Methods for estimating ice-encasement tolerance of grasses in the laboratory
|Bjarni E. Guleifsson, Hˇlmgeir Bj÷rnsson||Rannsˇknastofnun landb˙naarins, B˙naarfÚlag ═slands, BŠndaskˇlinn ß Hvanneyri, Rannsˇknast÷ SkˇgrŠktar rÝkisins, Tilraunast÷ hßskˇlans Ý meinafrŠi, Veiimßlastofnun||1989||ReykjavÝk|
Frß vefstjˇra: Greinina Ý heild sinni er a finna Ý pdf-skjalinu hÚr a ofan
The equipment and procedures used for testing ice-encasement tolerance in grasses and winter cereals at M÷ruvellir 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.
Aferir til mŠlinga ß svell■oli grasa ß rannsˇknastofu
TŠkjum og aferum sem notu eru ß Tilraunast÷inni ß M÷ruv÷llum til mŠlinga ß svell■oli grasa og vetrarkorns er lřst. Sveifla ß milli endurtekninga er mikil og lřst er endurbˇtum sem gerar hafa veri ß aferinni.
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 (Guleifsson 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 (Sj°seth, 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 M÷ruvellir Agricultural Experiment Station. Gudleifsson et al. (1986) observed considerable variation between beakers of equal treatment in excess of that expected by binomial variation alone. Bj÷rnsson (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.