, 1997 ), iron ( Schmidt and Schikora, 2001 ), manganese, and zinc ( Ma et al. The final hair length is determined by plant species and genotype ( Dittmer, 1947, 1949 Bole, 1973 Gahoonia and Nielsen, 1997 ) and is influenced by a number of environmental factors, including the availability of nutrients and water. Root hairs have also been shown to confer an advantage in terms of soil penetration into high-strength soil layers, which is particularly relevant to modern low or no-till practices ( Haling et al. Additionally, there is less mechanical resistance to the growth of hairs through the soil than to the growth of larger structures ( Bates and Lynch, 2000 b ). Root hairs are produced at the actively growing extremities of the root system in response to environmental cues, and thus they require less investment in biomass than other strategies for increasing soil contact such as producing longer or thicker roots. The structure of the hairs means that they can forage between the soil particles, creating a diffusion gradient between the root and hair tip, intercepting moisture and nutrients ( Segal et al. By greatly increasing the effective radial surface area of the root, root hairs increase the volume of the soil from which immobile nutrients can be absorbed ( Gahoonia and Nielsen, 1997 Bates and Lynch, 2000 a Parker et al. Root hairs are fast growing, short-lived, tubular, unicellular outgrowths of the root epidermis that serve to interact with the soil and mycorrhizae as well as to anchor the plant ( Stolzy and Barley, 1968 ). Even prime agricultural land can suffer from low nutrient status due to the immobilization of nutrients with low diffusion rates such as phosphate and iron, as well as loss of fertilizer from surface run-off, leaching, remobilization by soil biota, and gaseous plant emission ( Raun, 1999 ). This is due to a number of factors including environmental and man-made depletion of agronomic soils, mismanagement of existing land, climate change, and demand-led increases in use of low-grade agronomic land ( FAO, 2009 ). Current and projected increases in demand for cereal production necessitate the development of wheat varieties with improved yield on drought stricken and impoverished soils. Wheat is increasingly being produced under suboptimal conditions, where irrigation, fertilization, or both are economically and practically non-viable.

Yield is limited by nutrient deficiency, both directly and as a result of increased vulnerability to biotic factors. Grain yield under drought conditions is determined by the amount of water the plant can extract from the soil and its subsequent conversion to biomass and partitioning to grain ( Foulkes et al.

, 1988 ), yet their contribution to yield in wheat has been largely overlooked. Root hairs greatly increase the effective surface area of the root in the root zone where the majority of the water and nutrients occur ( Doussan et al. This first QTL analysis of root hair length in wheat identifies loci that could usefully be further investigated for their role in tolerance to limiting conditions. Longer root hairs may confer an advantage by exploiting limiting mineral and water resources. The QTLs on 2A and 6A co-localized with previously described QTLs for yield components. In Spark Г— Rialto, QTLs on chromosomes 1A, 2A and 6A were associated with variation in RHL, whilst in Charger Г— Badger, a QTL for RHL was identified on 2BL. We identified quantitative trait loci (QTLs) for RHL in the populations derived from these crosses. Parents of two populations derived from inter-varietal crosses differed for RHL: Spark vs Rialto and Charger vs Badger. This method was used to screen a number of wheat mapping population parental lines for variation in RHL. We describe the development of a medium-to-high throughput screening method for assessing RHL in wheat at the seedling stage. Variation in root hair length (RHL) between varieties has been shown to be genetically determined, and could, therefore, have consequences for nutrient capture and yield potential in crops. They arise in the unsuberized maturation zone of the root, effectively increasing the root surface area in the region over which nutrient and water uptake occur. Root hairs are fast growing, ephemeral tubular extensions of the root epidermis.

Use imagej software for grain map