Hybrid varieties boost yields in Chinese cotton

New varieties of cotton developed in east China's Shandong province are producing results comparable to the increases in harvests of wheat, rice, and maize produced by the green revolution.

In just seven years the new varieties have trebled Shandong's per hectare yield, and last year, as farmers extended acreage, total cotton output reached 942 500 tons, or 5.6 times that of 1979. Shandong has been propelled to the position of China's largest cotton producer and exporter and accounts for about one fourth of the nation's annual output Prosperous peasants are now able to invest more in chemical fertilizer and in grain and sideline production, and an all-round growth of the rural economy is occurring as a result.

Four prefectures in western Shandong reflect the economic power of the "cotton revolution". They were designated by the state as among the ten poorest areas in China at the end of the 1970s, with large numbers of peasants depending on government relief and grain supplies. But in 1986, the four prefectures together, with a population of 22 million, sold 540 000 tons of surplus grain to the government. Between 1978 and 1986, in Linqing county in northwestern Shandong, per caput income rose from 42.3 yuan renmimbi to 441. "Cotton has brought us big fortunes," farmers say.

Shandong province, located at the lower reaches of the Yellow River, has a warm, temperate climate. With deep and fertile soil and moderate rainfall, the vast alluvial plain is ideally suited for growing cotton, but from 1949 to 1979, output was low and unstable. Per-hactare cotton yield averaged only 258 kg annually. Year after year, cotton production met only half the demand of the province's textile industry. For more than a century, Shandong grew cotton varieties known as Trice, Stoneville, and Deltapine-15, which had been introduced from the United States, and from them, the province bred new varieties, but no good strain suited to local conditions emerged. Finally, Qin Hezhen, a leading provincial official in charge of agriculture, asked, "Why can't we have varieties of our own?" His question took 15 years to answer.

Progress was slow at first. Early in 1961, the provincial Cotton Research Institute had abandoned the practice of developing better varieties through selection in favour of cross-breeding, but their 10-year efforts with hybrids still did not produce remarkable results. Then in 1971, Pang Juqin, in charge of the experiment, learned that radiation could vary the inner genes of seeds. He sent a researcher at once to the Atomic Energy Research Office in the provincial Academy of Agriculture Science, where the seeds were treated with Cobalt 60.

A year later, the first seedlings to appear amazed scientists. "Many of them were abnormal," Pang Juqin recalled. Some had incomplete "limbs," some several "heads", and some no heads at ail. "But the deformed seedlings didn't make us feel dejected," said Pang, now the vice director of the China Cotton Research Centre. The scientist discarded the abnormal strains and continued to experiment with normal ones. Three years of experiments produced better plants. Then came regional experiments that showed one new strain produced higher yields than any other strain or variety.

The strain, named SC-1 by the institute in 1976, soon began to replace foreign varieties. Four years later, in 1980, it had become the variety of choice and spread to 573 000 hectares, accounting for 77 per cent of the area sown to cotton in the province. Early that year, scientists at the provincial Cotton Research Institute wrote, and rushprinted, a 45 000 -word booklet on methods of cultivating the new strain. Some 150 000 copies of the booklet were distributed to farmers before the cotton planting season, and that year the province produced 537 000 tons of cotton, almost double the record 270 000 tons in 1973. The average per-hectare yield reached 727 kg (in terms of ginned cotton), 2.3 times that of the previous year. It has been calculated that the adoption of the new variety in China had produced a direct economic result of 5.7 billion yuan renmimbi (about US$1.54 billion) by 1984.

Then followed SC-2, SC-3, SC-4, SC-5, and SC-6, bred by scientists from the same institute, Jinan's Shandong Agricultural University and Huimin's Agriculture Research institute. All produced yields equalling or surpassing SC-1. Moreover, the fibre strength of SC-1 did not meet export quality standards, and as a result it has been replaced by SC-6, which yields 13.5 per cent more than SC-1. By 1986, the sown areas of SC-6 in Shandong extended 705 000 hectares, 70 per cent of the total cotton acreage. SC-6 became a standard variety; that means that a new strain can be confirmed as excellent only if its quality compares favourably with SC-6.

In the last two years, many buyers have come to Shandong from Canada, Japan, the USSR, Europe, Hong Kong, and Southeast Asia. The province exported 140 000 tons of cotton in 1986-one-fourth of China's total cotton exports. Contracts for exporting 210 000 tons of cotton have already been signed by the province this year.

However, SC-6, like SC-1, still has its weak points: small seeds and poor disease resistance, agronomists say. However, some promising new strains are being tested. Early this year, China set up its first cotton research centre in Shandong with 2 million yuan renminbi (about $540 000) invested by the province and $693 000 contributed by the United Nations Development Programme (UNDP).

The centre will carry out research, sponsor academic exchanges between scientists of China and other countries, train technical personnel, and offer consulting services. It brightens prospects for further development of cotton production and the promotion of the textile industry in Shandong province as well as elsewhere in China, which has become the world's leading cotton producer since 1982 (see table).

Zhu Wenzhi and Hou Dan