Sharp frost also occurs in the higher districts, which are usually blanketed with snow during the first months of the year.
It also survives in areas where severe annual frosts occur.
The first frosts of the year usually occur in April, but are not particularly severe.
There, in the central part where most species come from, frost occasionally occurs.
During the winter, snowfall is common, and frosts occur on most mornings.
Temperatures are cool even during the growing season and frost can occur 12 months of the year.
If frost does occur, the results can be disastrous for production.
Scientists said they hoped a natural frost would occur and confirm the laboratory results.
The first frost occurs on average in mid November.
When frost does occur it is usually of short duration and not of great severity.