A German botanist once reported radishes weighing 45 kilograms
Most radishes are ready to pull within a month and fit in the palm of a hand. Yet in 1544 a German botanist described roots of 45 kilograms and nearly a metre long. Only one variety still reaches that size today: Japan's Sakurajima radish, grown near a volcano.
The radish is a member of the mustard family, and while its swollen taproot gets the attention, the whole plant can be eaten, from leaves to young seed pods. Its bite comes from chemistry. When tissue is damaged, glucosinolates meet the enzyme myrosinase and produce sharp isothiocyanates, and the strength varies with growing conditions, so homegrown roots can be notably fiercer than shop-bought ones.
Colour is equally chemical. Skins run from white through pink, purple, yellow and green to black, while the flesh usually stays white. Anthocyanin pigments do the work: pelargonidin gives red varieties their hue and cyanidin the purple ones. Small salad types have roots about 2.5 centimetres wide, whereas long winter forms such as daikon can reach 60 centimetres.
Where it came from is murky, because archaeology offers almost nothing. Southeast Asia is the tentative homeland, the only region where truly wild forms turn up, with South Asia, central China and Central Asia serving as later centres of development. Radishes appear in writing by the third century BC, and Greek and Roman farmers of the first century AD already distinguished mild, sharp, round and long kinds. It was also among the first European crops carried to the Americas. The big white East Asian type was developed in China, even though the West associates it with Japanese daikon because Japan bred and exported it on a larger scale.
Speed is the radish's great virtue. Seeds sprout in three or four days in warm, moist soil, and a crop usually matures in 3 to 4 weeks, stretching to 6 or 7 when it is cold. Left too long in the ground, the roots turn tough and bitter, which is why gardeners sow a fresh batch every week or two.
Source: Radish
