Chlorophyll Meter to Predict Nitrogen Topdress Requirement for Semidwarf Rice

DOI Web Site Web Site 被引用文献6件
  • Fred T. Turner
    Texas A&M Univ. Agri. Res. and Ext. Center Route 7 Box 999 Beaumont Texas 77713
  • Michael F. Jund
    Texas A&M Univ. Agri. Res. and Ext. Center Route 7 Box 999 Beaumont Texas 77713

書誌事項

公開日
1991-09
権利情報
  • http://onlinelibrary.wiley.com/termsAndConditions#vor
DOI
  • 10.2134/agronj1991.00021962008300050029x
公開者
Wiley

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説明

<jats:title>Abstract</jats:title><jats:p>Semidwarf rice (<jats:italic>Oryza sativa</jats:italic> L.) tolerates excessive N fertilizer without lodging. In fact, it is difficult to maximize semidwarf rice yield without applying excessive N fertilizer since most farmers have not found a quick, unbiased, reliable method for assessing the N requirement for rice plants. A portable chlorophyll meter that instantly provides a measure of leaf chlorophyll may quickly monitor the need for additional N fertilizer. The Minolta model SPAD 502 chlorophyll meter was evaluated during a 3‐yr period for its potential to determine the need for N fertilizer by semidwarf ‘Lemont’ rice grown in research plots on several soils and locations in Texas. Preplant N rates ranging from 56 to 280 kg N ha<jats:sup>−1</jats:sup> were applied to paired plots to develop plots with a range in leaf chlorophyll. At one of four plant growth stages, one of the pair of plots was topdressed with 50 kg N ha<jats:sup>−1</jats:sup> after measuring leaf chlorophyll. At the prepanicle initiation and panicle differentiation stages, the rice yield increase due to N topdressing dropped from about 1600 to 100 kg ha<jats:sup>−1</jats:sup> as the chlorophyll meter readings of the most recently matured leaf increased from 24 to 42, respectively. As chlorophyll readings exceeded 40, N fertilizer did not increase yield. However, at the tillering and heading growth stages chlorophyll readings were not well correlated with N fertilizer needs. These data provide evidence that the chlorophyll meter can be used to determine topdress N needs of semidwarf rice at pre‐panicle initiation and panicle differentiation.</jats:p>

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