Early seed development in the Triticeae

摘要: The rates of early seed development were compared in several species the Triticeae which play a major role human nutrition, and related genotypes whose reproductive is current interest to plant breeders. Embryo endosperm during first five days after pollination was studied plants 22 grown at 20 °C with continuous light. Spikes emasculated before anther dehiscence then pollinated once full female receptivity reached. numbers embryo nuclei or cells individual florets ascertained by using large samples fertilized fixed various known times pollination. pattern essentially same wheat, rye, Triticale barley, although some interspecific variation rate between noted. Fertilization occurred within 40-60 min Mitosis primary nucleus completed about 6-7 h During next 24-48 number increased geometrically, doubling every 4-5 h. coenocytic but usually 72 it became cellular. nuclear declined on each successive day, greatest fall occurring time cell wall formation. zygote 18-30 later than mitosis nucleus. cycle varied from 12 18 h, similar its duration other meristematic tissues species. Cell remained fairly constant 5 unlike endosperm. Thus, very slow that nuclei, however, end fifth day had become equal longer cells. nature possible cause (s) rapid discussed. While volume steadily over period studied, mean decreased tenfold. This because increase lower number. Eventually these two thereafter further gave rise roughly equivalent as rule much faster wheat rye. By comparison, hexaploid slower sometimes even Results for wheat-rye chromosome addition lines, disomic rye chromosome, show most chromosomes apparently pronounced effect slowing both development. Indeed, VI V II an presence whole genome. Comparison maximum diploid polyploid shows there no polyploidy 48 phase Concurrently, cellular clear ploidy level, positive relation level developmental rate. These results are effects Hordeum vulgare H. bulbosum . result discussed reference mechanism elimination Fj-hybrids present provide detailed picture course normal wide range cereal respect characters affect tissues. They provide, therefore, baseline comparative studies aim describe abnormal quantify extent, instance withshrivelled grain. At they indication factors influence control extent important crop