Iman Ali Sarder paused by the side of the road outside this village northeast of Dacca, holding up an old black umbrella with a caraved, wooden handle to shade himself from the blazing sun.

The 67-year-old farmer listened stoically to a visitor's question, but as he answered a tear welled up in the corner of his eye and began to roll down his wizened, gray-bearded face.

"It is as if we are now left orphans," he said. "I doubt whether any other president will go from village to village, door to door as he did. It will probably be very difficult to replace him."

While the assassination a week ago of Bangladesh's president, Ziaur Rahman, has left the capital in a mood of sorrow and uncertainty, at the village level the feeling is closer to despair.

In a land where much of the population lives constantly on the margin of subsistence, Zia's death illustrates the impact one man can have on the economic life of a Third World country.

While critics complain that the young general often pursued his goals with a dictatorial, sometimes ruthless, hand and tolerated too much corruption among his associates, he is generally credited with bringing new dynamism to development efforts.

Thus for poor villagers like Sarder, the death of Zia, as Ziaur was known here, is more than just the passing of a political leader. For them it could mean economic stagnation, and that could spell the difference between plenty and hunger.

The problem is even more acute because Zia's death coincides with a tapering off of foreign aid commitments because of Western economic difficulties. And even the reduced commitments could be jeopardized, aid officials say, if the military takes over and reverses democratic reforms begun by Zia after he came to power following a series of military coups in 1975.

According to aid experts, Western assistance to Bangladesh has not grown in real economic terms for the last two years.

Moreover, although the important sector of commodity aid shows a $58 million increase next year, total Western aid commitments for 1982 fall nearly $400 million short of this year's $1.9 billion level, and aid experts say there is little chance that others donors will make up the gap.

Part of the problem is that Bangladesh has budgeted $2.6 billion in foreign aid for the next fiscal year, a figure that aid officials consider unrealistic given tighter Western budgets.

Even without these higher expectations, the failure of aid levels to increase in real terms could have serious consequences in a country already one of the poorest in the world. Some economists foresee an economic slowdown, which in Bangladesh can mean not only more unemployment but food shortages, malnutrition and political instability.

"There is nothing more political in this countryf than food," one official said.

In addition, the death of the 45-year-old president raises questions about the future of population control, which he considered to be the country's primary long-range problem because of its serious economic consequences.

With more than 90 million inhabitants, Bangladesh already ranks as the world's eighth most populous country even though it is slightly smaller than Wisconsin.

This makes it the most densely populated country in the world apart from city-states such as Hong Kong and Singapore. According to U.S. statistics, a population density in America that matched Bangladesh's average 1,530 persons per square mile would be equivalent to the entire world's current population living in the continental United States.

Moreover, Bangladesh's population is growing at a rate of 2.8 percent, one of the highest on earth. For this reason, Zia had been pushing a nationwide family planning program that reportedly had been making some gains despite the opposition of influential Islamic fundamentalists.

For villagers such as Sarder, Zia's greatest contribution was his tireless traveling to implement and supervise rural development projects. One of his leading priorities was a relatively simple program of canal digging.

Because the timing of a few weeks of rainfall in Bangladesh can practically mean the difference between feast and famine, the canals serve the key function of providing irrigation water in times of drought and carrying off flood water when the monsoons are particularly heavy, Bangladeshi officials say. In addition, the canals are used for fishing and the transportation of commodities in small boats.

"These projects depend on constant supervision," Sarder said. "Now we have more roads, more canals, and we get a better price for our goods."

So great was the grief over Zia's death in a short-lived Army rebellion May 30 that in Sarder's village of Mirkundi, five miles south of Sonargaon, "nobody slept or ate anything for two days until we heard what happened to his body," Sarder said. The president's bullet-riddled corpse was recovered when the rebellion collapsed two days later.

Sarder said he deeply regretted that he could not afford the 20 taka (about $1.17) it would have cost him for transportation to attend Zia's funeral in Dacca about 20 miles away, but, he said, his brother went on behalf of the family.

Wearing a pink shirt, black plastic slippers mand a green lungee , the traditional wraparound skirt worn by most men here, the old farmer struggled to keep his composure.

"I feel so sorry about him," Sarder said. "We were almost starving, but these projects have opened the villagers' eyes. Now they don't move to the towns; they stay and cultivate the crops."

Indeed, the specter of starvation still looms large over Bangladesh, and many villagers retain painful memories of the famine that claimed thousands of lives in 1974.

In Sonargaon, for example, a small private art gallery in the dark foyer of a crumbling two-story building includes several paintings depicting the misery of hunger. One of them shows a husband, wife and child, all with skinny limbs and distended bellies, sharing a meager bowl of rice.

Formerly the capital of the kingdom of Bangal during the 14th century, Sonargaon has long since fallen into disrepair. The elaborate friezes and brickwork of its once ornate buildings are crumbling with age, and majestic houses stand eerily abandoned, like memorials to some lost civilization. The population has dwindled to about 1,000, making the place too small to put on most Bangladeshi maps.

In recent years, however, some efforts have been made to revive the village and restore some of its buildings. Besides its private art gallery, Sonargaon now boasts a handicraft center started two years ago by the American Save the Children program. Now run independently, the center sells handicrafts made by village women, including pottery, dolls, batik and even Bionic Woman T-shirts. In addition, there is a folk art museum opened by Zia.

The measure of pride generated by even these small achievements -- and the uncertainty now that Zia is gone -- are reflected by villagers in talking about their future.

"We were known as the sick man of the world," said Shajad Ali, 85, as he sat in a market stall outside the village entrance. "But because of Zia our prestige has gone up. If we're lucky, we'll get another man like him. But if we're unlucky, we will have a lot of suffering."