Isolation of plant growth promoting rhizobacteria from soils of north- western himalayan region of Uttarakhand, their characterization and evaluation in vegetable pea (Pisum sativum)
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Date
2018-05
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The studies were conducted to isolate various plant growth promoting rhizobacteria from the rhizosphere and rhizoplane of vegetable pea by raising it in soils of different locations of North-West Himalayan region of Uttarakhand; their characterization and evaluation for improved growth of vegetable pea under controlled conditions. The microbiological and chemical analyses were carried out in the Central Analytical Laboratory and Department of Soil Science, College of Agriculture, GBPUA&T, Pantnagar (Uttarakhand) during 2016-2018. Total of forty-three isolates were isolated and purified from the rhizosphere and rhizoplane of vegetable pea grown in the soils from varying locations of the North-West Himalayan region of Uttarakhand. Further these isolates were characterized on the basis of morphological, biochemical characteristics and plant growth promoting (PGP) traits. Out of forty-three rhizobacterial isolates 29, 25, 35, 37 and 32 tested positive for amylase, protease, catalae, oxidase, and chitinase, respectively. However, 32.55, 13.95, 9.30, 69.76, 67.44 and 100 percent isolates were P-solubilizer, Zn-soubilizer, HCN producer, IAA synthesizer, GA synthesizer and ammonia producer, respectively. These rhizobacterial isolates also expressed the great diversity in terms of carbohydrate utilization. On the basis of the PGP traits expressed by various isolates 30 were selected for evaluating their potential to improve growth and development of vegetable pea in sand under controlled conditions. After 45 days of plant growth i.e. at the time of flowering PGPR isolates A17-RP-KB (T7) produced maximum shoot length (40.24 cm), root length (20.62 cm), lateral root emergence (61.17 number plant-1), dry root biomass (1.06g plant-1), total dry weight (2.11g plant-1) and root: shoot ratio (1.01). The highest root volume (7.3 cm3 plant-1), fresh root weight (9.023 g plant-1), fresh shoot weight (7.87 g plant-1), shoot: root ratio (2.84) and dry shoot biomass (1.13 g plant-1) was produced due to an inoculation with PGPR isolates LG-RS-1-KB (T8), A15-RP-KB (T28), SH-RP-NA (T15), PL-RS-1-NA (T16) and P2-RP-KB (T1), respectively. Inoculation with PGPR isolate CRC-RP-NA (T20) facilitated synthesis of higher amount of
chlorophyll ‘a’; 14.23 mg g-1) and ‘b’ ( 6.44 mg g-1) while the highest leaf area (5.35cm2 plant-1) was produced due to LG-RS-1-KB (T8). Total N and P-uptake of 28.22 and 2.51 a l p g m t n -1 R P G P h t i w n o i t a l u c o n i o t e u d t s e h g i h s a w , a e p e l b a t e g e v n i , y l e v i t c e p s e r ,7 isolate A1 -RP-KB (T7). However, highest amount of total K-uptake (32.41 mg plant-1) was recorded in plants inoculated with PGPR isolate CRC-RS-2-NA (T6). The highest root acid phosphates activity (12.76 mg p-nitrophenol g-1 fresh root hr-1) was demonstrated due to inoculation with PGPR isolate SH-RS-2-KB (T24).