Sodium in the leaf apoplast does not affect growth of maize (Zea mays L.) under saline field conditions

  • Muhammad Shahzad COMSATS University Islamabad, Abbottabad, Pakistan
  • Haris Usman COMSATS University Islamabad, Abbottabad, Pakistan
  • Rafiq Ahmad COMSATS University Islamabad, Abbottabad, Pakistan
  • Sabaz Ali Khan COMSATS University Islamabad, Abbottabad, Pakistan
  • Zulfiqar A. Saqib Saline Agriculture Research Centre, University of Agriculture, Faisalabad, Pakistan https://orcid.org/0000-0002-7718-873X
  • Karl H. Mühling Institute of Plant Nutrition and Soil Science, Kiel University, Kiel, Germany http://orcid.org/0000-0002-9922-6581

Abstract

Studies dealing with leaf apoplastic Na+ concentration of monocots, such as maize, under actual saline soils are scarce. Therefore, the current study was aimed to investigate the growth, total ions and leaf apoplastic Na+ concentration of salt sensitive maize plants growing in saline soils. Plants were subjected to salt stress with an electrical conductivity (EC) of 3, 8 10 and 14 dS m-1 using completely randomized design (CRD) for 3 weeks. Shoot fresh weight, plant height, leaf area and leaf length of maize plants drastically decreased when plants were exposed to increasing salt stress. We found that maize could display a steep increase in Na+ concentration in the total shoot biomass with maximum 82.3 μmol g-1 FW, when plants were subjected to highest soil salinity at 14 dS m-1. As expected, other cations i.e., K+, Ca2+ and Mg2+ decreased with increasing EC of the soil compared to Na+. Surprisingly, a maximum of 17 mM Na+ were found in the leaf apoplast of maize grown under very high soil salinity at EC 14 dS m-1. Considering this lower leaf apoplastic Na+ concentration at such a high EC level in maize plants, current study does not corroborate that surplus sodium in the leaf apoplast can result in dehydration and cell death under salt stress.

Author Biography

Karl H. Mühling, Institute of Plant Nutrition and Soil Science, Kiel University, Kiel, Germany
Institute of Plant Nutrition and Soil Science
Published
2019-05-16