Cucumber culture on wood fiber substrate amended with Greenchar^®

Many studies have focused on the effects of biochar as a soil amendment. In many cases, its application has been reported to increase the water holding capacity, the porosity, the root growth, the microbial activity and production yields. Yet, few studies took an interest in the effects of biochar addition to a soilless culture substrate, and among these, none are available about culture on wood fiber. A two-year study was led in our experimental greenhouse and at a cucumber producer in the Pays de la Loire region (France), using Florentaise Hortipains^® (wood fiber Hortifiber^® in culture bag) and Pine bark Greenchar^® (Pyro6^® technology, Florentaise). Several proportions of Greenchar^® were incorporated to Hortipain^® and tested by comparison with a control without Greenchar^®. The culture was hydroponic, with two plants of cucumber per bag, and lasted 2 to 5 months per crop. Root development was faster in the bags with Greenchar^® rather than in the control, especially during the first crop. An effect on the number of fruits was observed in 2016, with an increase up to 17%, while a lesser effect was shown in 2017 on the number of fruits but on the biomass produced. A low-quality irrigation water was used in 2016 and the role of Greenchar^® as a filter may explain the first increase observed. Greenchar^® can reduce the fungal colonization by parasitic fungi, and increased the rate of secondary metabolites in the cucumber leaves, which can potentially improve the plant resistance toward abiotic stress.