POTASSIUM INPUT, EITHER AS KNO₃, K₂SO₄ OR KCL, ON GROWTH AND YIELD OF SAND-POTTED TOMATO PLANTS GROWN IN SALINE CONDITIONS

In a consideration of desert tomato (Solanum lycopersicum) culture, three acidic, NaCl-enhanced complete-nutrient solutions differing essentially in potassium (K) source, being either KCl, K₂SO₄ or KNO₃, were applied to indeterminate ‘Rodade’ tomato seedlings.
The plants were grown in pots under shade in river sand.
The aim was to assess differences in health as affected by differences in NO₃, SO₄, NH₄, and Cl levels.
Plant chlorosis severity was an adequate indicator of plant health, correlating strongly with height growth, fruit set, fruit size, and leaf necrosis incidence.
Where KNO₃ was the K source, the plants were healthy.
Ill health occurred where KCl or K₂SO₄ was the K source.
Presumed inhibition of Na⁺ and Cl^– uptake, and promotion or inhibition of nutrient cation uptake adequately explained the diverse differences in plant health.
It was concluded that health may be better assured using KNO₃ as opposed to K₂SO₄ as the K source in sodic sandy desert environments.
Addition of K₂SO₄ would be expected to enhance salinity, mainly due to the lower propensity for SO₄ as opposed to NO₃ uptake.
Excess SO₄ has been associated with suppressed Ca⁺⁺ and enhanced Na⁺ uptake.

VII International Symposium on Mineral Nutrition of Fruit Crops

S.A. Oosthuyse

Solanum lycopersicum, desert, salinity, chlorosis, plant health, sodium chloride, sulfate, nitrate, ammonium

https://doi.org/10.17660/ActaHortic.2013.984.32