New Zealand Journal of Crop and Horticultural Science abstracts
Effects of frost during grain filling on wheat yield and grain structure
M. G. CROMEY
D. S. C. WRIGHT
H. J. BODDINGTON
New Zealand Institute for Crop & Food
Research Limited
Private Bag 4704
Christchurch, New Zealand
email: cromeym@crop.cri.nz
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.
Keywords wheat; Triticum aestivum; frost; scanning
electron microscopy; anatomy; yield; spike; grain
H98015
Received 2 March 1998; accepted 13 July 1998
PDF file of entire paper: medium quality (3450K); (scanned from paper original: notes about this process)
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