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    Bing-Xin WANG, Anouschka R. HOF, Chun-Sen MA
    Frontiers of Agricultural Science and Engineering, 2022, 9(1): 4-18.

    ● An overview of impacts of climate change on wheat and rice crops.

    ● A review on impacts of climate change on insect pests and fungal pathogens of wheat and rice.

    ● A selection of adaptation strategies to mitigate impacts of climate change on crop production and pest and disease management.

    Ongoing climate change is expected to have impacts on crops, insect pests, and plant pathogens and poses considerable threats to sustainable food security. Existing reviews have summarized impacts of a changing climate on agriculture, but the majority of these are presented from an ecological point of view, and scant information is available on specific species in agricultural applications. This paper provides an overview of impacts of climate change on two staple crops, wheat and rice. First, the direct effects of climate change on crop growth, yield formation, and geographic distribution of wheat and rice are reviewed. Then, the effects of climate change on pests and pathogens related with wheat and rice, and their interactions with the crops are summarized. Finally, potential management strategies to mitigate the direct impacts of climate change on crops, and the indirect impacts on crops through pests and pathogens are outlined. The present overview aims to aid agriculture practitioners and researchers who are interested in wheat and rice to better understand climate change related impacts on the target species.

    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.

    Guirong WANG, Yuanchao WANG, Guangfu YANG, Kongming WU
    Frontiers of Agricultural Science and Engineering, 2022, 9(1): 1-3.
    Enzai DU, Nan XIA, Yuying GUO, Yuehan TIAN, Binghe LI, Xuejun LIU, Wim de VRIES
    Frontiers of Agricultural Science and Engineering,

    ● Patterns and effects of N deposition on urban forests are reviewed.

    ● N deposition generally shows an urban hotspot phenomenon.

    ● Urban N deposition shows high ratios of ammonium to nitrate.

    ● N deposition likely has distinct effects on urban and natural forests.

    The global urban area is expanding continuously, resulting in unprecedented emissions and deposition of reactive nitrogen (N) in urban environments. However, large knowledge gaps remain in the ecological effects of N deposition on urban forests that provide key ecosystem services for an increasing majority of city dwellers. The current understanding of the spatial patterns and ecological effects of N deposition in urban forests was synthesized based on a literature review of observational and experimental studies. Nitrogen deposition generally increases closer to cities, resulting in an urban hotspot phenomenon. Chemical components of N deposition also shift across urban-suburban-rural gradients, showing higher ratios of ammonium to nitrate in and around urban areas. The ecological effects of N deposition on urban forest ecosystems are overviewed with a special focus on ecosystem N cycling, soil acidification, nutrient imbalances, soil greenhouse gas emissions, tree growth and forest productivity, and plant and soil microbial diversity. The distinct effects of unprecedented N deposition on urban forests are discussed in comparison with the common effects in natural forests. Despite the existing research efforts, several key research needs are highlighted to fill the knowledge gaps in the ecological effects of N deposition on urban forests.

    Gang HE, Zhaohui WANG, Jianbo SHEN, Zhenling CUI, Fusuo ZHANG
    Frontiers of Agricultural Science and Engineering, 2021, 8(4): 491-500.

    ● Agriculture on Loess Plateau has transformed from food shortage to green development.

    ● Terracing and check-dams are the key engineering measures to increase crop yields.

    ● Agronomic measures and policy support greatly increased crop production.

    ● Increasing non-agricultural income is a key part of increasing farmers’ income.

    ● Grain for Green Program had an overwhelming advantage in protecting environment.

    Loess Plateau of China is a typical dryland agricultural area. Agriculture there has transformed from food shortage toward green development over the past seven decades, and has achieved world-renowned achievements. During 1950–1980, the population increased from 42 to 77 million, increasing grain production to meet food demand of rapid population growth was the greatest challenge. Engineering measures such as terracing and check-dam were the crucial strategies to increase crop production. From 1981 to 2000, most of agronomic measures played a key role in increasing crops yield, and a series of policy support has benefited millions of smallholders. As expected, these measures and policies greatly increased crop production and basically achieved food security; but, low per capita GDP (only about 620 USD in 2000) was still a big challenge. During 2001–2015, the increase in agricultural and non-agricultural income together supported the increase in farmer income to 5781 USD·yr–1. Intensive agriculture that relies heavily on chemicals increased crop productivity by 56%. Steadfast policy support such as “Grain for Green Program” had an overwhelming advantage in protecting the natural ecological environment. In the new era, the integration of science and technology innovations, policy support and positive societal factors will be the golden key to further improve food production, protect environment, and increase smallholder income.

    Zhizhi WANG, Pu TANG, Min SHI, Jianhua HUANG, Xuexin CHEN
    Frontiers of Agricultural Science and Engineering, 2022, 9(1): 63-74.

    ● Most entomophagous arthropods consume nectar or pollen as alternative diets.

    ● The attractive of floral resource with different traits varies in a wide degree.

    ● Floral resource plays positive effects on not only entomophagous insects but also agricultural biodiversity, multiple ecosystem services and crop production.

    There is a growing demand for high-quality agricultural products and more countries have adopted landscape management by sowing flowering plants in agricultural fields as an important branch of conservation biological control. However, there has been less concern over the interactions and trade-offs between floral plants and entomophagous arthropods. This paper review progress in pollen/nectar feeding habits of entomophagous insects including parasitoids and predators which are important natural enemies of crop pests in agricultural fields. Factors that influence the preference of different guilds of natural enemies are reviewed to guide the selection of flowering plants in conservation biological control practices. Most studies find that floral resources have positive effects on both biological traits of natural enemies and their abundance and diversity, and this is believed to contribute greatly to pest control. Furthermore, the potential impacts of floral resources on crop yields are also discussed with an emphasis on a guild of entomophagous insects that provides both pest control and pollination services.

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    Xiaofei LI, Ruipeng YU, Long LI
    Frontiers of Agricultural Science and Engineering, 2021, 8(4): 659-661.
    Jingyuan XIA, Alexandre LATCHININSKY, Buyung HADI, Maged ELKAHKY
    Frontiers of Agricultural Science and Engineering, 2022, 9(1): 161-166.

    Plant pests and diseases have significant negative impacts on global food security, world trade and rural livelihoods. Climate change exacerbates these impacts in certain parts of the world. Overreliance on pesticides as the primary tool for plant pest management leads to problems such as pesticide resistance and pest resurgence. Environmental and food safety concerns are also associated with overuse of pesticides in crop production. There is clearly a need for a shift in pest management strategies and practices globally. Optimization of structures and functions in crop production agroecosystems through soil conservation practices and cropping diversification can improve pest regulation services provided in the systems. Prioritization of safer alternatives and practices in the IPM pyramid, such as resistant varieties and biopesticides, helps minimize the use of potentially risky agricultural inputs such as synthetic pesticides. Investment is needed to boost the development of innovative green technologies and practices. Production, distribution, use and regulatory capacities need to be strengthened to facilitate large-scale adoption of green technologies and practices. Finally, policy, financial and market instruments should be wielded to provide an enabling environment for the transformation to sustainable plant pest and disease management strategies and practices worldwide.

    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.

    Xiangyang LI, Linhong JIN, Zhuo CHEN, Baoan SONG
    Frontiers of Agricultural Science and Engineering, 2022, 9(1): 75-81.

    ● Application of plant defense inducers against tea diseases.

    ● Application of natural enemies against insect pests.

    ● Application of Trifolium repens against weeds.

    The application and development of ‘green’ preventive technologies in tea plantations is an important means of ensuring tea quality and ecological safety. Ecological, agronomic and biological controls are the main preventive measures used in Guizhou Province. This paper summarizes the ‘green’ preventive technologies being applied in Guizhou tea plantations, including the use of plant defense inducers to regulate tea plant responses to pathogens, natural enemies to control pest species causing damage to shoots and Trifolium repens to control the main weed species. In addition, it summarizes the integrated ‘green’ preventive technologies being used in Guizhou and provides a foundation for the ecological maintenance of tea plantations.

    Monica K. KANSIIME, Idah MUGAMBI, Harrison RWARE, Christine ALOKIT, Caroline ALIAMO, Feng ZHANG, Jakob LATZKO, Puyun YANG, Daniel KARANJA, Dannie ROMNEY
    Frontiers of Agricultural Science and Engineering,

    ● Seventy-eight percent of farmers accessed extension and advisory services from electronic sources dominated by radio.

    ● Low digital literacy and high cost of internet and digital devices were key barriers to digital extension and advisory services use.

    ● Farmers need information to make decisions, e.g., fertilizers, seeds or pesticides to use.

    ● Integrating digital and face-to-face methods can enhance inclusive scaling of extension activities.

    An assessment of the challenges and capacity gaps in smallholder access to digital extension and advisory services (EAS) was made by surveying 197 female and 239 male farmers in Kenya and Uganda. Non-digital extension approaches remain dominant but at least 78% of farmers accessed EAS from electronic sources dominated by radio. This is attributed to the fact that ownership of radios was more widespread than of other digital devices. Challenges that particularly limit the use of digital services included low digital literacy and prohibitive cost of internet and mobile devices. Female and elderly farmers were more likely to report these challenges than their counterparts. Logistic regression model results show that ownership of digital devices, participation in post-production activities, and access to extension were enablers of digital EAS use. Farmers mentioned gaps in obtaining information on crop pest/disease diagnosis and management, fertilizer application, pesticide safety and quality seed. Given the diversity in smallholder technological capabilities and information needs, the recommendations made include integration of digital communication within multimode advisory services that use different but linked communication channels, continued farmer digital innovation capacity enhancement, and participatory design approaches that deliver relevant and actionable information for inclusive scaling of extension activities.

    Lei DENG, Zhouping SHANGGUAN
    Frontiers of Agricultural Science and Engineering, 2021, 8(4): 501-511.

    ● Analyse the effects of ecological management measures undertaken so far.

    ● Point out the main problems that confront effective ecological management.

    ● Suggest some measures to guide ecological management and high-quality development.

    ● Develop some models to improve the quality of clear waters and green mountains.

    ● Provide scientific and technological support for green and eco-friendly development.

    The Loess Plateau is the core area in the Yellow River basin for implementing environmental protection and high-quality development strategies. A series of ecological projects has implemented aimed at soil and water conservation and ecological management on the Loess Plateau over the past 70 years. The effects of the ecological projects are apparent mainly through a marked increase in vegetation cover, controlled soil erosion and reduced flow of sediment into the Yellow River, continual optimization of the industrial structure and increased production from arable land, poverty alleviation and greater prosperity, and optimal allocation of space for biological organisms. Major problems have also been analyzed in ecological management including the fragile ecosystem of the region, maintaining the stability of vegetation, lower agricultural productivity and continued risk from natural disasters. Some suitable schemes and models have been developed for the coordinated development of the region through research and demonstration, striking the optimum balance between rural industry and ecology, and increased regional capacity to supply high-quality ecological products. Countermeasures to address the problems are suggested to guide ecological management and high-quality development in the future.

    Cathryn A. O'SULLIVAN, Elliott G. DUNCAN, Margaret M. ROPER, Alan E. RICHARDSON, John A. KIRKEGAARD, Mark B. PEOPLES
    Frontiers of Agricultural Science and Engineering,

    ● First evidence of BNI capacity in canola.

    ● BNI level was higher in canola cv. Hyola 404RR than in B. humidicola, the BNI positive control.

    ● BNI in canola may explain increased N immobilization and mineralization rates following a canola crop which may have implications for N management in rotational farming systems that include canola.

    A range of plant species produce root exudates that inhibit ammonia-oxidizing microorganisms. This biological nitrification inhibition (BNI) capacity can decrease N loss and increase N uptake from the rhizosphere. This study sought evidence for the existence and magnitude of BNI capacity in canola ( Brassica napus). Seedlings of three canola cultivars, Brachiaria humidicola (BNI positive) and wheat ( Triticum aestivum) were grown in a hydroponic system. Root exudates were collected and their inhibition of the ammonia oxidizing bacterium, Nitrosospira multiformis, was tested. Subsequent pot experiments were used to test the inhibition of native nitrifying communities in soil. Root exudates from canola significantly reduced nitrification rates of both N. multiformis cultures and native soil microbial communities. The level of nitrification inhibition across the three cultivars was similar to the well-studied high-BNI species B. humidicola. BNI capacity of canola may have implications for the N dynamics in farming systems and the N uptake efficiency of crops in rotational farming systems. By reducing nitrification rates canola crops may decrease N losses, increase plant N uptake and encourage microbial N immobilization and subsequently increase the pool of organic N that is available for mineralization during the following cereal crops.

    Thierry LONHIENNE, Mario Daniel GARCIA, Yu Shang LOW, Luke W. GUDDAT
    Frontiers of Agricultural Science and Engineering, 2022, 9(1): 155-160.
    Li ZHANG, Jialin CUI, Qi HE, Qing X. LI
    Frontiers of Agricultural Science and Engineering, 2022, 9(1): 150-154.