Effects of shade on root characters associated with lodging in wheat (Triticum aestivum)

Abstract

AbstractPrevious work has shown that as the density of wheat plants increase, the spread of the root plate, root length and root number per plant decrease, leading to reduced anchorage strength and increased lodging susceptibility. The aim of this study was to determine which aspect of mutual plant shading [reduction of photosynthetically active radiation (PAR) or the ratio of red to far red light (R : FR)] is associated with this reduction in anchorage strength. Field experiments were conducted at Sutton Bonington, Leicestershire, UK, in two seasons using a range of plant densities in conjunction with shading materials to manipulate PAR and R : FR independently. The spread of the root plate, which has been linked most strongly with anchorage strength, was almost exclusively influenced by PAR intercepted per plant at the beginning of stem extension. Root number and root length were influenced by both PAR and R : FR. When structural roots (defined as thicker than 0.5 mm) and nonstructural roots were considered separately, it was discovered that increasing plant density and PAR shading reduced the length of both structural and nonstructural roots. However, reducing R : FR only reduced the length of structural roots without affecting the length of nonstructural roots.