Características morfogênicas e estruturais de cultivares de azevém.

Abstract

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.