Mandarin 'Satsuma Xie Shan'

Citrus reticulata subsp. unshiu (formerly Citrus unshiu) is a mandarin tree resulting from a mutation that occurred in 1429 in Japan. The fruit is a sweet and usually seedless mandarin, popular in Japan as mikan, a name also used in France and Belgium. It is called satsuma mandarin or unshu-mikan tangerine in many English-speaking countries, satsuma in the United Kingdom, and mandarin or tangerine in Canada, less commonly satsuma mandarin or satsuma orange.

Satsumas are early, productive mandarin trees; the first fruits (Hashimoto and Miyamoto cultivars in Japan) are harvested from early September to December in the northern hemisphere, from March to May in the southern hemisphere, in other words 2 months before Mediterranean mandarins or ponkan. This is why the great cultivation of satsumas quickly spread to California, Florida, Brazil, Spain, Italy and Morocco. In these countries, they are harvested green since night temperatures are still regularly above 14°C, then treated (degreening), generally by cold or by ethylene, to make the color of the pericarp orange, like the Western consumers demand.

In Asia, the fruits are often sold green, or green with an orange base (the maturity of the pulp is independent of that of the pericarp in citrus fruits). Inside, the pulp is a beautiful bright orange. Cutting these green satsumas in half is a pleasure for the eyes. Their consumption is always preceded by at least a week of rest after harvest, generally at 20°C, rest which gives a sweeter fruit, although the mandarin is not a climacteric fruit.

Signs of maturity are soft concave base, shiny pericarp with open pores, high fruit density (heavy fruit). Over-maturity is observed when the mesocarp (bark) no longer adheres to the quarters.

The satsuma mandarin is not a ponkan (Citrus tangerina Tanaka), a hybrid mandarin reminiscent of orange. The ponkan variety is later (December, January in Japan) and originates from tropical Asia, common in China and also produced in Japan (cultivars Ota, Morita, Yoshida, and Imazu), and in large cultivation in Taiwan where it is popular.