To fundamentally explore the correlation between crop nutritional quality and mineral elements, specific tests and accurate analysis were carried out on all organs and root soil of watermelon (Citrullus lanatus). The results showed that the distribution patterns of nitrogen and phosphorus at watermelon maturity were similar, and the average nitrogen and phosphorus contents were in the orders of leaf and seed > stem, peel, root > pulp > root soil, and peel > seed > root, stem, leaf > root soil > pulp, respectively. From the perspective of element geochemistry, biophile and lithophile elements had the strongest correlation with nitrogen and phosphorus, and watermelon did not antagonize soil nitrogen and phosphorus uptake. The prediction model of nitrogen translocation factor in watermelon organs to total acid was established by partial least squares with R2 = 0.81. Significantly, when the isometric log-ratio of nitrogen to phosphorus in watermelon leaves was 1.97 to 2.19, the watermelon pulp showed better quality with total acid > 0.5%, total sugar > 5% and soluble solids > 10%. Therefore, the characterization of nitrogen and phosphorus in watermelon leaves can serve as a non-destructive analysis to predict watermelon fruit quality.

中文翻译：

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土壤-西瓜（Citrullus lanatus）系统矿质元素（氮、磷）与营养品质关系的探索

为从根本上探究作物营养品质与矿质元素的相关性，对西瓜（Citrullus lanatus）各器官和根土进行了专项试验和精准分析。结果表明，西瓜成熟期氮、磷的分布规律相似，平均氮、磷含量依次为叶和种子>茎、果皮、根>果肉>根土，果皮>种子>根、茎、叶>根土>果肉。从元素地球化学角度看，亲生物元素和亲石元素与氮磷的相关性最强，西瓜对土壤氮磷吸收没有拮抗作用。采用偏最小二乘法建立西瓜各脏器氮转运因子对总酸的预测模型，R2=0.81。值得注意的是，当西瓜叶片氮磷等距对数比为1.97~2.19时，西瓜果肉品质较好，总酸>0.5%，总糖>5%，可溶性固形物>10%。因此，西瓜叶片中氮磷的表征可以作为预测西瓜果实品质的无损分析。