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

MANZUR ME, HALL AJ, Y CHIMENTI CA

PLANT AND SOIL

SPRINGER

Lugar: Berlin; Año: 2014 vol. 381 p. 71 - 83

0032-079X

The objectives of this study wereto quantify the morphological and mechanical propertiesof the root-plate within two sunflower hybrids ofcontrasting susceptibility to root lodging; and to evaluatethe effects of crop population density on these propertiesat two different development stages.Methods Two hybrids (CF29: tolerant, Zenit: sensitive)were grown at three densities: 5.6, 10 and 16 plantsm−2.At R2 (early reproductive) and R6 (end anthesis) developmentstages, plants were artificially lodged and stembiomass, total root biomass in the whole root-plate andin the 0?5 and >5 cm layers of the plate, root number(three diametrical categories: 0?1, 1.1?2, >2 mm), totalroot length, and root axial breakage force were assessed.Results CF29 root mass was twice that of Zenit withdifferences mainly in the top 5 cm of soil. This higherroot-plate biomass of CF29 was associated with a greaterroot number and root length compared to Zenit withinall root diameter categories. Roots of CF29 exhibitedhigher axial tension failure thresholds than those ofZenit, and these thresholds increased more sharply withroot diameter in CF29 than in Zenit.Conclusions The better anchorage and tolerance tolodging of CF29 with respect to Zenit arose from additiveactions of traits at both whole root-plate and individualroot levels. These included total root-plate rootlength, root number, root biomass and root axial breakageforce.