Exploiting the potential of Trichoderma species against root rot in selected cotton germplasm

Root rot causing fungi result in more severe yield losses than the loss caused by any other pathogen. This study is designed to investigate the role of fungi in root rot of cotton and its management through the use of Trichoderma species (T. harzianum and T. viride). The crop was sampled during mid to late-season during a survey of different districts of South Punjab in order to optimize the detection of fungi in the roots and rhizosphere of crop. Disease incidence and prevalence were recorded and maximum disease incidence (7.8%) was recorded in Dakota and Tibba Sultan Pur a district of Multan. Soil and root sampling and extraction procedures were used to determine the fungi present. Identification of fungi was made and the fungus Rhizoctonia bataticola was most prevalent in all the regions. Live cultures of fungi were developed for use in subsequent screening and pathogenicity experiments. Pot trials were conducted for screening and application of biocontrol agents. Hypodermic needle inoculation method of the pathogen and biocontrol agents was followed in both experiments. 15 cotton germplasm including both Bt and non Bt namely Bt VH-148, FH-142, NIAB-820, AA-703, NS-121, FH-159, MNH-886, CIM-602, FH-182, KZ-191, BH-95, FH-901, VH-28, BH-121 and MS-39 were collected from Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad. According to disease rating scale severity was assessed and NIAB-820 (1.5) was found resistant and KZ-191 (8.33) was found highly susceptible to root rot. Eight treatments were used for biological control of root rot includingT1 = R. bataticola + cotton, T2= T. harzianum + R. bataticola + cotton, T3= T. viride + R. bataticola + cotton, T4= T. harzianum + T. viride + R. bataticola + cotton, T5= T. harzianum + T. viride + cotton, T6= T. harzianum + cotton, T7= T. viride + cotton, T8= Healthy control (cotton). Combination of T. harzianum and T. viride was most effective in controlling the disease with severity of 1.33 and 1 after 15 and 30 days of inoculation respectively. Growth parameters like plant weight, root weight, no of leaves were also recorded. Highest plant weight, no of leaves and root weight was recorded in T1 (healthy control) and T6 (T. harzianum + cotton) and the lowest in treatment containing the pathogen alone. Treatment containing T. harzianum promoted the growth of plants. In dual culture plate technique T. harzianum inhibited the growth of R. bataticola with 62.55% inhibition.