A STUDY ON THE NPK NUTRITION IN AUTUMN SHOOTS OF 'FEIZIXIAO' LITCHI

Low yield is a common problem in litchi (Litchi chinensis Sonn.) production. Fertilization is an important factor that affects the yield. Knowing the nutritive patterns is the basis for optimized fertilization. In the study, ‘Feizixiao’ was used. A autumn shoots from three cycles of flush growth after harvest were sampled and divided into three sections corresponding to the three flushes, i.e. the primary flush shoot, the secondary flush shoot and the tertiary flush shoot. Leaves, stalks, xylem and phloem of each section were separated, and their N, P and K contents were analyzed in order to reveal the change patterns of the nutrients in various organs in different flushing shoots and to provide theoretical basis for nutrient management in litchi. The results showed that the changes in NPK contents in shoot sections were different. The contents of NPK in the last flush shoot significantly decreased at the pre-blossoming stage, while those in the primary flush shoot hardly changed. After harvest, the content of P in the leaves and stalks of the primary flush shoot and the secondary flush shoot decreased significantly, but that in the tertiary flush shoot had no change. Change patterns in NPK contents in different organs or tissues were different. NPK contents in the phloem were relatively stable. Contents of NK in leaves significantly decreased to low values at the pre-heading stage and the pre-blossoming stage, and the contents of PK in stalks also significantly decreased at the two stages. After harvest, the N contents in leaves and stalks rose while PK contents in them continued to decline. The N content in xylem significantly increased at the pre-heading stage, but the PK contents significantly decreased, and only P content significantly declined at the pre-blossoming stage, while NP contents significantly rose after harvest. The change patterns of the contents of different element were different. In the five major phenophases of litchi, the K content in different organs basically declined with development, while N and P contents fluctuated. The NPK contents in different organs were different. The NPK content was the highest in leaves t; P content was the highest in the xylem and leaves; N and K contents were the highest in xylem, and K content was the most abundant in the stalks and phloem.