-optimum vernalization and photoperiod (that is when the response to these factors is saturated), were not exclusively due to parallel differences in the length of the vegetative phase, and the length of the reproductive phase was independent of that of the vegetative phase. Thus, it would be possible to change the relative allocation of time to vegetative and reproductive periods with no change in the full period to ear emergence.

The differences in intrinsic earliness between cultivars were modified by the temperature regime under which they were grown, i.e. the difference between cultivars (both considering the full phase to ear emergence or some sub-phases) was not a constant amount of time or thermal time at different temperatures. In addition, in some instances genotypes changed their ranking for ‘intrinsic earliness’ depending on the temperature regime. This was interpreted to mean that while all genotypes are sensitive to temperature they differ amongst themselves in the extent of that sensitivity.

Therefore, ‘intrinsic earliness’ should not be considered as a static genotypic characteristic, but the result of the interaction between the genotype and temperature. Intrinsic earliness is therefore likely to be related to temperature sensitivity. Some implications of these conclusions for plant breeding and crop simulation modelling are discussed.



Hide All
Aitken, Y. (1974). Flowering Time, Climate and Genotype. Melbourne: Melbourne University Press.
Angus, J. F., MacKenzie, D. H., Morton, R. & Schafer, C.A (1981 a). Phasic development in field crops. II. Thermal and photoperiodic responses of spring wheat. Field Crops Research 4, 269283.
Angus, J. F., Cunningham, R. B., Moncur, M. W. & MacKenzie, D.H. (1981 b). Phasic development in field crops. I. Thermal response in the seedling phase. Field Crops Research 3, 365378.
Bauer, A., Garcia, R., Kanemasu, E. T., Blad, B. L., Hatfield, J. L., Major, D. J., Reginato, R. J. & Hubbard, K. G. (1988). Effect of latitude on phenology of ‘Colt’ winter wheat. Agricultural and Forest Meteorology 44, 131140.
Beavis, W. D., Grant, D., Albertson, M. & Fincher, R. (1991). Quantitative trait loci for plant height in four maize populations and their associations with qualitative genetic loci. Theoretical and Applied Genetics 83, 141145.
Boyd, W. J. R., Kaveeta, L., Potipibod, S. & Rossnagel, B. (1991). Variation in basic vegetative period and minimum leaf numbers. In Proceedings of the Sixth International Barley Genetics Symposium (Ed Munck, L.), pp. 68. Helsingborg: Munksgaard International Publishers.
Davidson, J. L., Christian, K. R., Jones, D. B. & Bremner, P.M. (1985). Responses of wheat to vernalization and photoperiod. Australian Journal of Agricultural Research 36, 347359.
Evans, L. T. & Blundell, C. (1994). Some aspects of photoperiodism in wheat and its wild relatives. Australian Journal of Plant Physiology 21, 551562.
Fischer, R. A. (1984). Wheat. In Symposium on Potential sProductivity of Field Crops Under Different Environments (Eds Smith, W. H. & Banta, S. J.), pp. 129153. Los Bañios: IRRI.
Flood, R. G. & Halloran, G. M. (1984). Basic development rate in spring wheat. Agronomy Journal 76, 260264.
Flood, R. G. & Halloran, G. M. (1986). Genetics and physiology of vernalization response in wheat. Advances in Agronomy 39, 87125.
Ford, M. A., Austin, R. B., Angus, W. J. & Sage, G. C.M. (1981). Relationships between the responses of spring wheat genotypes to temperature and photoperiodic treatments and their performance in the field. Journal of Agricultural Science, Cambridge 96, 623634.
Frank, A. B., Bauer, A. & Black, A. L. (1987). Effects of air temperature and water stress on apex development in spring wheat. Crop Science 27, 113116.
Gallagher, J. N. (1979). Field studies of cereal leaf growth. I. Initiation and expansion in relation to temperature and ontogeny. Journal of Experimental Botany 30, 625636.
Halloran, G. M. (1977). Developmental basis of maturity differences in spring wheat. Agronomy Journa 69, 899902.
Halloran, G. M. & Pennell, A. L. (1982). Duration and rate of development phases in wheat in two environments. Annals of Botany 49, 115121.
Halse, N. J. & Weir, R. N. (1974). Effects of temperature on spikelet number of wheat. Australian Journal of Agricultural Research 25, 687695.
Hay, R. K. M. (1986). Sowing date and the relationships between plant and apex development in winter cereals. Field Crops Research 14, 321337.
Hay, R. K. M & Kirby, E. J.M. (1991). Convergence and synchrony – a review of the coordination of development in wheat. Australian Journal of Agricultural Research 42, 661700.
Hoogendoorn, J. (1985). The basis of variation in date of ear emergence under field conditions among the progeny of a cross between two winter wheat varieties. Journal of Agricultural Science, Cambridge 104, 493500.
Johnson, I. R. & Thornley, J. H. M. (1985). Temperature dependence of plant and crop processes. Annals of Botany 55, 124.
Kato, K. & Yamagata, H. (1988). Method for evaluation of chilling requirement and narrow-sense earliness of wheat cultivars. Japanese Journal of Breeding 38, 172186.
Keim, D. L., Welsh, J. R. & McConnell, R. L. (1973). Inheritance of photoperiodic heading response in winter and spring cultivars of bread wheat. Canadian Journal of Plant Science 53, 247250.
Kirby, E. J. M., Appleyard, M. & Fellowes, G. (1985) Variation in development of wheat and barley in response to sowing date and variety. Journal of Agricultural Science, Cambridge 104, 383396.
Kirby, E. J. M., Porter, J. R., Day, W., Adam, J. S., Appleyard, M., Ayling, S., Baker, C. K., Belford, R. K., Biscoe, P. V., Chapman, A., Fuller, M. P., Hampson, J., Hay, R. K. M., Matthews, S., Thompson, W. J., Weir, A. H., Willington, V. B. A. & Wood, D. W. (1987). An analysis of primordium initiation in Avalon winter wheat crops with different sowing dates and at nine sites in England and Scotland. Journal of Agricultural Science, Cambridge 109, 123134.
Koester, R. P., Sisco, P. H. & Stuber, C. W. (1993). Identification of quantitative trait loci controlling days to flowering and plant height in two near isogenic lines of maize. Crop Science 33, 12091216.
Major, D. J. (1980). Photoperiod response characteristics controlling flowering of nine crop species. Canadian Journal of Plant Science 60 777784.
Major, D. J. (1983). Determination of photoperiod response characteristics using a greenhouse. International Journal of Biometeorology 27, 117124.
Manupeerapan, T., Davidson, J. L., Pearson, C. J. & Christian, K. R. (1992). Differences in flowering responses of wheat to temperature and photoperiod. Australian Journal of Agricultural Research 43, 575584.
Masle, J., Doussinault, G. & Sun, B. (1989). Response of wheat genotypes to temperature and photoperiod in natural conditions. Crop Science 29, 712721.
Miura, H. & Worland, A. J. (1994). Genetic control of vernalization, day-length response, and earliness per se by homoeologous group-3 chromosomes in wheat. Plant Breeding 113, 160169.
Monteith, J. L. (1977). Climate. In Ecophysiology of Tropical Crops (Eds Alvim, P. de T. & Kozlowski, T. T.), pp. 127. New York: Academic Press.
Morrison, M. J., McVetty, P. B. E. & Shaykewich, C. F. (1989). The Determination and verification of a baseline temperature for the growth of Westar summer rape. Canadian Journal of Plant Science 69, 455464.
Penrose, L. D. J., Martin, R. H. & Landers, C. F. (1991). Measurement of response to vernalization in Australian wheats with winter habit. Euphytica 57, 917.
Pirasteh, B. & Welsh, J. R. (1980). Effect of temperature on the heading date of wheat cultivars under a lengthening photoperiod. Crop Science 20, p453–456.
Porter, J. R. & Delecolle, R. (1988). Interaction of temperature with other environmental factors in controlling the development of plants. In Plants and Temperature (Eds Long, S. P. & Woodward, F. I.), pp. 133156. Cambridge: The Company of Biologists Limited.
Rahman, M. S. (1980). Effect of photoperiod and vernalization on the rate of development and spikelet number per ear in 30 varieties of wheat. Journal of the Australian Institute of Agricultural Science 46, 6870
Rahman, M. S. & Wilson, J. H. (1977). Determination of spikelet number in wheat. I. Effect of varying photoperiod on ear development. Australian Journal of Agricultural Research 28, 565574.
Rahman, M. S. & Wilson, J. H. (1978). Determination of spikelet number in wheat. III. Effect of varying temperature on ear development. Australian Journal of Agricultural Research 29, 459467.
Rawson, H. M. (1970). Spikelet number, its control and relation to yield per ear in wheat. Australian Journal of Biological Sciences 23, 15.
Rawson, H. M. (1993). Prediction of heading time in wheat grown under high temperatures: effects of temperature, vernalisation and photoperiod. Indian Journal of Plant Physiology 36, 243249.
Rawson, H. M. & Zajac, M. (1993). Effects of higher temperatures, photoperiod and seed vernalisation on development in two spring wheats. Australian Journal of Plant Physiology 20, 211222.
Savin, R. (1993). Profundidad de enraizamiento, siembra temprana y sits efectos sobre el rendimiento de trigo sometido a sequias inverno-primaverales: Analisis de estrategias de manejo con un modelo de simulacion. MSc thesis, University of Buenos Aires.
Slafer, G. A. & Rawson, H. M. (1994). Sensitivity of wheat phasic development to major environmental factors: a reexamination of some assumptions made by physiologists and modellers. Australian Journal of Plant Physiology 21, 393426.
Slafer, G. A. & Rawson, H. M. (1995 a). Base and optimum temperatures vary with genotype and stage of development in wheat. Plant Cell & Environment 18, 671679.
Slafer, G. A. & Rawson, H. M. (1995 b). Intrinsic earliness and basic development rate assessed for their response to temperature in wheat genotypes. Euphytica 83, 175183.
Slafer, G. A. & Savin, R. (1991). Developmental base temperature in different phenological phases of wheat (Triticum aestivum). Journal of Experimental Botany 42, 10771082.
Slafer, G. A., Halloran, G. M. & Connor, D. J. (1994). Development rate in wheat as affected by duration and rate of change of photoperiod. Annals of Botany 73, 671677
Syme, J. R. (1968). Ear emergence of Australian, Mexican and European wheats in relation to time of sowing and their response to vernalization and daylength. Australian Journal of Experimental Agriculture and Animal Husbandry 8, 578581.
Takahashi, R. & Yasuda, S. (1971). Genetics of earliness and growth habit in barley. In Proceedings of the Second International Barley Genetics Symposium(Ed Nilan, R. A.) pp. 388408. Wageningen: Centre for Agricultural Publications and Documentation.
Vergara, B. S. & Chang, T. T. (1976). The flowering response of the rice plant to photoperiod. A review of the literature. International Rice Research Institute, Technical Bulletin 8.
Vongburi, K. (1992). Studies on developmental variation in wheat in relation to adaptation to the tropical environments. PhD thesis, The University of Western Australia.
Wall, P. C. & Cartwright, P. M. (1974). Effects of photoperiod, temperature and vernalization on the phenology and spikelet numbers of spring wheats. Annals of Applied Biology 76, 299309.
Wallace, D. H. (1985). Physiological genetics of plant maturity, adaptation, and yield. Plant Breeding Reviews 3, 21167.
Worland, A. J., Appendino, M. L. & Sayers, E. J. (1994). The distribution, in European winter wheats, of genes that influence ecoclimatic adaptability whilst determining photoperiodic insensitivity and plant height. Euphytica 80, 219228.
Yasuda, S. (1981). The physiology of earliness in barley. In Proceedings of the Fourth International Barley Genetics Symposium, pp. 507517. Edinburgh, UK.
Young, K. J. & Elliott, G. A. (1994). An evaluation of barley accessions for adaptation to the central growing regions of Western Australia, based on time to ear emergence. Australian Journal of Agricultural Research 45, 7592.

Related content

Powered by UNSILO

Differences in phasic development rate amongst wheat cultivars independent of responses to photoperiod and vernalization. A viewpoint of the intrinsic earliness hypothesis

  • G. A. Slafer (a1)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.