Brittle-stem rice: a new variety from the Chinese Academy of Sciences tackles the straw-returning problem

The reporter learned from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences that a new "brittle-stem" rice variety, Kefujing 7, jointly bred by the institute's Institute of Technical Biology and Agriculture Engineering and a local seed company, recently passed the brittle-stem characteristic identification at harvest time, completed by experts organized by the Anhui Provincial Seed Management Station. The expert panel concluded that this new rice variety not only has straw that is easy to crush and suitable for returning to the field, but also combines high yield, resistance to pests and diseases, and the trait of being "brittle but not lodging."

Authoritative experts from the fields of agronomy, cultivation, soil and agricultural machinery recently inspected experimental demonstration fields of Kefujing 7 and the conventional comparison variety Tianxie 1 at Longkang Farm in Huaiyuan County, Anhui. Both varieties were at the yellow-ripe stage, growing normally, with no pests or diseases. Comparison showed that Kefujing 7 has stronger straw rigidity and breaks relatively more brittlely, and the field growth was uniform and consistent with no lodging. On-site harvesting with a Chery Heavy Industry "Guwang" combine harvester (with the crushing device removed) showed that Kefujing 7's straw crushed well, with straw under 10 cm in length accounting for about 60 percent, more than 4 times that of Tianxie 1.

Many places are still troubled by the straw-returning problem. Agricultural experts say that because of the tight cropping schedule and the difficulty of crushing straw, farmers can only burn it. Experts at the Institute of Technical Biology of the Chinese Academy of Sciences developed brittle-stem rice through ion irradiation mutation technology. In recent years, by extensively screening rice mutants with different breaking resistance, they have bred the new variety Kefujing 7, which is not brittle in the early stage, shows stem brittleness at maturity, and is brittle but not lodging, and have carried out trial plantings in several major agricultural counties.

Field planting results show that Kefujing 7 has excellent agronomic production traits, with a yield of about 600 kg per mu under normal cultivation conditions, good resistance to rice blast, and excellent grain quality. Because of changes in the straw's lignin and cellulose, its straw degrades about 1/4 faster than normal rice straw. In addition, as feed for ruminants such as cattle and sheep, brittle-stem rice straw has reduced cellulose, high nutritional value, good palatability and is easy to digest, broadening the ways straw can be used.

According to reports, Kefujing 7 is currently participating in the green channel for variety approval of the Anhui Provincial Agricultural Commission, with yield comparison trials, pest and disease resistance identification and production trial demonstrations in many places across the province, aiming to more comprehensively evaluate the variety's high-yield performance, stress resistance, quality, brittle-stem and lodging resistance, and lay the foundation for early entry into large-scale production.