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Research on Cereal Nitrogen Fixation at ICRISAT

OAR@ICRISAT

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Relation http://oar.icrisat.org/3675/
 
Title Research on Cereal Nitrogen Fixation at ICRISAT
 
Creator Wani, S P
 
Subject Millets
Sorghum
Soil Science
 
Description The acetylene-reduction assay for nitrogenase activity has shown that the roots ofsorghum and
pearl millet stimulate N,jixation. A soil-core assay usedfor measuring nitrogenase activity of
field-grown plants showed large planHo-plant variability. An improved core assay (planted core
assay) developed at ICRISAT Center showed higher activity than that recorded by regular core
assay. In greenhouse assay methods plants with shoots sustained higher activity than the ones
whose tops were cut before the assay. Nitrogen(Jse activity varied throughout the day, as well as
over the season. Activity was maximum at the lateflowering or early grain:/illing stage and it was
related to the ontogenetic development of the plant. Activity was favored in moist, warm (ca
35° C) soil and decreased with high levels of fertilizer N.
Genotypic variation in sorghum and pearl millet lines for stimulating rhizospheric nitrogenase
activity was observed. Out of 184 pearl millet lines tested, 18 lines stimulated high nitrogenase
activity (> 460 nmol C2H4 h-I 15 em diam core-I) in the rhizosphere. Two lines, Gam 73 and J
1407, were consistently active over several seasons. Similarly, 28 of 334 sorghum lines tested had
high nitrogenase activity (>460 nmol C2H4 h-I 15 cm diam core-I).
At ICRISAT Center, pot-culture experiments with sorghum and pearl millet grown in a
low-fertility Alflsol, or in unsterilized washed vermiculite, showed substantial positive balances
for N. Long-term N balance studies .in, 'the field with sorghum and pearl millet cultivars are
continuing.
Using IS N2 it has been shown that 10-days-old sorghum seedlingsfix N2 in the rhizosphere, and
part of it is taken up by the plant within 3 days after exposure. The 15 N isotope dilution technz'que
has been evaluated for studying genotypic variation in sorghum and pearl millet cultivars for N2
fixation.
Many different kinds of bacteria closely associated with the roots of sorghum and pearl millet
plants show nitrogenase activity. Responses to inoculation in terms of increased dry-matter
production and N uptake have been observed in pot experiments with sorghum and pearl millet
grown in Alfisols and vermiculite. In five out of nine field trials with pearl millet cultivars,
inoculations with N2:/ixing bacteria significantly increased the grain and plant dry-matter yields
in all the cultivars.
 
Date 1986
 
Type Conference or Workshop Item
PeerReviewed
 
Format application/pdf
 
Language en
 
Rights —
 
Identifier http://oar.icrisat.org/3675/1/Research_on_cereal_nitrogen_fixation_at_ICRISAT_SPW_1986.pdf
Wani, S P (1986) Research on Cereal Nitrogen Fixation at ICRISAT. In: Cereal nitrogen fixation. Proceedings of the Working Group Meeting, 9-12 Oct 1984, ICRISAT Center, Patancheru, India.