Contribution from Stolons and Roots to Estimates of the Total Amount of N₂Fixed by White Clover (Trifolium repensL.)

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• 作者：JØ ; RGENSEN ; FINN VANMAN ; LEDGARD ; STEWART F.
• 刊名：Annals of Botany
• 出版年：1997
• 出版时间：November, 1997
• 年：1997
• 卷：80
• 期：5
• 页码：641-648
• 全文大小：247 K

文摘

Growth and N-accumulation rates in leaves, stolons and roots of individual white clover plants were studied in three experiments using two methods. In a growth chamber experiment, the relative differences between tissues were found to be almost constant for a wide range of clover plant sizes. The stolon dry matter (DM) production was 56 % and the root DM production 40 % of the DM production in leaves. The N yield of stolons was 30 % while N yield in roots was 34 % of N yield in leaves. The effect of N application on these relations was investigated in a glasshouse experiment. Application of N reduced the root:shoot N ratio from 0.50 to 0.28, whereas the stolon+root:leaf N ratio (i.e. for abovevs.below cutting-height tissues) was only reduced from 0.97 to 0.80. In a field trial with two contrasting N regimes, growth and N accumulation were measured on individual clover plants. Dinitrogen fixation was estimated by¹⁵N isotope dilution based on analysis of leaves-only or by including stolons. Using leaves-only did not affect the calculation of percentage of clover N derived from N₂fixation ( % Ndfa) since the¹⁵N enrichment was found to be uniform in all parts of the clover. A correction factor of 1.7 to account for N in below cutting-height tissue is suggested when N₂fixation in white clover is estimated by harvesting the leaves only.