Nodulation, nutrient accumulation and yield of rainfed soybean in response to indigenous soybean-nodulating Bradyrhizobia in the Himalayan region of Kashmir-Pakistan

Document Type: Research Paper

Authors

1 Department of Soil & Environmental Sciences, Faculty of Agriculture, The University of Poonch, Rawalakot Azad Jammu and Kashmir, Pakistan.

2 National Institute of Biology and Genetic Engineering (NIBGE), Faisalabad, Pakistan.

Abstract

The use of efficient and effective nodulating Bradyrhizobia strains considered as an
ecologically and environmentally sound management strategy for soybean production. A 2-yr
(2009 and 2010) field experiment was conducted to evaluate the effects of seven indigenous
Bradyrhizobium strains, one exotic TAL-102 and three N fertilizer rates, i.e., 25, 50 and 100
kg N ha-1 on the productivity and N2 fixation of rainfed soybean [Glycine max (L.) Merr.] grown
in the Himalayan region of Rawalakot Azad Jammu and Kashmir (AJK), Pakistan. The
experiment was conducted in a randomized complete block design with three replications.
Bradyrhizobium inoculation accelerated plant growth by increasing shoot length (26-47%), root
length (45-73%) and shoot dry weight (58-104%). Seed yield in the control was 861 kg ha-1 that
significantly increased to 1450–2072 kg ha-1 with Bradyrhizobium strains. Seed yields under
indigenous NR20 and NR22 strains was 24 and 28% higher than that recorded from the exotic
TAL-102. Number of nodules, nodules dry weight and acetylene reduction assay with
Bradyrhizobium strains were 55–123%, 94–178% and 38–103%, (respectively) higher than
the non-inoculated control. The higher N rate (N100) depressed nodulation and N2 fixation.
A significant variation in the symbiotic effectiveness and yield potential showed that inoculation
response was site/strain specific. Two indigenous strains NR20 and NR22 were found highly
efficient and displayed superiority over the exotic strain TAL-102. Multi-locational trials are
required to check the suitability of these isolated isolates for other agro-climatic conditions
before using as inoculants or bio-fertilizers.


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