Low-temperature damage to wheat in head - matching perceptions with reality.

Abstract

Wheat grown in eastern Australia can suffer severe frost damage during radiation frosts at ear emergence. Few studies have attempted to understand the characteristics of freezing and frost damage to wheat during late developmental stages. While the cultivars used in this region have adequate frost tolerance during their vegetative development, this is not maintained during ear emergence. It is perceived that this lack of head resistance is genetically controlled and that germplasm may be available for specific radiation frost resistance. Recent work has shown, however, that cold tolerance cannot be up-regulated at these developmental stages and that conventional screening of germplasm has little chance of producing field resistant material. However, wheat in head can tolerate a limited amount of freezing without damage and furthermore can supercool substantially in both controlled environments and in the field. The present chapter demonstrates the evidence for these findings and suggests new approaches for screening for resistance in an attempt to make headway in this recalcitrant phenomenon.