A pot experiment was conducted to study the effect of ammonium (NH4) and nitrate (NO3) on growth,
water relations and rhizodeposition (taking accumulation of sand on the root surface as an indirect
measure) of two varieties of maize (C-20 and C-77). Nitrogen was applied as ammonium sulphate or
potassium nitrate at 50 or 100 mg L-1 of the rooting medium solution and the plants were harvested 15
days after seed sowing when seed reserves were nearly exhausted. It was assumed that form and level of
N was the main variable affecting plant growth besides K that was added as potassium nitrate. Data were
recorded on root and shoot biomass (fresh and dry weight) and amount and water concentration of sand
adhering to the roots. In general, higher level of NH4-N had a negative effect on plant growth and a
positive effect on tissue water concentration. The amount of sand adhering to the roots increased in the
presence of lower levels of NH4 in both the maize varieties. The roots could adhere sand 2-3 times their
fresh weight and 30-43 times the dry weight and was assumed to reflect the amount of rhizodeposits. The
RAS showed significantly higher water concentration as compared to the bulk sand suggesting the
presence of polysaccharides that were assumed to be released from the roots or synthesized by
rhizospheric microorganisms. The water concentration of RAS was found to be higher in the presence of
NH4 suggesting a higher rhizodeposition and/or microbial synthesis of polysaccharides. Implications of
forms of N in the rooting medium to plant growth are discussed.
S. Gill, M. Abid, F. Azam. (2007) Ammonium And Nitrate Fertilization Effects On Biomass Yield Of Maize (Zea Mays L.) With Special Emphasis On Rhizodeposition, , Volume-44, Issue-3.
