Abstract

ALVES, Francisco Abel Lemos et al. Kinetics of K⁺ absorption in the absence and presence of Na⁺ in roots cashew tree. Rev. Ciênc. Agron. [online]. 2012, vol.43, n.3, pp. 439-445. ISSN 1806-6690.  http://dx.doi.org/10.1590/S1806-66902012000300004.

One effect of the salinity caused by an excess of Na⁺ in soils, is the reduction in levels of K⁺ in plant tissue. The study aimed to characterize the process of high and low-affinity absorption of K⁺ in cashew roots, in both the absence and presence of concentrations of Na⁺. Studies of the kinetics of K⁺ absorption in the absence and presence of NaCl were carried out using detached roots from cashew seedlings grown under K⁺ deprivation. The excess of Na⁺ in the external environment caused a reduction in K⁺ absorption by both the high and low-affinity systems. The reduction in the absorption of K⁺ in the roots of the cashew tree, caused by the excess Na⁺ in the environment, happens through competitive means. This type of competition was evidenced by the increase in Km values for the K+ absorption induced by the external Na⁺, without changing the values of Vmax. The results show that salinity may affect the acquisition and use of K⁺ in cashew plants.

Keywords : Cashew; Plants-effect of salt; Plants-effect of potassium.