Tolerance to water deficiency in safflower (Carthamus tinctorius L.) modulated by potassium fertilization

Water deficit affects safflower development, but its effects can be mitigated by potassium fertilization. Physiological and biochemical variables were used to evaluate the effect of potassium fertilization in safflower response to water deficiency and subsequent rehydration. A completely randomized experiment was setup in a factorial scheme (3 x 3), consisting three doses of KCl (0, 80, 160 kg ha(-1)) and three soil water potentials (- 10, - 50, - 70 kPa), with four repetitions. Chloroplast pigments, water relations, gas exchange, chlorophyll a fluorescence, cell membrane damage, hydrogen peroxide, antioxidant enzymes and proline were evaluated 30 days after set up water potentials in the soil and 20 days after rehydration. Under water deficit, all parameters were positively influenced by doses of KCl, mainly by the 160 kg ha(-1) dose, which it does not only reduced the magnitude of the decline in photosynthetic activity in plants stressed by drought, but also favored recovery after rehydration. Therefore, potassium fertilization improved the potential of safflower to maintain physiological and biochemical functionality in dry conditions and to recover after rehydration.