Department of plant pathology college of agriculture university of zabol-Iran.Email : mor812001@yahoo.co.in
More than 15 plant species were tested for their antifungal effects on radial growth and spore germination fusarium oxysporum f.sp cumini causing cumin wilt and fusarium equisetii causing dry rot of potato tubers and Rhizoctonia solani causing sugar beet root rot. In this experiment seed extractof Trachyspermum copticum , leaf extract of lavandula angustifolia and flower extractof Rhjeum ribes effectively inhibited the radial growth and spore germination of these fungi by using filter paper and poisoned food methods. Steams of Trachyspermum copticum and Mentha polegium extracts effectively inhibited the radial growth of pathogens.The invivo tests indicated that these extracts reduce disease incidence of cumin wilt.
Three plant products could inhibit radial growth and spore germination in studied fungi.
Key words
Antifungal effect, cold water extract, methanol extract, cumin wilt, potato dry rot.
Introduction
Using plant products in plant disease control is one aspect of applying allelopathy phenomena in plant protection.The effect of plant products on fungi has been studied in two directions, on growth of mycellium and spore germination of fungi. Plant products are safer to environment when compared to chemichal synthetic products.In this study we used some plant products to control some important plant diseases in khorasan province of Iran. including dry rot of potato tubers caused by Fusarium equisetii,sugar beet root rot caused by Rhizoctonia solani and cumin wilt caused by fusarium oxysporum.
Materials and Methods
Fresh and dried tissues of various plant species were ground along with sterile water and methanol at the rate of 1 ml per g of tissue and the macerate was placed in layer of sterile cotton wool and expressed to get the extract and then we used millipore filter to sterile the extracts.The effect of various extracts on growth of mycelium was tested by three methods, filter paper disc, poisoned food and steam of extracts.
In filter paper disc method we used 15 mm diameter filter paper discs and soaked them in methanol extract of plants then put disc at the centre of 9 cm diameter petri dishes which had PDA medium culture and then 5 mm diameter mycelial disc of the pathogen was placed at the centre of filter paper disc and put petri dishes in incubator with 25 C. The PDA medium with filter paper soaked in distilled water served as control.Three replications were maintained. The colony diameter of pathogen was measured after 24 , 48 , 72h and 96 h of incubation and inhibition percent calculated using the formula : I = 100×( C – T)/C where I=inhibition percent of pathogen growth , C = average growth in control and T= average growth in treatment.
In poisoned food method we obtained 10,15, 25, 40 and 50 percent concentration of plant extracts in potato dextrose agar medium and autoclaved in 1.5 kg/cm² pressure and 121ºC for 20 minutes.The poisoned medium was poured in sterile petri dishes and 5 mm diameter mycelial discs of pathogens was placed at the centre of petri dishes.We used distilled water instead of plant extracts in control and three replications were maintained. the colony diameter of the pathogen was measured and inhibition percent calculated as described above.
In third method we measured the effect of steam of extracts on radial growth of fungal pathogens in this method 20ml cold water extract of plants poured in sterile petri dishes and then PDA petri dishes with 5 mm diameter mycelial disc of the pathogen at the centre was inverted and placed on cold water extract Petri dishes. Then we fixed them with parafilm and incubated in 25±1°C.We used distilled water instead of plant extracts in control and three replication were maintained the colony diameter of the pathogen was measured and growth inhibition percent calculated.
The effect of plant extracts on spore germination was measured by poisoned food method, In this method we obtained 25, 40 and 50 percent concentration of plant extracts in potato dextrose agar medium and autoclaved in 1.5 kg/cm² pressure and 121°C for 20 minutes.
The poisoned medium was poured in sterile petri dishes and one drop of the spore suspension (2×10*6 spore/ml) in distilled water was placed at the centre of petri dishes and distributed over the poisoned
medium culture, we used distilled water instead of plant extracts in control and three replications were maintained the spore germination percent measured in different treatments after 20 h.The inhibition percent of extracts on spore germination was calculated.
Greenhouse assays was done for cumin wilt.At first we reproduced the pathogen on cornmeal- sand medium and then mixed 100g of inoculum with 1000g of potting soil and added the mixture to pots.In non infected control we mixed cornmeal sand medium with potting soil. Twenty cumin seeds were sown in each pot.90 ml of cold water plant extracts was added to treated pots 48h after sowing the seeds and 90 ml distilled water in controls.
Five plants in each pot were selected at random after 5 weeks. roots were cut in 5mm pieces and three pieces of root were selected for each plant.. the pieces of roots were cultured in petri dishes containing PDA medium culture and petris incubated in 25±1°C.After 4 days the infected pieces of roots was counted and disease inhibition percent was calculated.
Results
Table 1. Effect of different plant extracts (methanol extracts) on mycelial growth of Fusarium oxysporum f.sp cumini with filter paper disc method
*Mean of 3 replications
In a column means followed by same alphabet are not significantly different(P= 0.05)by duncan
Table2. Effect of different plant extracts( methanol extracts)on mycelial growth of Fusarium equiseti with filter paper disc method
TIME(h) |
Average diameter of colony(mm)* |
Inhibition percent | |||
24 |
48 |
72 |
96 | ||
Rheum ribes (Flower) |
2.50I |
3.37H |
4.60H |
4.90I |
91 |
*Mean of 3 replications
In a column means followed by same alphabet are not significantly different(P= 0.05)by duncan
Table3. Effect of different plant extracts( methanol extracts)on mycelial growth of Rhizoctonia solani with filter paper disc method
TIME(h) |
Average diameter of colony(mm)* |
Inhibition percent | |||
24 |
48 |
72 |
96 | ||
0C |
0C |
0D |
0E |
100 |
*Mean of 3 replications
In a column means followed by same alphabet are not significantly different(P= 0.05)by duncan
In Table 1 the highest inhibitory effect was found in plant extracts of Trachyspermum copticum with 100% inhibition , Rheum ribes with 97, lavandula angustifolia with 91 and Chamomilla recutita with 86, While the extract of Juglans regia had the lowest inhibitory effect on mycelial growth of cumin wilt agent by filter paper disc method.
In Table2 plant extracts of Lavandula angustifolia inhibited mycelial growth of potato tuber dry rot by 100%, Rheum ribes 91%, Eucalyptus globoulus 74% and Chamomilla recutita 72%.The plant extract of papaver somniferum had the lowest inhibitory effect.
In table 3 we can see plant extracts of Rheum ribes and Trachyspermum copticum with 100 and piper nigrum with 84 percent have the highest inhibitory effect on sugar beet root rot agent.
Consequently in filter paper disc method flower extract of Rheum ribes with 96 Trachyspermum coptimum with 80 and Lavandula angustifolia with average77 percent have the highest inhibitory effect on mycelial growth of tested fungi.
In poisoned food method for agent of cumin wilt 50 percent concentration of Trachyspermum copticum and 10 percent concentration of Rheum ribes with 96 and 8 inhibitory percent have the highest and lowest inhibitory effect on mycelial growth.
In poisoned food method for agent of potato tuber dry rot 50 and 40 percent concentration of lavandula angustifolia and 10 percent concentration of Rheum ribes with 100 and 10 inhibitory percent have the highest and lowest inhibitory effect on mycelial growth.
In poisoned food method for agent of sugar beet root rot 50, 40 and 25 percent concentration of Lavandula angustifolia and 10 percent concentration of Rheum ribes with 100 and 2 inhibitory percent have the highest and lowest inhibitory effect on mycelial growth.
Steams of mentha polegium and Trachyspermum copticum significantly inhibited the mycelial growth of tested fungi.Steams of Mentha polegium has93 and Trachyspermum copticum has 89 inhibition percent on mycelial growth of Fusarium oxysporum f.sp cumini and for Fusarium equiseti inhibition percent was 96 in Mentha polegium and 100 in Trachyspermum copticum .
In spore germination assays 40 percent concentration of Trachyspermum copticum with 100 inhibition percent and 25 percent concentration of Lavandula angustifolia with 3 inhibition percent have the highest and lowest inhibitory effect on spore germination of Fusarium oxysporum f.sp cumini and for Fusarium equiseti 40 percent concentration of Trachyspermum copticum with 100 inhibition percent and 25 percent concentration of Lavandula angustifolia without inhibition have the highest and lowest inhibitory effect on spore germination
In green house assays for cumin wilt disease Trachyspermum copticum with 60 and Rheum ribes with 15 inhibitory percent have the highest and lowest inhibitory effect on disease incidence.
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