R. Acuña, I. Gil, S. Bonachela, J.J. Magán
Even well-aerated substrate crops may suffer oxygen deficiency as the result of factors, such as high root respiration rates, high crop water demands and high substrate temperatures. Several methods of nutrient solution oxygen-enrichment have been used to improve oxygen supply to the roots in hydroponic and substrate crops. The injection of pure, pressurized oxygen gas to the nutrient solution above saturation levels, known as oxyfertigation, has been commercially adapted for use in horticultural greenhouses on the Spanish Mediterranean coast. This work analyses the behaviour of a melon crop (Cucumis melo L.), one of the main greenhouse spring crops on the Almería coast, grown in rockwool slabs (open system) in a typical "Parral" type greenhouse under two oxygen treatments: one with an oxygen-enriched nutrient solution (T+) and one without (T-). The oxygen was supplied with an oxyfertigation facility. Crop management was the same for both oxygen treatments and no differences were found between them in the irrigation and fertigation parameters evaluated: volume, electrical conductivity and pH of applied and drainage nutrient solutions. The dissolved oxygen concentration ([O2]) in the nutrient solution was higher for the T+ than for the T- treatment throughout the whole crop cycle (average seasonal values of 20.1 and 4.2 mg L-1, respectively). However, the [O2] in the nutrient solution extracted from rockwool slabs was similar for both treatments, although slightly higher for the T+ treatment during mid-cycle when the fruit number was set. In both treatments, the [O2] in the substrate solution was below 3 mg L-1 during mid and final cycle, especially for the T- treatment. No significant differences were found between oxygen treatments for the final aerial biomass and its partitioning, although the biomass was slightly higher for the T+ treatment. However, the final yield of marketable and first category fruits was significantly higher for the oxygen-enriched treatment (P<0.05), which was associated to a higher marketable fruit number. Mean values of final marketable production were 6.1 and 5.7 kg m-2 for the T+ and T- treatments, respectively.
Acuña, R., Gil, I., Bonachela, S. and Magán, J.J. (2008). OXYFERTIGATION OF A GREENHOUSE MELON CROP GROWN IN ROCKWOOL SLABS IN A MEDITERRANEAN AREA. Acta Hortic. 779, 447-454
DOI: 10.17660/ActaHortic.2008.779.56
Cucumis melo, fruit yield, oxygen deficiency, oxygen-enrichment, soilless culture, substrate

Acta Horticulturae