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United States Department of Agriculture

Agricultural Research Service

Research Project: ECONOMIC AND ENVIRONMENTAL BENEFITS FROM MULTIUSE AGRICULTURAL LANDSCAPES TO FAMILY FARMS

Location: Dale Bumpers Small Farms Research Center

Title: Diurnal pollen tube growth is exceptionally sensitive to high temperature in field-grown Gossypium hirsutum pistils

Authors
item Snider, John
item Oosterhuis, Derrick -
item Kawakami, Eduardo -

Submitted to: Journal of Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 13, 2010
Publication Date: December 14, 2010
Citation: Snider, J.L., Oosterhuis, D.M., Kawakami, E.M. 2010. Diurnal pollen tube growth is exceptionally sensitive to high temperature in field-grown Gossypium hirsutum pistils. Journal of Plant Physiology. 168(5):411-8.

Interpretive Summary: Understanding how high temperature exposure under natural conditions influences fertilization in cotton flowers is important because fertilization is a prerequisite for the development of seeds and yield. However, the influence of high temperature on pollen germination, pollen tube growth and fertilization is not well understood in field grown cotton. To determine the effect of high temperature on reproductive processes occurring on the day of flowering, cotton seeds were sown on different dates to obtain flowers exposed to different temperatures but at the same developmental stage. Flowers were collected throughout the day, and light intensity, relative humidity, air temperature, pistil temperature, pollen germination, pollen tube growth, fertilization efficiency, fertilized ovule number, and total number of ovules per ovary were determined. Under high temperatures the first measureable pollen tube growth occurred earlier than under cooler conditions. Also, high temperature resulted in slower pollen tube growth through the style (2.05 mm h-1) relative to cooler conditions (3.35 mm h-1). Because pollen tube growth was negatively impacted under high temperature without a concomitant decline in pollen germination, or fertilization, it was concluded that pollen tube growth is exceptionally sensitive to high temperature. These findings suggest that selection of cultivars with heat tolerant pollen tube growth may help cotton producers maintain stable yields under high temperature.

Technical Abstract: For Gossypium hirsutum L. pollination, germination, and pollen tube growth must occur in a highly concerted fashion on the day of flowering for fertilization to occur. Because reproductive success is influenced by photosynthetic activity of major source leaves, we hypothesized that high temperatures under field conditions would limit fertilization by inhibiting diurnal pollen tube growth through the style and decreasing subtending leaf photosynthesis. To address this hypothesis, G. hirsutum seeds were sown on different dates to obtain flowers exposed to contrasting ambient temperature conditions but at the same developmental stage (node 8 above the cotyledons). Collection and measurement were conducted at 0600, 0900, 1200, 1500, and 1800 h on August 4 (34.6°C maximum air temperature) and 14, 2009 (29.9°C maximum air temperature). Microclimate measurements included photosynthetically active radiation, relative humidity, and air temperature. Pistil measurements included pistil surface temperature, pollen germination, pollen tube growth through the style, fertilization efficiency, fertilized ovule number, and total number of ovules per ovary. Subtending leaf measurements included leaf temperature, photosynthesis, and stomatal conductance. Under high temperatures the first measureable pollen tube growth through the style was observed earlier in the day (1200 h) than under cooler conditions (1500 h). Also, high temperature resulted in slower pollen tube growth through the style (2.05 mm h-1) relative to cooler conditions (3.35 mm h-1), but there were no differences in fertilization efficiency, number of fertilized ovules, or ovule number. There was no effect of sampling date on diurnal photosynthetic patterns, where the maximum photosynthetic rate was observed at 1200 h. Because in vivo pollen tube growth was negatively impacted under high temperature without a concomitant decline in pollen germination, ovule fertilization, or subtending leaf photosynthesis, we conclude that diurnal pollen tube growth is exceptionally sensitive to high temperature.

Last Modified: 9/2/2014
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