Effects of vernalization, photoperiod, and temperature on phenological development and spikelet number of Australian wheat

Abstract

Sixteen Australian wheat cultivars grown in controlled environment cabinets demonstrated a range of responses to seed vernalization varying from little or no promotion of floral initiation in Darkan, Kondut, Falcon, and Sunset to about 3 weeks in Festiguay, Claymore, and Mexico 120. Under short days (10 hr photoperiod v. 14 hr) or cold temperatures (12/7�C day/night v. 18/13�) the response to seed vernalization was reduced. None of the cultivars responsive to vernalization achieved floral initiation earlier under cold temperatures than under warm temperatures, even in the absence of seed vernalization. All cultivars achieved floral initiation earlier in long days but the magnitude of the response varied considerably among them. Long days similarly accelerated development from initiation to anthesis. Higher temperatures accelerated development to initiation and anthesis in all cultivars, with only minor differences in magnitude of response. Selected treatments in the cabinets gave rates of development to initiation which closely paralleled results for the same cultivars in field experiments. The number of spikelets per head varied considerably with cultivar, day length, and vernalization treatment. Within the range of conditions of the experiments, temperature did not affect spikelet number other than through vernalization. At either temperature, the spikelet number was closely and positively related to the number of days to floral initiation.

Environmental Interaction and The Genetics of Flowering

“…Blackhull) dominant late genes whose delaying action is wholly suppressed by Ppd I and par tially suppressed by Ppd2.] Photoperiod seems to influence flower initiation more strongly than floral development (59), but the degree of development of the basal spikelets in the ears of sensitive cultivars like Thatcher is influenced by the photoperiod during the early stages of growth-SD result in rather rudimentary development (146). The development of the fl orets at the basal end of the spikelets is under both major gene and polygenic control, and in the base sterile wheats the zone of fl oral competence is shifted distally on the spikelet axis by a period of SD at above normal temperatures given around the time fl ower initiation is taking place (47, 48).…”

Allocation patterns and phenology in wild and selected accessions of annual and perennial Physaria (Lesquerella, Brassicaceae)

“…The increase in seed yield achieved in annual crops has been associated with the reallocation of photoassimilates (i.e. improved harvest index ;Evans 1993;Slafer 1994), and early anthesis (Halse and Weir 1970;Austin et al 1980). Both characters are linked to reduced allocation of assimilates to competing sinks, especially roots and leaves (Donald and Hamblin 1976).…”

Temperature as a component of the expression of developmental responses in wheat

“…The nature and extent of this interaction over different temperatures in the growth range, as it influences time of flowering, is not clearly understood . Temperature and photoperiod also exhibit interaction in determining the rate of reproductive development in wheat (HALSE & WEIR, 1970 ;MARCELLOS & SINGLE, 1971 ;WALL & CARTWRIGHT, 1974;HALLORAN & PENNELL, 1982) . It is often difficult in field studies to separate the influences of photoperiod from temperature on growth rate and development because of the usually strong correlation between the length of photoperiod and daily levels of solar radiation .…”