Root architecture alteration of narrow-leafed lupin and wheat in response to soil compaction

Root system architecture influences nutrient and water uptake efficiency and thus plant growth and productivity. Root architecture traits conferring efficiency in capturing resources from soil are considered a key factor in crop breeding for enhanced water and nutrient uptake. Mechanical impedance such as soil compaction is common in the Western Australian wheatbelt, limiting root growth and crop productivity. The present study investigated root responses to subsoil compaction in two field trials at Wongan Hills (central wheatbelt) and Buntine (northern wheatbelt) in Western Australia. Substantial alteration to rooting patterns was observed in the commercial wheat cultivar Wyalkatchem and in narrow-leafed lupin (Lupinus angustifolius) grown in sandy soils where compaction is common. The root systems of narrow-leafed lupin plants were dominated by a short and thickened taproot (10-26. cm depth, 7-14. mm root-collar diameter) and horizontally distributed primary lateral roots when compared to previous observations of the same genotypes under non-compacted soil conditions. Genotypic variability in root architecture traits among four wild genotypes and four commercial cultivars (Mandelup, Merrit, Quilinock and Tanjil) of narrow-leafed lupin was demonstrated. Taproot length, total root length, root surface area, root mass and root collar diameter were the most important root traits correlated to shoot yield (P