Identifying the constraining factors of production and yield gap is very important. Therefore; this research was performed to identify the production constraining factors of local rice cultivars. All management practices from nursery preparation to harvesting stages for 100 paddy fields of local rice cultivars were recorded through field studies, in Sari, from 2015-2016. In the CPA, the actual and calculated potential yield were 4495 and 5703 kg/ha, respectively and the gap was 1221 kg/ha. The yield gap caused by number of top-dressing variables was 324 kg/ha, equal to 27% of the total yield gap. The yield gap related to previous year of legumes cultivation was 218 kg ha-1, equal to 18% of the total yield variation. Among the 10 variables entered in the CPA model, the effects of top-dress fertilizer application and its application frequency and foliar application were remarkable, which could compensate a significant part of the yield gap (444 kg/ha, 37% of total) in the farmers’ fields by managing these variables. According to boundary line analysis (BLA) finding, actual yield mean on the basis of optimal limit related to 12 variables under study was 5369 kg/ha, with 881 kg/ha yield gap . Mean relative yield and relative yield gap for 12 variables (transplanting date, seedling age, number of seedlings per hill, planting density, nitrogen and phosphorous per hectare, nitrogen before transplanting, harvesting date, lodging problem, pest problem, diseases problem and weeds problem) were 83.64 and 16.35 kg/ha, respectively. Based on the finding, it can be stated that the model precision is appropriate and can be applied for both estimation of the quantity of yield gap and determining the portion of each restricting yield variables.

Today, human capital has an important role in growth and economic development. In recent decades, economic studies of education, specially higher education, have analysed the educational process through production function specification. A major problem of studies in higher education is the complexity which is introduced by joint production. Common sense is that higher education, and universities in particular, produce three outputs jointly, education, research and public services. In this study, it is assumed that the universities produce only education.This research by considering 21 state Universities as single output production units (as education procedures) investigates the relationship between human resources and physical resource for period of 1373-1377.Using a three - equation simultanious model, the university output quality, the university student admissior policy and the teaching staff quality are treated endognously. The results that have been generated by weighted least-squares (WLS) illustrate that in recent years, the student admission policies has decreased the university output quality. But the teaching staff quality as a human resource, has increased the educational production quality.In the other hands, physical resources, for example, educational department budgets, educational aid budgets and self-financed budgets have increased the educational production quality. Research budgets have declined educational activites domain and administrative; budgets have declined educational output quality. So, this is obvious that output variable reflects quantity and quality of educational production. Finally, the results are included the suitable offers for policy decisions in area of higher education.

Due to the limited water resources, the deficit irrigation would be one of the most relevant methods in this situation. The purpose of this study was to optimize the water consumption and nitrogen level simultaneously. In this research, two different irrigation strategies of 75% (I2), 50% (I3) and 25% (I4) of water requirement and full irrigation (I1) and different nitrogen treatments with application of 150 (N1), 112. 5 (N2) and 75 (N3) Kg/ha was investigated on yield production. Optimization of water and nitrogen showed that the proper yield function of soybean is the transcendental model among linear, Cobb-Douglas, quadratic and transcendental models. The optimum water and nitrogen levels of soybeans under water-nitrogen stress conditions was estimated 230 and 216. 5 mm of water and 150 kg of nitrogen in two years. The results showed that the yield production was increased by 33. 28% in N3 with deficit irrigation treatment (I2) as compared with full irrigation method.

Concerning the importance of production of pipes in oil and gas industries, the estimation of oil and gas pipe production function is of great interest. To this end, Ahvaz pipe mill, the largest pipe mill in Iran, has been chosen as a case study and its production function during 1979-2003 has been estimated. This estimation is based on time-series techniques, using unit root tests, cointegration and error correction models. The results suggest that Cobb- Douglas production function is more compatible with theory of production function & the data them alternatives. The empirical findings show that the error correction term is 0.96 as well as labour elasticity and capital elasticity are 0.58 and 0.53, respectively. The world test result indicate that there is increasing return to scale.

Various studies estimating the production functions (P.Fs) in both agricultural and industry sectors have been conducted so far. Most of these studies have relied on formal P.Fs, such as Cobb-Douglas, Translog and Constant Elasticity Substitution P.Fs; and they have considered mines sector in less extent. The aim of this paper is an estimation of P.Fs in different provinces of the country over the 1996-2002 periods. To do this, various P.Fs were specified in which Cobb-Douglas P.F gave us economic theory-based results. According to our calculations based on Pooled Least Squares (PLS) and Generalized Least Squares (GLS), Iranian mines have labor-intensive structure; and also P.F. coefficient (the sum of elasticities) is greater than one indicating the increasing returns to scale in mines production. So, increased number of employees in both assembly and support lines; and also upgraded level and amount of developmental and exploratory investments can play an effective role in mineral production which is demanded by construction, industry, auto-making, medicine, transport and other sectors.