Green-Sprouting of Potato Seed Tubers (Solanum tuberosum L.)-Influence of Daily Light Exposure

Pre-sprouting of potato seed tubers (Solanum tuberosum L.) in light (green-sprouting) is an established practice in short growing seasons to speed up plant development. Light exposure secures short and robust sprouts for mechanical planting. In 2014-2015, different pre-sprouting treatments were investigated, including different daily durations of light exposure during 6 to 12 weeks at 10 degrees C in controlled environments. The effects on sprout growth, early growth vigour and field performance in four cultivars were assessed in the greenhouse and in the field. Results indicated that the light treatments involving 8, 16 and 24 h light exposure per day all strongly inhibited sprout growth, with only minor differences between treatments. Compared to untreated tubers, within all cultivars, emergence and early plant growth was clearly and similarly accelerated by all light treatments. At harvest, cultivars were differently affected by the pre-sprouting treatments with regard to haulm senescence (greenness), tuber DM and total yield, and the latest cultivars seemed to benefit more from green-sprouting than the earliest. Different daily durations of light exposure during green-sprouting had a largely similar impact on seed tuber performance in all cultivars. Dark-sprouted tubers (de-sprouted before planting) performed largely similar to control tubers from 4 degrees C storage. Results demonstrate a potential for shorter daily light exposure during green-sprouting with less energy use and heating problems.