Chrysanthemum (Dendranthema grandiflora, Tzevelev.) is one of the most important flowers traded both in Brazil and in the world. In spite of that, chrysanthemum irrigation management in Brazil is characterized by empiricism, therefore deeper studies related to the plant water use are needed. This work aimed to study the effects of irrigation depths on chrysanthemum grown in protected cultivation. The experiment was conducted from August 6 to the October 27 of 2003, in Guaramiranga, Ceará State, Brazil, under a 9 x 30 m protected cultivation structure. The experimental design was completely randomized blocks, with four treatments (irrigation depths corresponding to 50; 75; 100, and 125% of the evaporation of the class "A" evaporation pan, ECA), and four replications. The crop cycle lasted for 82 days and the total water amounts applied were: 192.2; 246.4; 300.9, and 355.4 mm for the 50, 75, 100 and 125% of ECA treatments, respectively. No significant differences were found in the number of stems per pack, in packages per m², and even in productivity (Table 1). Among treatments, the number of stems per package varied from 21 (75, 100 e 125% ECA) to 22 (50% ECA), the number of packages per m² from 3,63 (100% ECA) to 4,28 (75% ECA), and the productivity from 3,94 (125% ECA) to 4,36 kg m-2 (75% ECA). As the amount of water used increased, the efficiency of water use decreased. Irrigation using the water amount corresponding to 125% of ECA presented the lowest (significant) water use efficiency (0,0107 pacotes m-2 mm-1), while treatments with irrigation corresponding to 50 and 75% of ECA were the most efficient ones (0,0210 e 0,0174 packages m-2 mm-1, respectively).
Dendranthema grandiflora; irrigation management; protected cultivation; floriculture
