Dynamics of phosphorus fractions in the rhizosphere of common bean (Phaseolus vulgaris L.) and durum wheat (Triticum turgidum durum L.) grown in monocropping and intercropping systems

Abstract

The main objective of the present study was to investigate phosphorus (P) dynamics in the rhizosphere of durum wheat (Triticum turgidum durum L.) and common bean (Phaseolus vulgaris L.) grown in monocropping and intercropping systems with nitrate supply. Wheat and common bean were grown either alone or in association in a cropping device with a thin (1 mm) soil layer sandwiched between large root mats. Wheat intercropped with common bean exhibited a 33% increase in shoot biomass and a 22% increased root biomass, without significantly affecting common bean growth. After 12 days of culture, rhizosphere pH decreased by 1.66 and 1.13 units in monocropping system of common bean and intercropping system, respectively. Wheat increased intercropped common bean proton release by 36% compared with monocropped beans. Common bean and wheat exhibited different behaviors in rhizosphere P dynamics. Monocropped wheat decreased Resin-P, NaHCO 3 -P and NaOH-P in its rhizosphere by 24, 96 and 10%, respectively. However, NaHCO 3 -P and NaOH-P were increased by 61 and 10% in the rhizosphere of intercropping. Almost all values about P fraction in intercropping system were between those in monocropped common bean and monocropped wheat. Through taping different P fraction, different plants species possibly can alleviate competition for phosphorus in intercropping system.

Crop acquisition of phosphorus, iron and zinc from soil in cereal/legume intercropping systems: a critical review

“…Biochemical niche complementarity can occur when two intercropped species tap into different pools of soil P (Fig. 1), such as inorganic and organic pools (Li et al, 2008), or different chemical forms of each of these pools (Turner, 2008;Wang et al, 2012). Wheat and associated white lupin plants in mixed culture were shown to deplete water-extractable and citric-acidextractable inorganic P fractions in a low-P soil (four parts washed sand, one part garden soil), respectively (Cu et al, 2005).…”

“…Increased N 2 fixation in legumes as a consequence of competition of cereals for nitrate further stimulates P acquisition (Hinsinger et al, 2011). Several experiments have shown a lower rhizosphere pH for legumes than cereals, while pH values in the rhizospheres of cereal-legume mixtures have been found to be intermediate (Li et al, 2003a;Cu et al, 2005;Li et al, 2008). In addition, not only proton excretion and hence rhizosphere acidification but also reduced N 2 fixation and release of hydroxyl ions and consequent increase in rhizosphere pH can raise P availability in the rhizosphere of durum wheat and chickpea in a P-limited neutral soil (Betencourt et al, 2012).…”

“…This may occur as a consequence of changes in surface charges of (hydr)oxides and clay minerals to which phosphate ions are bound, and enhanced desorption of phosphate ions (Hinsinger, 2001). However, causal relationships between pH changes and changes in P availability and P uptake or plant growth in intercropping conditions remain to be established (Li et al, 2008;Betencourt et al, 2012).…”

Long-term effect of different soil management systems and winter crops on soil acidity and vertical distribution of nutrients in a Brazilian Oxisol

“…This shows that the effects of soil management systems are preponderant on the soil acidity attributes compared to the cultivation of different cover crops. In fact, the effects of cultivation of different plants on soil acidity attributes are most frequently determined at rhizosphere level (Li et al, 2008). As we did not evaluate the rhizosphere soil, but the bulk soil, it is possible that the winter cover crops effect on soil acidity attributes may have been diluted.…”

“…Furthermore, Wang et al (2008) reported that the acquisition of phosphate in low availability conditions was improved by the release of protons by wheat. Li et al (2008) showed that common bean decreased the rhizosphere pH by 1.66 units reducing also the available P-resin to 43% of the no-plant control soil. Many factors contribute to this pH change, including the imbalance in cation-anion uptake, particularly affected by nitrogen sources, and increased efflux of protons as a result of P deficiency (Gahoonia and Nielsen, 2004).…”