Allelopathic potential of Lolium rigidum Gaud. on the early growth of three associated pasture species

Abstract

In Mediterranean areas, the establishment of multispecies pastures for extensive livestock use is an alternative to the growing of traditional cereal crops. Lolium rigidum Gaud. is one of the most valuable forage grasses adapted to semiarid environments but its performance in mixtures is not fully understood. Field observations suggest that the species exerts allelopathic effects, although there is no evidence in the literature to support this assumption. The objective of the study was to determine whether L. rigidum affects the germination and seedling growth of common forage species by allelopathic means. Two bioassays were conducted to test for the allelopathic potential of seeds and adult (shoot and root) tissues of L. rigidum on two grasses, Lolium multiflorum Lam. and Dactylis glomerata L., and a legume, Medicago sativa L. The three species showed different degrees of sensitivity to L. rigidum with L. multiflorum being particularly sensitive to allelopathy. Positive and negative effects of L. rigidum on seedling development were noted. Shoot extracts of L. rigidum displayed the most consistent negative effects by inhibiting elongation of the radicle of the three target species. The significance of the results is that in drought-prone environments and where water resources are scarce poor root development decreases the ability of the plants to grow and survive.

Effects of Pinus pinea litter on seed germination and seedling performance of three Mediterranean shrub species

“…The extract was diluted with distilled water to obtain concentrations of 3.4 and 10 g L -1 and these were stored in a refrigerator at 4°C. These extract concentrations were chosen in order to simulate plant material left in the field after a low and high productive year, respectively (Emeterio et al 2004). These concentrations are similar to those used by Fernandez et al (2006) in a study involving P. halepensis about its potential allelopathic effect in the secondary succession.…”

Evaluation of allelopathic potential of safflower genotypes (Carthamus tinctorius L.)

“…Kong et al (2002) discovered that Ageratum conyzoides L. under water deficit and nutrient stress showed strong allelopathic potential. Emeterio et al (2004) observed that the inhibitory allelopathic effect of Lolium rigidum Gaud. on the root growth of other plants increased under drought stress.…”

Potencial alelopático de extratos aquosos de culturas de cobertura de solo na germinação e desenvolvimento inicial de Bidens pilosa

“…O potencial alelopático do sistema radicular tem baixa atividade, quando comparado a parte aérea (WANDSCHEER; PASTORINI, 2008), podendo em alguns casos ocorrer estímulo no desenvolvimento inicial de algumas espécies, L. multiflorum, Dactylis glomerata e Medicago sativa (EMETERIO; ARROYO;CANALS, 2004).Quando comparado o potencial alelopático das partes das plantas, para cada cultura, de modo geral, na média das concentrações dos extratos da planta inteira e parte aérea, excluindo as testemunhas, reduziram em 27 e 54% a germinação, comparativamente ao sistema radicular (Tabela 2).…”