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    Ying GONG, Langqin YU, Lei ZHAO
    Frontiers of Agricultural Science and Engineering,

    ● Agricultural intensification reduced the complexity and connectance of soil food webs.

    ● Agricultural intensification impaired the robustness of pollination networks.

    ● High connectance in co-occurrence networks indicates efficient nutrient utilization.

    Complex network theory has been increasingly used in various research areas, including agroecosystems. This paper summarizes the basic concepts and approaches commonly used in complex network theory, and then reviews recent studies on the applications in agroecosystems of three types of common ecological networks, i.e., food webs, pollination networks and microbial co-occurrence networks. In general, agricultural intensification is considered to be a key driver of the change of agroecosystems. It causes the simplification of landscape, leads to the loss of biocontrol through cascading effect in food webs, and also reduces the complexity and connectance of soil food webs. For pollination networks, agricultural intensification impaired the robustness by reducing specialization and enhancing generality. The microbial co-occurrence networks with high connectance and low modularity generally corresponded to high efficiency in utilization of nutrients, and high resistance to crop pathogens. This review aims to show the readers the advances of ecological networks in agroecosystems and inspire the researchers to conduct their studies in a new network perspective.

    Jinghan LI, Cees LEEUWIS, Nico HEERINK, Weifeng ZHANG
    Frontiers of Agricultural Science and Engineering,

    ● Agricultural innovation is a coevolution process of hardware, software and orgware.

    ● Innovation intermediaries is important for the coevolution process of agricultural innovation.

    ● The roles of STBs have evolved from a knowledge broker to a broader innovation intermediary at the village level.

    ● Facilitating orgware is more effective than enabling software in promoting farmers’ adoption of improved tillage practice.

    ● Collaboration between individual STBs is needed to support the coevolution process of innovation at a larger scale.

    Agricultural innovation can be described as a coevolutionary process of technological innovation, symbolic change, and social or institutional innovation, which relies on the interactions and collaboration between multiple stakeholders. This view emphasizes the significance of innovation intermediaries in supporting the coevolution process of innovation. Many studies have provided evidence on how innovation intermediaries play roles in supporting the coevolution innovation process at a broader innovation system level. However, little emphasis has been given to the role of innovation intermediaries in supporting the coevolution process of innovation at the community level in rural China. To address this research gap, this paper offers a case study of a novel type of innovation support intervention designed to promote technical change at the community level, the Science and Technology Backyard (STB). The paper focuses on the efforts of a specific STB in Wangzhuang village to promote innovation in tillage methods in wheat production. The aims was to examine the role of this newly emerging innovation support intervention in supporting the coevolution process of innovation at the community level, and compare the outcome of the coevolution process in the village with an STB to that in villages without an STB. Innovation journey analysis is applied to understand the evolved intermediation roles in the innovation process, and multivariate regression analysis is employed to assess the outcome of the coevolution process in villages with and without an STB. The findings suggest that the roles of STBs have evolved from knowledge brokers to systemic innovation intermediaries that facilitate the coevolution process of innovation inside an STB village. It has led to a higher adoption rate of improved technology, a better enabling environment for learning, and more effective institutional support in STB villages than in non-STB villages. However, the effect of support provided by a single STB on the coevolution process outside the community was limited. This finding points to a need for collaboration mechanisms and for connecting single STBs to support the coevolution process of innovation at a larger scale.

    Yifeng ZHANG, Chunfang YANG, Bright OBUOBI, Martin Kobby GRANT
    Frontiers of Agricultural Science and Engineering,

    ● The choice of a modern agriculture project was found to be rational for professional farmers to reduce interference from non-market factors. The success of this project is due to its capacity to successfully fill the structural hole in the market transaction network.

    ● Professional farmers were shown to start their businesses by occupying the ‘self-benefit’ or ‘mutual-benefit’ structural hole of the market transaction network in economically developed areas.

    ● Professional farmers were found to occupy the organizational-governance structural hole of the rural social relationship network and the ‘mutual-benefit’ structural hole of the market network to start their businesses in traditional agricultural areas.

    A comparative multi-case analysis of professional farmer entrepreneurship cases in China was performed by applying the structural hole theory. The results confirmed four views. (1) Choosing the modern agriculture project entrepreneurship is rational for professional farmers, who return from urban, to reduce the interference from non-market factors. The success of this project stems from its ability to successfully occupy the structural hole of the market trading network. (2) In economically developed areas, professional farmers start their businesses and reduce transaction costs with factors by occupying ‘self-benefit’ or ‘mutual-benefit’ structural holes in market networks. (3) In traditional agricultural areas, for reducing factor transaction costs, professional farmers occupy the organizational-governance structural hole of rural social relationship networks and the mutual-benefit structural hole of market networks to start their businesses. (4) The embedding order of these two structural holes will change depending on the differences in the local resource endowment. This article proposes some suggestions to encourage professional farmers to develop featured agricultural projects, build a close benefit-linked mechanism with smallholders through the provision of socialized services, and participate in the governance of rural communities.

    Xiaoxia GUO, Chong WANG, Fusuo ZHANG
    Frontiers of Agricultural Science and Engineering,

    ● A five-step process for quantifying smallholder farming system sustainability is proposed.

    ● Definition of system boundary, functional unit, and indicators depends on research issues.

    ● Weighting, conversion, and aggregation methods tightly relates to the validity of assessment results.

    Smallholder farming systems are important for global food security, but these faces multiple environmental challenges hindering sustainable development. Although sustainable smallholder agriculture issues have been widely discussed and addressed by scientists globally, harmonized approaches in evaluating sustainability are still lacking. This paper proposes a five-step process for constructing a sustainability assessment method for smallholder farming systems, namely definition of system boundary & functional unit, indicator selection, indicator weighting, indicator conversion, and indicator aggregation. The paper summarizes the state-of-art progresses in agricultural sustainability assessment at different stages, and systematically discussed the benefits and limitations of weighting and aggregation methods. Overall, this evaluation process should be useful by providing rational and comprehensive results for quantifying the sustainability of smallholder farming systems, and will contribute to practice by providing decision-makers with directions for improving sustainable strategies.

    Tao WANG
    Frontiers of Agricultural Science and Engineering,

    ● This review systematically raises the subject concept of alfalfa biology.

    ● The discipline of alfalfa biology has been divided into six major sections.

    ● The recent advances from the perspective of discipline system have been reviewed.

    Alfalfa (Medicago sativa) is the main leguminous forage crop with great ecologic and economic value. The research of alfalfa in various fields has exploded, but has not been included in a systematic framework. This paper summarizes the status of global alfalfa research over the past 10 years, raise the subject concept of alfalfa biology, and review the recent advances from the perspective of discipline system as germplasm resources, multiomics and biotechnology, environmental biology, symbiotic nitrogen fixation, biological breeding and cultivation. This paper proposes the key unsolved scientific and technical issues in alfalfa biology, and hope to appeal the research interest of more plant scientists and to promote the development of alfalfa industry.

    Yajuan LI, Qianni HUANG
    Frontiers of Agricultural Science and Engineering,

    ● A systematical technology diffusion mode that can simultaneously achieve smallholders’ technology adoption to different scales was discovered.

    ● Collaborative, tree-shaped and jump-start modes are the main forms to promote technology diffusion.

    ● The combination of three modes above facilitates technology diffusion to different scales.

    ● The STB-based technology diffusion empowered smallholders through technology adoption.

    ● Trust is the key to promoting technology dependence and adoption among smallholders.

    Understanding the impact of agricultural socialized services on smallholder adoption of green production technologies and their mechanisms of action is of great importance for sustainability of farming systems. Currently, there were numerous related studies, but it is still unclear how to gradually achieve the diffusion of technological innovations on pilot sites to a regional level. To answer this question, this paper presents the pathways and mechanisms of green production technologies diffusion by comparing international typical service organizations or modes such as agricultural technology extension service centers (ATESC), farmer field schools (FFS), participatory technology innovation (PTI) and integrated colearning approach (ICLA), while taking Wangzhuang Science and Technology Backyard (WZ STB) in Quzhou, Hebei Province, China as an example. This research had three key outcomes. (1) The combination of collaborative, tree-shaped and jump-start diffusion modes promotes the diffusion of participatory technology innovation to different scales, such as farmers, villages and counties. (2) The three diffusion modes combine and expand the advantages of existing international modes. The collaborative diffusion mode not only provides full scope for the advantages of PTI, but also provides smallholders with service supply for the whole production period. The tree-shaped diffusion mode combines the advantages of FFS from point technology innovation to village diffusion, while achieving a full range of technical service support. The jump-start diffusion mode cannot only achieve large-scale technology diffusion like ATESC and ICLA, but also empower smallholders through adaptive technology innovation. (3) Trust is the key to promoting smallholder reliance on the science and technology provided by STB and to promote their adoption of green production technologies. Accordingly, the following policy recommendations were proposed: strengthen the combination of top-down and bottom-up technology innovation and diffusion models, establish an effective service communication platform and evaluation mechanism, and strengthen the linkage mechanism between socialized services providers and smallholders, which will provide a realistic basis for the national policy of targeted socialized services provision and promote smallholder adoption of green production technologies.

    Jie YAN, Yize LIU, Rui ZHANG, Chenhui CUI, Yingying ZHENG, Minghao ZHUANG
    Frontiers of Agricultural Science and Engineering,

    ● County-level sustainability assessment of maize production is presented.

    ● County-level improvement potential exhibits a large spatial heterogeneity.

    ● Promoting technical innovations can facilitate China’s agricultural transition.

    Agricultural production by smallholders is crucial for ensuring food provision in China. However, smallholders face a series of challenges on their farms including high-to-excess resource inputs, low use efficiency, as well as negative environmental impacts, which may be unfavorable for sustainable agriculture production. This study developed a county-level sustainability assessment of maize production in Hebei, China, by applying multiple data sources in combination with emergy, carbon footprint, nitrogen footprint and cost-benefit analyses. Scenario analysis was applied to explore the localized implementation strategies to achieve the sustainable farming system. The results show that the average emergy sustainability index (ESI) of maize at 2.31 is relatively low. The average greenhouse gas (GHG) emissions and reactive nitrogen (Nr) losses are 0.15 g·kcal−1 CO2-eq and 3.75 mg·kcal−1 N, respectively. The average cost and net income are 12,700 and 4340 CNY·ha−1, respectively. These results indicate a great potential to improve the environmental-economic sustainability of the maize production system of smallholders. In addition, the environmental and economic indicators calculated from the maize production show a substantial spatial heterogeneity among counties, indicating a requirement for different optimization strategies to improve the environment-economy sustainability at a finer scale. Based on the multiple scenario analysis, optimal strategies targeting each county are proposed. By adopting the optimal strategies, the average ESI and net income could increase by 32% and 83%, respectively, and the average GHG emissions and Nr losses reduce by 33% and 35%, respectively. These findings provide an important reference for adopting different strategies to achieve environment-economy sustainability for smallholders production systems with diverse landscapes in North China and propose a transition pathway toward achieving agriculture sustainability for smallholders worldwide.

    Chenqiao ZHU, Peng CHEN, Junli YE, Hang LI, Yue HUANG, Xiaoming YANG, Chuanwu CHEN, Chenglei ZHANG, Yuantao XU, Xiaoli WANG, Xiang YAN, Guangzhou DENG, Xiaolin JIANG, Nan WANG, Hongxing WANG, Quan SUN, Yun LIU, Di FENG, Min YU, Xietian SONG, Zongzhou XIE, Yunliu ZENG, Lijun CHAI, Qiang XU, Chongling DENG, Yunjiang CHENG, Xiuxin DENG
    Frontiers of Agricultural Science and Engineering,

    Fortunella genus consists of two populations: cultivated kumquat and wild Hong Kong kumquat.

    ● Artificial selection might involve in the origin of cultivated Fortunella species.

    ● A hypothesis for the differentiation and speciation of Fortunella species is proposed.

    Kumquat (Fortunella spp.) is a fruit and ornamental crop worldwide due to the palatable taste and high ornamental value of its fruit. Although Fortunella is classified into the economically important true citrus fruit tree group together with Citrus and Poncirus, few studies have been focused on its evolutionary scenario. In this study, analysis of five chloroplast loci and 47 nuclear microsatellites (nSSR) loci from 38 kumquat and 10 citrus accessions revealed the independent phylogeny of Fortunella among citrus taxa, and that Fortunella mainly comprises two populations: CUL, cultivated Fortunella spp. (F. margarita, F. crassifolia and F. japonica); and HK, wild Hong Kong kumquat (Fortunella hindsii). Genomic analysis based on whole-genome SNPs indicated that the allele frequency of both pupations deviated from the neutral selection model, suggesting directional selection was a force driving their evolutions. CUL exhibited lower genomic diversity and higher linkage strength than HK, suggesting artificial selection involved in its origin. A high level of genetic differentiation (Fst = 0.364) was detected and obviously asynchronous demographic changes were observed between CUL and HK. Based on these results, a new hypothesis for the speciation of Fortunella is proposed.

    Ning WANG, Fengxin WANG, Clinton C. SHOCK, Lei GAO, Chaobiao MENG, Zejun HUANG, Jianyu ZHAO
    Frontiers of Agricultural Science and Engineering,

    ● A moderate irrigation threshold of −25 kPa gave the greatest actual yield.

    ● Nitrogen rates of 80−160 kg·ha−1 reduced lodging risk without yield decrease.

    ● Planting density of 30 plants·m−2 provided both high yield and lodging resistance.

    ● A lower-stem lodging index was best for prediction of quinoa lodging risk.

    Lodging is a major yield-limiting factor of quinoa production. In 2018 and 2019, the orthogonal field experiments were conducted to investigate the responses of quinoa lodging risk and yield to irrigation threshold (soil matric potential of −15, −25 and −55 kPa), nitrogen rate (80, 160 and 240 kg·ha−1) and planting density (20, 30 and 40 plants m−2). Results showed that high irrigation thresholds and nitrogen rates significantly (P < 0.05) increased plant height and fresh weight per plant, and high planting densities reduced stem diameter and strength, all of those led to significantly ( P < 0.05) high lodging risks. The −15 and −55 kPa treatments gave the lowest actual yield ( P < 0.05) in 2018 and 2019, respectively. Higher lodging rate with a nitrogen rate of 240 kg·ha −1 resulted in a lower actual yield than 80 and 160 kg·ha−1 in both years. Planting density of 30 plants m−2 gave a significantly (P < 0.05) greater estimated yield than 20 plants m −2 and had a lower lodging rate than 40 plants m−2, resulting in the maximum actual yield among planting densities. In conclusion, a moderate irrigation threshold of −25 kPa, a nitrogen rate of 80−160 kg·ha−1 and an intermediate planting density of 30 plants m−2 were determined to be best for quinoa cultivation in North-western China. In addition, the lower-stem lodging index (quarter plant height) could evaluate lodging risk more accurately than middle-stem (half plant height) or upper-stem (three quarters plant height) lodging indexes.

    Philippe YAMEOGO, Saturnin ZIGANI, Xiaoqiang JIAO, Hongyan ZHANG, Junling ZHANG
    Frontiers of Agricultural Science and Engineering,

    ● Constraints in cultivation and production of pearl millet in West Africa are summarized.

    ● Production systems and fertilization methods in pearl millet production are highlighted.

    ● Sustainable production needs integrated cropping systems and fertilizer use efficiency.

    ● A holistic approach is required to establish a strong collaboration among rural actors.

    West African countries are among the larger global millet producers but have low yields mainly due to the low quality of their marginal soils. The objectives of this work were to analyze the benefits and constraints of pearl millet production, to summarize the impact of different cropping systems and fertilization modes while proposing a holistic approach for sustainable production. The major constraints on millet yields are low rates or absence of fertilizers, unsuitable cropping systems, and the proliferation of pests and diseases. Intercropping with cowpea is a widely used cropping system in addition to crop rotation, monocropping and agroforestry systems. Microdosing is the best fertilization mode for West African smallholders. It is concluded that integrated systems (breeding new cultivars, intercropping and microdosing) in tied ridges or infiltration pit practices, sustained by the implementation of innovative approaches such as the ‘Science and Technology Backyards’ from China are a promising approach for increasing pearl millet production. In addition, policies such as land protection of the farmers and subsidies of inputs from the government and the effective involvement of farmers and extension officers are necessary in sustaining millet production in West Africa.