01296nas a2200145   4500008004100000245007800041210006900119300001000188490000700198520085700205653001201062100001801074700001801092856004001110       1969                        eng d00aDiurnal Patterns of Pollen Emission in Ambrosia, Phleum, Zea, and Ricinus0 aDiurnal Patterns of Pollen Emission in Ambrosia Phleum Zea and R  a16-210 v563 a<div>
<div>Hourly measu rements of pollen emission were made from cultivated plots of Ambrosia, Phleum, Zea, and Ricinus over the course of several pollination seasons as part of a study of pollen dispersion from known sources. A characteristic diurnal emission pattern was found for each genus Ambrosia pollen emission normally begins an hour or two after sunrise, peaks a few hours later, and decreases through the afternoon. Phleum starts during the night, peaks about 2 hr after sunrise, and declines slowly through the day. Zea emits pollen fairly uniformly during the period from 2 hr after sunrise to about sunset, while Ricinus pollen was collected from several hours after sunrise to late afternoon with a peak in mid-morning. Daily patterns often vary from the seasonal mean in response to changing meteorological conditions.</div>
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10abiology1 aOgden, E., C.1 aHayes, J., V.  uhttp://www.jstor.org/stable/2440389