Effects of Sodium on Potassium Nutrition in Three Tropical Root Crop Species

Abstract

The potassium (K) nutrition and high K requirement of tropical root crops may be affected by their sodium (Na) status, as has been observed in a number of plant species. Solution culture was used to study the effects of K and Na supplies in tannia [Xanthosoma sagittifolium (L.) Schott.], sweetpotato [Ipomoea batatas (L.) Lam.] and taro [Colocasia esculenta (L.) Schott]. At low K supply, Na ameliorated symptoms of K deficiency and increased growth in tannia, and to a lesser extent in sweetpotato, but not in taro. None of the species responded to Na at adequate K supply. Differences in response to Na were attributed to differences in Na translocation to plant tops. At maximum Na supply, the Na concentration in index leaves averaged 1.82% in tannia, 0.205% in sweetpotato, and 0.0067% in taro. An increase in the supply of Na resulted in a shift in the critical K concentration for deficiency (i.e., 90% of maximum yield) in index leaves from 2.9% to 1.2% in tannia, and from 4.8% to 2.5% in sweetpotato. The critical K concentration in taro was 3.3%, irrespective of Na supply. To overcome the problem in tannia and sweetpotato of determining the critical concentration relevant to a leaf sample of unknown K status, a relationship was established for each species relating the critical K concentration to the concentration of Na in the index leaves.

Partial Substitution of K by Na Alleviates Drought Stress and Increases Water Use Efficiency in Eucalyptus Species Seedlings

“…Our studies indicate that, to a certain degree, the replacement of K by Na promoted Eucalyptus growth ( Subbarao et al, 1999 ; Krishnasamy et al, 2014 ), with a small amount of Na being equivalent to K in their function ( Ivahupa et al, 2006 ). Plants with low K replacement by Na showed higher TDM compared to those receiving only K (0 mmol c dm –3 of Na) or of K-deficient plants (0.9 mmol c dm –3 of Na) even in those under WS, except for E. saligna , the drought-sensitive genotype ( Table 1 ).…”

“…A comprehensive literature indicates the benefits of Na supply to plants ( Hampe and Marschner, 1982 ; Subbarao et al, 1999 ; Martínez et al, 2005 ; Idowu and Aduayi, 2006 ; Ivahupa et al, 2006 ; Ma et al, 2011 ; Wakeel et al, 2011 ; Kronzucker et al, 2013 ; Erel et al, 2014 ; Krishnasamy et al, 2014 ; Pi et al, 2014 ), as also in drought adaptations of halophyte plants ( Lv et al, 2012 ; Yue et al, 2012 ; Xi et al, 2018 ). Non-halophytic plants, such as Eucalyptus , although salt-sensitive ( Pardo and Quintero, 2002 ), are also able to utilize Na to some extent ( Subbarao et al, 2003 ; Mateus et al, 2019 ).…”

A positive growth response to NaCl applications in Eucalyptus plantations established on K-deficient soils

“…In Aracruz's Eucalyptus plantations close to the ocean, the absence of foliar symptoms of K deficiency, despite low K contents in soils, suggests that the supply of Na from atmospheric deposits might lead to a drop in the critical K concentration for deficiency in leaves, as reported in tannia and sweet potato (Ivahupa et al, 2006) or sugar beet (Marschner, 1995). Potassium has an important osmotic function in the vacuole.…”

Potássio e sódio na composição mineral e crescimento em plantas de Zingiber spectabile

“…Além disso, esses elementos benéficos reduzem o nível crítico de um elemento essencial (Wakeel et al, 2010). Ivahupa et al (2006) estudando plantas de batata doce e taioba, verificaram que, a presença de Na em solução nutritiva diminuiu o nível critico de K dessas espécies, no caso da batata doce de 4,8 para 2,5% e para taioba de 25, para 1,2%.…”