Trichoderma-Enriched Vermicompost Extracts Reduces Nematode Biotic Stress in Tomato and Bell Pepper Crops

Keiji Jindo,Tiago dos Santos Pereira,Sabrina Magaly Navas Cajamarca,Luis Henrique Ferrari,Jadir Borges Pinheiro,Daniel Basílio Zandonadi,Juscimar da Silva,Mirella Pupo Santos,Alessandra Monteiro de Paula,Jader Galba Busato

doi:10.3390/agronomy11081655

Abstract

Root-knot nematode (RKN) is a serious threat to crops worldwide due to the difficulty in controlling it and the limited eco-friendly alternatives to deal with the biotic stress it causes. In the present work, water-extractable fractions obtained from vermicompost (WSFv), vermicompost enriched with Trichoderma asperellum (WSFta) and T. virens (WSFtv) were tested as biotechnological tools to reduce the impacts of RKN on gas exchange, water use efficiency (WUE) and nutrient concentration in tomato and bell pepper plants. The plants were infected with 5000 eggs and eventual J2 of RKN and then treated with the water-extractable fractions for seven weeks. It was observed that the addition of WSFta, WSFtv and WSFv increased the CO2 assimilation, stomatal conductance and WUE in the tomato plants. In the bell pepper plants, WSFta, WSFtv, WSFv increased the stomatal conductance, while WUE was higher in the treatment with WSFtv. In fact, the parameters associated with the gas exchange were usually higher in the bell pepper than in the tomato plants. Overall, higher contents of N, Mg, B and Mn were detected when the extracts were applied in both bell pepper and tomato plants. The application of the water-extractable fractions, inoculated or not with Trichoderma, attenuates the RKN damage on the gas exchange parameters and successfully enhanced the nutrient concentration in the infected tomato and bell pepper plants, showing that it could be an important and promising tool for reducing the damage caused by this pathogen. We suggest that both the tomato and pepper plants can cope with the dilemma between growth and stress response via stomata regulation that are modulated by the WSF and Trichoderma.

Highlights

Root-knot nematodes (RKN) (e.g., Meloidogyne incognita) are endoparasites that invade the roots of the plant in the zone of elongation and migrate to the vascular cylinder, where they exhibit the formation of galls, which deform the vascular tissue [2,3]
We have recently shown that Watersoluble fraction (WSF) enriched with Trichoderma boosts the yield of tomato and bell pepper plants infected with RKN [29]
This study examined the potential physiological mechanisms related to the stress alleviation of M. incognita in infected tomato and bell pepper plants using WSF extracted from vermicompost of cow manure (WSFv), vermicompost enriched with Trichoderma asperellum (WSFta) or with

Summary

Introduction

Reduction in the photosynthesis rates in tomato plants might occur only two days after RKN infestation [6] and, since the nutrient concentration is a process related to the water flow and dependent of the energy from the photosynthesis, RKN can affect the nutrition of the plant [8] According to these authors, infected tomato plants reduced their phosphorus uptake, while infected chickpea and mung bean plans showed decreased levels of nitrogen, phosphorus and potassium [9]. Certain strategies such as covering crops, soil flooding and solarization have been used to overcome the adverse effects of RKN [10,11], but these strategies are insufficient. Products such as methyl bromide are efficient in controlling RKN [12], but their negative impact on both the environment and on human health have led many countries to ban bromide pesticides [13]

Methods

Results

Discussion

Conclusion