YIELDING AND CHEMICAL COMPOSITION OF GREENHOUSE TOMATO FRUIT GROWN ON STRAW OR ROCKWOOL SUBSTRATE

Studies were conducted with tomato of Admiro F-1 cultivar grown in glasshouse in the years 2008-2009. Four substrates were applied: 1) triticale straw, 2) triticale straw + high peat (3:1 v:v), 3) triticale straw + pine bark (3:1 v:v), 4) rockwool (100 x 20 x 7.5 cm = 15 dm(3)). Straw, cut into pieces, (2-3 cm) was put in plastic boxes (height of the box ca. twice its width) with the capacity of 15 liters. In each box/slab two plants grew. Experiments were conducted with the use of complete randomization method, in seven repetitions. Drop fertigation was applied in a closed system, without nutrient solution recirculation. In the period of high temperatures the daily nutrient solution consumption equaled 4.2 dm(3) on a one-off basis in 10-12 doses with about 20% overflow. In the conducted studies full usefulness of triticale straw was demonstrated as the substrate for tomato grown in glasshouse. Higher yield was obtained from growing in the substrate of triticale straw+ pine bark, as well as triticale straw + peat compared to rockwool, and these differences were not statistically significant. The highest dry matter content was found in the fruit grown in straw substrates, the least - in those from rockwool substrates. No significant differences were demonstrated in the contents of N, P, K, Ca and Mg in fruit with reference to the examined substrates. After 33 weeks of vegetation (end of the studies) about 70% of the straw was mineralized.