Morphology, mode of reproduction, and fertility of Pennisetum orientale L. C. Rich.

摘要

Eleven Pennisetum orientale L. C. Rich. accessions from different geographical regions were studied at College Station, Texas for chromosome number, morphology, method of reproduction, and fertility. Differences were observed among accessions in salient morphological characters such as plant height, leaf size, rhizomes, inflorescence length and density, seed size, ligule length, central spikelet length, and veins on the glumes. Rhizome characteristics could be a valuable source of germplasm for improving winterhardiness. The accessions Cowboy, 269961, 271595, 330717, and 433 appeared to have good forage potential with 269961 being exceptional.; Cytological studies revealed that all accessions were tetraploid (2n = 36), facultative apomicts. Embryo sac (ES) analysis of a sample of 1,569 ovules from field and greenhouse studies showed three ovule types present in all accessions. Of these 6.3% of the ovules had only aposporous ES, 27.6% contained a single sexual ES, and 66.1% of the ovules had one or more aposporous ES's in addition to a sexual ES (facultative apomictic). The plant introduction (PI) 315867, was found to be highly sexual (85.5% sexual ES's). The level of sexuality differed between sampling dates in the field and between the field and the greenhouse grown material indicating that environment might have influenced ES type. Also, there appeared to be differential influence of environment on the level of sexuality among field grown accessions compared to greenhouse grown accessions. In general, the inflorescences of greenhouse grown plants had ovules with higher percentages of mixed ES's (facultative apomicts) and healthy sexual ES. Fertility varied among accessions as well as with season. Open-pollinated seed set for most accessions was higher than self-pollinated seed set. This was probably due to low pollen viability in the self-pollinated plants. The PI's 269961 and 330717 had the highest seed set as well as the greatest percentage stainable pollen and should be considered as good pollen parents for future hybridization studies.