Potassium Nutrition Affects Leaf Growth, Anatomy, and Macroelements of Guzmania

Guzmania lingulata (L.) Mez. 'Cherry' plants were grown in coconut husk chips. All plants were given 8 mM nitrogen (N), 2 mM phosphorus (P), 4 mM calcium (Ca), and 1 mM magnesium (Mg) at each irrigation with potassium (K) concentration at 0, 2, 4, or 6 mM. After 9 months, K concentration did not alter the number of new leaves, and shoot and root dry weights. Increasing K concentration did not affect the length but increased the width of the most recently fully expanded leaves (the sixth leaves). Plants under 0 K exhibited yellow spots and irregular chlorosis on old leaves being more severe at the middle of the blade and leaf tip. Numbers of leaves with yellow spots or chlorosis decreased with increasing K concentration. Chlorenchyma thickness was unaffected by K concentration, whereas water storage tissue and total leaf thickness increased with increasing K concentration. Leaf N concentration in the sixth or 10th leaf was unaffected by solution K concentration. However, plants at 0 mM K had higher N concentration in the 14th leaf than those in sixth and 10th leaves. Leaf P, Ca, and Mg concentrations decreased with increasing solution K concentration. K concentrations were higher in the sixth leaf than the 14th leaf in plants at 0, 2, or 4 mM K, whereas leafK concentration was 15 g·kg -1 on dry weight basis in the sixth, 10th, or 14th leaves in plants treated with 6 mM K.