Salinity tolerant Trichoderma harzianum reinforces NaCl tolerance and reduces population dynamics of Fusarium oxysporum f.sp. ciceri in chickpea (Cicer arietinum L.) under salt stress conditions

Abstract

The antagonistic potential of salinity tolerant (ST) Trichoderma (Th) isolates against Fusarium oxysporum f.sp. ciceri (foc) was tested, along with their capability to induce relative salt stress tolerance in chickpea with the aim to exploit their use as biological agents in reducing deleterious effects of salinity and controlling Fusarium wilt of chickpea under saline soil conditions. Under laboratory conditions, salt stress was created by supplementing nutrient medium with different concentrations of NaCl viz. 0, 70, 150 and 240 mM NaCl and a pot experiment was conducted using natural saline soil (EC – 6.6 dS m−1). Out of 45 Th isolates studied, only five isolates viz. Th-13, Th-14, Th-19, Th-33 and Th-50 were selected to be ST as these were able to grow and sporulate in growth medium containing up to 240 mM NaCl. In saline medium, ST isolates greatly surpassed salinity sensitive (SS) isolate with respect to growth rate, mycelial dry weight, sporulation and biological proficiency against foc. Out of five ST isolates that retained their tolerance to different salt stress levels, Th-14 and Th-19 showed maximum antagonism against foc. Under greenhouse conditions, chickpea plants obtained from seeds bioprimed with Th-14 and Th-19 performed well both at germination and seedling stage in comparison to control in saline soil. As compared to untreated plants, characterisation of Th treated plants confirmed that they had reinforced contents of proline along with relatively higher levels of total phenols, membrane stability index and superoxide dismutase activity while lower accumulation of hydrogen peroxide and malondealdehyde contents. ST isolates, Th-14 and Th-19 significantly reduced foc-induced wilt disease incidence in chickpea plants. The population density of both the Th isolates in rhizosphere far exceeded that of foc under both saline and non-saline soils. However, Th-14 was found more efficient in increasing relative salt stress tolerance in chickpea and reducing the foc growth in rhizosphere under present materials and conditions. These findings provide a novel paradigm for developing alternative, environmentally safe strategy to alleviate salt stress and manage fungal diseases such as foc that aggravates under saline soils.