Greinasafn: Methods for estimating ice-encasement tolerance of grasses in the laboratory

Methods for estimating ice-encasement tolerance of grasses in the laboratory


Höfundur	Útgefandi	Útgáfuár	Útgáfustaður
Bjarni E. Guðleifsson, Hólmgeir Björnsson	Rannsóknastofnun landbúnaðarins, Búnaðarfélag Íslands, Bændaskólinn á Hvanneyri, Rannsóknastöð Skógræktar ríkisins, Tilraunastöð háskólans í meinafræði, Veiðimálastofnun	1989	Reykjavík

Rit	Árgangur	Tölublað	Bls.
Búvísindi		2	99-103

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ABSTRACT

The equipment and procedures used for testing ice-encasement tolerance in grasses and winter cereals at Möðruvellir Agricultural Experiment Station, N-Iceland is described. Laboratory experiments testing ice-encasement tolerance of grasses have been used but the variability between parallels is higher than expected. Attempts to improve the procedure are described.

Key words: grasses, ice encasement, winter hardiness.

YFIRLIT

Aðferðir til mælinga á svellþoli grasa á rannsóknastofu

Tækjum og aðferðum sem notuð eru á Tilraunastöðinni á Möðruvöllum til mælinga á svellþoli grasa og vetrarkorns er lýst. Sveifla á milli endurtekninga er mikil og lýst er endurbótum sem gerðar hafa verið á aðferðinni.

INTRODUCTION

Measurement of winter hardiness of grasses has mostly been carried out in field experiments. In these experiments the tolerance to each of the damaging factors (frost, ice, fungi) are not easily separated. Field experiments are also unreliable because the damages can either be too severe or too small for screening the material. Furthermore, small topographical differences can result in unequal stress levels (Guðleifsson and Sigvaldason, 1972).

In tests carried out in controlled environments, the tolerance to each of the stress factors can be separated. These methods have been used in small scale for many plant species (Levytt, 1980). For grasses and winter cereals, tests for frost tolerance (Sjøseth, 1963; Larne, 1978; Carson, 1983) and snow mould tolerance (Blomquist and Jamalainen, 1968; Jamalainen 1974; Arsvoll, 1977) have been used for some time in breeding programs. Laboratory tests for ice-encasement tolerance have been in use in Canada for winter cereals (Andrews and Pomeroy, 1975). The same laboratory method has later been used for grasses (Andrews and Gudleifsson, 1983; Gudleifsson et al., 1986), and is currently being used at Möðruvellir Agricultural Experiment Station. Gudleifsson et al. (1986) observed considerable variation between beakers of equal treatment in excess of that expected by binomial variation alone. Björnsson (1986) emphasized the need for improved experimental procedure in order to reduce or eliminate this extra-binomial variation.

This paper presents a comparison of two methods for the testing of ice-encasement tolerance.