Relationship between Floral Bud Induction by Application of KClO3 and Nitrate Reductase Activity of Leaves on Longan

Longan (Dimocarpus longan Lour.) trees were treated with potassium chlorate (KClO3) in soil in June. The changes of nitrate reductase activity, C/N and the main nutrient elements in the leaves were determined in a period of floral bud formation. Results showed that the trees were induced to form floral bud and bloom 30 days after the trees were treated with KClO3. Floral bud differentiation began after the trees were treated for 75 days with both KClO3 and Padobutrazol (PP333). The content of nitrate reductase in the leaves was reduced on a period of time after treatment began after. It began to increase at the floral physiological phase and reached the peaks at the morphological differentiation, then fell down. The content of nitrate reductase of control (CK) was kept on a lower level. Otherwise, relationship between flower bud formation induced and changes of the content of chlorate in the leaves were undefined.