The share of agriculture in the gross domestic product of (GDP) in many countries has been declining. Yet agriculture still plays an important role in many developing country economies as the sector is a source of employment for an estimated 60 to 70 percent of the population in most developing countries. Most agricultural production in developing countries is associated with low productivity and poor income due to high dependence on subsistence farming with minimal technology as well as poor access to markets. Contract farming is believed to improve productivity and income because it facilitates coordination between farmers and other actors in terms of production, processing and marketing of agricultural products. The effect of contract farming on income and productivity has been a subject of increasing research but most of the available information is aggregated and there is lack of detail analysis on the mechanisms of the effects. We conducted a systematic literature review of contract farming studies using keyword search strategy Econlit, Scopus and Science Direct search engines. The keywords "contract", "farming", "contract farming" were used in combination with the words "income", "productivity", "quantitative", "qualitative", "agriculture", "aquaculture", "developing", "developed" and "country". Initially a selection criteria for the potential studies were defined and used by the authors separately to select and rank 20 studies by importance. In the second round, the authors were provided with their own rankings as well as with the results of the first round for others. A revision of ranking was requested. Based on this approach a shortlist of 23 studies emerged; 11 on the impact of contract farming on productivity and 12 were on the effects of contract farming on income of producers. We conduct an in depth analyses of the selected studies and present evidence on the effect of contract farming on farmer productivity and income. Almost all the selected studies analyzing the impact of contract farming on income argue that farmers' on contract farming schemes experienced some increase in their income. JEL Classifications: Q12, Q18

This article aims to explore the relationship between economic growth, energy consumption and CO2 emissions of five Central Asian countries between 1998 and 2017. We found that per capita energy consumption has a positive relationship with per capita GDP, while per capita CO2 emissions negatively affect per capita GDP in Central Asia. Further, per capita GDP has a negative impact on per capita energy consumption in the region. Results reflect that the economic growth of Central Asian countries still heavily depends upon energy consumption. However, CO2 emissions in this region should be reduced because it has been defined as a determinant leading to a decrease in economic growth. In the short run, we also found that there is a directional relationship running from per capita GDP to per capita energy consumption and per capita CO2 emissions; and from per capita energy consumption to per capita GDP. Results show that there is a co-integration among variables in the long run. Finally, policies are recommended to enhance economic growth and achieve sustainable development in Central Asia.

Ri chicken is the most popular backyard chicken breed in Vietnam, but little is known about the growth curve of this breed. This study compared the performances of models with three parameters (Gompertz, Brody, and Logistic) and models containing four parameters (Richards, Bridges, and Janoschek) for describing the growth of Ri chicken. The bodyweight of Ri chicken was recorded weekly from week 1 to week 19. Growth models were fitted using minpack.lm package in R software and Akaike’s information criterion (AIC), Bayesian information criterion (BIC), and root mean square error (RMSE) were used for model comparison. Based on these criteria, the models having four parameters showed better performance than the ones with three parameters, and the Richards model was the best one for males and females. The lowest and highest value of asymmetric weights (α) were obtained by Bridges and Brody models for each of sexes, respectively. Age and weight estimated by the Richard model were 8.46 and 7.51 weeks and 696.88 and 487.58 g for males and for females, respectively. Differences in the growth curves were observed between males and female chicken. Overall, the results suggested using the Richards model for describing the growth curve of Ri chickens. Further studies on the genetics and genomics of the obtained growth parameters are required before using them for the genetic improvement of Ri chickens.

Interest in contract farming is increasing because of its potential as an alternative channel for linking producers to international markets. However, there is limited knowledge on contract farming of tea production in Viet Nam, especially in more inaccessible provinces where tea production plays an important role in generating employment, improving livelihood and reducing poverty. In the present paper, the impact of contract farming on productivity is reviewed in Pho Tho province, a major tea production area that has not been the focus of any other studies. Using survey data, an analysis is conducted on the factors affecting tea productivity and the impact of contract farming on tea productivity in the province. The results indicate that the impact of factors on tea productivity is ambiguous. They also indicate that technical efficiency of tea production of contracted farmers is higher than that of other types of farmers by almost 5 per cent and that contract farming has a positive influence on tea productivity in the province. Because of different climatic conditions, the results from this study are not generalizable across Viet Nam, but they can be applied in the Northern midlands and mountainous areas.

The article examines the relationship between external debt, economic growth, unemployment and national expenditure in Viet Nam between 1987 and 2016. We found that the influence of a variable on other variables varies in the short run. We found that there are directional relationships between GDP and external debt and GDP and national expenditure. We also found that there are directional relationships between unemployment and external debt, GDP, and national expenditure. Results addressed directional relationships between national expenditure and external debt and GDP. There are two co-integrations among variables. In order to sustain macroeconomic stability in Viet Nam, fiscal policy should be re-examined to meet large development needs and monetary policy should be tightened to reduce credit growth. Specifically, external debt should be effectively managed by the government because an increase in external debt leads to a decrease in GDP and a growth of unemployment. Moreover, GDP should be facilitated to reduce unemployment in the economy. Lastly, unemployment needs to be controlled because it generates a boom of national expenditure and vice versa.