Influence of growing conditions at different latitudes of Europe on strawberry growth performance, yield and quality

The site effect of five locations from north (Stjordal, Norway, 63 degrees 36 ' N) to south (Ancona, Italy, 43 degrees 31 ' N) was evaluated in strawberry regarding yield performance, fruit quality, length of fruit developing time from anthesis to harvest start and length of the harvest season. Cv. Elsanta was grown at all sites while cv. Korona was cultivated in north and central Europe and cv. Clery in central and south Europe. Yield was more affected by seasonal and growing conditions than by latitude. Anthesis was delayed as influenced by cultivar up to 58 days from south to north and was nearly maintained until harvest start. Duration of fruit development was negatively related to daily mean temperature and increased with higher latitude. 29-34 days were required from anthesis to harvest start for cv. Elsanta, 29-36 for cv. Korona and 27-38 for cv. Clery. Corresponding GDD values (growing degree days; 3 degrees C base temperature) were independent from latitude and accounted to 334-355 for cv. Elsanta, 301-385 for cv. Korona and 320-434 for cv. Clery. Daily mean temperature decreased about 2 degrees C from south to north during anthesis to harvest start which induced a calculated 5.2 days longer fruit development period in the north. From harvest start to harvest end, GDD values varied for all cultivars between 297-402 GDD showing no influence of the latitude. However, simple summing of GDD values do not correctly describe the time of fruit development (from anthesis to the ripe fruit) for the whole fruiting period of a plant. GDDs for individually tagged flowers increased notably from the first third to the last third of the developing period due to increasing temperature as the season proceeded. The fruit quality standards dry matter, soluble solids and titratable acidity were influenced by latitude giving northern sites in general the highest values. Fruits grown at the southern sites were redder compared to those of the north.