2019 Vol. 18 No. 8 Previous Issue    Next Issue

    Special Focus: Science and Technology Backyard
    Special Focus: Food economics and policies
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    Special Focus: Science and Technology Backyard
    Editorial – Science and Technology Backyard: A novel model for technology innovation and agriculture transformation towards sustainable intensification
    JIAO Xiao-qiang, WANG Chong, ZHANG Fu-suo
    2019, 18(8): 1655-1656.  DOI: 10.1016/S2095-3119(19)62770-X
    Abstract ( )   PDF in ScienceDirect  
    Science and Technology Backyard (STB) is an integrated platform for technology innovation, knowledge transfer, people training and agricultural transformation towards sustainable intensification. STB professors, graduate students and extension workers lived and worked together with smallholder farmers in rural areas. They identified the problems that limit sustainable agriculture and provided smallholder farmers systematic, integrated and holistic solutions without time lags, limitation, fees and distances. Many people, including farmers, graduate students, extension workers, have been trained via more than 100 STBs during the last decade (Zhang et al. 2016). 

    The bottom-up approach has been developed and broadly used in the STBs to study the “field-farm-agriculture” ecosystem and the “Three Rural Issues”, and to explore possible measures for achieving the three major pillars of sustainable intensification: food security, resource conservation and environmental sustainability. With the involvement of various stakeholders, e.g., government, industry, university and farmer, a series of single and integrated technologies have been developed and tested in farmers’ fields. Based on the results, the major limiting factors of crop production were identified, key technologies and models for realizing sustainable crop production have been developed. 

    In this special focus, we systematically summarize the methods of technology innovation in the STBs, especially focus on identifying the problems in agricultural production and give suggestions for achieving sustainable intensification (Jiao et al. 2019). For example, we have identified that low planting density is the major limiting factor for maize production in North China, followed by inappropriate nutrient management approach, based on the data collected from 235 farmer plots in three villages in the North China Plain (Chen et al. 2019). Maize yield could be improved by 20%, and partial factor productivity (kg of grain produced per kg N applied) could be improved by 30%, by integrated soil-crop system management and improving plant density in smallholder farmers’ plots in North China Plain (Chen et al. 2019). Similar results were obtained in other crops and places, such as in wheat production of North China Plain and Northeast China Plain (Cao et al. 2019; Huang et al. 2019; Zhao et al. 2019). 

    For cash crops, e.g., mango, inappropriate nutrient management and low plant density were the major limiting factors, based on data collected from 103 farmers’ field plots. By improving plant density and nutrient management, mango yield could be improved by 50%, and 20% chemical N could be saved (Zhang et al. 2019b). This has provided important value and great significance for mango production. Similar results were obtained on apple production in Shaanxi Province (Zhang et al. 2019a). In this special focus, we present seven papers about the methodology of conducting technology innovation in the STBs. We hope to improve our understanding of research approach of STBs and provide guidance for countries facing similar challenges worldwide.
    Science and Technology Backyard: A novel approach to empower smallholder farmers for sustainable intensification of agriculture in China
    JIAO Xiao-qiang, ZHANG Hong-yan, MA Wen-qi, WANG Chong, LI Xiao-lin, ZHANG Fu-suo
    2019, 18(8): 1657-1666.  DOI: 10.1016/S2095-3119(19)62592-X
    Abstract ( )   PDF in ScienceDirect  
    Sustainable feeding of the growing population in China without ecological destabilization is a grand challenge.  In this populous country where agriculture is dominated by smallholder farming, developing innovative technology and translating scientific knowledge into action for smallholder farmers is a crucial step in addressing this challenge.  Here, we present a novel approach for technology innovation and dissemination to achieve sustainable intensification in the fields of smallholder farmers.  The Science and Technology Backyard (STB) is a hub in a rural area that links knowledge with practices to promote technology innovation and exchange.  In this study, the framework and functions of STB are introduced, and the key implications for sustainable intensification across millions of smallholder farmers are explicitly stated: (i) develop innovative technology based on stated demands of farmers; (ii) disseminate technology by innovative social service models though combined top-down approaches with bottom-up measures to enable smallholders in rural areas.  This paper provides a perspective on transformation of small-scale agriculture toward sustainable intensification in China and useful knowledge applicable to other developing countries.
    Developing sustainable summer maize production for smallholder farmers in the North China Plain: An agronomic diagnosis method
    CHEN Guang-feng, CAO Hong-zhu, CHEN Dong-dong, ZHANG Ling-bo, ZHAO Wei-li, ZHANG Yu, MA Wen-qi, JIANG Rong-feng, ZHANG Hong-yan, ZHANG Fu-suo
    2019, 18(8): 1667-1679.  DOI: 10.1016/S2095-3119(18)62151-3
    Abstract ( )   PDF in ScienceDirect  
    With an increasing population and changing diet structure, summer maize is increasingly becoming an important energy crop in China.  However, traditional farmer practices for maize production are inefficient and unsustainable.  To ensure food security and sustainable development of summer maize production in China, an improved, more sustainable farmer management system is needed.  Establishing this system requires a comprehensive understanding of the limitations of current farming practice and the ways it could be improved.  In our study, 235 plots from three villages in the North China Plain (NCP) were monitored.  Maize production on farms was evaluated; our results showed that the maize yield and nitrogen partial factor productivity (PFPN) were variable on smallholder farms at 6.6–13.7 t ha–1 and 15.4–88.7 kg kg–1, respectively.  Traditional farming practices also have a large environmental impact (nitrogen surplus: –64.2–323.78 kg ha–1).  Key yield components were identified by agronomic diagnosis.  Grain yield depend heavily on grain numbers per hectare rather than on the 1 000-grain weight.  A set of improved management practices (IP) for maize production was designed by employing a boundary line (BL) approach and tested on farms.  Results showed that the IP could increase yield by 18.4% and PFPN by 31.1%, compared with traditional farmer practices (FP), and reduce the nitrogen (N) surplus by 57.9 kg ha–1.  However, in terms of IP effect, there was a large heterogeneity among different smallholder farmers’ fields, meaning that, precise technologies were needed in different sites especially for N fertilizer management.  Our results are valuable for policymakers and smallholder farmers for meeting the objectives of green development in agricultural production.
    Causes of maize density loss in farmers’ fields in Northeast China
    ZHAO Ying-jie, XING Sen, ZHANG Qing-song, ZHANG Fu-suo, MA Wen-qi
    2019, 18(8): 1680-1689.  DOI: 10.1016/S2095-3119(18)62101-X
    Abstract ( )   PDF in ScienceDirect  
    Increasing plant density is an effective and important way to reduce maize yield gaps in Northeast China.  However, the fact is that a significant plant density gap exists between optimum plant density and actual plant density in farmers’ fields.  To quantify the density gap between planned planting density and final harvest plant density (HPD), we studied 60 farmers’ fields on three types of soil for three crop seasons from 2015 to 2017 by measuring their plant-plant distance, actual seedlings density (ASD), final HPD and yield.  We also explored the potential causes of density loss by digging the places where the seedlings were missing for two consecutive years in 2016–2017.  Results show that the three-year average HPD in farmers’ fields was 59 699 plants ha–1, which was significantly lower than the planned density, including both the machine setting density (MSD; 67 962 plants ha–1) and theoretical plant density (TPD; 67 467 plants ha–1).  No significant difference was found in HPD between years and soil types.  However, for MSD and TPD, the average value in 2015 was significantly higher than that in 2016 and 2017.  No significant difference between soil types was observed.  Furthermore, the results from 2016 till 2017 indicated that a lack of seeds in the soil, a failure to germinate due to low-quality seeds, and a lack of seedlings breaking out of the soil due to environmental problems explained approximately 60.88, 10.33 and 28.80% of density loss, respectively.  According to our survey, 63% of farmers did not know their own TPD and HPD, and 54% of farmers did not know the density loss.  Therefore, we argue that farmers’ limited knowledge of density and density loss is an urgent problem that needs to be solved in maize production.  These observations will be useful for determining best management practices for maize production and for providing helpful suggestions for machine improvement. 
    Effect of intercropping on maize grain yield and yield components
    HUANG Cheng-dong, LIU Quan-qing, LI Xiao-lin, ZHANG Chao-chun
    2019, 18(8): 1690-1700.  DOI: 10.1016/S2095-3119(19)62648-1
    Abstract ( )   PDF in ScienceDirect  
    Smallholders in developing countries commonly use intercropping to produce crops with higher yield and value.  Many intercropping studies have been conducted under experimental conditions, but few studies have been performed in farmers’ fields.  We conducted a 4-year study using data from real farms to examine the relationships between yield and yield components of intercropped maize in the North China Plain.  Three field experiments were conducted to compare the suitability of different maize varieties in intercropping.  In the farm study, the grain yield of maize intercropped with watermelon was reduced by more than one third as compared to maize in wheat-maize double cropping, mainly due to lower ear density and lower 100-grain weight.  Under real farm conditions, the yield of intercropped maize increased with increasing ear density and 100-grain weight, while yield of sole maize increased with increasing grain number per ear and 100-grain weight.  In the field experiments, the maize cultivars commonly used in double cropping gave similar yields when grown in the intercropping system and their yields were closely related to ear density and 100-grain weight.  Our results demonstrated that ear density, rather cultivar, was a key factor affecting the productivity of intercropped maize.  Therefore, maintaining high ear density is a practical way for promoting productivity of maize in farmers’ intercropping practices.
    Identifying the limiting factors driving the winter wheat yield gap on smallholder farms by agronomic diagnosis in North China Plain
    CAO Hong-zhu, LI Ya-nan, CHEN Guang-feng, CHEN Dong-dong, QU Hong-rui1, MA Wen-qi
    2019, 18(8): 1701-1713.  DOI: 10.1016/S2095-3119(19)62574-8
    Abstract ( )   PDF in ScienceDirect  
    North China Plain (NCP) is the primary winter wheat production region in China, characterized by smallholder farming systems.  Whereas the winter wheat average yield of smallholder farmers is currently low, the yield potential and limiting factors driving the current yield gap remain unclear.  Therefore, increasing the wheat yield in NCP is essential for the national food security.  This study monitored wheat yield, management practices and soil nutrient data in 132 farmers’ fields of Xushui County, Baoding City, Hebei Province during 2014–2016.  These data were analyzed using variance and path analysis to determine the yield gap and the contribution of yield components (i.e., spikes per hectare, grain number per spike and 1 000-grain weight) to wheat yield.  Then, the limiting factors of yield components and the optimizing strategies were identified by a boundary line approach.  The results showed that the attainable potential yield for winter wheat was 10 514 kg ha–1.  The yield gaps varied strongly between three yield groups (i.e., high, middle and low), which were divided by yield level and contained 44 farmers in each group, and amounted to 2 493, 1 636 and 814 kg ha–1, respectively.  For the three yield components, only spikes per hectare was significantly different (P<0.01) among the three yield groups.  For all 132 farmers’ fields, correlation between yield and spikes per hectare (r=0.51, P<0.01), was significantly positive, while correlations with grain number per spike (r=–0.16) and 1 000-grain weight (r=–0.10) were not significant.  The path analysis also showed that the spikes per hectare of winter wheat were the most important component to the wheat yield.  Boundary line analysis showed that seeding date was the most limiting factor of spikes per hectare with the highest contribution rate (26.7%), followed by basal N input (22.1%) and seeding rate (14.5%), which indicated that management factors in the seeding step were the most important for affecting spikes per hectare.  For desired spikes per hectare (>6.598×106 ha–1), the seeding rate should range from 210–300 kg ha–1, seeding date should range from 3th to 8th October, and basal N input should range from 90–180 kg ha–1.  Compared to these reasonable ranges of management measures, most of the farmers’ practices were not suitable, and both lower and higher levels of management existed.  It is concluded that the strategies for optimizing yield components could be achieved by improving wheat seeding quality and optimizing farmers’ nutrient management practices in the NCP.
    Correlation of production constraints with the yield gap of apple cropping systems in Luochuan County, China
    ZHANG Dong, WANG Chong, LI Xiao-lin, YANG Xiu-shan, ZHAO Lu-bang, XIA Shao-jie
    2019, 18(8): 1714-1725.  DOI: 10.1016/S2095-3119(18)62098-2
    Abstract ( )   PDF in ScienceDirect  
    Apple occupies a dominant position in fruit production globally, and has become the main income source of local smallholder farmers in Luochuan County in the Loess Plateau area, one of the largest apple production areas in China.  However, the annual productivity of apple orchards in this region remains low and has gradually declined over the years.  The distinction and correlation of production constraints can contribute to the promotion of apple orchard productivity and the development of a sustainable orchard system.  In the present study, survey data from 71 smallholder farmers were analyzed using a yield gap model to distinguish the production constraints and determine their correlation with the yield gap based on the structural equation model (SEM).  The results indicated that the average apple yield in Luochuan County was 29.9 t ha–1 yr–1, while the attainable yield (Yatt; the highest yield obtained from the on-farm surveys) was 58.1 t ha–1 yr–1.  The average explained and unexplainable yield gaps were 26.3 and 1.87 t ha–1 yr–1.  According to the boundary line analysis, crop load, number of sprayings and base fertilizer N were the top three constraints on apple production in 9.8, 7.8 and 7.8% of the plots, respectively.  Among the production constraints, crop load and fruit weight affected apple yield through direct pathways, whereas other constraints influenced apple yield through an indirect pathway based on the SEM, explaining 51% of the yield variance by all the main production constraints.  These results can improve the current understanding of production constraints and contribute to the development of management strategies and policies for improving apple yield.
    Yield gap and production constraints of mango (Mangifera indica) cropping systems in Tianyang County, China
    ZHANG Dong, WANG Chong, LI Xiao-lin
    2019, 18(8): 1726-1736.  DOI: 10.1016/S2095-3119(18)62099-4
    Abstract ( )   PDF in ScienceDirect  
    Mango is an important cash crop in the tropics and subtropics.  Determining the yield gap of mango and production constraints can potentially promote the sustainable development of the mango industry.  In this study, boundary line analysis based on survey data from 103 smallholder farmers and a yield gap model were used to determine the yield gap and production constraints in mango plantations in the northern mountain, central valley and southern mountains regions of Tianyang County, Guangxi, China.  The results indicated that the yield of mango in three representing regions of Tianyang County, Northern Mountains, Central Valley and Southern Mountains, was 18.3, 17.0 and 15.4 t ha–1 yr–1, with an explainable yield gap of 10.9, 6.1 and 14.8 t ha–1 yr–1, respectively.  Fertilization management, including fertilizer N, P2O5 and K2O application rates, and planting density were the main limiting factors of mango yield in all three regions.  In addition, tree age influenced mango yield in the Northern Mountains (11.1%) and Central Valley (11.7%) regions.  Irrigation time influenced mango yield in the Northern Mountains (9.9%) and Southern Mountains (12.2%).  Based on a scenario analysis, the predicted yield would increase by up to 50%, and fertilizer N use would be reduced by as much as approximately 20%.  An improved understanding of production constraints will aid in the development of management strategy measures to increase mango yield.
    Special Focus: Food economics and policies
    Food economics and policies: Challenges and approaches toward better nutrition and safer food in China
    2019, 18(8): 1737-1739.  DOI: 10.1016/S2095-3119(19)62771-1
    Abstract ( )   PDF in ScienceDirect  
    China has achieved unprecedented successes in feeding the 1.3 billion population in the past few decades.  Per capita occupation of grain and milk increased from 316.6 and 1 kg in 1978 to 445.7 and 26.85 kg in 2016, respectively.  Per capita meat occupation also reached 61.9 kg in 2016 from nearly nothing at the beginning of the reform and opening (NBSC 1979–2018).  With these successes in agricultural production, the quality of food consumption has also improved significantly.  Although food remains the largest household expenditure, the Engel coefficient, an average ratio of food expenditure over income, has declined from 67.7% in 1978 to 29.33% in 2017 (NBSC 1979–2018).  In addition, the enriched food consumption has generated remarkable human welfare improvement.  A newborn boy in 1970 could expect to live to age 63, but by 2015, that same boy could expect to live to 73.64 years (WHO 2001, 2016).  In 2010, the underweight rate for children less than 5 years old, a commonly used proxy for health status, was 3.6% compared with 74% in 1990.  Such improvements are ascribed to the market-oriented pricing reform of agricultural commodities, the household responsibility system, and a series of other technological progresses, institutional innovations and market reforms.
    Yet, new challenges have occurred in the recent decade.  Particularly, the increasing prevalence of obesity and chronic diseases has become a serious public concern in China (Popkin et?al. 2012; Du et?al. 2014; Gordon-Larsen et?al. 2014; Yuan et?al. 2019).  A recent article in The Lancet shows that China has passed the United States to become the frontrunner in the absolute number of obese citizens (NCD-RisC 2016).  In 2014, China’s men and women contributed 16.3 and 12.4%, respectively, to global obesity.  Although these numbers did not consider China’s huge population base, they reflect a sharp increase from 1975 when only 2.1% of men and 2.5% of women were obese (NCD-RisC 2016), but with a high prevalence of undernutrition.  It is unbelievable that in just 40 years China has transitioned from a country in which parents worried about where their children’s next meal would come from to one where overweight has become one of the top public concerns. 
    Another challenge is related to food safety.  The globally well-publicized melamine-contaminated baby formula scandal disclosed in 2008 was a milestone triggering public concerns about Chinese food safety.  That desperate Chinese parents seeking baby formula outside the country was often listed on the top in both international and domestic news media.  The series of food safety issues involving meat, eggs, and other fresh vegetables following the baby formula scandal further put Chinese consumers at the peak of panic.  Facing the challenges, the Chinese government and the entire agricultural and food industries carried out a series of active measures to ensure food safety, including significantly enhancing laws and regulations, tremendously investing in R&D for food safety detection and new technology implementation, and so forth.  These active measures have largely strengthened and improved China’s food safety environment, but there is certainly still a long way to go to win back consumers’ confidence in domestic food and food products. 
    It is no doubt that technological progress played critical roles and will continue to play the role in the future in curving these challenges.  Yet, establishing an efficient food system with healthier, more nutritious, and safer food needs a better understanding of the economic behaviors of all agents in the market.  This is particularly important for food-related policymaking in many emerging economies like China where the coexistence of undernutrition, deficiency of micronutrients, and overweight and obesity is a common challenge to the society and individual households.  Though related literature has shed light on these issues, this special combination provides more frontier research updates and more pieces of evidence. 
    We start this summary by asking a fundamental question: do improvements in living standards lead to the increase in obesity?  To answer this question, Zhao and Zheng (2019) employ the neoclassic theory of economics in obesity and China Health and Nutrition Survey (CHNS) data to empirically estimate the impact of income, often a most powerful driver, on adults’ body mass indices (BMIs).  The results of their study indicate that the income had a significant and inverted U-shaped impact on weight for both urban and rural males, while the effect is negative for urban but positive for rural females.  These findings suggest a continuing growth of overweight and obesity prevalence in China for both urban and rural male and rural female adults with further income growth in the near future.  The turning point without any intervention is unlikely to appear in a foreseeable period.  Measures stimulating physical activities to burn the over intakes of nutrients could be effective in mitigating the rising burden both for individual adults and the society. 
    The main findings from Zhao and Zheng (2019) are further confirmed by Ren et?al. (2019) who use a different method and more indicators reflecting overweight initiation, cessation, and termination.  Their results show that body weight and the likelihood of overweight commencement are concavely associated with income, while the likelihood of overweight discontinuance posts a convex relation with income.  This finding suggests that low-income people in China are less likely to be overweight than their counterparts in many developed countries.  Heterogeneous effects by gender and between urban and rural are also discussed in their study. 
    This session also includes two papers that focus on the health and nutrient intake issues for two specific population groups.  Liu et?al. (2019) try to build up a linkage between nutrient intake and primary students’ mental performance.  Using a randomized controlled trial involving 6 044 fourth and fifth graders in rural Northwestern China, their results show that a nutrition subsidy provided significantly improved students’ mental health status as measured by anxiety scale.  However, the add-on incentive provided to school principals could almost entirely offset the beneficial impact of the nutrition subsidy.  Therefore, to improve students’ mental health in rural China, direct subsidies, such as low-priced school meals, and correct incentives tied closely to students’ mental health outcomes should be considered simultaneously. 
    Min et?al. (2019) move their focus to left-behind family members’ food consumption and nutrient intake in remote areas of Southwestern China.  Based on household survey data collected from 611 smallholder rubber farmers in Xishuangbanna Dai Autonomous Prefecture, they find that the migration of family members contributes to improving household net income, whereas it negatively affects left-behind family members’ consumption of grain and pork.  These results suggest that, in some remote areas such as in Southwestern China, rising income may not automatically translate into a structural change in food consumption and better nutrient intake that was observed in other regions or countries.  Future research should pay more attention to reveal the reasons and mechanisms behind this stickiness. 
    The rest of this column selects three studies that examine food safety related issues.  The first one is by Li et?al. (2019) which studies Chinese consumers’ confidence in domestic dairy products.  Since the infant formula scandal in 2008, dairy products have been on a hot-pot of public criticism and always in the center of food safety related discussions.  The Chinese government and the entire dairy industry have made tremendous efforts to improve the safety level and to bring consumers back to the market.  Results from surveying consumers in Beijing, Tianjin and Shijiazhuang, however, are not that optimistic as expected.  The safety of domestically produced infant formulas is still heavily doubted (Li et?al. 2019), despite that quality certification, being produced organically, and being fully traceable can positively affect consumers’ confidence in these products. 
    However, whether being traceable can enhance consumer’s confidence in food safety and reshape their risk attitudes towards domestically produced food products as expected may depend on individual exposure to social media and the various relationships he/she has with the cultural environment he/she is embedded in.  In the study by Yan et?al. (2019), researchers employ an analytical framework based on the social embeddedness theory to reveal the impact of consumers’ social activities on their risk perception.  The results of quantile regression models show that interpersonal relationships, organizational relationships, and social relationships have significant impacts on consumer’s risk perception at different quantile levels. 
    In addition to enhance consumer’s risk perception of food safety, food traceability can also promote a firm’s performance.  Using a dataset of 216 food manufacturing firms in China, Song et?al. (2019) reveal the existence of the association between food traceability information sharing and corporate performance.  The fundamental mechanism is that food traceability information sharing can enhance a firm’s operational and marketing capabilities, and further contribute to its profitability.  This hypothesis is verified by using hierarchical regressions and bootstrapping methods.  They also show that operations and marketing capabilities translate the interactive impacts of environmental turbulence and traceability information sharing into firm performance.  Moreover, this study demonstrates for the first time that at both high and medium levels of environmental turbulence, food traceability information sharing strengthens operations and marketing capabilities, consequently contributing to firm performance.
    It has been a long time since the entire Chinese academia gave dominated priority to agricultural production when a higher yield was needed to meet the growing food demand.  Yet, this situation has gradually changed with the 13-year-in-a-row yield increase of three major grains (corn, wheat and rice) by 2016.  The continuously rising income and upgrading consumer taste for healthier, safer and better-quality food are posing substantial challenges to China’s traditional agricultural production system.  They are also exerting considerable pressure on individual households and the society in handling the rising overweight and obesity problems.  Studies combined in this column shed more light on understanding these issues from the perspective of food demand which was commonly ignored, and thus will serve as a starting point for more future research. 
    BAI Jun-fei
    Guest Editor
    Beijing Food Safety Policy & Strategy Research Base
    China Agricultural University
    Beijing 100193, P.R.China
    ZHU Chen
    Guest co-Editor
    Beijing Food Safety Policy & Strategy Research Base
    China Agricultural University
    Beijing 100193, P.R.China
    Do Improvements of living standards lead to growth of obesity?  Evidence from Chinese adults
    ZHAO Yin-yu, ZHENG Zhi-hao
    2019, 18(8): 1740-1752.  DOI: 10.1016/S2095-3119(19)62690-0
    Abstract ( )   PDF in ScienceDirect  
    This study estimates the impacts of income on body mass indices (BMIs) of male and female adults from both urban and rural areas in China under the neoclassic theory of obesity, using China Health and Nutrition Survey data during 1991–2011.  Results of this study show that incomes has a significant inverted U-shaped impact on weight for both urban and rural males while having a negative effect on weight for urban females and positive effect on BMI for rural female, suggesting that further income growth is expected to lead to continuing growth of obesity for both urban and rural male adults as well as for rural female adults.  Moreover, the strenuousness of physical activity, which is represented by types of jobs, significantly reduced the BMI for all adults except for urban females, implying that a decrease in the strenuousness of physical activity stemming from economic development and technological changes is an important factor leading to the growth of obesity for all adults and rural female adults.   
    Low-income and overweight in China: Evidence from a life-course utility model
    REN Yan-jun, Bente Castro Campos, Jens-Peter Loy, Stephan Brosig
    2019, 18(8): 1757-1763.  DOI: 10.1016/S2095-3119(19)62691-2
    Abstract ( )   PDF in ScienceDirect  
    Previous literature has demonstrated that low-income people are more likely to settle for poor health choices in developed countries.  By using income as a budget constraint and signal for future wellbeing in a life-course utility model, we examine the association amongst income and overweight.  The data used for this study are from the China Health and Nutrition Survey (CHNS).  Estimations are conducted for overweight initiation, cessation, and participation mirroring a decision to begin and a past decision to not terminate.  Our findings propose that body weight and the likelihood of overweight commencement rise with additional income but at a diminishing degree, representing a concave relation; while the likelihood of overweight discontinuance declines with additional income but at an accelerating degree, suggesting a convex relation.  We presume that, as opposed to developed countries, low-income people are less inclined to be overweight in China, a country in transition.  This could be explained by an income constraint for unhealthy foodstuff.  Nevertheless, it will switch when income surpasses the critical threshold of the concave or inverted U-shape curve indicating that low-income people appear to receive not as much utility from future health.  Specifically, this adjustment seems to occur earlier for females and inhabitants of urban areas.
    Better nutrition, healthier mind?  Experimental evidence from primary schools in rural northwestern China
    LIU Xiao-yue, ZHAO Qi-ran, CHEN Qi-hui
    2019, 18(8): 1768-1779.  DOI: 10.1016/S2095-3119(19)62587-6
    Abstract ( )   PDF in ScienceDirect  
    Malnutrition and mental health problems are both prevalent among rural students in China.  To provide a better understanding of the functional linkage between these two problems, this study estimates the causal effect of improved nutrition on rural students’ mental health status, exploiting a randomized controlled trial involving 6 044 fourth and fifth graders in rural northwestern China.  Estimation results show that a nutrition subsidy provided by the project significantly improved students’ mental health status (measured by their anxiety scale).  However, an add-on incentive provided to school principals, which was tied to anemia reduction, almost entirely offset the beneficial impact of the nutrition subsidy.  These findings suggest that to improve students’ mental health in rural China, not only direct subsidies, such as low-priced school meals, but also correct incentives, especially those tied closely to students’ mental health outcomes, should be provided.
    The impact of migration on the food consumption and nutrition of left-behind family members: Evidence from a minority mountainous region of southwestern China
    MIN Shi, HOU Ling-ling, Hermann Waibel, HUANG Ji-kun, MU Yue-ying
    2019, 18(8): 1780-1792.  DOI: 10.1016/S2095-3119(19)62588-8
    Abstract ( )   PDF in ScienceDirect  
    While migration is widely recognized as a valid option for improving farmers’ income, the welfare effects of migration on left-behind family members are ambiguous.  This study examines the impacts of migration on left-behind family members’ food consumption and nutrient intake, particularly in remote rural areas in China.  Based on household survey data collected from 611 smallholder rubber farmers in Xishuangbanna Dai Autonomous Prefecture of southwestern China, the empirical results suggest that the migration of family members contributes to improving household net income, whereas it negatively affects left-behind family members’ consumption of grain and pork.  Migration also leads to a decrease in left-behind family members’ nutrient intake.  Surprisingly, the economic returns of farmers’ migration not only do not foster the transformation of household food consumption from a staple food-dominated dietary structure to one including more meat and dairy products but also reduce left-behind family members’ nutrient intake.  This study adds to the literature on the impact of farmers’ migration.  The findings have important implications for better understanding the impacts of migration on farmers’ livelihood and human capital development in rural China.
    Consumer confidence and consumers’ preferences for infant formulas in China
    LI Sai-wei, ZHU Chen, CHEN Qi-hui, LIU Yu-mei
    2019, 18(8): 1793-1803.  DOI: 10.1016/S2095-3119(19)62589-X
    Abstract ( )   PDF in ScienceDirect  
    A series of safety incidents related to domestically-produced infant formulas (DIFs) almost destroyed Chinese consumer confidence in domestic dairy products.  Understanding consumer confidence and its effect on consumption behavior is important to restore consumer confidence and enhance the competitiveness of domestic dairy industry.  This article first measures Chinese consumer confidence in DIFs safety using a two-dimension scale (optimism and pessimism) and then investigates its effect on consumers’ preferences for DIFs through a choice experiment.  Involving 450 consumers residing in Beijing, Tianjin and Shijiazhuang, the experiment elicited information on their preferences for DIFs with six attributes (organic raw milk, farm-to-table traceability, region of origin, quality certification, animal welfare, and price).  Our analysis yields four findings.  First, Chinese consumers still lack confidence in DIFs safety.  Second, quality certification is the most preferred product characteristic, followed by organic raw milk and farm-to-table traceability.  Third, serving as a signal of high quality, price exerts a positive impact on choices of DIFs for pessimistic consumers.  Finally, consumer preferences for farm-to-table traceability and region of origin are significantly influenced by consumer confidence.
    Are social embeddedness associated with food risk perception under media coverage?
    YAN Zhen, HUANG Zu-hui, WANG Yu, ZHOU Jie-hong
    2019, 18(8): 1804-1809.  DOI: 10.1016/S2095-3119(19)62586-4
    Abstract ( )   PDF in ScienceDirect  
    Traceability system has received wide attention in solving food safety issues, via which food information could be tracked back to producer/farmers.  Consumers need to obtain this information from producers or social networks, trust in the information,  and consequently assess perceived risks, especially when food scandals are exposed to the media.  In this study, we introduce the social embeddedness theory to understand how consumers’ social activities affect their risk perceptions on traceable food.  Specifically, we investigate how risk perceptions are predicted by the interpersonal relationships, organizational level and social-level relationships.  Results show that the interpersonal relationships were associated with lower levels of risk perceptions, while organizational and social relationships impacted consumer’s risk perceptions at middle and higher levels, respectively.  Results also show that the “ripple effect” extended to effect of risk events with negative information, however, did not exist for the group exposed to positive information.  Potential food safety implications have been proposed to identify for effective risk mitigation under media coverages.
    Leveraging core capabilities and environmental dynamism for food traceability and firm performance in a food supply chain: A moderated mediation model
    SONG Mo-xi, YANG Morgan Xin
    2019, 18(8): 1820-1837.  DOI: 10.1016/S2095-3119(19)62590-6
    Abstract ( )   PDF in ScienceDirect  
    This paper develops a moderated mediation model in which the interactive effects of food traceability and environmental dynamism on firm performance are mediated by the core capabilities (operating capabilities and marketing capabilities) in food supply chain context, by invoking the indirect view of organizational learning theory.  Our hypotheses were tested using hierarchical regression and bootstrapping methods with a sample of 216 food manufacturing firms in China, and a survey-based, two-informant design was used to collect data.  The results revealed that operating and marketing capabilities fully mediate the food traceability-performance link.  In addition, environmental dynamism positively moderates the food traceability-core capabilities link.  Moreover, it is found that operating and marketing capabilities transform the interactive impacts of environmental dynamism and food traceability into firm performance.  Our study offers a fine-grained picture of the essential food traceability-performance link by revealing for the first time that there is an interactive impacts of food traceability and environmental dynamism on firm performance via core capabilities.
    Crop Science
    Mapping and genetic validation of a grain size QTL qGS7.1 in rice (Oryza sativa L.)
    XUE Pao1, ZHANG Ying-xin1, LOU Xiang-yang1, ZHU Ai-ke, CHEN Yu-yu, SUN Bin, YU Ping, CHENG Shi-hua, CAO Li-yong, ZHAN Xiao-deng
    2019, 18(8): 1838-1850.  DOI: 10.1016/S2095-3119(18)62113-6
    Abstract ( )   PDF in ScienceDirect  
    Grain size is a major determinant of grain weight, which is one of the components of rice yield.  The objective o this study was to identify novel, and important quantitative trait loci (QTLs) for grain size and weight in rice.  QTLs were mapped using a BC4F4 population including 192 backcross inbred lines (BILs) derived from a backcross between Xiaolijing (XLJ) and recombinant inbred lines (RILs).  The mapping population was planted in both Lingshui (Hainan, 2015) and Fuyang (Zhejiang, 2016), with the short- and long-day conditions, respectively.  A total of 10 QTLs for grain length, four for grain width, four for the ratio of grain length to width, and 11 for grain weight were detected in at least one environment and were distributed across 11 chromosomes.  The phenotypic variance explained ranged from 6.76–25.68%, 14.30–34.03%, 5.28–26.50%, and 3.01–22.87% for grain length, grain width, the ratio of grain length to width, and thousand grain weight, respectively.  Using the sequential residual heterozygotes (SeqRHs) method, qGS7.1, a QTL for grain size and weight, was mapped in a 3.2-Mb interval on chromosome 7.  No QTLs about grain size and weight were reported in previous studies in this region, providing a good candidate for functional analysis and breeding utilization.
    Overexpression of G10-EPSPS in soybean provides high glyphosate tolerance
    XIAO Pei-ying, LIU Yi, CAO Yue-ping
    2019, 18(8): 1851-1858.  DOI: 10.1016/S2095-3119(18)62124-0
    Abstract ( )   PDF in ScienceDirect  
    Glyphosate is a highly efficient, broad-spectrum nonspecific herbicide that inhibits the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS)-mediated pathway of shikimic acid.  The screening of glyphosate-resistant EPSPS gene is a major means for the development of new genetically modified glyphosate-resistant transgenic crop.  Currently, the main commercialized glyphosate-resistant soybean contains glyphosate-resistant gene CP4-EPSPS.  In this study, a G10-EPSPS gene was reported providing glyphosate resistance in Zhongdou 32.  Here, G10-EPSPS gene was introduced into soybeans through Agrobacterium-mediated soybean cotyledon node.  PCR, Southern blotting, semi-quantitative RT-PCR, qRT-PCR, and Western blotting were used, and the results revealed that G10-EPSPS had been integrated into the soybean genome and could be expressed steadily at both mRNA and protein levels.  In addition, glyphosate resistance analysis showed that the growth of transgenic soybean had not been affected by concentrations of 900 and 2 700 g a.e. ha–1 of glyphosate.  All the results indicated that G10-EPSPS could provide high glyphosate resistance in soybeans and be applied in production of glyphosate-resistant soybean.
    Low soil temperature and drought stress conditions at flowering stage affect physiology and pollen traits of rice
    RAO Gang-shun, Umair Ashraf, KONG Lei-lei, MO Zhao-wen, XIAO Li-zhong, ZHONG Ke-you, Fahd Rasul, TANG Xiang-ru
    2019, 18(8): 1859-1870.  DOI: 10.1016/S2095-3119(18)62067-2
    Abstract ( )   PDF in ScienceDirect  
    Low temperature and drought stress are the major constraints in rice productivity worldwide.  This study investigated the influence of low soil temperature and/or drought stress on physiology and pollen traits of two rice genotypes viz., Guinongzhan and Yueza 763 at flowering stage.  The experiment included four treatments, i.e., under the greenhouse natural growth conditions (UC) taken as control, drought stress (DS), the soil water potential was kept at −0.035 to −0.045 MPa (DS), low soil temperature (LT) maintained at 19 to 21°C, combined LT and DS (LT+DS, LD).  Results showed that LT, DS, and LD substantially reduced net photosynthetic rate (Pn) and the maximal photochemical efficiency of PSII (Fv/Fm), whilst transpiration rate (Tr) was markedly enhanced by under LT in both rice genotypes.  The malondialdehyde (MDA) contents were enhanced under LT, DS, and LD in Guinongzhan, whilst the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were regulated by LT, DS, and LD in both rice genotypes.  Furthermore, anther dehiscence rate, pollen numbers on stigma, pollen viability and pollen germination rate, and anther starch contents were obviously reduced under LT and DS of both rice genotypes.  Stress conditions substantially reduced the yield and yield components, i.e., effective panicles, seed set percentage, grain/panicles, 1 000-grain weight, and grain yield of both genotypes and the effects were more apparent in Guinongzhan than those in Yueza 763 whilst combined LT and DS proved more damaging than individual stress.
    Effect of nanosilver (nAg) on disinfection, growth, and chemical composition of young barley leaves under in vitro conditions
    Marcelina Krupa-Ma?kiewicz, Jan Oszmiański, Sabina Lachowicz, Ma?gorzata Szczepanek, Bogus?awa Ja?kiewicz, Kamila Pachnowska, Ireneusz Ochmian
    2019, 18(8): 1871-1881.  DOI: 10.1016/S2095-3119(18)62146-X
    Abstract ( )   PDF in ScienceDirect  
    Cereals, including barley, have been playing a key role in human diet for a long time.  The objective of the present study was to determine the effect of nanosilver (nAg) on limitation of infections, morphological features, and their chemical composition of young barley seedlings under in vitro condition.  Addition of 0, 2, 4, 6 and 8 mg dm–3 nAg into MS medium was used.  Obtained results showed that the effect on the morphological features depended on the nAg concentration.  The addition of 6 and 8 mg dm–3 nAg into MS medium limited the number of infected barley embryos in vitro, whereas 4 and 8 mg dm–3 nAg resulted in the highest seedlings with the longest roots.  nAg in the medium affected the colour of leaves and increased the contents of chlorophyll and β-carotene, in particular in seedlings growing in MS medium supplied with 6 mg dm–3 nAg.  The addition of 8 mg dm–3 had the greatest effect on the contents of vitamin C and E in young barley seedlings.  It was found that the contents of K and Ca in the young barley leaves were lower, as compared to control plants.  The presence of 6 mg dm–3 nAg in the medium resulted in an increased contents of N, Mg, Zn, Cu, and P.  Hence, a diversified effect of nAg on individual groups of polyphenolic compounds was noticed.  The presence of 2 and 8 mg dm–3 nAg caused higher content values of polyphenolic compounds in young barley leaves.
    Post-silking nitrogen accumulation and remobilization are associated with green leaf persistence and plant density in maize
    ZHANG Li-li, ZHOU Xiang-li, FAN Ye, FU Jun, HOU Peng, YANG Hai-long, QI Hua
    2019, 18(8): 1882-1892.  DOI: 10.1016/S2095-3119(18)62087-8
    Abstract ( )   PDF in ScienceDirect  
    Stay green (SG) maize was found to have higher grain yield and post-silking nitrogen (N) uptake (PostN) compared with a non-stay green (NSG) hybrid.  To understand the effects of plant density on grain yield (GY) and N efficiency in modern maize hybrids, we compared two modern hybrids (SG hybrid DY508 and NSG hybrid NH101) with similar maturity ratings at three plant densities (45 000, 60 000, and 75 000 pl ha–1) in 2014 and 2015.  GY, leaf senescence, dry matter (DM) accumulation, N accumulation, PostN, and post-silking N remobilization (RemN) were analyzed.  DY508 and NH101 had similar GY, but DY508 had higher thousand kernel weight (TKW) and lower kernel number (KN) than NH101.  Plant density significantly increased GY in the two hybrids.  On average, over the two years, plant density improved GY in DY508 and NH101 by 18.5 and 11.1%, respectively, but there were no differences in total dry matter (TDM) and post-silking DM (PostDM) between the two hybrids.  Plant density improved leaf N, stem N, and grain N at the silking and maturity stages in 2014 and 2015.  DY508 was lower in harvest index (HI), nitrogen harvest index (NHI), and grain N concentration (GNC) than NH101.  Grain N in DY508 was 2.61 kg ha–1 less than in NH101, and this was caused by lower GNC and leaf RemN.  On the average, DY508 was 1.62 kg ha–1 less in leaf remobilized N (leaf RemN) than NH101, but was similar in stem remobilized N (stem RemN; 2.47 kg ha–1 vs. 3.41 kg ha–1).  Maize hybrid DY508 shows delayed leaf senescence in the upper and bottom canopy layers in the later stages of growth.  The present study provides evidence that the NH101, which has rapid leaf senescence at the late grain-filling stage, has gained equivalent GY and higher leaf RemN, and was more efficient in N utilization.
    Exploration of the key microbes and composition stability of microbial consortium GF-20 with efficiently decomposes corn stover at low temperatures
    YU Xiao-fang, BORJIGIN Qinggeer, GAO Ju-lin, WANG Zhi-gang, HU Shu-ping, BORJIGIN Naoganchaolu, WANG Zhen, SUN Ji-ying, HAN Sheng-cai
    2019, 18(8): 1893-1904.  DOI: 10.1016/S2095-3119(19)62609-2
    Abstract ( )   PDF in ScienceDirect  
    The microbial consortium GF-20 (GF-20) can efficiently decompose corn stover at low temperatures.  The present study explored the key microbes of GF-20 and evaluated different culture conditions on its composition stability to promote the utilization of corn stover decomposing microbes in low temperature regions.  GF-20 was subcultured to the 15th generation under different temperatures, pHs, carbon, and nitrogen sources.  Then, the dynamics of fermenting pH, cellulose enzyme activities, carbohydrate concentration, and oxidation reduction potential were determined to estimate the degradation efficiency of corn stover with GF-20.  Furthermore, the structural stability and functional microbes of GF-20 were identified on the basis of PCR-denaturing gradient gel electrophoresis (DGGE) profiling and principal component analysis.  The results showed that the offspring of GF-20 subcultured under different temperatures (4–30°C) and pH (6.0–9.0) conditions maintained stable growth, decomposition function, and composition structure.  Furthermore, consortia GF-20 had a stable composition structure, which induced GF-20 to secrete cellulose and promote substrate decomposition as corn stover and ammonium were used as sources of carbon and nitrogen, respectively.  According to the PCR-DGGE profiles, the key strains of GF-20 were determined to be Bacillus licheniformis, Cellvibrio mixtus subsp. mixtus, Bacillus tequilensis, Clostridium populeti, and Clostridium xylanolyticum.
    Plant Protection
    Isolation and identification of Fusarium oxysporum f. sp. cubense in Fujian Province, China
    WU Kai-li, CHEN Wei-zhong, YANG Shuai, WEN Ya, ZHENG Yu-ru, Wilfred Mabeche Anjago, YUN Ying-zi, WANG Zong-hua
    2019, 18(8): 1905-1913.  DOI: 10.1016/S2095-3119(18)62149-5
    Abstract ( )   PDF in ScienceDirect  
    Fusarium wilt, caused by Fusarium oxyporum f. sp. cubense (Foc), is the most serious disease affecting banana production.  To clarify the distribution of the Foc races in Fujian Province of China, 79 soil samples were collected from four regions of Zhangzhou City, the primary banana production area in Fujian.  We isolated and identified 12 Foc strains based on internal transcribed spacer (ITS) sequence analysis, PCR amplification by using Foc-specific primers and pathogenicity assays.  Our analysis indicated that 11 isolates belong to Foc race 1, and 1 isolate belongs to the Foc tropical species race 4 (TR4).  Although TR4 has previously been reported to occur in primary banana-producing provinces, such as Hainan, Guangxi, and Guangdong of China, this is the first report of TR4 isolated from the soil in Fujian Province.  Monitoring the presence of Foc, in particular, the TR4 strains in the soil, is the basic strategy to prevent and control Fusarium wilt.
    Effect of tillage and burial depth and density of seed on viability and seedling emergence of weedy rice
    ZHANG Zheng, GAO Ping-lei, DAI Wei-min, SONG Xiao-ling, HU Feng, QIANG Sheng
    2019, 18(8): 1914-1923.  DOI: 10.1016/S2095-3119(19)62583-9
    Abstract ( )   PDF in ScienceDirect  
    Weedy rice (Oryza sativa f. spontanea) is one of the three worst paddy weeds in most rice growing areas.  The unexpected heavy infestation is derived from a persistence of soil seed bank of weedy rice, which the shattered seeds chiefly feed back to.  Information on soil seed bank dynamics is imperative to predict the infestation of weeds.  In the present paper, the effect of rotary tillage on weedy rice seed bank structure was studied first, and a burial experiment of marked seeds was conducted to observe the overwintering survival, seed viability and seedling emergence of weedy rice.  The results showed that the proportion of weedy rice seeds in deeper soil increased but seedling emergence decreased with increasing plowing depth.  The viability of weedy rice seeds decreased as the burial duration time extended but more slowly in deeper soil layers.  Additionally, there was no significant effect of burial density on seed viability.  Moreover, the logistic model fitted well (R2≥0.95, P≤0.01) with the depressive trends of seed viability with increasing burial time under all burial depths and densities which can provide us further information about seed survival.  In field experiments, number of seedling emergence significantly decreased as seed burial depth increased, conversely, proportion of seedling emergence increased as seed burial density decreased.  This study has important implications for determining strategies for weedy rice management by exhausting its seed bank through the alteration of tillage practices.
    Animal Science · Veterinary Medicine
    miR-10b promotes porcine immature Sertoli cell proliferation by targeting the DAZAP1 gene  
    WENG Bo, RAN Mao-liang, Cao Rong, PENG Fu-zhi, LUO Hui, GAO Hu, TANG Xiang-wei, Yang An-qi, CHEN Bin
    2019, 18(8): 1924-1935.  DOI: 10.1016/S2095-3119(19)62564-5
    Abstract ( )   PDF in ScienceDirect  
    MicroRNAs (miRNAs) have been widely identified in porcine testicular tissues and implicated as crucial regulators of proliferation, apoptosis, and differentiation in porcine spermatogenesis related cells.  However, the function roles of most of the miRNAs that have been identified in Sertoli cells are poorly understood.  In the present study, six experiments were conducted to study the regulatory role of miR-10b in porcine immature Sertoli cells.  In experiment 1, the results showed that the relative mRNA expression level of miR-10b in porcine testicular tissues decreased quadratically (P<0.001) with increasing age, while the relative mRNA expression level of DAZAP1 gene increased (P<0.001).  In addition, the mRNA expression of miR-10b was negatively (P<0.01) correlated with DAZAP1 mRNA expression (r=–0.550).  In experiment 2, the results from the bioinformatic analysis and a luciferase reporter assay demonstrated that miR-10b directly targeted the DAZAP1 gene in porcine immature Sertoli cells.  DAZAP1 mRNA and protein expressions were both regulated (P<0.05) by miR-10b.  In experiments 3 to 5, the over-expression of miR-10b or the siRNA-mediated knockdown of the DAZAP1 gene promoted (P<0.05) porcine immature Sertoli cell proliferation, as determined by the Cell Counting Kit-8 (CCK-8) assay and the 5-Ethynyl-2´-deoxyuridine (EdU) assay.  However, an annexin V-FITC/PI staining assay and the expression of cell survival-related genes indicated that over-expression of miR-10b or knockdown of DAZAP1 had no effect (P>0.05) on porcine immature Sertoli cell apoptosis.  In experiment 6, the co-transfection treatment results showed that miR-10b promoted (P<0.05) porcine immature Sertoli cell proliferation by targeting DAZAP1 gene.  Overall, these experiments demonstrated that miR-10b promotes porcine immature Sertoli cell proliferation by targeting the DAZAP1 gene.
    A rapid, simple, and sensitive immunoagglutination assay with silica nanoparticles for serotype identification of Pseudomonas aeruginosa
    DONG Xiu-mei, TAO Jing, LI Ting-ting, ZHANG Ping, ZHU Yan, TANG Yu, SU Rui-hong, SHI Dong-fang
    2019, 18(8): 1936-1943.  DOI: 10.1016/S2095-3119(18)62135-5
    Abstract ( )   PDF in ScienceDirect  
    An agglutination test based on colored silica nanoparticles (colored SiNps) was established to detect serotypes of Pseudomonas aeruginosa.  Monodisperse colored SiNps were used as agglutination test carriers.  The colored SiNps were prepared through reverse microemulsion with reactive dyes, sensitized with 11 kinds of mono-specific antibodies against P. aeruginosa, and denoted as IgG-colored SiNps.  Eleven kinds of IgG-colored SiNps were individually mixed with P. aeruginosa on a glass slide.  Different serotypes of P. aeruginosa could be identified by agglutination test with evident agglutination.  The P. aeruginosa could be detected in a range from 3.6×105 to 3.6×1012 cfu mL–1.  This new agglutination test was confirmed to be a speci?c, sensitive, fast, easy-to-perform, and cost-ef?cient tool for the routine diagnosis of P. aeruginosa.