A Generalized Function of Wheat's Root Length Density Distributions

Abstract

temporal distributions of RLD using experimental measurements and simulations. The root length density (RLD) is an important parameter to modelExperimental measurement approaches of RLD diswater and nutrient movement in the vadose zone and to study soiltributions include the root sampling method (Kumar root-shoot-atmosphere interactions. However, it is difficult and time- et al., 1993) and rhizotron (or minirhizotron) method consuming to measure and determine RLD distributions accurately. Especially RLD distributions change with different soil environment, (Ephrath et al., 1999). The root sampling method is plant species, growing seasons, and climatic conditions. In this study, direct and reliable, however, time-consuming and demeasured data sets of wheat RLD distributions were collected from structive. The rhizotron method can be used to monitor the literature and transformed into normalized root length density root development under almost undisturbed conditions (NRLD) distributions. A total of 610 values of wheat NRLD distribuby comparing a series of root photographs taken during tions were pooled together. These data showed a general trend, indesuccessive time periods. Nevertheless, reliability of the pendent of soil environment, wheat species, growing seasons, and rhizotron technique has yet to be fully assessed. Many climates. A generalized function was established to characterize the factors, such as insertion angles of observation tubes NRLD distributions versus normalized root depths. To verify the for photographs and the calibration curve between root generalized function, we measured RLD distributions of winter wheat count and RLD can affect the accuracy of the RLD (Triticum aestivum L.) using laboratory and field experiments for distribution. Therefore, the accurate and effective meadifferent soils, growing stages of wheat, atmospheric conditions, and surement of transient RLD distributions is still a chalwater supplies. Using the generalized function, we predicted winter wheat RLD and compared the predicted results with the experimental lenging task. data and with results using other NRLD functions. The comparison Simulation approaches of RLD distributions include showed that the generalized function predicted RLD distributions root architecture models (Diggle, 1988; Grabarnik et more accurately than the other functions. Although simulated results al., 1998; Thaler and Pagè s, 1998; Bidel et al., 2000), of soil water dynamics in soil-wheat systems were similar for the plant growth models (e.g., AFRCWHEAT2, CERESdifferent NRLD functions, the generalized function should be advan-Wheat, Jamieson et al., 1998; Jamieson and Ewert, tageous for applications that require accurate information of root 1999), and shoot and root models (Thornley, 1995, development and distribution. use a single L nrd function for each crop. Nonetheless, 430072, China; and Dep. of Renewable Resources, University of Wyothe results need additional examinations because of the ming, Laramie, WY 82071-3354, USA

Roots, rhizosphere and soil: the route to a better understanding of soil science?

“…Such general relations mean that for a few crops grown on deep, uniform soils, generalized functions of root distribution are possible (e.g. winter wheat, Zuo et al, 2004).…”

Residual Effects of Fertilization with Pig Slurry: Double Cropping and Soil

“…Water and N extraction by a wheat crop below 0.60 m is not generally significant (Hoad et al, 2004). Zuo et al (2004) estimated that the root‐length density below 0.60 m is <7%. Therefore, we believe that N uptake below 0.60 m was small in comparison to the N uptake between 0 and 0.60 m during this experiment.…”

Direct and residual response of wheat to swine slurry application method

“…It was assumed that water and N extraction by the wheat crop below 0.60 m was not significant (Hoad et al 2004). The generalized root length density (RLD) model defined by Zuo et al (2004) using 610 data sets of RLD winter wheat, estimates that RLD for the 0-0.60 m depth was higher than 93% of total RLD.…”