Root proliferation in native perennial grasses of arid Patagonia, Argentina

TORRES,Y.; BUSSO, C.; MONTENEGRO, O; ITHURRART, L.; GIORGETTI, H.; RODRIGUEZ, G; BENTIVEGNA, D; BREVEDAN, R.; FERNANDEZ, O; MUJICA, M; BAIONI, S.; FIORETTI, M; ENTÍO, J; TUCAT, G.

Journal of Arid Land

Intitute of Ecology and Geography, Chinese Academy of Sciences

Lugar: Xinjiang; Año: 2013 vol. 6 p. 195 - 204

1674-6767

Pappophorum vaginatum is the most abundant C4 perennial desirable to livestock in rangelands of northerastern Patagonia, Argentina. We hypothesized that (1) defoliation reduce net primary productivity, and root length density and weight in the native species, and (2) root net primary productivity, and root length density and weight , are greater in P. vaignatum than on the other , less desirable, native species (i.e. , Aristida spegazziniii,  A. subulata and Sporobolus c ryptandrus). Plants of all species were either exposed or not to a severe defoliation twice a year during two growing seasons. Root proliferation was measured using the cylinder method. Cylindricial, iron structures, wrapped up using nylon mesh, were buried diagonally from the the periphery to the center on individual plants. These structures, initially filled with soil without any organic residue, were dug up from the soil on 25 April 2008, after two successive defoliatios in mid-spring 2007. During the secon growing seasons (2008/2009), cylinders were desructively harvested on 4 April 2009, after one or two defoliations in mid- and /or late-spring, respectively. Root  grown into the cylinders were obtained after washing the soil manually. Defoliation during two succesive years did reduce the study variables only after plants of all species were defoliated twice, which supported the first hypothesis. The greater root net primary productivity, and root length density and weight in P. vaginatum than in the other native species, in support of the second hypothesis, could help to explain its greater abundance in rangelands of Argentina.