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Bioscience in brief

Plant genetics and crop breeding

How do you develop a new crop variety by conventional breeding?


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The creation IR36 – the semi-dwarf rice variety that became one of the most widely planted food crop variety worldwide in just a few years

By cross-breeding  the rice variety IR8 with 13 parent varieties from six nations (India, Indonesia, China, Vietnam, the Philippines, and the USA), Dr Khush developed IR36, a semi-dwarf variety highly resistant to a number of the major insect pests and diseases afflicting rice fields in Asia, and with increased tolerance to environmental stresses such as drought. IR36 matures rapidly – 105 days compared to 130 days for IR8 and 150–170 days for traditional types – and produces the slender grain preferred in many countries. The combination of these characteristics soon made IR36 one of the most widely planted cultivars of the Green Revolution. About 110,000 km² were planted with IR36 worldwide in the 1980s, a success which Dr Khush topped with IR64 and again with IR72 in 1990.