GROWTH AND YIELD OF TOMATO GROWN ON REUSED ROCKWOOL SLABS

Abstract

Rockwool is the most used substrate for soilless culture in Croatia. Multiple use would greatly contribute to the waste management of the rockwool slabs. The aim of the research was to determine the influence of rockwool slab age on tomato plant growth and marketable yield. In the trial reported, new, one and two year old slabs were used. Different age of rockwool slabs did not significantly affect plant height and leaf number. The harvest periods in 2005 and 2006 lasted 171 and 168 days respectively. For early yield, defined as yield during first 10 days of harvest, total yield and fruit weight were determined. In 2005 early yield achieved on new rockwool slabs (0.99 kg plant-1) was 10.4 % lower, and total yield (12.95 kg plant-1) 6.8 % higher than on one year old slabs. During 2006 the highest early yield (1.76 kg plant-1) obtained on two year old rockwool slabs was 6.4 % higher than on one year old slabs, and 10.1 % higher than on new slabs. The highest marketable yield (12.86 kg plant-1), significantly higher than the yield on two year old slabs (11.09 kg plant-1), was obtained on new rockwool slabs. Throughout the harvest period fruit weight varied from 183 to 186 g during 2005 and between 161 to 164 g in 2006. Because new and one year old slabs achieved statistically identical values of researched parameters, but lower values during the third year of use, biennial use of rockwool slabs could be recommended.