2.7. Identification of growing seasons
At our study site, in normal years, the jujube trees sprout generally in middle April and leaf-fall occurs in mid-October, by which time the fruit are mature. Root growth, however, generally commences earlier and ceases later than shoot growth (Gregory, 2006). Therefore, for this study, we defined the growing season of jujube trees as being from April 10 to October 20. Each growing season was divided into four different growth periods based on records from several years, i.e., the sprouting (SPR) period from April 10 to May 20, the blossom & young fruit (BYF) period from May 21 to July 10, the fruit swelling (FRS) period from July 11 to September 10, and the fruit maturation (FRM) period from September 11 to October 20.