Abstract
Pot experiments were carried out to compare (1) the suitability of different substrates, and (2) crop yields achieved by direct sowing into different sized pots (7, 8, 9 or 10 cm diameter). Since watercress in its natural habitat grows in slowly flowing water, one experiment was set up in a basin with water dammed to a depth of 3 cm flowing through the basin. During cultivation, a liquid fertilizer was applied as required. In another experiment, the pots were placed in a flowing fertilizer solution dammed to a depth of 2 cm. The harvested crop was assessed for FW, plant length and degree of branching. The highest FW was recorded in plants grown in a substrate mixture of TKS 1 (poorly decomposed peat) + Humosoil (poorly + well decomposed peat); plants in this substrate were well branched and compact. The FW of direct-sown plants increased with pot size, but plants grown in large pots produced thicker stems and had higher nitrate levels than plants grown in smaller pots, and their quality was therefore poorer.