Prediction of ear emergence in winter wheats grown at Temora, New South Wales

Abstract

This study examined factors that determine ear emergence in winter wheats grown at Temora, New South Wales. Three development factors were considered: degree of winter habit, response to photoperiod, and intrinsic earliness.

The effect of winter habit was first examined by using 3 pairs of related wheats that differed for spring–winter habit. Wheats were sown under irrigation from mid February to June, for up to 4 consecutive years. Ear emergence was recorded in days of the year for ease of field interpretation, and in photo-thermal time to measure delay in development. Winter habit was found to delay ear emergence throughout this sowing range. Ear emergence was then studied in 23 winter wheats that as a group encompassed a broad range for each of the 3 development factors, and these winter wheats were grouped on the basis of combinations of development factors. Differences in ear emergence between these groups guided the construction and testing of regression equations that described ear emergence as a function of sowing date and of the 3 development factors. Many combinations of factors were associated with the time of ear emergence (i.e. 1 October) at Temora that best optimises the balance between frost risk and yield potential. Combinations of development factors also influenced the flexibility of sowing time for winter wheats grown at Temora. These findings may assist the breeding of new winter wheats that can be sown over a longer period than current winter cultivars.