Harnessing biochar for sustainable management of root-knot nematode (Meloidogyne javanica) in cucumber cultivation

Abstract

Root-knot nematodes represent a significant challenge to the cucumber crop, causing extensive yield and economic losses. As chemical nematicides and pesticides face increasing restrictions, the development of sustainable management practices is urgently needed. This study evaluates forestry waste wood biochar for its potential to control root-knot nematodes and enhance cucumber yield at different concentrations: 1.5 %, 2.5 %, 3.5 %, and 4.5 % biochar using a combination of morphological, biochemical, physiological, and microscopic techniques. Treatments were applied under greenhouse conditions, and comprehensive assessments were conducted to determine plant health and nematode suppression. The results indicate that 3.5 % biochar application significantly increased the plant's growth, yield, and photosynthetic performance relative to the untreated uninoculated control. However, higher biochar levels (>3.5 %) had a negative impact on cucumber growth and yield. Biotic stress caused by Meloidogyne javanica was significantly mitigated by 3.5 % biochar, reducing ROS accumulation. Moreover, the 3.5 % biochar application enhanced antioxidant defense enzymes SOD (superoxide dismutase), POX (peroxidase), and CAT (catalase) to combat nematode-induced biotic stress. Biochar also upregulated proline content and promoted the activities of nitrate reductase and carbonic anhydrase, which were impaired due to nematode stress. Furthermore, the significant reduction of nematode reproduction factor, egg masses, and root galling demonstrated biochar as an eco-friendly root-knot nematode control agent.