Role of sulphur for potassium/sodium ratio in sunflower under saline conditions

Abstract

A hydroponic study was conducted to investigate the role of sulphur application on K/Na selectivity by sunflower and alleviation effect of sulphur on plant growth under saline conditions. Three salinity levels (0, 75, and 150 mM sodium chloride) and two sulphur levels (1 and 4 mM magnesium sulphate) were maintained in the root medium. The treatments were replicated thrice and arranged on growth chamber bench according to a complete randomized design (CRD). Seeds of Helianthus annuus (cv. Hysun-33) were germinated in quartz sand under standard conditions. One-week old seedlings were transferred to pots containing 2.5 l continuously aerated half strength modified Hoagland, s nutrient solution. The plants were provided optimum growth conditions. First harvest on 25th and second harvest on 30th day were taken after germination. Plants grown with 4 mM sulphur level showed significant growth whereas interaction between sulphur and salinity was highly significant (P <0.01) for growth parameters like fresh weight, dry matter yield of shoot and root, diameter and length of stem and root. The positive correlation of dry matter yield with sulfur (r=0.93), potassium (r=0.99) and calcium (r=0.83) were observed, whereas sodium had negative relationship (r=-0.99) with dry matter yield. Potassium/sodium selectivity in plants was significantly higher (P < 0.01) at 4 mM sulphur level than at 1 mM. © 2002, by Walter de Gruyter Berlin/Boston. All rights reserved.