ISHS Acta Horticulturae 98: Symposium on Research on Recirculating Water Culture
COMMERCIAL NFT-LETTUCE GROWING IN HOLLAND |
| Author: | J.T.W. Fransen |
| Abstract:
At the trial nursery of Priva B.V. in Holland the first experiments with lettuce in NFT started on 24 October, 1978. The area of the first trial was 130 m2 and the varieties used were Ravel, No. 83 and Plus. The lettuce was planted in grey PVC gullies 8 cm wide, 4 cm high and 2.95 m long so that two rows of gullies could be placed in a 6.40 m bay. The gullies were supported 70 cm above ground level. Trials were done with steel gullies of different widths (6 to 15 cm) covered with white plastic. The white plastic improved the growth rate and the most suitable width of the gully turned out to be 8 cm. Gullies of polystyrene, chosen for their white colour and low price, were unsuitable because the roots penetrated the polystyrene. In February we extended the area to 1,750 m2 of which 400 m2 was used for young plants. The intention was to propagate the lettuce on aluminium benches in a flowing solution and to place the young plants at double the final planting density for about the first third of the growing period. In this way there was a space-saving of 15%. On the third of February we planted 950 m2 with Pallas which was harvested on the second of April and 800 m2 with Cristallo (a crisp lettuce) which was harvested on the 18th of April. From April on we used the butterhead lettuce Salina all through the spring and summer with 20–25 plants m-2. For crisp lettuce we used the varieties Fortessa, Marmer, Alora, Minetto and Ithaca of which Marmer gave the best results (planting date 20.2, harvesting date 18.4). The other varieties tended to get tipburn and, secondarily, Botrytis. During the months of May - August the time between planting and harvesting was 4–5 weeks with a weight of 19–23 kilograms per 100 heads. | |
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