Frost trends and their estimated impact on yield in the Australian wheatbelt.

Bangyou Zheng,Troy M Frederiks,Jack T Christopher,Scott C Chapman,Karine Chenu

doi:10.1093/jxb/erv163

Abstract

Radiant spring frosts occurring during reproductive developmental stages can result in catastrophic yield loss for wheat producers. To better understand the spatial and temporal variability of frost, the occurrence and impact of frost events on rain-fed wheat production was estimated across the Australian wheatbelt for 1957-2013 using a 0.05 ° gridded weather data set. Simulated yield outcomes at 60 key locations were compared with those for virtual genotypes with different levels of frost tolerance. Over the last six decades, more frost events, later last frost day, and a significant increase in frost impact on yield were found in certain regions of the Australian wheatbelt, in particular in the South-East and West. Increasing trends in frost-related yield losses were simulated in regions where no significant trend of frost occurrence was observed, due to higher mean temperatures accelerating crop development and causing sensitive post-heading stages to occur earlier, during the frost risk period. Simulations indicated that with frost-tolerant lines the mean national yield could be improved by up to 20% through (i) reduced frost damage (~10% improvement) and (ii) the ability to use earlier sowing dates (adding a further 10% improvement). In the simulations, genotypes with an improved frost tolerance to temperatures 1 °C lower than the current 0 °C reference provided substantial benefit in most cropping regions, while greater tolerance (to 3 °C lower temperatures) brought further benefits in the East. The results indicate that breeding for improved reproductive frost tolerance should remain a priority for the Australian wheat industry, despite warming climates.

Highlights

Post-head-emergence frosts (PHEF) are catastrophic in wheat, with a single frost event having the potential to devastate individual crops by damaging stems and killing whole heads (Frederiks et al, 2012)
To investigate the potential yield benefits of improved frost tolerance, including associated benefits related to earlier sowing dates, 60 sites were selected across the Australian wheatbelt (Fig. 1), each representing a similar average annual area planted to wheat as described by Chenu et al (2013)
Frost can occur in most parts of the Australian wheatbelt at times which potentially correspond to the post-heading stage in wheat, for example August–September (Fig. 2a)

Summary

Introduction

Post-head-emergence frosts (PHEF) are catastrophic in wheat, with a single frost event having the potential to devastate individual crops by damaging stems and killing whole heads (Frederiks et al, 2012). Regional PHEF yield penalties of 10% commonly occur, but losses in excess of 85% have been observed in certain seasons in the USA and Australia (Paulsen and Heyne, 1983; Boer et al, 1993). The fragile reproductive structures are partially protected from frost by the flag leaf sheath, which reduces damage and subsequent yield losses (Fuller et al, 2007). Sensitivity to frost increases sharply after the awns or spikes start to emerge from the auricle of the flag leaf (Livingston and Swinbank, 1950; Single, 1964; Afanasev, 1966; Paulsen and Heyne, 1983). Where frost risk is high, management of crop phenology is necessary to avoid post-heading frosts and maintain an acceptable frost risk (Frederiks et al, 2004)

Objectives

Methods

Results

Discussion

Conclusion