BASIL IONIC RESPONSES TO SEAWATER STRESS AND THE IDENTIFICATION OF GLAND SALT SECRETION
J. F. Ninga, L. H. Cuib, S. H. Yanga, S. Y. Ai*a, M.J. Lia, L. L. Suna, Y. Chena, R.H. Wanga and Z. B. Zenga
aInstitute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou 510640, P.R. China
bCollege of Natural Resources and Environmental Science, South China Agricultural University, Guangzhou 510642, P.R. China
*Corresponding author Email: 136860345@qq.com;shaoyingai@21cn.com
ABSTRACT
Basil (Ocimum Basilicum) seedlings were subjected to 0,5%,10%,20% and 40% seawater for 10 days under shade house conditions. Increasing seawater concentration led to considerable reduction in plant dry matter accumulation. However, root growth was not affected till treated with 40% seawater. Accumulations of Na+ and Cl- were correlated with decline of Ca2+ and K+ in stems, roots or both. Contents of Ca2+ and K+ in leaves increased or remained relatively unchanged with increasing salt levels. In salinity-stressed plants, Na+ were partitioned mainly in roots and more than 50% of the K+ and Ca2+ were stored in leaves. Higher K+/Na+ and Ca2+/Na+ ratios in leaves rather than in roots and stems were observed in Basil plants. Scanning electron microscopy coupled with X-ray microanalysis showed that Basil leaf gland secretions contained Na+ and Ca2+. The Na+ secretion increased while Ca2+ secretion decreased with the increasing seawater concentration. These results suggested that Basil salt tolerance is associated with the compartmentation of Na+ in roots and the balance of K+, Na+ and Ca2+ in leaves as well as the salt secretion by the leaf glands.
Key words: Ocimumbasilicum L.; Basil; Ion balance; Salt secretion; Seawater stress; X-ray microanalysis
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