Wheat variety yield data: Do commercial and public performance tests provide the same information?

Wheat yields from reported performance test results are of economic importance to wheat producers, since their profits depend on selecting the optimal variety for their location. However, our data shows differences in absolute and relative wheat yields between commercial and public wheat breeding program's performance test data in Kansas. Newly available data are used to test if the difference in yields arose from potential selectivity bias, and to determine the contribution of private and public wheat breeding programs to varietal yield improvement during 2007–2012. Both Heckman selection models and multiple regression showed no statistical evidence of the potential presence of selectivity bias rather, managerial practices, agronomic conditions, field location, and inherent genetic traits of the seed variety were identify as the source of yield differences.     

小麦价格波动的时间序列分析

粮食价格波动的成因一直是学术界关注的问题。本文通过对1995年1月至2005年12月全国小麦批发市场月度价格序列的分析，表明所观察的小麦价格序列的分布不符合传统线性回归模型关于独立同方差的假设，其特征比较适合使用ARCH族模型来描述。GARCH（1，1）模型的结果显示，由前期价格代表的存粮情况对现期小麦价格影响显著，前期的高价会引发未来小麦市场较大的价格波动；考察期间两次大的粮食市场改革虽然对短期小麦价格有影响，但并未引发剧烈的小麦价格波动。     

Is the variability of world wheat prices increasing?

Estimates are derived of the potential variability of world wheat prices and the sources of this variability. These indicate a sizable increase in the probability of large short-run fluctuations in price. The bulk of this variability is due to fluctuations in the domestic grain production of developing and centrally-planned economies. However, most market participants are unresponsive to short-run changes in world price, and transmit a substantial amount of domestic variability to the world market. The key factor in world price stability is the short-run responsiveness of wheat exports from the USA. It is likely that both the physical and policy factors that have contributed to increased variability will persist.     

Major International Information Flows Across the Safex Wheat Market

We study information flows across four wheat futures markets on four continents: Zhengzhou Commodity Exchange (ZCE), South African Futures Exchange (SAFEX), Euronext/Liffe and Kansas City Board of Trade (KCBT). Three approaches for studying information flows among non‐synchronous markets are applied: cointegration techniques, vector autoregressive analysis and multiple regression proposed. Although comparable underlying assets are traded in the four markets, our results indicate that no long‐run links exist among them. ZCE is by far the most endogenous market, and Euronext/Liffe is the most exogenous one. Finally, the model points to KCBT as the most influential and sensitive wheat market. Our findings indicate that the relative openness of the SAFEX wheat market supports information flows and linkages from KCBT and Euronext/Liffe. Therefore, our results suggest that more supportive policies to incentivise higher wheat production in South Africa are required to mitigate the impact of price shocks emanating from the global wheat markets.     

The growing importance of the former USSR countries in world agricultural markets

The major countries of the former Soviet Union—specifically Russia, Ukraine, and Kazakhstan—are becoming increasingly important in world agricultural markets. The two main developments are that this region has become a large grain exporter, especially of wheat and barley, and Russia a big agricultural importer, especially of meat. These trends should continue for the next decade. However, policies to expand the livestock sector could mitigate these developments, as increased domestic meat production would reduce both meat imports and surplus feed grain for export. Also, further growth in the region's grain exports will require improvement in the infrastructure for storing and transporting grain.     

Efficiency of research investments in the presence of international spillovers: wheat research in developing countries⋆

Expenditures on agricultural research in the public sector, including the International Agricultural Research Centers (IARCs) have stagnated and in some cases, declined sharply in recent years. This has focused attention on issues of efficiency of agricultural research systems, especially the number, size, scope, type, and locations of their programs. This paper examines the issue of research efficiency through a case study of wheat improvement research in developing countries. The basic premise of this study is that the optimal level of research investment should be determined in a global model that incorporates direct research spill‐ins. An analytical framework is developed to determine the threshold levels of crop production in a country (or a region within a country) needed to justify crop improvement research programs of different sizes in the presence of spill‐ins from abroad. Spill‐in coefficients are estimated from yield performance of varieties of different origins grown across a range of environments. The model is then applied to analyze the efficiency of current investments in 69 wheat improvement research programs in 35 developing countries. A major conclusion of the paper is that given the magnitude of potential spill‐ins from the international research system, many wheat research programs could significantly increase the efficiency of resource use by reducing the size of their wheat research programs and focusing on the screening of varieties developed elsewhere. ©2000 Elsevier Science B.V. All rights reserved.     

小麦胚芽的综合利用

本文对麦胚油、谷胱甘肽、天然维生素E、麦胚凝集素的提取和麦胚焙烤食品、蛋白饮料、豆制品等麦胚食品的开发利用进行较为全面的论述,并分析小麦胚芽资源开发利用存在的问题和应用前景。     

Market integration and market efficiency: The case of 19th century Italy

This paper examines market integration in Italy in the 19th century, focusing on wheat. Wheat prices converged well before political Unification (1859-1861) but the process halted during the 1860s only to resume in the 1870s and 1880s. The first wave of integration was caused mainly by improvements in market efficiency while the second wave owed much to a reduction in transport costs.     

Linking technical change to research effort: an examination of aggregation and spillovers effects

We used a disaggregate approach to examine investment efficiency of wheat breeding research in India. India's total research effort comprizes 20 research programs spread across 50 experiment stations. A technology spillover matrix was constructed for both potential and actual spillovers. Spillovers and free‐riding were dominant characteristics of technical change during the period studied. Although the aggregate rate of return to wheat improvement research in India was estimated to be 55%, eight programs were found to have earned a negative rate of return when spillins were taken into account. Research output is concentrated on a few strong programs. The two strongest programs generated 75% of all the technical change benefits, even though they claimed just 22% of research resources. These two programs include a significant degree of overlap, while on the other hand many farmers were not reached by any of the programs – 56 and 78% of rainfed and durum area, respectively, in 1990 was still sown with pre‐1976 varieties.     

The rise and fall of public sector plant breeding in the United Kingdom: a causal chain model of basic and applied research and diffusion

This paper examines the barley and wheat breeding programmes of the Plant Breeding Institute (PBI), which was the most successful public plant breeding institute in the UK, until privatization in 1987. The PBI's shares in barley and wheat seed sales are explained, showing that the success with barley was largely a matter of serendipity, whereas the wheat programme followed a more normal pattern. For wheat, the causal chain, or recursive, model decomposes the well-documented link between research expenditures and increases in agricultural productivity into three stages. These are the effects of R&D expenditures on basic research output, measured by publications, the effect of publications and applied R&D expenditures on trial plot yields, and the diffusion of the trial plot technologies, which raises yields on farms. Applying the model to the FBI's wheat varieties allows estimation of the lag structures. In contrast to the results for aggregate agricultural research, for a single plant breeding programme alone there is a considerable lead time before there is any response, followed by a lag distribution only a few years long. The returns to the R&D investments are calculated from the causal chain model, from single equation estimates and by evaluating the yield advantage of the PBI varieties. All three approaches give consistent results, which show that the returns to barley and wheat alone were sufficient to support the entire PBI budget and still give rates of return to applied research of between 14 and 25%. The return to the basic science expenditures of the John Innes Institute has a lower bound of 17%, but must have been even higher than for the PBI if the other Institutes were taken into account. The paper concludes by commenting on the effects of the privatization of the PBI.