|RAMIREZ DE LEON, H|
Submitted to: American Society of Agronomy
Publication Type: Abstract Only
Publication Acceptance Date: 4/12/2005
Publication Date: 6/19/2005
Citation: Ramirez De Leon, H., Burson, B.L., Ocumpaugh, W.R., Jessup, R.W., Rooney, W.L., Tischler, C.R. 2005. Pollen germination and tube growth in switchgrass [abstract]. Southern Branch of American Society of Agronomy. 2005 CDROM.
Technical Abstract: Switchgrass (Panicum virgatum L.) is an important warm-season bunchgrass that is native to much of North America. It is used for forage and erosion control in the southern Great Plains of the United States and is a promising biofuel crop. Little is known about its mode of pollination. Based on seed set data, it is considered to be cross-pollinated but there have been no studies of pollen-pistil interactions to confirm this assumption. To determine the method of pollination of switchgrass, pollen germination and pollen tube growth were observed in self- and cross-pollinated pistils using fluorescent microscopy. Six progeny of 'Alamo' switchgrass were self-pollinated and their pistils were observed at 1, 2, and 3 hours after pollination. Pollen germination ranged from 27 to 82%. Most of the pollen tubes did not grow beyond the stigma and none grew to the micropyle. These plants did not produce seed when self-pollinated and were self-incompatible. Four of the plants were cross-pollinated and their pistils were observed at 1, 2, and 3 hours after pollination. Pollen germination ranged from 7 to 89%. In all of the crosses, except one, the pollen tubes had grown into the ovule and entered the micropyle within 2 hours after pollination. However, in one cross, the tubes never grew out of the stigma indicating cross-incompatibility between the two genotypes that were crossed. These findings support information in the literature regarding the mode of pollination based on seed set. The species is highly cross-pollinated and self-incompatible, but cross-incompatibilities can occur between some genotypes.