Rough lemon (Citrus jambhiri) is a distinctive citrus fruit known for its bumpy, irregular skin. It serves a dual purpose in horticulture: as a direct source of acidic juice and as a widely used rootstock for grafting other citrus varieties.
Understanding Rough Lemon
Rough lemon is a citrus hybrid believed to have originated in the Himalayan foothills of India, where it still grows wild. It is a cross between a mandarin orange and a citron. The fruit has a rough, bumpy, and irregularly shaped rind that ranges from lemon-yellow to brownish-orange when ripe. The rind is medium-thick and easily separable from the pulp.
Internally, the fruit contains about ten segments, a large, hollow central axis, and numerous small seeds. The flesh is light yellow to pale orange and is moderately juicy. Rough lemon is characterized by its highly acidic flavor and strong citrus aroma, making it considerably more sour than a common Eureka lemon.
Cultivating Rough Lemon
Rough lemon trees thrive in full sun exposure, requiring ample light for optimal growth and fruit development. The ideal soil is well-draining, with a pH ranging from slightly acidic to neutral, typically between 5.5 and 7.5. While they tolerate alkaline soils and moderate salinity, proper drainage is important to prevent root rot. Consistent moisture is beneficial, especially during dry periods, but avoid overwatering. Rough lemon trees are notably drought-tolerant once established due to their extensive root system, which helps them forage for soil nutrients.
Rough lemon prefers warm climates and exhibits relative cold hardiness compared to some other citrus types, though it can be sensitive to frost. Fertilization should follow general citrus guidelines to ensure the tree receives necessary nutrients for vigorous growth. Pruning helps maintain the tree’s shape, promotes air circulation, and supports overall health, contributing to better fruit production. Planting can be done from seed or nursery stock, with nursery trees on rough lemon having high nutritional requirements due to their fast growth.
Uses and Applications of Rough Lemon
Rough lemon primarily serves as a rootstock for other citrus varieties. Its vigorous growth promotes strong tree development and a larger canopy, making it a foundation for many commercial citrus orchards. This rootstock is valued for its drought tolerance, adaptability to various soil types, including sandy or low-fertility soils, and its ability to encourage earlier fruit bearing in grafted trees. It is highly compatible with lemon varieties, as well as oranges, grapefruit, and most mandarin types, although it may be incompatible with some specific mandarins. Its robust root system enhances mineral and nutrient absorption for the scion.
Culinary applications of rough lemon highlight its intense acidity and strong flavor. The fruit can be juiced for lemonade, used in marinades for fish or meat, and incorporated into salad dressings. Its tartness makes it suitable as a souring agent in various dishes where a pronounced lemon taste is desired. In certain regions, particularly India and South Africa, it is consumed as a table fruit or as a substitute for other limes in pickles and for garnishing.
Common Rough Lemon Challenges
Rough lemon trees can encounter several challenges related to pests, diseases, and environmental stress. Common citrus pests such as aphids, scale insects, and citrus leafminers can affect rough lemon.
Regarding diseases, rough lemon is highly susceptible to Phytophthora root rot and gummosis. It is also sensitive to citrus nematodes and lemon scab. While susceptible to some diseases, rough lemon rootstock is tolerant to citrus tristeza virus and exocortis. However, it can be highly susceptible to citrus greening disease.
Environmental stress can manifest as nutrient deficiencies or issues related to improper watering. Overwatering can lead to root rot, while insufficient watering can cause wilting.