Skip to main content
ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #206821

Title: Emission rates, survival and modeled dispersal of viable pollen of creeping bentgrass

item Pfender, William

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2007
Publication Date: 11/30/2007
Citation: Pfender, W.F., Graw, R., Bradley, W., Carney, M., Maxwell, L. 2007. Emission rates, survival and modeled dispersal of viable pollen of creeping bentgrass. Crop Science.47:2529-2539.

Interpretive Summary: In this research we estimated the distance that wind-blown pollen can move from a bentgrass field during the time that it remains viable to fertilize other bentgrass. We found that only 1% of the bentgrass pollen is still viable after two hours, and none is alive by three hours, after release. At the daily peak of pollen shedding (between 10 AM and noon) when the grass is in full flower, approximately one million pollen grains are released per minute from each square meter of the bentgrass stand. Using this information about release rate and pollen survival, we used a complex mathematical model and the daily weather data to calculate the amount of viable pollen that would be deposited at various distances from the source field. Although the estimated amounts of pollen deposited varied with weather conditions, the general pattern showed high amounts of pollen (100,000 viable pollen grains per square meter) deposited at distances of 2 to 3 km from the source field, and low levels (one pollen grain per 10 square meters) reaching distances of 4.6 to 6.7 km from the source field. When we modeled pollen dispersal caused by a small thermal vortex ("dust devil"), which is a common phenomenon over agricultural fields in the summer, we calculated one of viable pollen grain per 10 square meters being deposited 15 km from the source field.

Technical Abstract: Dispersal and deposition of pollen of Agrostis stolonifera was estimated through the use of CALPUFF, a complex model originally developed to simulate dispersal of particulates and other air pollutants. Rate and diurnal pattern of pollen emission, as well as pollen survival characteristics, were determined in field experiments. Peak pollen emission rates were 0.2 to 5 X 106 pollen grains per min per m2 of a bentgrass stand. Peak pollen emission occurred between 10 AM and noon. Pollen survival under outdoor conditions was well described by a negative exponential, with 1% surviving for 2 h and none for 3 h. CALPUFF simulations produced deposition of 100,000 viable pollen grains per m2 at distances of 2 to 3 km from the source field, and deposition of 1 pollen grain per 10 m2 at distances of 4.6 to 6.7 km from the source field. Amount, extent and pattern of simulated deposition varied with weather conditions and, to a lesser extent, source field size. Simulation of a “dust devil” scenario, in which a small thermal vortex lifted pollen from the field, produced deposition of 1 pollen grain per m2 and 1 grain per 10 m2 at distances of 9.5 and 15.3 km, respectively, from the source field. Fertilization rates can not be estimated directly from pollen deposition estimates, because fertilization also depends on pollen competition at the recipient plants. However, the deposition modeling results suggest that pollen-mediated gene flow is likely at distances of at 2 to 3 km from a source field, and possible at distances of 15 km or more.