Manila — Some Asian food experts like to tell the tale of ancient Chinese emperors, including Kublai Khan, who wanted fresh vegetables. For over 2,000 years, several of the warlords helped build the 1,200-mile Grand Canal, which enabled transport of leafy greens, such as mustard cabbage, from the south to the imperial palaces of the north.
''That was one solution to the food problem in Asian cities,'' comments Ronald D. Zweig, an acquaculture expert working in Wuxi, China.
For today's Asian urban dwellers, finding or buying cheap vegetables is not so easy.
Slums bulge with poor newcomers, and while basic foodstuffs such as rice are generally abundant, essential nonstaples, such as starchy roots, edible oils, and yellow vegetables, are harder to come by.
Hunger has been appeased, but nutritional needs have not been met. ''The food situation for Asian cities will be devilish by the end of the century,'' says John E. Bardach, member of a team studying the problem at the East-West Center in Honolulu.
Dr. Bardach adds: ''Two decades ago, we said, 'Man needs bread.' Now we must say that he needs more than bread.''
The drama of success for Asia's Green Revolution, which increased rice yields spectacularly, is being overshadowed by malnutrition among the poorest urban Asians. For 30 years, Asia's biggest challenge was increasing rice production, a task successfully accomplished with hybrid rice seeds, new irrigation, and fertilizer. In the last couple of years, in fact, most Asian nations have begun to show a rice surplus during fair-weather years.
But Asia's cities, from Seoul to Bombay, are growing fast, and the flow of food to market is not keeping pace. In 1950, there were 21 cities in Asia with over a million inhabitants. By 1980, there were 81. By the year 2000, nearly 160 cities are expected to top 1 million in population. Also by the turn of the century, according to UN projections, 9 out of 14 of the world's largest cities will be in Asia.
Here in Manila, where over 2 million people endure the stench and grime of overcrowded alleys and makeshift houses in squatter slums, the deficiency of food intake among the poorest third of the population is nearly twice that of its rural counterpart, according to surveys.
Manila slum dwellers pay dearly, if they can pay at all, for the nonstaple foods transported into the cities by middlemen. In addition, cooking fuel is expensive and many mothers are forced to take jobs, leaving less time for shopping and cooking. The result: a monotonous diet for many city families (average size: 7.6 members).
The Philippine government has set up special food stores, known as kadiwa (togetherness), to meet the needs of the urban poor. Urban land owners are being required to let people cultivate unused plots.
Researchers are trying to find ways to improve the role of food hawkers and vendors, whose small carts ply the back streets, giving Asian cities a unique and memorable character - and smell. In Shanghai and Singapore, there are few food shortages, says Dr. Bardach, because the Chinese are good organizers. Other cities might learn their techniques, such as setting up contracts between vendors and farmers for advance purchase of vegetables, he says.
In the late 1970s, China allowed free food markets in a few cities and ''trade fairs'' in rural areas in an attenpt to improve the flow of food. Bargaining for such items as mushrooms and Chinese cabbage usually results in lower prices than those at state-run markets.
In Wuxi, a city of about 1 million people, the United Nations Food and Agriculture Organization has been studying how the Chinese have integrated fish, rice, pig, and duck production on small plots around the city. This intensive agriculture, which requires less land and allows farms to exist closer to urban areas, is slowly increasing in Asia.
''Chinese cities and farms have a direct linkage, a compactness and synergy.'' says Mr. Zweig. ''Fish farms on the city's periphery have an intimacy which reduces transport and also allows the city to recycle its waste immediately on the farms.''
This ''horizontal integration,'' he says, is still very undeveloped in Asia. At the same time, Mr. Zweig adds, the Chinese government's push for higher production of certain foods is resulting in less integration and thus less efficiency.
Adding to the food problems of Asian cities is the fact that general food production may not continue to increase as fast as it has in the last two decades. Although promoting more urban garden plots will help city food supplies , this is not sufficient, Dr. Bardach says.
Government must find the right balance between preserving the income of farmers and providing adequate food for the cities. ''This is very often a seesaw,'' he says, ''between the interests of farmers and city dwellers.
''It isn't as simple as building a canal for the emperor.''