Subirrigation vs drip-irrigation: Effects on yield and quality of soilless grown cherry tomato

This research was carried out with the aim of comparing drip-irrigation with the trough bench technique of growing a cherry tomato crop, in terms of i) pH and EC of the substrate, ii) production and quality of the fruits and iii) efficiency in the use of the water. In the latter system, pots of opaque plastic with different characteristics were also used: i) with six bottom holes for subirrigation and without risers on the bottom; ii) with four bottom holes and with 3 mm risers on the bottom; iii) with a furrow cross on the bottom and with eight holes and 3 mm risers. This last pot was also used for the drip-irrigation. With both the fertigation methods the EC of the substrate showed a similar pattern over time in the lower and middle layers (always below 3 dS m(-1)), whereas in the upper layer of the substrate it increased during the growing cycle with higher values with subirrigation compared with drip-irrigation, reaching 7.7 and 3.4 dS m-1, respectively. The pots without risers used for the subirrigation showed the highest variations and values of EC of the recirculating nutrient solution, and the pots with risers and four holes the lowest. Tomato yield was lower with subirrigation than with the traditional free drainage drip-irrigation technique, but the quality was higher (dry matter, total soluble solids, and titratable acidity). Furthermore, with subirrigation the most frequent size class of the fruits was that with a diameter between 25 and 35 mm (considered optimal for cherry tomato), while with the open cycle it was that greater than 35 mm. No significant differences emerged between the three pot types. The water efficiency of the system was greater with subirrigation than with drip-irrigation. To produce 1 kg of fruits, 411 of nutrient solution were necessary with the subirrigation (closed system) and 591 with the drip-irrigation (open system).