<p>Wilt caused by <italic>Ralstonia solanacearum</italic> is considered as an important disease of chilli which cause economic loss up to 40–50% during flowering stage of the crop. The present study was undertaken to explore the usefulness of two VAM fungi <italic>viz., Glomus fasciculatum</italic> and <italic>Gigaspora</italic> sp. in reducing bacterial wilt incidence in chilli and their role in enhancements of plant growth characters. The VAMF strains were isolated locally following wet sieving and decanting method (<xref ref-type="bibr" rid="bib002">Khan, 1999</xref>) and the pathogen was isolated from diseased chilli plants in triphenyl tetrazolium chloride medium. At the time of transplanting of 28 days old chilli (cv. Pusa Jwala) seedlings, VAM fungi were inoculated into the soil of earthen pots @ 500 spores/kg of soil. After 15 days of transplanting the chilli seedlings were inoculated with 24 hrs old cells of <italic>R. solanacearum</italic>(1 x 10<sup>9</sup> cfu/ml) in a R.B.D. with six treatments and five replications.</p><p>Observations were recorded on disease incidence after 45 days of inoculation with <italic>R. solanacearum</italic> and bacterial populations were estimated by sampling rhizosphere soil at 15 days interval following inoculation of <italic>R. solanacearum</italic>. The important plant growth parameters were recorded to evaluate the beneficial effect of VAMF in crop rhizosphere. The plants were harvested after 90 days of inoculation with VAMF to estimate % root colonization with the mycorrhizal fungi. The effect of <italic>Glomus fasciculatum</italic> was significantly better over <italic>Gigaspora</italic> sp. Mycorrhizal plants with <italic>G. fasciculatum</italic>+<italic>R. solanacearum</italic> showed significantly better increase in leaf number (120.8), shoot fresh weight (50.0 g), shoot nitrogen (2.5% dry matter), shoot phosphorus (0.5% dry matter) over non-mycorrhizal and <italic>Gigaspora</italic> sp. +<italic>R. solanacearum</italic> inoculated plants (<xref ref-type="table" rid="tab001">Table 1</xref>). The % of VAM fungi colonization was significantly higher for <italic>G. fasciculatum</italic>(64%) as compared to <italic>Gigaspora</italic> sp. (43%) (<xref ref-type="table" rid="tab001">Table 1</xref>). Similar results were recorded by Borah and Phukan (<xref ref-type="bibr" rid="bib001">2003</xref>) on brinjal. The mycorrhizal plants with <italic>G. fasciculatum</italic> was more effective in disease suppression and showed significantly better wilt incidence (40%) as compared to <italic>Gigaspora</italic> sp. (60%). <table-wrap id="tab001"><label>Table 1</label><caption><p>Effect of VAM fungi on growth parameters, dry matter content and root colonization of chilli plants</p></caption><table><thead><tr><th rowspan="5" align="center">Treatments</th><th colspan="3" align="center">Growth parameters</th><th colspan="2" align="center">Dry matter content (%)</th><th rowspan="5" align="center">VAM fungi colonization</th><th colspan="3" align="center"><italic>R. solanacearum</italic> (cfu/g dry soil)</th><th rowspan="5" align="center">Wilt incidence</th></tr><tr><th colspan="3" align="center"><hr /></th><th colspan="2" align="center"><hr /></th><th colspan="3" align="center"><hr /></th></tr><tr><th rowspan="3" align="center">Leaf No.</th><th rowspan="3" align="center">Shoot fresh (g)</th><th rowspan="3" align="center">Root fresh (g)</th><th rowspan="3" align="center">N</th><th rowspan="3" align="center">P</th><th colspan="3" align="center">Days after inoculation</th></tr><tr><th colspan="3" align="center"><hr /></th></tr><tr><th align="center">5</th><th align="center">20</th><th align="center">35</th></tr></thead><tbody><tr><td colspan="11"><hr /></td></tr><tr><td align="left"><italic>Gigaspora</italic> sp.</td><td align="center">113.6</td><td align="center">65.0</td><td align="center">18.0</td><td align="center">2.4</td><td align="center">0.3</td><td align="center">43(41.0)</td><td align="center">–</td><td align="center">–</td><td align="center">–</td><td align="center">–</td></tr><tr><td align="left"><italic>Glomus fasciculatum</italic></td><td align="center">145.6</td><td align="center">98.0</td><td align="center">40.0</td><td align="center">2.6</td><td align="center">0.5</td><td align="center">64(33.2)</td><td align="center">–</td><td align="center">–</td><td align="center">–</td><td align="center">–</td></tr><tr><td align="left"><italic>R. solanacearum + <italic>Gigaspora</italic> sp</italic>.</td><td align="center">110.2</td><td align="center">40.0</td><td align="center">10.0</td><td align="center">2.3</td><td align="center">0.3</td><td align="center">35(36.2)</td><td align="center">129</td><td align="center">95</td><td align="center">75</td><td align="center">60(50.8)</td></tr><tr><td align="left"><italic>R. solanacearum</italic>+ <italic>G. fasciculatum</italic></td><td align="center">120.8</td><td align="center">50.0</td><td align="center">10.3</td><td align="center">2.5</td><td align="center">0.4</td><td align="center">46(42.7)</td><td align="center">110</td><td align="center">70</td><td align="center">53</td><td align="center">40(39.2)</td></tr><tr><td align="left"><italic>R. solanacearum</italic></td><td align="center">0.0</td><td align="center">0.0</td><td align="center">0.0</td><td align="center">0.0</td><td align="center">0.0</td><td align="center">0(1.8)</td><td align="center">162</td><td align="center">185</td><td align="center">114</td><td align="center">100(90.0)</td></tr><tr><td align="left">Control</td><td align="center">89.2</td><td align="center">37.0</td><td align="center">9.0</td><td align="center">2.1</td><td align="center">0.3</td><td align="center">0(1.8)</td><td /><td /><td /><td /></tr><tr><td align="left">CD (P = 0.05)</td><td align="center">12.6</td><td align="center">4.71</td><td align="center">2.3</td><td align="center">0.2</td><td align="center">0.02</td><td align="center">1.5</td><td align="center">14.9</td><td align="center">27.6</td><td align="center">16.6</td><td align="center">2.5</td></tr></tbody><tfoot><tr><td colspan="11"><hr /></td></tr><tr><td colspan="11" align="left">Figures in the parentheses represent angular transformed values.</td></tr></tfoot></table></table-wrap></p><p>The number of <italic>R. solanacearum</italic> population (cfu/g soil) in rhizosphere soil of mycorrhizal plants decreased in <italic>G. fasciculatum</italic> inoculated plants than <italic>Gigaspora</italic> sp. inoculation. The enhancement of plant height and leaf number, increase in fresh and dry weight of roots and shoots of chilli plants due to enhanced nutrient uptake and synthesis of photosynthesis in the VAMF inoculated plants as reported by Pradhan <italic>et al</italic>. (<xref ref-type="bibr" rid="bib003">2003</xref>). Per cent of chilli root colonization by VAMF was significantly higher for <italic>G. fasciculatum</italic>(<xref ref-type="table" rid="tab001">Table 1</xref>). The results showed that non-mycorrhizal plants inoculated with <italic>R. solanacearum</italic> were completely destroyed due to bacterial wilt which was attributed to host resistance (<xref ref-type="bibr" rid="bib004">Satya <italic>et al</italic>., 2004</xref>). However, mycorrhizal plants with both the strains of VAMF could overcome the pathogen aggression which might be due to the nutritional superiority associated with the coloniation of roots by VAM fungi.</p></sec></body><back><ref-list><title>References

APPS

Annals of Plant Protection Sciences

0971-3573

Society of Plant Protection Sciences

apps-13-2-061

SHORT COMMUNICATION

Growth response of chillies to VAM fungi and reduction of bacterial wilt

Islam

Bora

L.C.

Department of Plant Pathology, Assam Agricultural University, Jorhat – 785 013, India

92005

132493494

<p>Wilt caused by <italic>Ralstonia solanacearum</italic> is considered as an important disease of chilli which cause economic loss up to 40–50% during flowering stage of the crop. The present study was undertaken to explore the usefulness of two VAM fungi <italic>viz., Glomus fasciculatum</italic> and <italic>Gigaspora</italic> sp. in reducing bacterial wilt incidence in chilli and their role in enhancements of plant growth characters. The VAMF strains were isolated locally following wet sieving and decanting method (<xref ref-type="bibr" rid="bib002">Khan, 1999</xref>) and the pathogen was isolated from diseased chilli plants in triphenyl tetrazolium chloride medium. At the time of transplanting of 28 days old chilli (cv. Pusa Jwala) seedlings, VAM fungi were inoculated into the soil of earthen pots @ 500 spores/kg of soil. After 15 days of transplanting the chilli seedlings were inoculated with 24 hrs old cells of <italic>R. solanacearum</italic>(1 x 10<sup>9</sup> cfu/ml) in a R.B.D. with six treatments and five replications.</p><p>Observations were recorded on disease incidence after 45 days of inoculation with <italic>R. solanacearum</italic> and bacterial populations were estimated by sampling rhizosphere soil at 15 days interval following inoculation of <italic>R. solanacearum</italic>. The important plant growth parameters were recorded to evaluate the beneficial effect of VAMF in crop rhizosphere. The plants were harvested after 90 days of inoculation with VAMF to estimate % root colonization with the mycorrhizal fungi. The effect of <italic>Glomus fasciculatum</italic> was significantly better over <italic>Gigaspora</italic> sp. Mycorrhizal plants with <italic>G. fasciculatum</italic>+<italic>R. solanacearum</italic> showed significantly better increase in leaf number (120.8), shoot fresh weight (50.0 g), shoot nitrogen (2.5% dry matter), shoot phosphorus (0.5% dry matter) over non-mycorrhizal and <italic>Gigaspora</italic> sp. +<italic>R. solanacearum</italic> inoculated plants (<xref ref-type="table" rid="tab001">Table 1</xref>). The % of VAM fungi colonization was significantly higher for <italic>G. fasciculatum</italic>(64%) as compared to <italic>Gigaspora</italic> sp. (43%) (<xref ref-type="table" rid="tab001">Table 1</xref>). Similar results were recorded by Borah and Phukan (<xref ref-type="bibr" rid="bib001">2003</xref>) on brinjal. The mycorrhizal plants with <italic>G. fasciculatum</italic> was more effective in disease suppression and showed significantly better wilt incidence (40%) as compared to <italic>Gigaspora</italic> sp. (60%). <table-wrap id="tab001"><label>Table 1</label><caption><p>Effect of VAM fungi on growth parameters, dry matter content and root colonization of chilli plants</p></caption><table><thead><tr><th rowspan="5" align="center">Treatments</th><th colspan="3" align="center">Growth parameters</th><th colspan="2" align="center">Dry matter content (%)</th><th rowspan="5" align="center">VAM fungi colonization</th><th colspan="3" align="center"><italic>R. solanacearum</italic> (cfu/g dry soil)</th><th rowspan="5" align="center">Wilt incidence</th></tr><tr><th colspan="3" align="center"><hr /></th><th colspan="2" align="center"><hr /></th><th colspan="3" align="center"><hr /></th></tr><tr><th rowspan="3" align="center">Leaf No.</th><th rowspan="3" align="center">Shoot fresh (g)</th><th rowspan="3" align="center">Root fresh (g)</th><th rowspan="3" align="center">N</th><th rowspan="3" align="center">P</th><th colspan="3" align="center">Days after inoculation</th></tr><tr><th colspan="3" align="center"><hr /></th></tr><tr><th align="center">5</th><th align="center">20</th><th align="center">35</th></tr></thead><tbody><tr><td colspan="11"><hr /></td></tr><tr><td align="left"><italic>Gigaspora</italic> sp.</td><td align="center">113.6</td><td align="center">65.0</td><td align="center">18.0</td><td align="center">2.4</td><td align="center">0.3</td><td align="center">43(41.0)</td><td align="center">–</td><td align="center">–</td><td align="center">–</td><td align="center">–</td></tr><tr><td align="left"><italic>Glomus fasciculatum</italic></td><td align="center">145.6</td><td align="center">98.0</td><td align="center">40.0</td><td align="center">2.6</td><td align="center">0.5</td><td align="center">64(33.2)</td><td align="center">–</td><td align="center">–</td><td align="center">–</td><td align="center">–</td></tr><tr><td align="left"><italic>R. solanacearum + <italic>Gigaspora</italic> sp</italic>.</td><td align="center">110.2</td><td align="center">40.0</td><td align="center">10.0</td><td align="center">2.3</td><td align="center">0.3</td><td align="center">35(36.2)</td><td align="center">129</td><td align="center">95</td><td align="center">75</td><td align="center">60(50.8)</td></tr><tr><td align="left"><italic>R. solanacearum</italic>+ <italic>G. fasciculatum</italic></td><td align="center">120.8</td><td align="center">50.0</td><td align="center">10.3</td><td align="center">2.5</td><td align="center">0.4</td><td align="center">46(42.7)</td><td align="center">110</td><td align="center">70</td><td align="center">53</td><td align="center">40(39.2)</td></tr><tr><td align="left"><italic>R. solanacearum</italic></td><td align="center">0.0</td><td align="center">0.0</td><td align="center">0.0</td><td align="center">0.0</td><td align="center">0.0</td><td align="center">0(1.8)</td><td align="center">162</td><td align="center">185</td><td align="center">114</td><td align="center">100(90.0)</td></tr><tr><td align="left">Control</td><td align="center">89.2</td><td align="center">37.0</td><td align="center">9.0</td><td align="center">2.1</td><td align="center">0.3</td><td align="center">0(1.8)</td><td /><td /><td /><td /></tr><tr><td align="left">CD (P = 0.05)</td><td align="center">12.6</td><td align="center">4.71</td><td align="center">2.3</td><td align="center">0.2</td><td align="center">0.02</td><td align="center">1.5</td><td align="center">14.9</td><td align="center">27.6</td><td align="center">16.6</td><td align="center">2.5</td></tr></tbody><tfoot><tr><td colspan="11"><hr /></td></tr><tr><td colspan="11" align="left">Figures in the parentheses represent angular transformed values.</td></tr></tfoot></table></table-wrap></p><p>The number of <italic>R. solanacearum</italic> population (cfu/g soil) in rhizosphere soil of mycorrhizal plants decreased in <italic>G. fasciculatum</italic> inoculated plants than <italic>Gigaspora</italic> sp. inoculation. The enhancement of plant height and leaf number, increase in fresh and dry weight of roots and shoots of chilli plants due to enhanced nutrient uptake and synthesis of photosynthesis in the VAMF inoculated plants as reported by Pradhan <italic>et al</italic>. (<xref ref-type="bibr" rid="bib003">2003</xref>). Per cent of chilli root colonization by VAMF was significantly higher for <italic>G. fasciculatum</italic>(<xref ref-type="table" rid="tab001">Table 1</xref>). The results showed that non-mycorrhizal plants inoculated with <italic>R. solanacearum</italic> were completely destroyed due to bacterial wilt which was attributed to host resistance (<xref ref-type="bibr" rid="bib004">Satya <italic>et al</italic>., 2004</xref>). However, mycorrhizal plants with both the strains of VAMF could overcome the pathogen aggression which might be due to the nutritional superiority associated with the coloniation of roots by VAM fungi.</p></sec></body><back><ref-list><title>ReferencesBorah

Phukan

P.N.

(2003). Effect of interaction of Glomus fasciculatum and Meloidogyne incognita on growth of brinjal. Ann. Pl. Protec. Sci. 11: 352-354.Khan

Q.Z.

(1999). Evaluation of different mount for preservation of VAM fungi. Ann. Pl. Protec. Sci.7: 63-66.Pradhan

Ganguly

A.K.

Singh

C.P.

(2003). Influence of Glomus fasciculatus on Meloidogyne incognita infected tomato. Ann. Pl. Protec. Sci.11: 347-350.Satya

Singh

V.P.

Singh

A.K.

Gopalakrishnan

(2004). Identification of resistance genes against some bacterial blight isolates of rice. Ann. Pl. Protec. Sci. 12: 347-351.Borah

Phukan

P.N.

(2003) Effect of interaction of Glomus fasciculatum and Meloidogyne incognita on growth of brinjal. Ann. Pl. Protec. Sci. 11: 352–354.Khan

Q.Z.

(1999) Evaluation of different mount for preservation of VAM fungi. Ann. Pl. Protec. Sci. 7: 63–66.Pradhan

Ganguly

A.K.

Singh

C.P.

(2003) Influence of Glomus fasciculatus on Meloidogyne incognita infected tomato. Ann. Pl. Protec. Sci. 11: 347–350.Satya

Singh

V.P.

Singh

A.K.

Gopalakrishnan

(2004) Identification of resistance genes against some bacterial blight isolates of rice. Ann. Pl. Protec. Sci. 12: 347–351.