Morphogenics and structural characteristics of ryegrass cultivars.

The objective of this experiment was to determine, under greenhouse conditions, at Faculdade de Agronomia Eliseu Maciel (UFPEL), Campus Capão Leão, RS, Brasil, ryegrass morphogenesis and structural traits of diploid and tetraploid cultivars. Treatments consisted of three diploid cultivars [Comum-RS (Lolium multiflorum), Pronto® (L. multiflorum var. westerwoldicum) and Conquest® (L. multiflorum var. Italicum)], and four tetraploids [INIA Titan® (L. multiflorum var. Italicum), Winter Star® (L. multiflorum var. westerwoldicum), KLM 138® (L. multiflorum var. italicum) and Banquet II® (L. perenne)], in a completely randomized design with seven treatments and six replications. Cultivars were sown in 06/06/2011 at a density of 10 seeds pot-1 2500g of soil; correction and fertilization was performed in a single dose before sowing. When plants reached 20 cm height the first cutting was made, to allow for appropriate establishment. The following cuttings were made when when plants reached 15 cm average height, always leaving a residue of 7 cm. Weekly evaluations of morphogenesis were made prior to each cutting. Data were submitted to analysis of variance and means compared by Tukey test (P <0.05). The following variables were analyzed: leaf expansion of rate (LER), senescence rate (SR), leaf appearance rate (LAR), phyllochron (Ph), leaf lifetime (LL) and final length leaf (FLL), number of life leaves (NLL), populations tiller density (PTD), plant length (CP) and leaf/sheath ratio (L/S), determined in each cutting.There were significant differences (P<0.0001) among the cultivars for all variables. Banquet II® cultivar, depending on the height pre-cut used and its growth habit, showed reduced number of cuts and higher rates of expansion and leaf appearance, and also better structural characteristic of forage interest. KLM 138® cultivar for its phyllochron and leaf lifetime has lower renewal of leaves in canopy and allows longer intervals between defoliation. Winter Star® showed the best leaf/stem ratio, while Conquest®, INIA Titan®, KLM 138® and Banquet II® showed only leaves throughout the experimental period.Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPqForam avaliadas, em casa de vegetação (Faculdade de Agronomia Eliseu Maciel- UFPEL-Campus Capão do Leão, RS), as características morfogênicas e estruturais de cultivares diplóides e tetraplóides de azevém. Os tratamentos constaram de três cultivares diploides [Comum-RS (Lolium multiflorum), Pronto® (L. multiflorum var. westerwoldicum) e Conquest® (L. multiflorum var. italicum)]; e quatro tetraploides [INIA Titan® (L. multiflorum var. italicum), Winter Star® (L. multiflorum var. westerwoldicum), KLM 138® (L. multiflorum var. italicum) e Banquet II® (L. perenne)], alocados em delineamento inteiramente ao acaso, com sete tratamentos e seis repetições. As cultivares foram semeados em 06/06/2011 na densidade de 10 sementes vaso-1 de 2500g de solo, a correção e fertilização foi realizada em dose única antes da semeadura. Quando as plantas atingiram em média 20 cm de altura foi realizado o primeiro corte, para dar condições ao adequado estabelecimento, enquanto os demais foram realizados quando era atingida altura média de 15 cm, deixando-se sempre resíduo de 7 cm. Momento antes do corte procedia-se uma das avaliações semanais de morfogênese. Por análise de variância e comparação de médias pelo teste de Tukey (P<0,05), foram analisadas as variáveis morfogênicas: taxa de expansão foliar (TEF), taxa de senescência (TS), taxa de surgimento de folhas (TSF), filocrono (Ph) e tempo de vida das folhas (TVF) e as estruturais: comprimento final da folha (CFF), número de folhas vivas por perfilho (NFVP), densidade populacional de perfilhos (DP), comprimento da planta (CP) e relação folha:colmo (F/C). Foram verificadas diferenças significativas (P