Potassium effect on the morphology, nutrition and production of Carthamus tinctorius L. under water deficiency and rehydration

Abstract

Water deficit affects safflower development, but its effects can be mitigated by potassium fertilization. We use morphological, nutritional and production components to evaluate the effect of potassium fertilization in safflower response to water deficiency and subsequent rehydration. The experimental design used was completely randomized in a 3 x 3 factorial scheme, consisting of doses (0, 80, 160 kg ha(-1)) of potassium chloride (KCl) and water tensions in the soil, - 10 kPa (without water deficiency), - 50 kPa (moderate water deficiency) and - 70 kPa (severe water deficiency), with four repetitions. Plant height, number of leaves, number of branches, number of capitula and stem diameter were evaluated at 30 days after the imposition of water regimes and at 20 days after rehydration. The nutritional status of leaves and grains was evaluated after rehydration and at harvest, respectively, through the levels of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). Potassium fertilization positively influenced morphology, nutrition and safflower production, and the effects were accentuated with the application of 160 kg ha(-1) of KCl without water deficiency and under moderate water deficiency. Under severe water deficiency, there was no recovery of safflower. Therefore, the dose of 160 kg ha(-1) of KCl is adequate to mitigate the effects of only moderate water deficiency in safflower.