Role of cytokinin in enhanced productivity of maize supplied with NH4+ and NO3

K. D. Smiciklas, F. E. Below

Research output: Contribution to journalArticlepeer-review


Supplying both N forms (NH4++NO3) to the maize (Zea mays L.) plant can optimize productivity by enhancing reproductive development. However, the physiological factors responsible for this enhancement have not been elucidated, and may include the supply of cytokinin, a growth-regulating substance. Therefore, field and gravel hydroponic studies were conducted to examine the effect of N form (NH4++NO3 versus predominantly NO3) and exogenous cytokinin treatment (six foliar applications of 22 μM 6-benzylaminopurine (BAP) during vegetative growth versus untreated) on productivity and yield of maize. For untreated plants, NH4++NO3 nutrition increased grain yield by 11% and whole shoot N content by 6% compared with predominantly NO3. Cytokinin application to NO3-grown field plants increased grain yield to that of NH4++NO3-grown plants, which was the result of enhanced dry matter partitioning to the grain and decreased kernel abortion. Likewise, hydroponically grown maize supplied with NH4++NO3 doubled anthesis earshoot weight, and enhanced the partitioning of dry matter to the shoot. NH4++NO3 nutrition also increased earshoot N content by 200%, and whole shoot N accumulation by 25%. During vegetative growth, NH4++NO3 plants had higher concentrations of endogenous cytokinins zeatin and zeatin riboside in root tips than NO3-grown plants. Based on these data, we suggest that the enhanced earshoot and grain production of plants supplied with NH4++NO3 may be partly associated with an increased endogenous cytokinin supply.

Original languageEnglish (US)
Pages (from-to)307-313
Number of pages7
JournalPlant and Soil: An International Journal on Plant-Soil Relationships
Issue number2
StatePublished - May 1992
Externally publishedYes


  • cytokinin
  • field
  • greenhouse
  • maize
  • nitrogen form

ASJC Scopus subject areas

  • Soil Science
  • Plant Science


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