Growth Response of a Plant Pathogenic Fungus To Potent Chemical And Herbal Defence Activators

In the present investigation an attempt has been made to study the in vitro growth response of a plant pathogenic oomycete fungus Pythium aphanidermatum to various chemical and herbal defence activators. Four plant defence activators viz. Salicylic acid (SA), Benzothiadiazole (BTH), p Aminobutyric (BABA) acid and Jasmonic acid (JA) were tested. SA, BTH, BABA and JA significantly inhibited mycelial growth at 0.5 mM concentration. Complete inhibition was observed at 0.5 mM SA. JA also inhibited growth at high concentration (0.5 mM) but stimulated at low dose (0.005 mM). BABA was least inhibitory for P. aphanidermatum. The inhibitory action of the chemical activators was found to decrease at lower concentration. Apart from chemical activators leaf extracts of Acalypha indica (ALE), Spinacea oleracea (SLE) and Centella asiatica (CLE) were also tested in this study. The herbal activators were found to stimulate the growth in vitro at higher concentration (5%). Results showed that the chemical and herbal activators can trigger defence mechanism in plants through the action of host metabolism.