The effect of phosphorus availability on the carbon economy of contrasting common bean (phaseolus vulgaris l.) genotypes

Kai L. Nielsen*, Amram Eshel, Jonathan P. Lynch

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

228 Scopus citations


A common response to low phosphorus availability is increased relative biomass allocation to roots. The resulting increase in root:shoot ratio presumably enhances phosphorus acquisition, but may also reduce growth rates by diverting carbon to the production of heterotrophic rather than photosynthetic tissues. To assess the importance of increased carbon allocation to roots for the adaptation of plants to low P availability, carbon budgets were constructed for four common bean genotypes with contrasting adaptation to low phosphorus availability in the field ('phosphorus efficiency'). Solid-phase-buffered silica sand provided low (1 μM), medium (10 μM), and high (30 μM) phosphorus availability. Compared to the high phosphorus treatment, plant growth was reduced by 20% by medium phosphorus availability and by more than 90% by low phosphorus availability. Low phosphorus plants utilized a significantly larger fraction of their daytime net carbon assimilation on root respiration (c. 40%) compared to medium and high phosphorus plants (c. 20%). No significant difference was found among genotypes in this respect. Genotypes also had similar rates of P absorption per unit root weight and plant growth per unit of P absorbed. However, P-efficient genotypes allocated a larger fraction of their biomass to root growth, especially under low P conditions. Efficient genotypes had lower rates of root respiration than inefficient genotypes, which enabled them to maintain greater root biomass allocation than inefficient genotypes without increasing overall root carbon costs.

Original languageEnglish
Pages (from-to)329-339
Number of pages11
JournalJournal of Experimental Botany
Issue number355
StatePublished - 2001


FundersFunder number
USDA/NRI99-351007596, 94371000311
Jet Propulsion Laboratory


    • Biomass allocation
    • Phaseolus vulgaris L. (common bean)
    • Phosphorus efficiency
    • Root respiration
    • Root:shoot ratio


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