AbstractTo contribute to the development of a novel cropping system for potato grown from greenhouse-derived seedlings from hybrid true potato seeds, planting density trials were carried out under normal Dutch agronomic conditions. For two consecutive years, 5-week-old seedlings of two experimental genotypes were transplanted into farmers’ potato production fields at two contrasting locations: a flat-bed system on sandy soil and a traditional ridge system on clay soil. Planting densities were 6.25, 12.5, 25, 50, 100 and 200 plants/m2 in the flat-bed system, and 3.125, 4.688, 6.25, 12.5, 25 and 50 plants/m2 in the ridge system. In general, increasing planting density of hybrid seedlings per area decreased tuber fresh weight per plant and reduced the number of tubers per plant. On a per hectare basis, an increased planting density resulted in increased total tuber yield and number of tubers up to very high densities, but finally both parameters levelled off. Highest total tuber yields harvested were 107 and 45 Mg/ha for the flat-bed and ridge system, respectively. On flat-beds, the optimal planting density for total yield was 50 plants/m2. On ridges, planting density interacted with year and genotype, resulting in an optimum planting density of 25 plants/m2 to reach the maximum total yield. Obtained yields in the commercial size classes Baby Baker (20 < size class ≤ 35 mm) and Seed Tubers (28 < size class ≤ 50 mm) were in general very high on the flat-beds, with a maximum Seed Tuber yield of 64 Mg/ha at 50 plants/m2. The current study showed that transplanted hybrid seedlings are feasible alternatives for seed-tuber-grown systems for certain potato outlets.
On the enigmatic birth of the Pacific Plate within the Panthalassa Ocean