Embryological Analysis of Facultative Apomixis in Panicum maximum Jacq.1

Eighty apomictic accessions of Guineagrass (Panicum maximum Jacq.) collected mainly in East Africa, and 80 apomictic hybrids from sexual ✕ apomictic crosses, were studied for their mode of reproduction. The objective was to determine to what extent percentage sexuality in facultative apomixis can be modified following hybridization. Apomictic accessions with a high percentage sexual reproduction were observed among biotypes from South Africa and the Antilles. Three of the hybrids also exhibited a high percentage of sexuality, while almost all the others appeared to be obligate or nearly obligate apomicts. The average percentage sexual reproduction observed in apomictic hybrids was 5.6 compared to 8.1 in apomictic accessions. Thus hybridization did not increase sexuality in apomicts of P.maximum. Embryological analyses appeared to be especially efficient and a rapid means for determining the mode of reproduction in P. maximum. However, because apomixis is essentially obligate or nearly obligate in this species, progeny tests are no less reliable than embryological analyses. Based on these and previous findings, there is no doubt that apomixis, although facultative, can be easily manipulated in P. maximum.