MSc.

ABSTRACT
An investigation entitled “Evaluation of native isolates of nematode antagonistic fungi against Meloidogyne incognita (Kofoid and White) Chitwood in tomato” was carried out at Department of Nematology, College of Agriculture, Vellayani during 2017-2019. The objective was to get native isolates of nematode antagonistic fungi and evaluate its bio-control potential against Meloidogyne incognita and growth promotion.
A survey was conducted in six Taluks of Thiruvananthapuram districts during 2017-18 for isolation of indigenous fungi. Twenty soil and root samples were collected from the rhizosphere of vegetable crops like bhindi, tomato, chilly, cucumber and cowpea grown in each taluk by random sampling. Preliminary screening of 32 fungal colonies showing characteristics similar to Trichoderma (colonies with green, cottony white mycelium) and Purpureocillium (colonies powdery or suede-like, gold, green-gold, yellow-brown, lilac or tan) were selected and brought to pure culture by sub culturing technique. Thirty-two fungal isolates were subjected to preliminary screening under invitro conditions for testing its efficacy to bring about J2 mortality at standard concentration (100%). Among them ten isolates showed more than 50.00 per cent mortality of M. incognita juveniles were selected for further studies.
Morphological and cultural characteristics of ten isolates were studied. Bio efficacy study of ten isolates against J2 mortality of M. incognita revealed that three isolates at lowest concentration (25%) showed 24.25, 34.00 and 34.50 per cent mortality of M. incognita juveniles 72 hrs after exposure. Isolate 10, 12, and 27 showed 85.05, 76.50 and 62.50 per cent mortality of M. incognita juveniles at 100 per cent concentration, 72 hr after treatment.
CFEs of these three isolates were screened for ovicidal effects against M. incognita in vitro. Sterile water and plain broth were maintained as control. Results of the in vitro screening studies revealed that CFE of isolate 10 (100% concentration) was effective in inhibiting the egg hatching at three to eight days after treatment (14.00 to 23.00 per cent).
Isolate 10 at 100% concentration was effective in increasing the mortality of M. incognita juveniles at 24, 48 and 72 hr after treatment (17.93 to 85.05 per cent).
Based on ovicidal properties of CFE, three isolates were selected for pot culture experiment to find out the efficacy in comparison with Cartap hydrochloride and P. indica. The results revealed that soil drenching of isolate 10 1%(w/v) with RKN inoculation was effective in reducing the nematode population in soil (83.88 per cent) and root (75.91 per cent) and it was significantly superior to isolate 12 and isolate 27.
The lowest number of nematodes were reported by isolate 10 (76.43). Lowest number of galls were reported by the soil drenching of isolate 10 (79.48 per cent). Efficacy of isolate 10 was found to be statistically on par with Cartap hydrochloride and P. indica in reducing the number of females and it also recorded the lowest number of egg masses. Isolate 10 was significantly superior to all other treatments in improving the growth parameters like plant height (86.05), fresh shoot weight (204.88), fresh root weight (81.00) compared to control plant height (59.50), fresh shoot weight (109.25), fresh root weight (48.50) respectively. Significantly superior yield was also recorded by Isolate 10 both with and without RKN inoculation.
Morphological, Cultural and Molecular characterization of the fungal isolates were done for identification of isolates. Internal transcribed regions of DNA of ITS regions were amplified by ITS1 (5’-TCCGTAGGTGAACCTGCGG-3’) and ITS4 (5’-TCCTCCGCTTATTGATATGC-3’) regions. Blast search of amplified DNA in NCBI data revealed the identity of isolate 10, 12 and 27 as Trichoderma viride and Metarhizium anisopliae and Fusarium verticillioides respectively.
Results revealed that these three isolates suppressed population of M. incognita and increased growth and yield in tomato plants. Soil drenching of this indigenous fungal isolates 1% (w/v) can be recommended to manage M. incognita in tomato without any detrimental effect on environment.