M. I. Faruk
Senior Scientific Officer
Plant Pathology Division, Bangladesh Agricultural Research Institute (BARI), Gazipur-1017
M. L. Rahman
Director (Research)
BARI, Gazipur-1017, Bangladesh
Cauliflower, Seedling disease, Sclerotium rolfsii, Bio-fungicide, Trichoderma harzianum.
Seedbed of Plant Pathology Division, Bangladesh Agricultural Research Institute (BARI), Gazipur
Pest Management
Diseases, Pesticide
Three organic substrates viz. rice bran, wheat bran, grasspea bran and their combinations were mixed with or without mustard oilcake (MOC) for mass multiplication of T. harzianum against seedling disease (S. rolfsii) of cauliflower in seedbed of Plant Pathology Division, Bangladesh Agricultural Research Institute (BARI), Gazipur during three consecutive seasons from 2011 to 2014.
a) Seedbed inoculation with S. rolfsii
Isolates of S. rolfsii was grown on potato dextrose agar (PDA) medium and used as inoculum. Two hundred gram of barley grains were taken in 500 ml Erlenmeyer flask and sterilized the grains in an autoclave at 1210C for 15 minutes. The sterilized barley grains were inoculated with mycelial blocks of S. rolfsii grown on PDA and allowed to grow. The completely colonized barley grains were air dried and incorporated with the seedbed soils @100 g/m2 soil. The pathogen was allowed to establish in seedbed soil for 10 days with proper soil moisture.
b) Substrates used for T. harzianum multiplication
Seventy two isolates of T. harzianum were obtained from different location of Bangladesh and their efficacy was tested against different soil borne pathogens including S. rolfsii in the laboratory using dual culture technique. Among them T. harzianum TM7 isolate was found most vigorous to suppress S. rolfsii. Therefore, a pure culture of T. harzianum (TM7) was grown in potato dextrose agar (PDA) medium and was used as source of bio -fungicide. The substrates rice bran, wheat bran, grass pea bran and their combination with or without mustard oilcake (MOC) were used for multiplication of T. harzianu.
c) Bio-fungicide application
The experiment was laid out in the S. rolfsii sick seedbed under net-house condition using completely randomized design with four replications where the treatment (substrates) combinations were T1= Rice bran, T2= Wheat bran, T3= Grasspea bran, T4= Rice bran + Wheat bran (1:1), T5=Rice bran + Grasspea bran (1:1), T6= Rice bran + Mustard oilcake (1:1), T7= Rice bran + Wheat bran + Mustard oilcake (1:1:1), T8= Rice bran + Grasspea bran + Mustard oilcake (1:1:1), T9= Wheat bran + Grasspea bran + Mustard oilcake (1:1:1), T10= Rice bran + Wheat bran + Grass pea bran+ Mustard oilcake (1:1:1:1), T11=Seed treatment with Provax and T12= Control. According to the treatment combinations 600 g of individual or mixed substrate materials were taken separately in 1000 ml Erlenmeyer flask and were sterilized. The sterilized substrate was inoculated individually with 5 mm diameter mycelia disc of five- day old T. harzianum culture grown on PDA and then incubated at room temperature (25±2 0C) for 15 days until complete colonization. After incubation the colonized substrates were removed from the flasks, air dried and finally preserved in refrigerator at 10 0C. The inoculum of T. harzianum, colonized on different substrates, were incorporated to the previously S. rolfsii inoculated seedbed soils @ 100 g/m2 (Faruk et. al., 2014) soil and kept for 7 days maintaining proper soil moisture to establish T. harzianum in the soils. The control bed did not receive any colonized substrate of T. harzianum except the inoculum of S. rolfsii.
d) Raising of Seedling
After 7 days of T. harzianum bio-fungicide incorporation in the soil, the seeds of cauliflower variety Rupa were sown in the seedbed @ 200 seeds (split in four which consider as a replication) per treatment. The initial germination of the seeds was 99% in blotter test. The percent emergence of the seedling was calculated on the basis of initial germination status of the seeds. The experiment was laid out in completely randomized design (CRD) with four replications. Proper weeding, irrigation and intercultural operations were done. Data were collected on seedling emergence after 15 days of seed sowing. Similarly seedling mortality was recorded at an interval of 7 days starting from seedling emergence and it was continued up to 35 days of seedling age. The height and weight of shoot and also length and weight of root of cauliflower seedlings were recorded at 35 days of seedling age. The percent data were converted into arcsine transformation values before statistical analysis. Data were analyzed statistically by using the MSTATC program. The treatment effects were compared by applying the least significant different (LSD) test at P=0.05 level.
Bangladesh J. Agril. Res. 42(4): 609-620, December 2017 ISSN 0258-7122 (Print), 2408-8293 (Online)
Journal