Diurnal variation in settling velocity of pollen released from maize and consequences for atmospheric dispersion and cross-pollination

• Published in: Agricultural and forest meteorology 2011-08, Vol.151 (8), p.1055-1065
• Main Authors: Chamecki, Marcelo, Gleicher, Simone C., Dufault, Nicholas S., Isard, Scott A.
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agronomy. Soil science and plant productions; Atmospherics; Biological and medical sciences; corn; Cross-pollination; Dispersal; Dispersions; diurnal variation; drying; Economic plant physiology; Flowering, floral biology, reproduction patterns; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Germination; Grains; Growth and development; Maize; Maize pollen; Pollen; pollen germination; probability; Probability density functions; Settling; Settling velocity; vapor pressure; Viability; Zea mays
• ISSN: 0168-1923; 1873-2240
• DOI: 10.1016/j.agrformet.2011.03.009

► Measurements show that settling velocity of maize pollen changes during the day. ► Changes are caused by drying of pollen grains and associated with atmospheric VPD. ► Simple models explore consequences for dispersion and cross-pollination. ► Results suggest that drier pollen is transported further but has decreased viability. ► Current models do not account for these processes and overestimate cross-pollination. Settling velocity of maize ( Zea mays L.) pollen plays an important role in its dispersal and, therefore, cross-pollination. Estimated probability density functions (PDFs) of settling velocity based on experimental measurements show strong variation between early morning and noon. The variation is correlated to the time-integrated vapor pressure deficit (VPDT) and reflects the drying of pollen grains. A model for the decrease in germination rate of pollen grains exposed to atmospheric conditions suggests that the decrease in settling velocity is accompanied by a decrease in pollen viability. A simple dispersion model is used to illustrate the possible consequences of changes in settling velocity and germination rate for pollen dispersal and cross-pollination of maize. Results suggest that current models of pollen dispersal that do not account for these changes overestimate cross-pollination rates.