Extent and importance of ice-encasement damages on gramineous plants in the Nordic countries
|Bjarni E. Guleifsson||B˙naarfÚlag ═slands, BŠndaskˇlinn ß Hvanneyri, Rannsˇknastofnun landb˙naarins, 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
Perennial crops are cultivated on 3-4 million hectares in the Nordic countries. These are subject to different types of winter stress and subsequent winter damages. Ice and water damages are not easily separated, but grasses can survive much longer low temperature flooding than ice encasement at subzero temperatures. Many external factors as treatment of grasses, fertilizing practice, soil type, topography and climate affect the extent of ice and water damages. Ice and water damages are most common in northern coastal areas. The annual economical losses by winter damages in the Nordic countries have been estimated to 900 million Nkk. and at least 30% of this can be ascribed to ice and water damages.
Key words: grasses, ice encasement (damages), winter cereals, winter damages.
┌tbreisla og mikilvŠgi svellkals ß gr÷sum og vetrarkorni ß Norurl÷ndum
TvÝ- og fj÷lŠrar jurtir eru rŠktaar ß 3-4 milljˇnum hektara ß Norurl÷ndum. ŮŠr vera fyrir margvÝslegu ßlagi yfir veturinn sem getur leitt til kalskemmda. Svellkal og k÷fnun er erfitt a agreina, en gr÷s geta lifa miklu lengur Ý vatni vi lßgan hita en Ý svelli undir frostmarki. Margir ytri ■Šttir hafa ßhrif ß ˙tbreislu kalskemmda, svo sem meh÷ndlun grasanna, ßburarnotkun, jarvegsger, landslag og loftslag. Svellkal er algengast ß norlŠgum strandsvŠum. Fjßrhagslegt tap af v÷ldum kalskemmda hefur ß Norurl÷ndum veri meti um 900 milljˇnir norskra krˇna ßrlega og a.m.k. 30% af ■vÝ mß rekja til svellkals.
In southern areas with long summer and mild winter, open fields with annual crops are dominating in agriculture. In northern latitudes on the other hand lays or permanent hayfields are more common and the use of winter cereals has been increasing. In 1985 the area used for winter annual and perennial crops was as shown in table 1.
In Denmark the area used for winter cereals and hayfields is almost equal, in the other countries hayfields are the most common.
The long and cold winter in northern latitudes results in great winter stress on wintering plants. These are therefore subject to different types of winter damages which are directly or indirectly related to low temperature and can weaken the plants or kill them completely and in both cases reduce the yield. The winter damages are often grouped with reference to the causes of the damages as follows: freezing injury, ice and water injury, frost heaving injury and biotic injuries caused by low-temperature fungi. These types of damages sometimes appear in combinations, plants weakened by one type of injury (i.e. ice) can subsequently be killed by another type (i.e. frost).