Nutrient availability and management in the rhizosphere: exploiting genotypic differences

Abstract

Summary Crop nutrition is frequently inadequate as a result of the expansion of cropping into marginal lands, elevated crop yields placing increasing demands on soil nutrient reserves, and environmental and economic concerns about applying fertilizers. Plants exposed to nutrient deficiency activate a range of mechanisms that result in increased nutrient availability in the rhizosphere compared with the bulk soil. Plants may change their root morphology, increase the affinity of nutrient transporters in the plasma membrane and exude organic compounds (carboxylates, phenolics, carbohydrates, enzymes, etc.) and protons. Chemical changes in the rhizosphere result in altered abundance and composition of microbial communities. Nutrient‐efficient genotypes are adapted to environments with low nutrient availability. Nutrient efficiency can be enhanced by targeted breeding through pyramiding efficiency mechanisms in a desirable genotype as well as by gene transfer and manipulation. Rhizosphere microorganisms influence nutrient availability; adding beneficial microorganisms may result in enhanced availability of nutrients to crops. Understanding the role of plant–microbe–soil interactions in governing nutrient availability in the rhizosphere will enhance the economic and environmental sustainability of crop production.

Biotic interactions, ecological knowledge and agriculture

“…Further, the presence of plant roots and the associated rhizosphere can greatly increase the rate of soil organic matter decomposition (the priming effect) by more than 300% for some plants during certain phonological stages (Cheng et al 2003), and some rhizosphere bacteria release potassium from insoluble forms in the soil (Sheng & He 2006). Plants can also change root structure and physiology in response to perceived nutrient deficiency, and there is the possibility of breeding plants more capable of secreting compounds that increase the availability of nutrients in the rhizophere as well as make them better hosts of rhizosphere organisms (Rengel & Marschner 2005).…”

Dissection of the Control of Anion Homeostasis by Associative Transcriptomics in Brassica napus

“…NUE is defined as yield per unit of input (Good et al, 2004). NUE depends on the ability to efficiently take up the nutrient from the soil but also on transport, storage, mobilization, usage within the plant, and even the environment (Good et al, 2004;Rengel and Marschner, 2005). The partitioning of the nutrients between vacuolar storage and assimilation is thus an important contributing factor of their use efficiency.…”

Genetic approaches to enhancing phosphorus-use efficiency (PUE) in crops: challenges and directions

“…Extracellular phosphatases can be released by plant roots in response to P starvation. Although there is genetic variation in phosphatase release in wheat, there is little association with growth and P nutrition when tested over a range of soil types (Rengel and Marschner 2005;George and Richardson 2008). The complexity of the rhizosphere environment may be a contributor to this lack of a clear link between phosphatase release and P uptake.…”

“…One of the ways in which plants respond to low supplies in soil P is to release several root exudates that increase the availability of inorganic and organic forms of P into the rhizosphere (Rengel and Marschner 2005;George and Richardson 2008). The exudates include several organic acid anions, protons that increase availability of the sparingly soluble forms of P, and enzymes such as phosphatases that increase the P availability from organic P.…”