46 7790-R. SOMU-Agro.Pmd

N 12(1): 457-462, 2017 (Supplement on Agronomy) Save Nature to Survive www.thebioscan.com GROWTH CHARACTERISTICS OF DIFFERENT ISOLATES, NITROGEN SOURCES AND EFFICACY OF BIOLOGICAL AGENT ON FUSARIUM OXYSPORUM F. SP. CUBENSE CAUSING PANAMA WILT IN BANANA R. SOMU*1 AND N. THAMMAIAH2 1College of Horticulture, UHS, Bagalkot-587104, Karnataka, INDIA 2Department of Horticultural Plant Pathology, K. R. C. College of Horticulture, Arabhavi - 591 307 Gokak , Belgaum, Karnataka, INDIA e-mail:[email protected] KEYWORDS ABSTRACT Panama wilt Fourteen different isolates of Fusarium oxysporum f. sp. cubense studied in vitro to know there growth and media morphological characteristics on Richard’s medium and Asthana and Hawkers medium.Among fourteen different morphology isolates grown in Richard’s agar, Maddur (Kowdle) and Mysore (Konnur) isolates produced maximum growth of 90.00mm and good sporulation (>75conidia per microscopic field) with pinkish to purple colour colony Nitrogen growth and maximum macro and micro conidial spore size of 33.4x3.8 and 13.1x3.3µm respectively.In Asthana and Hawkers medium Channapatna (Abbur)and Bangalore (Hessaraghatta)isolates showed best growth of 90.00 Received on : and 87.67 mm respectively with good sporulation and isolates produced whitish to purple colour mycelium and maximum macro and micro conidial spore size of 30.3x3.7 and 12.3x3.0µm respectively. Among the different 26.03.2016 nitrogen sources tested in Richard’s medium, ammonium nitrate was better utilized by Bangalore and Mysore Accepted on : isolates, sodium nitrate was better utilized by Channapatna isolate, the mean dry weight of mycelium was 351.77, 356.03 and 435.47 mg respectively. In Czapek’s medium all the three isolates of Bangalore, Channapatna, 14.01.2017 and Mysore produced maximum growth in sodium nitrate the mean dry weight of mycelium was 439.07, 436.50 and 452.13 mg respectively. Seven biological agents were tested against FOC, among them Trichoderma viride *Corresponding (NBAIT), Trichoderma viride-27 and Trichoderma harzianmum-55 showed maximum Per cent inhibition of author 70.42, 76.60 and 65.25 respectively over the control. INTRODUCTION prerequisite for implementing biological control using microbial antagonists (Lumsden and Lewis, 1989). Hence there Panama wilt caused by Fusarium oxysporum f. sp. cubense is a need to know about the variability produced by different (FOC) is the major constraint to banana production and the isolates on different media and nitrogen sources, at a same disease has been ranked as No.1 fungal disease of banana in time to obtain effective bio agent against FOC. India. In southern India, incidence of Panama wilt is The objective of the study is to screen the different isolates of widespread in some districts the disease incidence is as high FOC on different media to know the variability among the as 80-90% (Sivamani, 1987). isolates for their growth and morphological characteristics Every living being requires food for its growth and and also to evaluate different isolates for best nitrogen source. reproduction; fungi are not exception to it.Fungi secure food from the substrate upon which they live in.In order to culture the fungus in the laboratory, it is necessary to furnish the MATERIALS AND METHODS essential elements and compounds in the medium, for their growth and other life processes. All media are not equally An experiment was carried out during 2011-12 at Department good for all fungi, nor there is a universal substrate or artificial of Plant Pathology K. R. C. College of Horticulture, Arabhavi medium, upon which all fungi can grow (Lilly and Barnett, to know growth and morphological characters among different 1951). Various culture media showed differential effects on isolates of FOC,best nitrogen source for FOC and different the growth and cultural characteristics of different fungal bioagents were evaluated to find out which bioagent is effective against FOC. The experiment was designed in Complete pathogen on various host plants (Singh and Kaiser, 1994). In Randomized Design (CRD). the same way different isolates of same species show difference in their growth and morphological characters when they grow Growth characteristics of different isolates of Fusarium on same medium or different medium.Nitrogen is an important oxysporum f. sp. cubense element for protein synthesis and like carbon it is used by Fourteen different isolates were studied on two media fungi for functional as well as structural purpose. Developing viz.,Richard’s agar and Asthana and Hawker’s medium.All appropriate formulation and delivery systems is the the media were sterilized at 1.1 kg cm-2 pressure for 15 min.To 457 R. SOMU*1 AND N. THAMMAIAH carry out the study, 30 ml of each of this medium was poured agents and test fungus were cultured on potato dextrose agar into 90 mm diameter pertidishes.After solidification 5 mm discs in orderto get fresh and active growth of fungus. of Fusarium oxysporum.f. sp. cubense were prepared and a The 5 mm of fungal disc of the antagonist along with test single disc was placed at the center of the plate.Each set was fungus were kept on the potato dextrose agar medium in replicated thrice and plates were incubated at opposite direction.The plates were incubated for a week.The 26±1ºC.Observations were recorded with respect to mycelial observation on interaction zone or inhibition zone was colour, substrate colour, margin of the colony, topography, measured.The growth of antagonistic fungus and growth of centre of the colony, colony size, sporulation and spore size. pathogen were also recorded separately.The bacterial The data on radial growth was analyzed statistically.(Khan et antagonist viz.,Bacillus subtilis,Pseudomonas fluorescens and al., 2011). Pseudomonas virideflava were streaked on side of the potato Effect of nitrogen source on growth of Fusarium oxysporum dextrose agar medium and on other side Fusarium oxysporum f. sp. cubense f. sp. cubense disc was placed.The inhibition zone was This experiment was conducted to find out the sources of measured.After the period of incubation, the growth of the nitrogen, which is used most efficiently by the fungus for its Fusarium oxysporum f.sp. cubense colony was recorded and growth.Several nitrogen sources were tried by incorporating the per cent inhibition of the colony over control was them in Richard’s and Czapek’s broth for different isolates calculated. (Thangavelu et al.,2004) viz., Bangalore, Channapatna and Mysore. The quantity of each nitrogen compound to be added was determined on the RESULTS AND DISCUSSION basis of their molecular weight, so as to provide equivalent amount of nitrogen as was of potassium nitrate present in the In the present study, the growth characteristics of different basal medium.The nitrogen compounds used were isolates and sporulation of the pathogen were studied on Ammonium chloride, Ammonium nitrate, Asparagine, Richard’s agar, Asthana and Hawker’s medium and results Potassium nitrate, Sodium nitrate, Ammonium sulphate and are presented in Table 1-4.Seven nitrogen sources on the Ammonium orthophosphate.30 ml of each media were growth of three different isolates of FOC were studied by poured into 100 ml flasks plugged with nonabsorbent cotton incorporating in to Richard’s broth and Czapek’s broth.The and autoclaved at 1.1 kg/cm2 pressure for 15 min.Each of the data on dry weight of mycelium was noted after nine days of treatment was replicated thrice. All the flasks were aseptically incubation. The results are furnished in Table 5 and 6. Bio- inoculated with 5 mm of prepared suspension of 10 days old agents were evaluated against FOC data on per cent inhibition culture of Fusarium oxysporum. f. sp. cubense.Inoculated flasks over control was recorded and presented in table 7. were incubated at 26±1ºC for nine days. The mycelia were Growth characteristics of different isolates of Fusarium harvested and dried to a constant weight.Results were analyzed oxysporum f. sp. cubense statistically.(Ramteke and Kamble, 2011). Richard’s agar medium Evaluation of bio-agents against Fusarium oxysporum f. sp. The Maddur (Kowdle) isolate produced maximum growth of cubense 90.00 mm on Richard’s agar at 8th day of inoculation followed Seven biocontrol agents such as Trichoderma harzianum-55, by Mysore (Konnur) (90.00 mm), Mysore (Thandavapura) Trichoderma viride-27, Trichoderma viride (NBAIT), (84.00 mm), Channapatna (Tagachagere) (84.00 mm), Trichoderma viride(Local), Pseudomonas fluorescens, Channapatna (Chikkanahalli) (84.00 mm), Channapatna Pseudomonas virideflava and Bacillus subtilis were tested (Abbur) (83.33 mm), Bangalore (Mathikere) (83.33 mm), against Fusarium oxysporum f. sp. cubense. Both biocontrol Bangalore (Hessaraghatta) (82.67 mm), Mysore Table 1: Studies on Radial growth of different isolates of Fusarium oxysporum f. sp. cubense on Richards’s media Isolate Colony diameter (mm) 2nd day 4th day 6th day 7th day 8th day Bangalore (Hessaraghatta) 23.33 43.00 61.00 72.33 82.67 Bangalore (Mathikere) 25.00 44.67 64.00 74.33 83.33 Bangalore (Shivakote) 22.33 42.00 62.00 72.67 82.33 Channapatna (Abbur) 25.33 43.00 64.00 74.67 83.33 Channapatna (Chikkanahalli) 24.33 42.33 62.67 73.67 84.00 Channapatna (Tagachagere) 23.67 42.67 63.33 73.67 84.00 Maddur (Koppa) 21.67 42.00 61.33 72.00 81.33 Maddur (Kowdle) 26.67 51.00 70.67 80.33 90.00 Mandya (Kotigere) 21.67 41.67 59.00 68.33 77.67 Mandya (Bukanakere) 24.00 43.67 61.67 71.00 81.00 Mysore (Nanjanagudu) 23.00 41.67 62.33 72.00 81.33 Mysore (Devarasanahalli) 20.67 41.33 61.00 71.67 82.67 Mysore (Konnur) 27.67 54.00 72.67 83.00 90.00 Mysore (Thandavapura) 24.33 43.67 62.33 72.67 84.00 S.Em ± 0.67 1.07 0.97 0.82 0.85 CD @ 1% 2.61 4.16 3.80 3.21 3.34 458 GROWTH CHARACTERISTICS Table 2 : Morphological characters of different isolates of Fusarium oxysporum f.

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