Different root strategies of perennial native grasses under two contrasting water availability conditions: implications for their spatial distribution in desert dunes

VEGA RIVEROS, CECILIA; VILLAGRA, PABLO E.; GRECO, SILVINA A.

PLANT ECOLOGY

SPRINGER

Año: 2020 vol. 221 p. 633 - 646

1385-0237

The distribution pattern of perennialnative grasses in the dune systems of the Monte desertmight be determined by the ability of plant roots toacquire water under drought conditions in differenttopographical positions and soil substrates. This studyexamined differences in root traits of two speciesgrowing in sand dunes, Aristida mendocina andPanicum urvilleanum, and two species growing ininterdune valleys, Pappophorum caespitosum andLeptochloa crinita, under different water availabilityconditions in a sand substrate. Grasses were grown inrhizotrons and the factorial design included species,irrigation treatments, days from sowing, and depth soilprofile. Root length, total root length, number of rootbranches, length of root branches-to-number of rootbranches ratio (LB:NB), daily elongation rate (DER),root length density (RLD), root angles, aerial and rootdry mass, and shoot-to-root ratio (S:R) were measured.The four species studied were affected by droughtconditions causing a decrease in root growth andmodifying root structure, partition of assimilates, rootangles, and exploration of the soil profile. However,we found that species from sand dunes were lessaffected by drought and showed a deeper rootexploration under drought conditions, mainly due toproliferation of longer and more lateral roots in thedeepest soil layer. The different root traits andresponses of the species under drought conditionswould imply adaptations to the topographical positioneach species occupies and could explain their spatialdistribution in desert dunes.