Growth and organic solutes accumulation in seedlings of Caatinga tree species in response of water deficit and potassium

Resumen

Drought stress negatively influences a variety of essential physiological process for plant growth and biomass production, and potassium contributes to the absorption of water and maintaining cell turgor, being crucial to understand the seedlings water stress responses. This research aimed to verify the effects to water deficiency and potassium on the growth and accumulation of organic solutes in Myracrodruon urundeuva, Libidibia ferrea, and Mimosa tenuiflora. The treatments were distributed in a 3 x 3 factorial scheme, with three water levels (100%pc - control, 50%pc - moderate water deficit, and 25%pc - severe water deficit) and three doses of potassium (0, 97.5 and 195 mg dm^-3 K). The plants were sown in black plastic bags, containing 5 kg of soil. Were evaluated plant height, stem diameter, and leaf concentrations of total soluble sugars, total free amino acids, and proteins. The water deficit caused a reduction in the growth of M. urundeuva and M. tenuiflora plants, regardless of the added potassium. The plants of M. urundeuva and M.  tenuiflora were not demanding in potassium, while potassium fertilization with 97.5 mg dm^-3 K favored L. ferrea plants, especially when kept under moderate water deficit. The moderate water deficit promoted accumulation of total free amino acids and soluble proteins in M. urundeuva, while in L. ferrea there was accumulation of total free amino acids under severe water deficit. Increase in the potassium promoted reduction in the concentrations of total soluble sugars and soluble proteins.