Large-fruit citron

The large-fruit citron (Latin: Citrus macrolimon Tanaka) is a horticultural crop belonging to the Rutaceae family. It is a distinct species of the genus Citrus, characterized by its substantial fruit size and specific biochemical composition. This evergreen woody plant is highly valued for its aromatic qualities and its potential as a breeding stock in citrus improvement programs.

Originating from the subtropical regions of Asia, the plant thrives in areas with consistent thermal regimes and high humidity. While it is not as cold-hardy as some other citrus species, it adapts well to container gardening and greenhouse cultivation in various parts of the world. It requires a protected environment in regions where winter temperatures drop below freezing.

Botanically, the plant is distinguished by large, deep green foliage and a complex inflorescence. The fruits are typically characterized by a thick, rugged albedo and a high concentration of essential oils within the zest. Its root system is relatively fibrous and requires well-drained substrate to maintain optimal health and facilitate nutrient uptake throughout the vegetative cycle.

Optimal agrotechnical practices for Citrus macrolimon include precise moisture management and regular fertilization with micronutrient-rich formulas. The plant performs best in slightly acidic soil (pH 5.5–6.5) with excellent drainage to prevent root asphyxiation. Pruning is essential to maintain structural integrity and to maximize fruit production by promoting the growth of new fruiting spurs.

The culinary and industrial applications of the fruit include the production of essential oils, confectionery, and traditional medicinal preparations. Like all citrus, this crop is susceptible to specific pathogens and pests that must be managed to ensure productivity. Key threats include:

• Citrus whitefly
• Spider mites
• Mealybugs
• Phytophthora root rot
• Leaf chlorosis caused by nutrient deficiency