Abstract
Fungicides – commonly used in plant disease control – are expensive; not only economically but environmentally too. It is one of the major sources of environment deterioration and evolution of new resistant strains. As an alternate, inducing the plants immune system at the early stage of plant growth with weak shocks of abiotic stress aiming disease resistance can be a novel approach, which is economical as well as eco-friendly. Tomato (Srijana hybrid) was used as model plant and to protect them from powdery mildew (Oidium spp. and Leveillula spp.), immune system, at an early seedling stage, was induced through application of drought and herbicide (glyphosate) stress. After 25 days of induction of abiotic stress, plants were inoculated with two doses of fungus: 104 conidia per ml, 106 conidia per ml for low and high dose respectively and the disease response was studied by using Area Under Disease Progression Curve (AUDPC) up to 27 days post inoculation (dpi). Hydrogen peroxide released by plants was quantified 20 days after abiotic stress induction (before the inoculation of powdery mildew fungus) and total phenolic content (TPC) at 7 days post inoculation (dpi).
Both drought and herbicide treated plants showed elevated levels of hydrogen peroxide compared to that of control. Drought stressed plants also showed enhanced levels of phenolic compounds and less area under the AUDPC – and higher biomass compared to that of the control plants showing increased resistance to the fungus. This refers to the induction of phenolic compounds synthesis by drought and the anti-fungal effect of the phenolic compounds to enhance the resistance of the plants.
