ISHS Acta Horticulturae 779: International Symposium on Growing Media
REUSED ORGANIC SUBSTRATES FOR LETTUCE CULTIVATION |
| Authors: | A.J. Stepowska, J.S. Nowak |
| Keywords: | growing media, straw, reusing, greenhouse, leafy vegetables |
| Abstract:
This study reports the growth of lettuce in reused straw-based-substrates. Butterhead lettuce was cultivated on organic substrates in a greenhouse directly after a cucumber crop (summer cycle) and after a previous lettuce crop (autumn cycle). The following substrates were tested: coarse chaff of cereal straw (1 cm pieces), fine chaff (0.5 cm pieces), fine chaff with aged pine bark mixed 2:1 and 1:2, fine chaff with pine saw-dust 2:1. The substrates were pressurized in the form of slabs 100 x 20 x 10 cm and covered with plastic film. The physical properties of substrates were measured before and after the cucumber crop, and chemical analysis after cucumber and both lettuce cycle. The velocity of head growth, its marketable quality and nitrate accumulation in leaves were evaluated. The lettuce heads quality and nitrate accumulation was affected by the physical properties of substrates and macroelements uptake. Fresh slabs had a high porosity (>92%) and low water retention (ca. 30% by –10 cm H2O). After the cucumber crop, the water retention was progressed. Due to the good air-water condition in mixed substrates the velocity of lettuce growth was better than in coarse and fine chaff. In consequence the appearance of heads was superior, although no significant differences between average head weights and nitrate accumulation on chaff or its mixture with pine bark were noted. The results from both lettuce cultivation cycles were comparable. | |
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