Biomass, nitrogen uptake and fixed nitrogen partitioning in field grown mungbean (Vigna radiata L. Wilczek) inoculated with Bradyrhizodium sp.

Issue Date

12-2008

Abstract

One of the options for the restoration of soil resource is through the incorporation of legumes into the cropping system because legumes have relatively short maturity period and can harness atmospheric nitrogen (N) through biological N fixation (BNF). A field trial was conducted at the University of the Philippines Los Baños (UPLB) to determine the effect of inoculation with Bradyrhizobium sp. strain M6 and host genotype on BNF and partitioning of fixed N, biomass accumulation and distribution, as well as total N uptake partitioning and N harvest index (NHI) in mungbean. The BNF was estimated using the ¹⁵N isotope dilution technique. In general, inoculation had no significant effect on biomass accumulation and partitioning despite an average 33% increase in yield obtained with inoculation. Inoculated mungbean had higher grain N content and net soil N removal than the control. Biomass accumulation and grain yield differed significantly among the four mungbean genotypes evaluated. The HI value ranged 0.34-0.40 among genotypes across treatments. Significant genotype variation in total N uptake and distribution to different plant parts were also obtained. The four varieties had a total amount of fixed N ranging 25.28-47.26 kg N ha¯¹ across treatments. Of the total fixed N, 45-56% was mobilized to the grains while 40-51% were stored in the shoots. Mungbean grains' high demand for N resulted in soil N removal of 22.66-33.57 kg N ha¯¹ among genotypes.

Source or Periodical Title

Philippine Journal of Crop Science

ISSN

0115-463x

Volume

33

Issue

3

Page

24-33

Document Type

Article

Frequency

tri-quarterly

Physical Description

tables/graphs

Language

English

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