Foliar nutrient diagnosis for fruit forest of Ginkgo biloba in Guangdong

Objective  To conduct foliar nutritional diagnosis on Ginkgo biloba located in Guangdong Meizhou ginkgo orchards based on diagnosis and recommendation integrated system (DRIS) index method, and provide a theoretical basis for nutrition management of ginkgo orchards in this region.

Method  Based on the amount of fruit, nine plots were clustered to get high, middle and low yield orchard. According to DRIS index method, the requirement degrees of G. biloba leaves to N, P, K, Ca, Mg, B, Zn and Mn fertilizers, and nutrient imbalance index (NII) were determined. The preliminary classification norms of DRIS index for nutrient element of fruit forest of G. biloba were established.

Result  The average NII of high and low yield orchard were 90.92 and 206.08, respectively. The average fertilizer requirements in high yield orchard were ranked as N>Mn>K>P>Zn>B>Ca>Mg, while those in low yield orchard were Mg>N>Ca>K>Mn>P>Zn>B. The balanced zones of DRIS index preliminary classification norms were N=−5.98±2.13, P=−0.97±4.43, K=−1.44±2.17, Mn=−1.70±11.82, Zn=−0.74±17.61, Ca=3.99±0.47, Mg=33.12±58.39, B=1.82±20.07.

Conclusion  The deficiency of N, K, Mg and Ca in G. biloba leaves in the orchard located in Meizhou was serious, followed by P and Mn, while the excess of Zn and B was observed. Through the ranking of the urgency of the fertilizer requirement and DRIS index grading, the balance of each nutrient element of G. biloba can be visually judged, and can be used as the basis for balanced fertilization of G. biloba.