Abstract:
Seven Australian wheat varieties were compared with six Mexican and four European spring wheats for the influence of sowing date on time to ear emergence in the field. Their sensitivities to daylength and vernalization were compared in a glasshouse experiment. The Australian varieties were intermediate in their response to daylength. Those suited to early autumn sowing depended on their vernalization sensitivity to delay ear emergence past the frost-liable period in the spring. The European varieties, with no vernalization response, were also suited to early sowing, the delay of ear emergence depending entirely on their high sensitivity to daylength. The Mexican varieties, with nil or small vernalization response and a low sensitivity to daylength developed too rapidly for early sowing, but were more suited to late sowing than the Australian varieties.