Effect of pH on Na induced Ca deficiency

Abstract

Although it is well known that high Na concentrations induce Ca deficiency in acidic conditions, the effect of high pH on this competitive mechanism is not so well understood. The effect of Ca activity ratio (CAR) and pH on the Ca uptake of mungbeans (Vigna radiata (L.) Wilczek cv. Emerald) and Rhodes grass (Chloris gayana cv. Pioneer) in Na dominated solution cultures and in soil was investigated. Changes in pH in the alkaline range were shown not to affect the critical CAR of 0.024 (corresponding to 90% relative root length) for mungbeans grown in solution culture. Results from soil grown mungbeans confirmed those from solution culture, with a critical CAR of 0.025. A critical CAR of 0.034 was also established for soil grown Rhodes grass. The similarity of critical values established for mungbeans and Rhodes grass in solution culture and soil justifies the use of both solution culture and soil solution measurement as techniques for studying plant growth and limitations across plant species.Abbreviations: CAR -calcium activity ratio; CRBD -completely randomised block design; CRD -completely randomised design; DI -deionised; EC -electrical conductivity; ICPAES -inductively coupled plasma atomic emission spectroscopy; TDI -triple deionised.

Mg induced Ca deficiency under alkaline conditions

“…While the critical CAR of 0.050 established in Mg dominated solutions in this study is consistent with published values for other Mg dominated systems, it is higher than the value of 0.024 obtained using mungbeans in this experimental system using nutrient solutions dominated by Na (Kopittke and Menzies, 2004b). This greater antagonistic effect of solution Mg on Ca uptake has previously been observed in acidic conditions.…”

“…Calculated Ca activities were greater than the critical value of 270 µM (corresponding to 90% relative mungbean root length (Kopittke and Menzies, 2004b)) in all treatments, being 426 µM Ca at a CAR of 0.074, 421 µM at 0.07, 410 µM at 0.06, 400 µM at 0.05, 373 µM at 0.04, 368 µM at 0.03, 363 µM at 0.02, and 337 µM at 0.015. However, although solution Ca activities were greater than that observed to reduce growth under normal conditions, the reduction in root growth observed below the critical CAR of 0.050 was due to Ca deficiency.…”

“…As found previously (Kopittke and Menzies, 2004b), CAR is therefore thought to be a suitable index of salinity toxicity under neutral to alkaline conditions, although under acidic conditions the empirical CAR equation is likely to fail due to the additional challenges placed on root growth (such as Al toxicity, and H + induced Ca deficiency).…”

Botanical composition, production and nutrient status of an originally Lolium perenne-dominant cut grass sward receiving long-term manure applications

“…In slurry application trials in Finland, in some circumstances Ca content in herbage declined as the availability of K increased (Mattila et al 2003). Low Na content in the cow slurry treated herbage would also have been caused by the high content of K in that slurry (Kopittke and Menzies 2005). Magnesium content was generally low in all principal species fractions.…”

Revegetation strategies for seawater neutralized bauxite residue at Rio Tinto Alcan using various amendments

“…Enzyme reactions can be inhibited by accumulation of Na in the cytoplasm while dehydration and death of leaf cells can occur where Na accumulates in the leaf apoplasm (Keren, 2000). In addition, high concentrations of Na in soil solution reduce Ca uptake (Kopittke and Menzies, 2005) and Ca deficiency often occurs (Kopittke and Menzies, 2005) while deficiencies of N, K, Mn, Zn and Cu have also been noted (Levy, 2000;Yadav et al, 2011). Although some previous studies have linked increased plant growth in bauxite residues to an increase in tissue K/Na ratios (Jones et al, 2012b;Chapter 5), no such trend was evident here except plants in amended treatments had a higher ratio than those from the Control treatment.…”