Effects of frost during grain filling on wheat yield and grain structure

Abstract

A late frost occurred in the Southland region of New Zealand in November 1995 when many winter wheat (Triticum aestivum L.) crops were at early grain fill, and resulted in a large number of insurance claims for frost damage. In this study, frost damage was characterised. Spikes in affected crops were sharply tapered from a point half to two-thirds from their bases. Grains were as much as 80% lighter in upper parts of affected spikes. Overall yield losses as a result of frost of between 13 and 33% were calculated in affected crops. Grains were sectioned and examined with a scanning electron microscope. Whereas in healthy grains, the layers making up the pericarp and testa were compressed, in frosted grains these layers comprised loosely compressed and unstructured networks of cells. The aleurone layer was less ordered in frosted than in normal grains, and was not always readily distinguished from the starchy endosperm. Rehydration of frosted grains was accompanied by expansion of pericarp and testa cells, whereas little cell expansion occurred in normal grains. Blisters were common in frosted grains, where the outer layers were detached from the remainder of the pericarp.

Irrigation of Field Crops in the Boreal Region

“…Frost affects the biological processes of grain filling and thus the grain weight remains low, the grain is of poor quality and in some cases only empty hulls remain. Occurrence of frost has resulted in formation of shrivelled and shrunken wheat grains and in less severe cases blistering of the grain surface and thus, low grain weight during the grain filling stage (Cromey et al, 1998). Cromey et al (1998) suggested that the damage was due to death of outer tissues of grains, most damage occurring in the testa and pericarp and to some extent in the endosperm.…”

“…Occurrence of frost has resulted in formation of shrivelled and shrunken wheat grains and in less severe cases blistering of the grain surface and thus, low grain weight during the grain filling stage (Cromey et al, 1998). Cromey et al (1998) suggested that the damage was due to death of outer tissues of grains, most damage occurring in the testa and pericarp and to some extent in the endosperm. The pericarp and testa were crushed and the dead cells were in a loose arrangement in frosted grains.…”

“…However, the surviving tissues could compensate to some degree for the damage. Cromey et al (1998) concluded that the original aleurone layer could have been reformed from the outermost endosperm cells, and therefore the germination ability of the grains was maintained. When frost occurred at the early dough stage, the germination of wheat decreased from 98 % to 62 % and barley from 82 % to 40 %, and oat completely failed to germinate, but at late dough stage the germination was not affected in any of the species studied (Gusta & O'Connor, 1987).…”

“…However, no sprout damage was observed, even though the falling number decreased and maltose content increased (Dexter et al, 1985). The estimate of yield loss in small-grain cereals caused by autumn frost varied from 13 to 33 %, although it could have been even more due to loss of shrivelled grain during harvest (Cromey et al, 1998).…”

In-field methods for rapid detection of frost damage in Australian dryland wheat during the reproductive and grain-filling phase

“…Frost can cause death of anthers and embryos (Cromey et al 1998), resulting in sterility of florets and whole spikelets (Marcellos and Single 1984;Al-Issawi et al 2013), thereby impacting yield. Visible symptoms may include bleaching of awns and anthers, which become pale yellow or white and shrivelled.…”