engleski

Autumn lettuce production on rockwool slabs

A trial was carried out to determine the possibility of re-using of rockwool slabs after tomato production. Since a short cycle was required, we considered lettuce as the second crop. In trial, seedlings of four iceberg lettuce cultivars were planted on rockwool slabs in September. Plants were fertigated with a standard nutrient solution and positioned at 0.25 m on the slab, with slabs placed 1.2 m apart. Every 10 days during the lettuce growing period vegetative growth and dry matter production were monitored. At harvest (47 Days After Transplanting, DAT), total head weight, diameter, height and marketable yield were determined. A positive correlation was observed between number of leaves and head weight (from 0.6583 to 0.8397), whereas correlations between head weight and dry matter content (from -0.574 to -0.9622) were negative. The highest total head weight (241 g) and marketable weight (222 g) was achieved by cv. Triathlon. Marketable yield of the other cultivars was reduced by 13.5 to 32.4 %. Diameter of marketable head varied from 18.9 to 23.5 cm depending upon cultivar. Cultivar Triathlon had the highest heads (20.4 cm) while other cultivars had statistically lower heads (from 17.2 to 18.2 cm). The experiment also show the possibility to grow lettuce without heating during autumn season in continental part of Croatia. Regardless to low yield achieved (from 495 to 733 g m-2) lettuce cultivation in unheated greenhouses showed to require a prolonged growing period.

Lactuca sativa L.; soilless culture; rockwool; yield

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