The world's northernmost commercial production of potato, vegetables and berries i located above the Arctic Circle in Troms and Finnmark county in Norway. Sowing in spring occurs here under snow clad mountains, and harvest in autumn is done under snowy mountains again. The unique light and temperature of the Arctic affects all plant growth in the far north. Due to Midnight sun and the warm Norwegian Ocean Current it is still possible to harvest crops here. In a short and hectic growth season, extra effort is required to produce potato, vegetables and berries before autumn frosts. New climate-improving methods have been introduced in recent years. Such as, non-vowen fiber cover or plast tunnel covering the plants. These measures enable the plants to better utilize the exceptionally good light conditions of midnight sun in spring, when the temperature normally is too low for plant growth. This leads to high growth rates, and sometimes growth related injuries. Swede root bulbs may crack, and stem growth may be too long in both potato and strawberry. Resulting in lodging or stem fractures. Fractures in strawberry also impairs the taste of the normally very sweet northern Norwegian berries. Crop losses due these type of injuries, reduces the income for northern growers/farmers. In addition, we know that fiber cover filters away about 1/3 of the sun light for photosynthesis. This may not be a limiting factor under midnight sun, although there may be exceptions to this in late summer. The project ARCTIC LIGHT therefore seeks to better understand how plants respond to the interaction between Arctic light conditions and temperature. ARCTIC LIGHT also want to see how fertilize management together with new climate enhancing practices: of fibre cover or plastic tunnels, can contribute to less crop injuries at the higher growth rates. The project ARCTIC LIGHT, will also develop new growth models, which accounts for also the amount of solar radiation together with temperature (heliothermal models). This in order to provide a tool for managing fertilizer amount and times of application of fertilizer.
Field experiments have been performed in the growth season of 2020 and 2021 with potato and Swede vegetable in Målselv, and in plastic tunnels with strawberry in Holt, Tromsø and Apelsvoll, Hedmark. In addition, climate controlled growth chamber experiments have been performed for these in the phytotron at Holt, with temperature and light as experimental factors. Gulløye and Mandel have been tested with different fertilization and with/without non-vowen fibre in fields at two farms both years. A similar experiment was done with swede in 2020 and different durations of fibre cover and fertilization at two farms, and planting small plants was tested against sowing seeds in 2021. In addition, insect nets were also tested at two locations in 2021. Experiments with strawberry cultivars were done in plastic tunnels at both Tromsø and Hedmark, for comparison of northern versus southern growth conditions in both years, and in 2021 a fertilization experiment was done to study influence on floral stem length. In all fields, soil and leaves were analyzed, together with collection of yield and crop quality data at harvest, as well as climatic data for light conditions/solar radiation, temperature, precipitation.
The results from the experiments indicate that both light and temperature affects elongation growth, development rates, yields and crop quality in strawberry and potato. Some types of cleft injuries in swede roots can also be related to fertilization and growth rate, but there was no significant difference in fertilization levels on inner or outer cracking. Experiments with strawberry in table-top systems in plastic tunnel and in phytotron show a clear relation between low temperature and problems with increased floral stem length, and phytotron experiments indicate some interaction with liqht-quality/colour for stem length. Fertilization did not influence stem length. Different strawberry cultivars differ greatly in production capacity under short and cold growth season in the north. Field experiment with potato, had increasing yields with higher fertilization levels, but the sweet spot for crop quality is in between the standard 7kg and 13 kg N per da. In controlled experiments, Gulløya has a higher development rate than Mandel, but Mandel again has a lower base temperature at 3 centigrades. Swede has a higher temperature optimum in vegetative phase, and a lower optimum below 17 degrees for root swelling. Gulløye?s photosynthetic light response in phytotron show a higher minimum light requirement for normal development and yield at low growth temperature compared to optimum temperature conditions. The string of results in the project has been presented throughout the project-period to growers for all cultivars at 'markdager' through the season and seminars/meetings for growers
Grøntsektoren i Nord-Norge opplever en oppsving i interesse og produksjon. Tromspotet AS har etablert seg som en ledende bedrift for omsetting av potet, kålrot og Målselvnepe. Når myndighetene åpnet opp for import av produksjonsklare jordbærplanter i 2015 gav dette nye muligheter også for bærproduksjon i den nordlige landsdelen. Dyrkning i av planter i nord med lave temperaturer og unike lysforhold kan gi en rekke positive produktkvaliteter. Med en vekstsesong som temperaturvis er i marginal ende for fullmodne produkter, er klimaforbedrende tiltak (lysgroing, fiberduk og plasttuneller) helt nødvendig for en stabil produksjon. Disse tiltakene i kombinasjon med de arktiske lysforhold med 24 t daglengde og fotosyntese ¾ av døgnet, gir en høyintensiv vekst i den korte sesongen. Per i dag erfarer flere produsenter at det oppstår utfordringer. Tidligere etablerte standarder for normgjødsling (uten klimaforbedring) i Nord-Norge gir dermed ikke fullt utnyttet avlingspotensiale i dagens produksjoner, og redusert konkurransekraft for nordnorsk grøntproduksjoner. ARKTISKLYS søker derfor å utvikle nye gjødselnormer og agrometeorologiske modeller som er spesielt tilpasset grøntproduksjoner under de unike lysforholdene nord for Polarsirkelen.
