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Tropentag, September 20 - 22, 2017 in Bonn

"Future Agriculture: Social-ecological transitions and bio-cultural shifts"

Impact of Deficit Irrigation on Biomass and Nitrogen Accumulation in Mungbean (Vigna radiata L.)

Lisa Pataczek1, Mikenna Smith1, Thomas Hilger1, Roland Schafleitner2, Zahir Ahmad Zahir3, Georg Cadisch1

1University of Hohenheim, Inst. of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), Germany
2AVRDC - The World Vegetable Center, Biotechnology and Molecular Breeding, Taiwan
3University of Agriculture Faisalabad, Inst. of Soil and Environmental Sciences, Pakistan


Legumes are important nitrogen (N) contributors to cropping systems, since they are able to fix atmospheric N symbiotically. Grain legumes offer even more benefits due to grain and straw production for human and animal consumption. Using pulses for N input in a cropping system, however, requires improved accuracy of estimating N balances and N benefits for the following crop in a rotation, since grain and aboveground residues are removed at harvest. Moreover, leguminous crops are often grown in dryland areas, exposed to water stress. This work aims at quantifying biomass and N accumulation as well as N partitioning to above and belowground parts by mungbean (Vigna radiata L.) under water stress.
In a controlled environment, four mungbean accessions were exposed to three irrigation treatments: recommended irrigation level (control), moderate deficit and severe deficit irrigation. Plants were harvested at maturity and dry matter and yield parameters were assessed. The stable isotope (δ13C/δ15N) composition of above and belowground plant parts showed differences in the response to drought stress among the accessions.
Water stress did not affect pod dry weight and total aboveground biomass, but number of seeds per plant. Root biomass either increased with moderate stress and decreased with severe stress, or vice versa. Three accessions produced higher root biomass with severe stress (+22%) than with recommended irrigation. Root-N accumulation was dependent on the treatment: The proportion of root-N to total plant-N was similar between both stress treatments and around 30-40% of the total plant-N at maturity. The control accumulated around 20% of total plant-N in the roots. The isotopic carbon discrimination (Δ13C) in the grain showed clear relations to water shortages.
The results suggest that water stress affected N partitioning between above and belowground parts.

Keywords: Carbon discrimination, deficit irrigation, nitrogen partitioning, stable isotopes, Vigna radiata, water stress

Contact Address: Lisa Pataczek, University of Hohenheim, Inst. of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), Garbenstraße 13, 70599 Stuttgart, Germany, e-mail: lisa.pataczek@uni-hohenheim.de

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