柑橘营养施肥推荐专家系统的建立与验证

为解决橘园果农经验施肥投入不平衡导致的果实品质降低的问题,构建基于果实品质综合评价的营养施肥推荐专家系统。通过2019—2020年连续两年定点跟踪,建立果实膨大期树体矿质营养和果实成熟期果实品质指标原始数据库,构建了基于果实综合品质指标的果实膨大期优质叶片养分适宜标准生成算法、基于“以产定量、总量控制和分期调控”原则的标准含量适宜偏差百分数有效养分配方矫正算法和基于当地肥料农资供应库的复混配方推荐算法,实现果实膨大期优质叶片养分适宜标准生成、橘园营养状况评价、有效养分施肥配方推荐以及基于当地肥料农资数据库的复混配方推荐4个主要功能。2021年度进行系统推荐施肥方案效果验证,结果表明：广安龙安柚产区以中产园区平均产量作为目标产量的矫正施肥方案效果最佳,龙安乡橘园矫正施肥方案的氮、钾和磷肥投入分别降低40.3%、43.6%和1.3%,崇望乡橘园矫正施肥方案的氮、钾和磷肥投入分别降低27.1%、30.8%和78.8%。该系统有效避免了化肥投入不平衡所致果皮着色延迟以及氮钾肥投入偏低导致果实偏小和果肉着色延迟,显著提高龙安柚产区果实综合品质,对柑橘叶片养分矫正配方施肥技术推广有较高适用性。

Establishing and verifying the nutrient expert system for citrus fertilization recommendation

Fertilization is one of the most important aspects during commercial citrus production. A better tradeoff is also required for the fruit quality with the fertilizer reduction and nutrients efficiency. In this study, an expert system was constructed for the citrus fertilization recommendation of mineral nutrients, according to the comprehensive evaluation of fruit quality. The 40 plots of 10-12a Longan pomelo (Citrus Grandis cv. ''Longan'') orchard were selected in the Modern Agricultural Industrial Park of Longan Pomelo, Guangan City, Sichuan Province, China. The indexes were tracked from 2019 to 2020, including the tree mineral nutrition at the fruit expansion stage (early June), and the fruit quality at the fruit maturity stage (mid-November). The original database was then established. Three algorithms were constructed, including the nutrient criteria generation of high-quality leaf at the fruit expansion stage, the correction fertilization of deviation from the optimum percentage (DOP), according to the standard of "yield quantification, the total quantity control, and staging control", and the compound fertilizer formula recommendation using the local fertilizer and agricultural materials supply database. Four functions were then achieved, namely, the automatic generation of high-quality leaf nutrient criteria during fruit expansion, the nutritional assessment of citrus orchards, the recommendation of available nutrient formulations, and the recommendation of compound fertilizer formulations. The system was distributed to the growers, government agencies, and system administrators with the different permissions using role-based access control (RBAC). A series of validation experiments were carried out on the nutrient expert system for the citrus fertilization recommendation at the early stage of fruit expansion in 2021. Two circus orchards were selected, where the chemical fertilizer was applied in the Longan Town, whereas, the organic fertilizer was in the Chongwang Town. The average low-, middle-, and high-yield plantations were taken as the system target yields. The effective formula of nutrient correction was used to generate three schemes of recommended fertilization for two orchards, labeled as the RF1, RF2, RF3. The FP control groups were marked as the experience fertilization schemes for the citrus orchards in Longan and Chongwang Town, respectively. The results showed that the RF2 treatments for two orchards performed the best with the average yield of 35.71 t/hm2, particularly serving as the recommended fertilization scheme. Specifically, the RF2 treatment for Longan was reduced by 40.3%, 43.6%, and 1.3% in the nitrogen (N), Kalium (K), and potassium (P) inputs, respectively, compared with the chemical experience fertilization schemes. By contrast, the RF2 treatment for Chongwang was reduced the N, K and P inputs by 27.1%, 30.8%, and 78.8%. Those two RF2 treatments were achieved in the optimal purpose of "Fertilizer reduction". At the same time, the treatments can be expected to effectively avoid the delays in the fruit coloring and the low overall fruit quality that caused by the excessive and imbalanced chemical fertilization inputs. The low inputs of N and P fertilizers can be alleviated the small fruit sizes and delayed fruit pulp color, due to the empirical organic fertilizer application. Therefore, the nutrient fertilization recommendation system can be promising potential to promote the nutrient correction formula fertilization for commercial citrus industry.