The effects of ploidy and seed mass on the emergence and early vigour of perennial ryegrass (Lolium perenne L.) cultivars

Abstract

Abstract. Genetic variation for seed mass and components of early vigour were measured on 120 seedlings of each of 18 diploid and 27 tetraploid perennial ryegrass (Lolium perenne L.) cultivars. Seeds of tetraploid cultivars were on average heavier (3.8 mg) than seed of diploid cultivars (2.4 mg). However, there was variation for mean seed mass both within and between ploidy classes and within cultivars. The components of early vigour measured on each of the seedlings were: date of emergence, leaf appearance rate, seedling height (10 days after germination), leaf length and width and dry matter at 33 days after emergence. Mean seed mass of a cultivar was significantly (P<0.05) positively correlated with seedling height, leaf length, leaf width, shoot length and shoot mass. Individual seed mass within a cultivar was significantly associated with all components of early vigour, except the date of emergence of the second true leaf. There was no difference in the rate of emergence of tetraploid and diploid cultivars, although tetraploid cultivars tended to have longer and wider leaves, greater seedling lengths and fewer leaves and tillers than diploid cultivars. There was also evidence of genetic variation for seedling vigour components in perennial ryegrass after seed mass and ploidy effects had been removed during analysis. These data suggest that seed mass has a large positive effect on early vigour of both diploid and tetraploid cultivars of perennial ryegrass and that, in the absence of any specific knowledge of the early vigour characteristics of a given cultivar, seed mass could be used as a surrogate when choosing between cultivars with similar adaptation and performance.

Assessment of morphological and phytochemical attributes in triploid and hexaploid plants of the bioenergy crop Miscanthus×giganteus

“…Hexaploid plants had higher fresh weights and were on average 44.35% larger than triploid plants. This finding is consistent with the reports that polyploids are often associated with superior agronomic traits such as an increase in leaf thickness (Sugiyama, 1998;Kermani et al, 2003;Shao et al, 2003;Vyas et al, 2007), larger and fewer leaves and tillers than the parental lines (Smith et al, 2000;Sugiyama, 2005), higher width/length ratios, a more compact growth habit (Kermani et al, 2003;Allum et al, 2007), and increased biomass, yield, and disease resistance (Osborn et al, 2003;Comai, 2005;Zhang et al, 2010a). It has been suggested that stronger stems, thicker leaves, and changes to the density and sizes of stomata in polyploid plants are associated with improved abiotic tolerance (Huang et al, 2001;Saleh et al, 2008) and with higher genetic adaptability and tolerance to environmental stresses (Xiong et al, 2006).…”

Sugar beet (Beta vulgarisL.) growth at different ploidy levels

“…The highest values of cell size were recorded in tetraploid genotypes, as reported by Smith et al (2003) who noted that polyploidy increased the cell size and volume. Decreased cell number in polyploid genotypes was compensated by increased cell size as reported by Doonan (2000) and Inze and De Veylder (2006).…”

Mitotic chromosome doubling of plant tissues in vitro

“…Tetraploidization of Chaenomeles japonica reduced seed set but increased the proportion of fruit flesh (Stanys et al 2006), while seed weight of ryegrass tetraploids was adequately higher (Dewey 1980). Also, tetraploid Lolium perenne and Lolium multiflorum were noted to have larger but fewer leaves and tillers than its diploid relatives (Smith et al 2003;Sugiyana 2005). Tetraploidization of Zizyphus jujube, an economically important fruit tree in Asia, resulted in thicker stems, rounder and succulent leaves, larger flowers and a delay in flowering time of 3-4 days (Gu et al 2005).…”