T. Jayasudha ¹, R. Rangeshwaran ², N. V. Vajid ²

Affiliations
1 Nallamuthu Gounder Mahalingam College, Pollachi, 642 001, Coimbatore, Tamil Nadu, IN
2 National Bureau of Agriculturally Important Insects, Post Bag No. 2491, H. A. Farm Post, Bellary Road, Hebbal, Bangalore, 560 024, Karnataka, IN

Abstract

Forty fluorescent pseudomonads were quantitatively evaluated for indole acetic acid (IAA) producing ability in the presence (trypt⁺) or absence (trypt^-) of tryptophan and growth promotion in groundnut in response to seed treatment with high IAA producers was analyzed. There were significant differences in the amounts of IAA produced by the isolates and more amounts of IAA were released in trypt⁺. In trypt^- increased IAA production was noticed for up to 144h and thereafter it stabilized or decreased. Analysis of plant growth promotion showed that the maximum ischolar_main length (187.5mm) was exhibited by plants treated with BA16(A)2 which was a medium IAA producer whereas the highest IAA producer BA1(E)2 (32.2 μg/ml of IAA) showed a ischolar_main length of 167.3mm. The isolate OTN7(E)2 which was a low IAA producer showed good ischolar_main lengths of 148.3mm (sterile soil) and 133.3mm (unsterile soil). When the shoot lengths were compared, highest shoot length of 213.3mm (sterile soil) was by BA4(D) which is a medium to high IAA producer and in unsterile soil highest shoot length of 198.67mm was shown by the isolate ND1which is also a medium to high IAA producer. The highest IAA producer BA1(E)2 showed a low shoot length of 156.7mm (sterile soil) and 115mm (unsterile soil). The results in some way do establish that plant growth is not directly influenced by high IAA producers. Root growth seemed to be more affected by high IAA producers in unsterile soil and maximum vigour index of 32600 was exhibited by BA2(D)1 which is a medium IAA producer and the minimum of 15750 was by BA1(E)2 which is a high IAA producer. Hence IAA producers of the fluorescent Pseudomonas group showed significant plant growth when compared with control but plant growth was not greatly influenced by those organisms that produced high amounts of IAA. Antagonistic Pseudomonas spp. able to release moderate or even low amounts of IAA may be better growth promoters.

Keywords

Pseudomonas, Indole Acetic Acid, Shoot Length, Root Length, Plant Growth Promotion, Tryptophan, Vigour Index.

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R. Rangeshwaran ¹, N. V. Vajid ¹, B. Ramanujam ¹, S. Sriram ¹, T. V. Bhaskaran ¹, Satendar Kumar ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, Post Bag No. 2491, H. A. Farm Post, Hebbal, Bellary Road, Bangalore 560 024, Karnataka, IN

Abstract

Studies were carried out to evaluate the effect of adding nutrient additives to talc based formulations on the shelf life of bacteria stored under room temperature. Two organisms namely, Pseudomonas fluorescens (PDBCAB2) and Bacillus sp. (MTCC6534 - chickpea endophyte), a spore forming bacterium, were tested. A gradual increase in P. fluorescens population up to 90 days was observed in almost all the treatments that were amended with nutrients. At 90 days highest population of log 10.38 cfu g⁻¹ was noticed in talc amended with 2 per cent tryptone and glycerol. Decline in the population was observed from 90 days onwards and was rapid from 150 days onwards. At 240 days highest count of log 1 x 10^4.2 cfu g⁻¹ was obtained with formulations amended with 2% tryptone and 2% glycerol and the results indicated that 2% peptone or 2% tryptone supplemented with 2% glycerol helped P. fluorescens in its better survival. The spore forming Bacillus sp. survived well throughout the study period. At 240 days all talc formulations amended with nutrient sources showed a population of log 9.0 cfu g⁻¹ or above and the population declined to below log 7.0 cfu g⁻¹ only in non amended treatments. Slow decline started from 240 days but high cfu of log 9.30 to 9.38 g⁻¹ were noticed in yeast extract or tryptone treated treatments. Hence talc formulations that had yeast extract or tryptone supplemented with glycerol enhanced shelf life of Bacillus spp.

Keywords

Pseudomonas fluorescens, Bacillus sp, Powder Based Formulation, Talc, Shelf Life, Gram Positive, Gram Negative.

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K. Ashwitha ¹, R. Rangeshwaran ¹, N. V. Vajid ², G. Sivakumar ¹, S. K. Jalali ¹, K. Rajalaksmi ³, H. Manjunath ⁴

Affiliations
1 National Bureau of Agriculturally Important Insects, H. A. Farm Post, Hebbal, Bellary Road, Bangalore 560 024, Karnataka, IN
2 Department of Biology, University of Hail, Jeddah, SA
3 Department of Plant Pathology, University of Agricultural Sciences, Dharwad 580 005, Karnataka, IN
4 Department of Plant Pathology, GKVK, UAS Bangalore 560 065, IN

Abstract

Abiotic stress tolerance of 230 Pseudomonas spp. Occurring in Indian soils was evaluated for tolerance to temperature, salinity and moisture stresses. Forty seven Pseudomonas spp. Were characterized as abiotic stress tolerant and were identified as P. aeruginosa (24), P. putida (14), P. plecoglossicida (4), P. mosselli (1), Pseudomonas sp. (1) and P. fluorescens (3). The temperature and salinity tolerance of these bacteria was 45°C and 1 M NaCl respectively. Most isolates (44 out of 47) produced indole acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity and 37 of them showed phosphatase activity. 2, 4-diacetyl phloroglucinol (DAPG) gene was detected in 10 isolates and pyoluteorin gene was detected in 4 isolates. Under water stress, seed treatment with P. putida (NBAII-RPF9) and P. fluorescens (PFDWD) showed its potential as plant growth promoter. The studies also indicated that stress tolerant Pseudomonas spp. may be used as plant protection agents in abiotically stressed soils.

Keywords

Pseudomonas, Abiotic Stress, Tolerance, DAPG, Pyoluteorin.

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