Abstract
Two experiments were conducted to evaluate the dynamics of nutrient uptake by strawberry plants grown under field conditions and the root nitrogen (N) uptake, storage and remobilisation by soilless grown plants. Uptake and partitioning of nutrients were determined by successive destructive plant harvest and mineral analysis of plant organs of two field grown varieties (‘Idea’ and ‘Marmolada’). Plants were destructively harvested at different developing stages and divided into roots, crowns, leaves, flower stalks, fruits. In an additional trial, the same approach was applied to two sets of plants either not fertilised or receiving (in kg ha−1) 55 N, 10 phosphorus (P), 108 potassium (K) and 22 magnesium (Mg). In both cultivars the growth rate increased after blossom until end of fruit ripening, and nutrient uptake rate was lower in autumn than in spring. For K no net uptake was observed between mid autumn and the dormant period. Potassium was the nutrient absorbed in spring at the highest rates followed by N, calcium (Ca), Mg and P. Calculated on hectare basis, total plant removal by fertilised plants ranged between 78 and 91 kg N, 12 and 17 kg P, 92 and 125 kg K, 58 and 91 kg Ca, 19 and 23 kg Mg. Mineral partitioning among plant organs varied with nutrients: Ca was mainly recovered in leaves, magnesium was almost equally partitioned between leaves and fruit while N, P and K were especially found in fruits. The roots and the crowns accounted for only small proportion of total plant nutrients at the end of fruiting season. Root N uptake in autumn, winter storage, remobilisation of N reserves and spring N uptake were studied applying 15N technique to potted strawberry plants of cv. Onda grown under greenhouse conditions. Nitrogen at high and low levels was supplied as unlabelled calcium nitrate in autumn. Plants were transferred in February into new pots filled with sterile sand. In spring both sets of plants were supplied with labelled Ca(15NO3)2. High N supply in autumn significantly increased biomass and N content in plant organs, but did not affect fruit yields and quality. In spring, N was remobilised from roots and crowns to sustain growth. Remobilisation of N to new growth was completed by blooming, and around 40% of stored N was translocated to new growth. Plant partitioned to fruits a significant fraction of absorbed N, especially during the fruit ripening stage.