A New Concept in Assessing Cotton Pollen Germinability1
- Jerry R. Barrow2
Contrary to current concepts of pollen germination and tube growth, intact pollen tube-like structures up to 4,000 µm in length were forcefully ejected, instantly, from pollen grains of cotton, Gossypium barbadense L. and G. hirsutum L., suspended in a hanging droplet, indicating a unique mechanism for pollen tube formation. Tubes disintegrated instantly after “germination” unless the germinating medium was supplemented with certain calcium, manganese, zinc, chlorine, or magnesium salts. The optimal combination was Ca[NO3]2 and MnSO4, each at 0.14 g, in 100 ml of distilled water. As sucrose concentration increased, the tubes became shorter and smaller in diameter and were ejected at a slower rate. The frequency of germination was unaffected until the sucrose concentration reached 1.7 M.
Germination dropped to about 50% in concentrations from 1.7 to 2.0 M. Cotton pollen did not germinate until after anthesis. From 30 min to 8 hours after anthesis, germination exceeded 98%. It dropped to 30% after 24 hours and to 1% in 32 hours. Cotton pollen viability was sensitive to temperature, in that full viability was observed in the range of 32 to 40 C with no germination above 42 C. This technique is a simple and effective method for inducing more than 98% germination in both G. hirsutum and G. barbadense and accurately measures cotton pollen viability.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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