GENOME SIZE AND PLANT DEVELOPMENT IN HEXAPLOID FESTUCA-ARUNDINACEA

The development of plants belonging to natural populations of hexaploi d Festuca arundinacea with different basic amounts of nuclear DNA was studied. A previous investigation showed that the genome sizes of the populations correlate positively with the mean temperature during the year and with that of the coldest month at the stations. Mitotic cycle time is affected by nuclear DNA content; in a population with a C-val ue of 6.05 pg, it is 3 h shorter than in a population with a C-value o f 8.28 pg. In contrast, the genome size affects neither the proportion of cells entering mitosis in the meristems, nor the enlargement of ce lls in differentiated leaf tissues. By studying plant development in 3 0 populations, it was found that their genome size correlates negative ly with the seed germination power (P=0.036) and the early growth of b oth the seminal root (P=0.009) and the first foliage leaf (P=0.099). B y contrast, the genome size correlates positively with the height of t he highest culm (P=0.014) and other quantitative characters of the pla nts at anthesis, as well as with their flowering time (P=0.037). It is suggested that the variations in the basic amount of nuclear DNA with in F. arundinacea have a role in improving the fitness of plants in en vironments differing in climatic factors such as temperature.