Root-knot nematodes (Meloidogyne spp.) are significant pests that cause considerable damage to crops, prompting a need for sustainable control methods. This study evaluated the nematicidal potential of fungal culture filtrates and botanicals as eco-friendly alternatives. In vitro tests demonstrated that Lemongrass oil (LG) (0.2%) achieved the highest mortality of nematode juveniles (J2s) at 99.44% within 48 h, while Pochonia chlamydosporia (Pc) (2%) and Purpuricillium lilacinum (Pl) (2%) reduced egg hatching rates to 9.57% and 11.43%, respectively. Neem oil (NM) (0.2%) was the most effective in preventing J2 root penetration (4.42%). In vivo, a combination treatment (T7) of NM (0.2%), Trichoderma harzianum (Tz) (2%), Pl (2%), and LG (0.2%) applied at 10 day intervals significantly reduced the nematode reproduction factor to 0.035, comparable to the chemical control Bayer Velum Prime (R) (Fluopyram 34.48% W/W SC) (0.031). T5 (NM and Tz) resulted in the highest shoot biomass (236.73 +/- 1.38 g), while Bayer Velum Prime (R) (Fluopyram 34.48% W/W SC) increased root biomass (31.75 +/- 1.24 g). Additionally, T7 produced the longest shoots (63.37 +/- 0.74 cm) and roots (36.80 +/- 0.3 cm), with fewer root galls (55.67 +/- 1.53) and egg masses (4 +/- 0.01). T7 also minimized the final soil nematode population to 106.33 +/- 1.01 per 100 g, closely followed by T8 (94.67 +/- 0.89). These results indicate that combining NM, Tz, Pl and LG provide effective nematode control without phytotoxic effects, enhancing plant growth and offering a promising sustainable alternative to chemical nematicides.

Root knot nematode (RKN), Meloidogyne incognita, , is considered a major soil-borne pathogen that can cause severe yield losses for vegetables and diverse crops. Usually, reducing of M. incognita damage is mainly relies on the application of nematicides and good agricultural practices. However, the use of synthetic nematicides is restricted due to concerns about their impact on the environment and human health. As a result, the use of alternative strategies is becoming necessary to combat RKN resistance. This study evaluates the antagonistic impact of the root mutualistic fungus Piriformospora indica on M. incognita. . It also assesses its influence on the nutritional status, photo-synthesis, antioxidant enzyme activity, endogenous abscisic acid (ABA) levels, and selected ABA related-responsive genes in cucumber plants. Roots of cucumber seedlings were inoculated with P. indica and the second-stage juveniles (1000 J2 per plant). The results demonstrated that P. indica significantly reduced M. incognita invasion in roots, resulting in a 24% reduction in root galling and 42.6% decline in final population. Inoculating plants with both P. indica and RKN increased performance of root fresh and dry weight, as well as improved photochemical efficiency of PSII (Fv/Fm), photosystem II efficiency (PSII), catalase (CAT), peroxidase (POD), and superoxide dis-mutase (SOD). Furthermore, P. indica colonization, either alone or in combination with M. incognita, , significantly improved number of fruits per plant, average fruit weight, the plant's marketable yield, and leaf nutrient content (N, P, K and Mg), Moreover, there was an increase in IAA content combined with a decrease in ABA content in roots of dual inoculation plants, if compared to M. incognita infested plants. The highest ABA content was recorded in the root of RKN-cucumber plants. The decline in ABA content due to P. indica treatment was consistent with the modulation of ABA pathway genes, specifically PP2C, PYL1, RK2,1, and RK2,2. The mixed of P. indica and M. incognita led to a decrease in the expression of PP2C, PLY1, RK2,1, and RK2,2 in comparison to the control group. These results indicate that P. indica application could help reduce the negative effects of RKN on important crops.