Articles
YIELD AND WATER USE EFFICIENCY OF SWEET CORN GROWN IN SOLUTION CULTURE AS AFFECTED BY KNO3 AND SALINITY LEVELS
The purpose of this study was to define and evaluate specific and interactive effects of salinity and nutrition on sweet corn yield and dry matter-transpiration relationships.
Two experiments were conducted in autumn and spring of 1989 in an unheated greenhouse, using an aero-hydroponic system.
This system consisted of a 130-L covered container for the nutrient solution, a pump for its circulation, and two 30-L boxes in which plants were grown.
The roots were continuously sprayed with the nutrient solution.
In each experiment, 15 treatments were tested: three KNO3 levels (2, 7 and 13 mM and 2, 8 and 14 mM in autumn and spring, respectively), and five salinity levels (2, 5, 7, 10 and 12 dS m-1, at a NaCl:CaCl2 molar ratio of 4:1).
In both experiments, fresh matter production was decreased by increasing salinity and increased by KNO3 concentration in the solution.
Salt stress above 5 dS m-1 at any of the KNO3 levels significantly decreased the fresh weight of the above ground plant organs, dry matter production and yield.
Salinity stress increased plant root/shoot ratio, while increasing KNO3 concentration decreased it, and the interaction between electrical conductivity and KNO3 was insignificant.
The effect of salinity-KNO3 interaction on dry matter production and ear yield was significant only in spring; its effect on transpiration was significant in both experiments.
The positive effect of fertilization on yield vanished under high salt stress.
A significant linear relationship between transpiration and dry matter production was found, regardless of the KNO3 concentration, plant age and growing season; it showed a water use efficiency of 7.2 g dry weight L-1.