Common or Round Oranges (e.g. cultivars (c.v.) 'Hamlin', 'Valencia', 'Shamouti', ‘Pera’) are the most important group commercially. They are mainly grown in more humid climates and widely used for processing. The USA and Brazil are the largest producers of common or round oranges.
Navel Oranges (e.g. c.v. 'Washington', 'Lane Late', 'Navelina') are larger than common oranges. They are mainly sold for fresh fruit as they contain limonin, which results in a bitter taste after processing.
Navel oranges are particularly susceptible to environmental stress. For example, high temperatures of 95-104°F during blossom production, especially in humid climates, can result in loss of fruitlets. Moisture stress may also result is significant yield loss.
The highest quality navel oranges are found in Mediterranean type climates which feature hot days and cool nights (e.g. Spain, Israel, Australia, South Africa, or the coast of California).
Pigmented (Blood) Orange production is limited primarily to Mediterranean type climates for the fresh market. Hot days and cool nights result in fruit with a deep red flesh color.
Mandarins can be divided into "common mandarins" (including "tangerines" and "clementines"), the Mediterranean group and the Satsuma group. The natural hybrids - crosses of mandarins and oranges (e.g. 'Temple', ‘Murcott’ and ‘Ortanique’) and artificially bred hybrids of mandarins and grapefruit or pomelos (Tangelos) - are also included in this category.
Mandarins are produced primarily for the fresh fruit market and as segments for canning (mainly satsumas). They are easier to peel and often contain fewer seeds than oranges. Deep colored juice can be blended with other citrus juices to improve the color.
The common mandarin has a close physical connection between the peel and the fruit. As a result, common mandarins are less prone to transportation damage and more tolerant of long-term storage. China, Spain and Japan are the leading producers of mandarins. The common mandarin group, known as ‘Clementine’, is particularly well adapted to the Mediterranean region.
Satsumas (e.g. c.v.Sunshui Marc.) have fruits which are larger and easier to peel than most other types of mandarin. They are usually oblate or obovate in shape. Satsumas are well suited for cool subtropical areas and have a lower heat unit requirement for fruit maturity compared to other mandarins.
The Mediterranean mandarin is also known as Willowleaf mandarin. This mandarin is rarely grown as the fruit is small and bruises easily because of its loose, puffy skin.
Grapefruit and Pomelo
Grapefruit production is more limited than that for sweet oranges or mandarins. Almost half of the world's production is in the USA.
Top quality grapefruit has a high heat requirement, so is best suited to tropical and hot, humid, subtropical climates. Crops grown in Mediterranean climates are more acid, have lower juice content and thicker peels.
Pomelos are primarily produced in China and south east Asia. They are similar to grapefruit but have a sweeter taste and thicker peel.
Lemons and Limes
Lemons and limes are the most frost-sensitive of all commercial citrus species. Minimum ambient temperatures should not drop below freezing point.
While limes grow well in the tropics, lemons are mainly produced in semiarid to arid climates because they are not well adapted to humid regions where disease pressure can be great. Mexico, India and Argentina are the leading producers of lemons and limes.
Lemons have the highest Acid content ranging from 5 to 8%, and the lowest TSS (Total Soluble Solids), from 7 to 9%. They are grown as fresh fruit and for their peel oils.
Kumquat / Limquat
Produced primarily in China and the Philippines, they are eaten fresh or candied with the whole fruit - including the peel - being consumed.