Effect of growing strawberries with superimposed levels of cropgutters on yield and quality

Abstract

This experiment was carried out to assess the effect of increasing plant density by superimposing immovable levels of cropgutters. The greenhouse glazing was an air-inflated double layer of F-CLEAN®, a specific version of ethylene tetrafluoroethylene. The inside layer was diffused F-CLEAN®, in order to reduce the direct shading of the lower gutters by the upper levels. In this multi-span greenhouse were arranged, each in an 8-m wide span: a) the traditional single-level crop of 7 cropping lines, density 8.75 plants m -2 ; b) two levels of five cropping lines each (12.5 plants m -2 ); c) three levels of five cropping lines each (18.75 plants m -2 ). In the two- and three-level system, the immovable cropgutters were vertically aligned: all the cropping operations could be done from the ground or using mobile platforms to adjust the working height to the upper levels. Two early cultivars, ‘Gariguette’ and ‘Ciflorette’, were grown as a soilless heated crop with trayplants planted on 14 December 2015. PAR light at the top of the canopy was reduced on the lower and the intermediate levels of the two- and three-level disposition; the highest reduction was measured on the lowest level of the three-level disposition. The changes observed in the content of total soluble solids (% Brix) and titratable acidity due to shading remained acceptable. Yield per plant was significantly reduced on the lower and intermediate levels of the three-level disposition, but not on the lower level of the two-level disposition, nor on the upper levels of both dispositions. However, with two and three levels, the higher density per square meter led to a higher yield per square meter, compared to the traditional single-level crop: +40% (two-level system) and +82% (three-level system) for ‘Gariguette’, +48% and +86% for ‘Ciflorette’.