Effect of Fertigation Management and the Composition of Nutrient Solution on the Yield and Quality of High Soluble Solid Content Tomatoes

The present experiment was conducted to clarify the effects of different fertigation systems (drip or sub fertigation) in combination with 2 formulae of nutrient solution (modified Enshi formulation or Shizudai tomato formulation) at EC 4 dS·m−1 on the response of “High soluble solid content tomato” grown in soilless culture systems from September, 2005 to February, 2006. The growth, total yield and size of fruit decreased in the sub fertigation system regardless of the nutrient solution formulation. On the other hand, the soluble solid content was higher in the sub fertigation system. Sub fertigation inhibited water uptake compared to drip fertigation. EC of the medium solution was higher in the sub than drip fertigation system, and higher with the Shizudai than the Enshi formulation. The highest and lowest EC values were 29.6 and 16.1 dS·m−1 in Sub × Shizudai and Drip × Enshi treatment, respectively. The matric potential of medium in the sub fertigation system was higher than that in the drip fertigation system. The proline concentration of leaves taken on November 17 and December 2 was higher in the sub than the drip fertigation system regardless of the nutrient solution formulation. Judging from the above results, growth and yield suppression in the sub fertigation system seems to be mainly caused by salinity stress, not by water stress.