In seeking to alleviate the main constraints of land and water, Chinese scientists have also made substantial progress in improving yields and water productivity. China has developed the most successful varieties of hybrid rice in the world, and more than one-third of the total rice area is planted to hybrids. More recently, scientists have developed irrigation techniques for rice that reduce water consumption by allowing intermittent drying of the paddy field, without sacrificing grain yields. The successful adaptation of aerobic rice (rice that is grown as an upland crop but still exhibits a substantial response to nitrogen fertilizer) to new areas would also allow rice to be grown in water-short environments. In the future, the construction of canals from southern to northern China may also help to alleviate water shortages in the Yellow River Basin.