Field studies were conducted to compare the barnyardgrass suppression by four U.S. (‘Starbonnet’, ‘Kaybonnet’, ‘Lemont’, and ‘Cypress’) and three highly competitive, high-yielding Asian cultivars (‘PI 312777′, ‘Guichao’, and ‘Teqing’). The economic consequence of applying less than the recommended propanil rates to these cultivars was also evaluated. Grain yields increased, and barnyardgrass biomass decreased with increasing propanil rates. With or without propanil, the Asian rice cultivars consistently suppressed barnyardgrass more and consequently produced higher grain yields than did U.S. cultivars. The economic benefit derived from propanil application was less for Asian than for U.S. cultivars. Asian cultivars produced higher rough rice yields, resulting in higher net returns (not adjusted for milling) than did the commercial cultivars, but this advantage was usually reduced when adjusting for their lower milling yields. These results suggest that growing weed-suppressive Asian rice cultivars in conjunction with reduced herbicide rates could be an effective and economical weed management strategy for rice in the southern United States. However, first, their plant type and grain quality characteristics must be improved.

A complete demand system of Chinese rural households is estimated using a twostage LES-AIDS model and pooled provincial and time-series data from 1982 to 1990. For commodity groups (food, clothing, fuel, housing, and other commodities), demand is price-inelastic. Housing and other commodities are luxury goods, while clothing and food are necessities. Within the food group, price elasticities range from -0.005 to -0.63. Expenditure elasticities are lower for grains and higher for meat, tobacco, and alcohol. The results imply a gap between food demand and supply growth. Therefore, China will face pressure to import food.

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In this paper we evaluate economic and demographic effects on China's rural household demand for nine food commodities: vegetables, pork, beef and lamb, poultry, eggs, fish, sugar, fruit, and grain; and five nonfood commodity groups: clothing, fuel, stimulants, housing, and durables. A two-stage budgeting allocation procedure is used to obtain an empirically tractable amalgamative demand system for food commodities which combine an upper-level AIDS model and a lower-level GLES as a modeling framework. The results indicate that the slow growth of food consumption in China during the latter half of the 1980s is a result of income stagnation rather than consumption saturation. Growth in the demand for better food and shelter by Chinese rural households will continue to be a major concern. Copyright 1996, Oxford University Press.

A shadow‐price profit frontier model is developed to examine production efficiency of Chinese rural households in farming operations. The model incorporates price distortions resulting from imperfect market conditions and socioeconomic and institutional constraints, but retains the advantages of stochastic frontier properties. The shadow prices are derived through a generalized profit function estimation. The shadow‐price profit frontier is then estimated and an efficiency index based on the estimated profit frontier is computed and decomposed to household characteristics. Empirical results using data from China's Rural Household Survey for 1991 reject the neoclassical profit maximization hypothesis based on market prices in favor of the general model with price distortions. Farmers' resource endowment and education influence their response to the market restrictions, thus alter their performance in terms of efficiency. The estimated efficiency index ranges from 6% to 93% with a sample average of 62%. Households' educational level, family size and per capita net income are positively related to production efficiency. Households living in mountain areas or with family members employed by the government or state industries are relatively inefficient. Reducing market intervention, allowing right of use of farm land to be transferred among households, encouraging migration of excess farm labor, and promoting farmers' education will improve rural households' efficiency in agricultural production.

A shadow-price profit frontier model is developed to examine production efficiency of Chinese farm households. The model incorporates price distortions but retains the advantages of stochastic frontier properties. The shadow prices and shadow profit are derived through a behavioral profit function. Empirical results using household survey data show that the conventional assumption of profit maximization based on market prices is inappropriate. Farmers' resource endowment and education influence their allocative efficiency. Family size, per capita net income, and family members operating as village leaders are positively related to households' production efficiency. Reducing market distortions should increase farm households' production efficiency. Copyright 1996, Oxford University Press.

A shadow-price profit frontier model is developed to examine production efficiency of Chinese rural households in fanning operations. The model incorporates price distortions resulting from imperfect market conditions and socioeconomic and institutional constraints, but retains the advantages of stochastic frontier properties. The shadow prices are derived through a generalized profit function estimation. The shadow-price profit frontier is then estimated and an efficiency index based on the estimated profit frontier is computed and decomposed to household characteristics. Empirical results using data from China's Rural Household Survey for 1991 reject the neoclassical profit maximization hypothesis based on market prices in favor of the general model with price distortions. Farmers' resource endowment and education influence their response to the market restrictions, thus alter their performance in terms of efficiency. The estimated efficiency index ranges from 6% to 93% with a sample average of 62%. Households' educational level, family size and per capita net income are positively related to production efficiency. Households living in mountain areas or with family members employed by the government or state industries are relatively inefficient. Reducing market intervention, allowing right of usc of farm land to be transferred among households, encouraging migration of excess farm labor, and promoting farmers' education will improve rural households' efficiency in agricultural production.

The recent rural reforms in China have had great cffects on agricultural production and productivity as weil as rural household consumption. While much has been writtcn on production and productivity cffccts of these reforms, very few Chinese studies have attcmptcd to analyze the changes in rural consumption patterns. This paper uses a dynamic AlOS model to estimate various food demand parametcrs for Chinesc rural households using rural household survey data recently rcteased by the China State Statistieal Bureau. The results show that ail important food commodities including riec, wheat, coarse grains, vegetables, meat, tobacco and alcohol have positive expenditure e!asticities. Riec, wheat and coarse grains arc necessities, while meat, vegetables, alcohol and tobacco arc Iuxurics. The expenditure clasticitics for riec, coarse grains and tobaceo arc declining, but those for whcat, meat, vegetables and alcohol are increasing. As per capita income rises and population incrcases, the dcmand for these items will continue to increase. Therefore, China must continue to increase its food production by a grcatcr rate in the future in order to avoid food shortagcs, 1 For more details on production and productivity effccts of the Chinese rural reforrns refer to Lin (I988, 1(92), Fan (I (91) and Sicular (I (88).