MSc

The study entitled “Development of root endophytic plant growth
promoters as bio-inoculants for pro-tray seedlings” was conducted at College of
Agriculture, Vellayani during the period 2013-15 with the objective to develop
microbial root endophytic plant growth-promoters as bio-inoculants in pro-tray
seedling production of major solanaceous vegetable crops chilli, tomato and
brinjal.
Microorganisms were isolated by triturating the roots of vigorously
growing seedlings of tomato, brinjal and chilli after surface sanitization. Bacterial
isolates were subjected to a preliminary screening on their respective hosts for
plant growth promotion.
Seedling vigour was assessed under green house
condition in portrays using sterile planting medium.
Endophytes with plant
growth promoting ability selected through the preliminary screening were
assessed under in vitro condition using dual culture plate assay for assessing the
compatibility with Piriformospora indica (Pi). Piriformospora indica is a wide
host root colonizing endophytic fungus which allows the plants to grow under
extreme physical and nutrient stress condition. It belongs to the Sebacinales in
Basidiomycota. Eight compatible bacterial endophytes (four from tomato, two
from chilli and two from brinjal) were further evaluated for their growth
promoting ability individually and in combination with P. indica. Bacterial
inoculants were provided as seed treatment and the fungal inoculant as additive in
the transplant medium. The bacteria were identified as Bacillus megaterium,
Alcaligenes faecalis, Streptomyces leeuwenhoekii, Bacillus pumilus, Bacillus
megaterium,
Bacillus licheniformis,
Bacillus thuringiensis
thuringiensis based on 16s rRNA sequence homology.
and
BacillusThe plant growth promoting experiments in tomato indicated that the
combination treatment of bacterial strain Streptomyces leeuwenhoekii with Pi
was found to be statistically superior in shoot fresh weight, root fresh weight and
root dry weight (1764.54 mg, 332.88 mg/plant and 26.45 mg/plant). Treatment
Alcaligenes faecalis + Pi was found to be statistically superior in shoot length
(15.23 cm) followed by the treatment Streptomyces leeuwenhoekii + Pi (14.45
cm). All the treatment were found to be superior over control. Root colonization
by P. indica was not found to be influenced by the combined application with
endophytic bacteria.
By assessing the plant growth promotion in brinjal, significantly higher
values with respect to
shoot fresh weight, and root fresh weight ( 844.27
mg/plant, 83.03 mg/plant) were observed with the plant treated with endophytic
bacterial isolate. Bacillus thuringiensis + P. indica showed superior mean height
of 6.95 cm which was on par with Bacillus thuringiensis (6.74 cm). However the
combination treatment of endophytic isolates with P. indica showed superior
values compared to control.
Analising the efficacy of the endophytic isolates in chilli for plant growth
promotion indicated that treatment with the endophytic isolate Bacillus
megaterium was found to be have significantly superior values in leaf number,
shoot length, shoot fresh weight, and shoot dry weight (5.66, 11.93 cm, 855.20
mg/plant and 87.97 mg/plant). All the treatments including the combinations
were found to be superior to control.
P. indica has capability to induce resistance against biotic and abiotic
stress, including drought, salinity resistance and bacterial, fungal and virus
infection in plants. The current experiment suggest that native root endophytic
bacteria can be used in combination with P. indica as far as plant growth is
concerned. Further studies are required to assess the potential of such
combinations in combating
drought, salinity etc.
plant diseases and helping the plant overcome