Abstract
Root hairs play an important role in phosphorus (P) nutrition of plants. To better understand the relationship between root hairs and P acquisition efficiency (PAE) in barley, experiments were conducted with the wild-type barley (cv. ’Pallas’) and its root-hairless mutant (brb). A hydroponic split-root system was used to supply P as Ca3(PO4)2 (tri-calcium phosphate, TCP) to one-half and other nutrients to the other half of the root system. Using TCP as a sole P source can simulate a soil solution with buffered low P concentration in hydroponics to induce prolific root hair growth. Root morphology, plant growth, and P uptake efficiency were measured with 50 mg L−1 TCP supplied to the roots in the split-root system and 0, 35, or 1000 μM NaH2PO4 in a non-split-root hydroponic system. The wild-type plants developed root hairs, but they did not contribute to the significant genotypic differences in the P uptake rate when a soluble P source was supplied in the non-split root system, indicating that root hair formation does not contribute to P uptake in a non-split root solution. On the other hand, when grown in a split-root system with one-half of the roots supplied with TCP, the wild-type showed 1.25-fold greater P uptake than the root hairless mutant. This study provides evidence that root hairs play an essential role in plant P uptake when P bioavailability is limited in the root zone.
Highlights
IntroductionDue to phosphate interaction with inorganic and organic components in soil, its mobility and accessibility are usually low [1,2]
Low phosphorus (P) bioavailability is one of the main constraints to plant growth and fecundity.Due to phosphate interaction with inorganic and organic components in soil, its mobility and accessibility are usually low [1,2]
Our results demonstrated that the wild-type plants had a greater P uptake rate when exposed low P in the root zone compared to high P in the root zone P (Figure 5), which was closely correlated with the variation in root hair development
Summary
Due to phosphate interaction with inorganic and organic components in soil, its mobility and accessibility are usually low [1,2]. As a consequence of P immobilization and competition between plants and soil microorganisms, almost 80% of applied P fertilizer is fixed in soil; unavailable for plant uptake [3]. The concentration of inorganic phosphate (Pi) is less than 10 μM, which is even lower than the concentrations of some micronutrients in many plants [4]. To ensure high productivity of crop and cropland, large amounts of P fertilizers are often applied for crop production in many agricultural areas throughout the world. Identifying elite genotypes efficient in P uptake and utilization to Agronomy 2020, 10, 1556; doi:10.3390/agronomy10101556 www.mdpi.com/journal/agronomy
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