Phosphorus concentrations in the leaves of defoliated white clover affect abscisic acid formation and transpiration in drying soil

Dhananjay K. Singh (Lead / Corresponding author), Peter W.G. Sale, Charles K. Pallaghy, Blair M. McKenzie

    Research output: Contribution to journalArticlepeer-review

    30 Citations (Scopus)

    Abstract

    Increased leaf phosphorus (P) concentration improved the water-use efficiency (WUE) and drought tolerance of regularly defoliated white clover plants by decreasing the rate of daily transpiration per unit leaf area in dry soil. Night transpiration was around 17% of the total daily transpiration. The improved control of transpiration in the high-P plants was associated with an increased individual leaf area and WUE that apparently resulted from net photosynthetic assimilation rate being reduced less than the reductions in the transpiration (27% vs 58%). On the other hand, greater transpiration from low-P plants was associated with poor stomatal control of transpirational loss of water, less ABA in the leaves when exposed to dry soil, and thicker and smaller leaf size compared with high-P leaves. The leaf P concentration was positively related with leaf ABA, and negatively with transpiration rates, under dry conditions (P <0.001). However, leaf ABA was not closely related to the transpiration rate, suggesting that leaf P concentration has a greater influence than ABA on the transpiration rates.

    Original languageEnglish
    Pages (from-to)249-259
    Number of pages11
    JournalNew Phytologist
    Volume146
    Issue number2
    DOIs
    Publication statusPublished - 7 Jul 2008

    Keywords

    • Abscisic acid (ABA)
    • Dry soil
    • Phosphorus
    • Transpiration rate
    • Water use efficiency (WUE)
    • White clover (Trifolium repens)

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