Pollen germination, pollen tube growth and fertilization following self and interspecific pollination ofPaspalumspecies

✍ Scribed by Byron L. Burson

• Publisher: Springer
• Year: 1987
• Tongue: English
• Weight: 650 KB
• Volume: 36
• Category: Article
• ISSN: 0014-2336
• DOI: 10.1007/bf00041514

✦ Synopsis

Crossability between most Puspalum species is very low. This study was undertaken to identify the impediments to hybridization. Accessions of P. intermedium MUNRO. ex MORONG, P. jurgensii HACKEL and P. dilututum POIR were self-pollinated and crossed with one another. Puspulum intermedium is essentially selfsterile but P. jurgensii and P. dilututum are highly self-fertile. Following pollination, pollen germination and tube growth were studied by observing the pollinated pistils with fluorescent microscopy. Examination of self-pollinated pistils revealed that the pollen germinated shortly after contacting the stigmas. Germination was over 80% for the P. intermedium and P. dilututum accessions but only 57% for P. jurgensii. Pollen tubes grew to the micropyle within 45 minutes after pollination in P. dilututum and 1 hour and 15 minutes in P. jurgensii. However, in the P. intermedium accessions most tubes did not grow beyond the stigma and very few penetrated the style and ovary. Apparently stylar-incompatibility is the reason for the low selfed seed set. In thecross-pollinations, pollen germinated shortly after pollination and germination ranged from 57 to 88% for the different crosses. In all crosses the pollen tubes grew to the micropyle within 30 minutes to 2 hours after pollination indicating that a cross-incompatibility system is not the cause for low crossability among these species. By examining embryo sacs from P. intermedium x P. dilatutum, its reciprocal and P. intermedium

x P. urvillei crosses, it was determined that gametes failed to unite in some crosses and this is a major reason for low crossability.