Differences in root morphological features and shoot P accumulation at different soil P levels

The morphology and architecture of roots affect plant nutrient uptake. The objective of this study was to investigate how soil initial phosphorus (P) fertility level (Fair P 6.2 mg l-1 soil, Good P 17.5 mg l-1 soil) and annual P application (20 kg ha-1) affected root morphology, P content of silage grass and concomitantly its nutritive value. Soil P levels were created in a 40-year fertilisation experiment (1973-2013). In a field trial (Kotkaniemi experimental farm) shoot and root samples were taken at the beginning of the growing season of 2018, at the time of the 1st and 3rd harvests and twice after 1st and 3rd harvests. Roots were washed, photographed and root area, mean root length, and diameter were analysed with ImageJ program. Root and shoot nutrient contents were analysed with ICP-OES. P application increased root area during the 1st harvest but it decreased at 3rd harvest. Soil fertility P and P fertilisation had a positive effect on root dry weight. Root area was negatively correlated with increasing shoot P content, which indicates that increase in root area compensated P uptake when less P was available. However, increased P foraging capacity was insufficient to elevate grass P content to an adequate level.Peer reviewe