Root lodging tolerance in Helianthus annuus(L.): associations with morphological and mechanical attributes of roots

MANZUR ME; HALL AJ.; CHIMENTI CA.

PLANT AND SOIL

SPRINGER

Lugar: Holanda; Año: 2014

0032-079X

Background and aims The objectives of this study were to quantify the morphological and mechanical properties of the root-plate within two sunflower hybrids of contrasting susceptibility to root lodging; and to evaluate the effects of crop population density on these properties at two different development stages. Methods Two hybrids (CF29: tolerant, Zenit: sensitive) were grown at three densities: 5.6, 10 and 16 plants m−2. At R2 (early reproductive) and R6 (end anthesis) development stages, plants were artificially lodged and stem biomass, total root biomass in the whole root-plate and in the 0?5 and >5 cm layers of the plate, root number (three diametrical categories: 0?1, 1.1?2, >2 mm), total root length, and root axial breakage force were assessed. Results CF29 root mass was twice that of Zenit with differences mainly in the top 5 cm of soil. This higher root-plate biomass of CF29 was associated with a greater root number and root length compared to Zenit within all root diameter categories. Roots of CF29 exhibited higher axial tension failure thresholds than those of Zenit, and these thresholds increased more sharply with root diameter in CF29 than in Zenit. Conclusions The better anchorage and tolerance to lodging of CF29 with respect to Zenit arose from additive actions of traits at both whole root-plate and individual root levels. These included total root-plate root length, root number, root biomass and root axial breakage force.