1. Effect of Plant Growth Promoting Rhizobacteria on Growth Attributes of Different Vegetable Crops under Greenhouse Conditions
Mahesh Adhikari, Kabir Lamsal, Sang Woo Kim, Dil Raj Yadav, Shahram Naeimi, and Youn Su Lee*
Department of Applied Plant Sciences, Kangwon National University, Chuncheon , Korea
ABSTRACT
A greenhouse experiment was conducted to assess the effect of plant growth promoting rhizobacteria on growth of vegetable crops. Five different bacterial isolates namely KFB09, KFB24, KFB25, KFB59 and KSB01 were selected as potential rhizobacteria from in vitro tests and were evaluated for their growth promoting activities on pepper, lettuce, Chinese cabbage and pak-choi. All the five bacterial strains showed significant enhancement in various growth parameters as compared to control plants. The performance of isolates varied among the crops with regard to growth parameters. The results showed that isolates KFB59 and KSB01 significantly increased the chlorophyll content, root and shoot dry matter as well as plant height of pepper, Chinese cabbage and lettuce, while the isolates KFB24 and KFB25 attributed higher root length and dry matter production in all the crops. 16S rDNA sequencing revealed that the isolate KFB9 belongs to Paenibacillus polymyxa, whereas, KFB25, KFB59 and KSB01 are closely related to Bacillus spp. and KFB24 belongs to Alcaligenes faecalis.
MATERIALS AND METHODS
Bacterial inoculum was made by taking a loop full of bacterial isolate transferred to 500 ml flasks containing TSB and grown aerobically in flasks on a rotating shaker (160 rpm) for 48 hrs at 28±ºC ( wisecube®, Daihan Scientific Co.Ltd, Korea).
The bacterial suspension was then diluted in sterile distilled water to a final concentration of 109 CFU ml-1 using haemocytometer and optical density measurement (OD= at 550 nm) and the resulting suspensions were used to treat targeted plants in green house condition.
Seeds of targeted plants ( pepper, tomato, spinach, lettuce, and Chinese cabbage) and seeds were surface sterilized for 25 min in 20% sodium hypochlorite solution followed by a brief rinse with 70 % methanol before planting in soil.
Seeds were sown in a plastic pot ( 50 holes, 4cm diameter each) filled with commercial soil ( Baroker®, Sam Son, Korea).
Seedlings were grown in a green house with maintaining 28º C at daytime and 25º C at night.
After two weeks all crops were transferred in a plastic pot containing the commercial soil ( Baroker®, Sam Son, Korea).
Each treatment consists five replications were used in a completely randomized block design.
Successive treatment was done in the form of soil drenching three times in one week interval with the bacterial concentration ( cfu/ml).
Plants were harvested three weeks after the last inoculation.
Plant height and root length as well as fresh and dry weight measurements were compared with the un-inoculated control.
Chlorophyll content was also measured by chlorophyll meter SPAD-502( Konica Minolta Sensing,Inc, Japan).
RESULTS
DISCUSSION
Rhizobacterial isolates selected from the in vitro essay have the ability to promote growth of various vegetable crops.
KFB59 and KSB01 significantly increased the chlorophyll content, root and shoot dry matter as well as plant height of pepper, Chinese cabbage, and lettuce.
KFB24 and KFB25 attributed higher root length and dry matter production in all selected crops.
REFERENCE
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