Proton release from tea plant (Camellia sinensis L.) roots induced by Al(III) under hydroponic conditions

Abstract

The mechanisms for soil acidification induced by tea plant growth are not well understood. Proton release from tea plant (Camellia sinensis L.) roots induced by aluminium (Al(III)) in solution-culture experiments was examined with an automatic titration system, to determine the effect of Al(III) uptake by the plants on soil acidification. Results indicated that the uptake of Al(III) by tea plants led to proton release from their roots and thus an increase in soil acidification. The uptake of Al(III) by tea plants and the amount of protons released from the roots were greater at pH 4.5 than at pH 5.0 and 4.0 and increased with increasing initial Al(III) concentration in the culture solutions. With the same initial pH, the amount of protons released from tea plant roots at a constant pH was much higher than that at non-constant pH. The presence of ammonium increased the amount of protons released from tea plant roots. Therefore, the uptake of Al by tea plants and subsequent release of protons from their roots may be an important mechanism by which they acidify soils in tea gardens.

Aluminum, a Friend or Foe of Higher Plants in Acid Soils

“…OA can also increase or reduce rhizosphere pH in the presence of other metals, as well as Al ( Kochian et al, 2004 ; Zeng et al, 2008 ; Javed et al, 2013 ). In the case of tea, the Al uptake induces H + efflux from the roots, suggesting a mechanism of soil acidification ( Wan et al, 2012 ). Aluminum plays a positive role in growth increase in tea ( Konishi et al, 1985 ), particularly in the promotion of root elongation.…”

Impact of Red Imported Fire Ant Nest-Building on Soil Properties and Bacterial Communities in Different Habitats

“…However, in recent years, soil acidification in tea plantations has become increasingly serious. Tea trees are “acid-producing plants”, absorbing large amounts of salt-based ions and active aluminum into the soil during growth and releasing large amounts of hydrogen ions and organic acids into the soil, causing soil acidification [ 23 , 24 , 25 ]. Further research is required to investigate whether the ‘acid production’ of tea trees causes defensive behavior in RIFAs, leading to a significant increase in pH in their nests.…”