The optimum fertilizer requirements of N, P, K were studied quantitative- ly for common jujube trees (Zizypus jujuba) by using the method of three- factor regressive opcimum design. An effector model between the amount of N, P, K fertilizer and the yield of jujube trees has been established, by which the optimum fertilization scheme, the main effector and intereffector of various ferti- lizers, and margining yield effector have been approached. Meanwhile, the diagnosis of nitrogen nutrition was studied; and inquired into the influence of nitrogen nutrient status on jujube trees growth, fruitag...
