Effect of Storage and Pre-sprouting Regimes on Seed Potato Performance in Norway

Physiological quality affects vigour and yield potential of potato seed tubers. Under short-season conditions, a seed tuber should preferably produce a short cycle and mature crop. The aim of the current studies was to assess how various storing and pre-sprouting treatments affect growth vigour and yield formation. Results showed that different low-temperature storage regimes before pre-sprouting treatments had no clear effects although some minor differences between treatments occurred. For pre-sprouted (‘green’-sprouted) seed tubers, results from field trials in southern Norway (2007–2008) showed that emergence of cvs Asterix and Saturna improved significantly compared to unsprouted seed. Total yields increased significantly for both cultivars in 1 out of 2?years. For Saturna, a major increase in number of tubers per plant resulted in larger proportions of smaller-size grades and thus lower marketable yields. In other trials (northern Norway, 2006–2007), varying duration of pre-sprouting did not affect growth vigour and yield. For number of tubers and size grades, the results varied significantly between pre-sprouting durations, but differently among trials, so no clear conclusions can be drawn. In one of the two trials, increased duration of pre-sprouting resulted in higher proportions of the smaller sizes at the expense of large tubers. Different levels of temperature sums during pre-sprouting (ca. 200 or 400?day-degrees >4?°C) did not affect seed performance. In conclusion, our studies showed that pre-sprouting may improve growth vigour and increase the proportion of smaller grade sizes.