Dec 2021, Volume 8 Issue 4

Cover illustration

  • The Loess Plateau is a key focus area in the Yellow River basin for implementing environmental protection and high-quality development strategies. Agricultural production on the Loess Plateau depends highly on a healthy natural environment. As the medium for crop growth, soils and water are vital for achieving desirable crop and water productivity. The development of soil and water conservation and the natural environment on the Loess Plateau are therefore matters of concern [Detail] ...

    Download cover

  • Select all
    Gang HE, Zhaohui WANG, Jianbo SHEN, Zhenling CUI, Fusuo ZHANG

    ● 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.

    Lei DENG, Zhouping SHANGGUAN

    ● 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.

    Andreas BUERKERT, Kotiganahalli Narayanagowda GANESHAIAH, Stefan SIEBERT

    • Access to water shapes determines rise and collapse of civilizations

    • Water conservation, human health and culture are closely connected

    • Agricultural intensification triggers multiple cropping, irrigation and fertilization

    • Mastering access to water will determine pace and sustainability of urbanization

    Settlement patterns and social structures have been shaped by access to water since the onset of human societies. This review covers historical and recent examples from Cambodia, Central Asia, India, Latin America and the Arabian Peninsula to analyze the role of water resources in determining the rise and collapse of civilizations. Over recent decades increasing globalization and concomitant possibilities to externalize water needs as virtual water have obscured global dependence on water resources via telecoupling, but rapid urbanization brings it now back to the political agenda. It is foremost in the urban arena of poorer countries where competing claims for water increasingly lead to scale-transcendent conflicts about ecosystem services. Solutions to the dilemma will require broad stakeholder-based agreements on water use taking into account the available data on water resources, their current and potential use efficiency, recycling of water after effective treatment, and social-ecological approaches of improved governance and conflict resolution.

    Xiuwei GUO, Manoj Kumar SHUKLA, Di WU, Shichao CHEN, Donghao LI, Taisheng DU

    • A relative yield of 70% was obtained under both border and drip irrigation.

    • Drip irrigation saved water and lowered yield variability compared to border irrigation.

    • Drip irrigation led to accumulation of soil nitrogen and phosphorus in the root zone.

    • Relative yield may increase 8% to 10% by optimizing field management.

    • Plant density, irrigation and nitrogen are major factors closing yield gap in NW China.

    Agriculture faces the dual challenges of food security and environmental sustainability. Here, we investigate current maize production at the field scale, analyze the yield gaps and impacting factors, and recommend measures for sustainably closing yield gaps. An experiment was conducted on a 3.9-ha maize seed production field in arid north-western China, managed with border and drip irrigation, respectively, in 2015 and 2016. The relative yield reached 70% in both years. However, drip irrigation saved 227 mm irrigation water during a drier growing season compared with traditional border irrigation, accounting for 44% of the maize evapotranspiration (ET). Yield variability under drip irrigation was 12.1%, lower than the 18.8% under border irrigation. Boundary line analysis indicates that a relative yield increase of 8% to 10% might be obtained by optimizing the yield-limiting factors. Plant density and soil available water content and available nitrogen were the three major factors involved. In conclusion, closing yield gaps with agricultural sustainability may be realized by optimizing agronomic, irrigation and fertilizer management, using water-saving irrigation methods and using site-specific management.

    Di WU, Allan A. ANDALES, Hui YANG, Qing SUN, Shichao CHEN, Xiuwei GUO, Donghao LI, Taisheng DU

    • The linkage between crop water productivity and soil properties were summarized

    • Knowledge of soil microbial effects on crop water productivity is still limited

    • Knowledge of interactions of soil factors on crop water productivity is still limited

    Agriculture uses a large proportion of global and regional water resources. Due to the rapid increase of population in the world, the increasing competition for water resources has led to an urgent need in increasing crop water productivity for agricultural sustainability. As the medium for crop growth, soils and their properties are important in affecting crop water productivity. This review examines the effects of soil physical, chemical, and microbial properties on crop water productivity and the quantitative relationships between them. A comprehensive view of these relationships may provide important insights for soil and water management in arable land for agriculture in the future.

    Yandan FU, Jiahui KANG, Ziyue LI, Xuejun LIU, Wen XU

    • Historic trends in nutrient loading and flux in the Yangtze River were analyzed

    • Decreasing trends in the concentrations and fluxes of DSi were found

    • Significant increasing trends in DIN and DIP concentrations were observed

    • The frequency of and area covered by red tide outbreaks substantially increased

    • Atmospheric deposition become a vital factor influencing DIN loadings and fluxes

    Intensifying human activity in the Yangtze River basin has substantially increased nutrient concentrations in the Yangtze River Estuary, leading to degradation of the coastal environment. Analysis of nutrient determinations published over the past 50 years reveals a gradual decreasing trend in the concentrations and fluxes of dissolved silicate (DSi). However, both dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphate (DIP) concentrations have increased significantly since the 1970s. The frequency of and area covered by red tide outbreaks have increased greatly during this period, mainly due to changes in nutrient supply ratios [i.e., N/P (DIN/DIP), N/Si (DIN/DSi), P/Si (DIP/DSi)]. A strong correlation was found between the riverine DIN fluxes and the estimated DIN inputs from the major N sources, particularly fertilizers and atmospheric deposition. The data provide a comprehensive assessment of nutrients in the Yangtze River basin and their ecological impacts and indicate a potentially significant influence of atmospheric deposition on DIN loadings and fluxes.

    Ian T. RILEY

    • Semi-arid ecosystems have been especially impacted by a long history of clearing, cropping and intensified grazing.

    • Selection of tree species for assessment for agroforestry needs to consider their utility and effectiveness in provision of ecosystem service, but also the wider consideration of preserving biodiversity.

    • Imperatives of agroecosystem services and biodiversity conservation (or restoration) will impact on species selection for agroforestry.

    • The potential of Allocasuarina and Casuarina for wider economic and ecosystem needs an endeavor to achieve demonstrable gains.

    Agroecosystems in water-limited contexts— Mediterranean, semi-arid and arid climatic zones—are too frequently degraded systems that will not provide the needed ecosystem services to ensure a future of sustainable agricultural production. The processes that have created this situation continue and are being accelerated by anthropogenic climate change. Increasing arboreal vegetation in these areas through agroforestry is an important strategy to conserve and improve their agroecosystems. Actinorhizal trees and shrubs in the Casurinaceae have a unique set of adaptations for heat and water stress, and/or infertile to hostile soils. Central Anatolia, Turkey is particularly at risk of increasing aridity and further degradation. Therefore, species of Allocasuarina and Casuarina have been evaluated for their potential use in agroecosystem improvement in semi-arid areas with a focus on Central Anatolia. Based on a semiquantitative environmental tolerance index and reported plant stature, eight species were identified as being of high (A. verticillata and C. pauper) to moderate (A. acutivalvis, A. decaisneana, A. dielsiana, A. huegeliana, C. cristata and C. obesa) priority for assessment, with none of these species having been adequately evaluated for agroforestry deployment in semi-arid agroecosystems in any context.

    Rachid RAZOUK, Abdellah KAJJI, Anas HAMDANI, Jamal CHARAFI, Lahcen HSSAINI, Said BOUDA

    • Regulated deficit irrigation was assessed in almond, peach and plum over 3 years.

    • Fruit-growth slowdown stages are appropriate periods to apply deficit irrigation.

    • Peach yields were unaffected under a regulated deficit irrigation of 75% ETC.

    • Regulated deficit irrigation of 50% ETC maintained yields of almond and plum.

    • Fruit quality improved under regulated deficit irrigation.

    The effects of regulated deficit irrigation (RDI) on the performance of almond cv. Tuono, peach cv. JH-Hall and plum cv. Stanley were assessed on the Saiss Plain (NW, Morocco) over three consecutive growing seasons (2011–2013). Irrigation treatments consisted of a control, irrigation applied to fully satisfy crop water requirements (100% ETC), and two RDI treatments, irrigation applied to 75% ETC (RDI-75) and 50% ETC (RDI-50). These three treatments were applied during fruit-growth slowdown periods corresponding to Stages II and III in almond and Stage II in peach and plum. Yield and fruit quality traits were determined. The effect of RDI differed between species. Yield and fruit size were reduced significantly only in peach under RDI-50. Fruit quality improved in this species in the first year of the experiment, with an increase of sugar/acid ratio and polyphenol content. Plum quality also improved but the effects were significant only in the second and third years. Similar results were recorded in almond kernel, but their epidermal grooves were deeper under RDI-50, and this may have affected their commercial value. It is concluded that water can be saved during the fruit-growth slowdown period by up to 25% in peach and 50% in almond and plum with improvements in fruit quality without affecting total yield.

    Tammo S. STEENHUIS, Xiaolin YANG

    Agricultural production in the North China Plain with rainfall of less than 500 mm·yr−1 has been steadily increasing over the past 40 years, with the groundwater levels decreasing at a rate of over 1 m·yr−1. In this paper, it is demonstrated theoretically that the water level in the aquifer can be expressed as a function of agricultural production and the sum of water added as rainfall and imported from outside the basin. Therefore, the most effective measures to halt groundwater depletion are importing water, decreasing cropping intensity and growing less thirsty crops. Irrigation improvements, mulching and agronomic measures that could increase the yield per unit area have less of an impact on solving the declining groundwater levels.

    Noreen ZAHRA, Muhammad FAROOQ, Kadambot H.M. SIDDIQUE
    Dipta DEY, Tanzila Ismail EMA, Partha BISWAS, Sharmin AKTAR, Shoeba ISLAM, Urmi Rahman RINIK, Mahmudul FIROZ, Shahlaa Zernaz AHMED, Salauddin AL AZAD, Ahsab RAHMAN, Sadia AFRIN, Rezwan Ahmed MAHEDI, Md. Nasir Uddin BADAL

    • Identification of bacteriocin sources

    • Classification of bacteriocins

    • Antiviral pathways of bacteriocins

    The COVID-19 infections caused by SARS-CoV-2 have resulted in millions of people being infected and thousands of deaths globally since November 2019. To date, no unique therapeutic agent has been developed to slow the progression of this pandemic. Despite possessing antiviral traits the potential of bacteriocins to combat SARS-CoV-2 infection has not been fully investigated. This review summarizes the mechanisms by which bacteriocins can be manipulated and implemented as effective virus entry blockers with infection suppression potential properties to highly transmissible viruses through comprehensive immune modulations that are potentially effective against COVID-19. These antimicrobial peptides have been suggested as effective antiviral therapeutics and therapeutic supplements to prevent rapid virus transmission. This review also provides a new insight into the cellular and molecular alterations which have made SARS-CoV-2 self-modified with diversified infection patterns. In addition, the possible applications of antimicrobial peptides through both natural and induced mechanisms in infection prevention perspectives on changeable virulence cases are comprehensively analyzed. Specific attention is given to the antiviral mechanisms of the molecules along with their integrative use with synthetic biology and nanosensor technology for rapid detection. Novel bacteriocin based therapeutics with cutting-edge technologies might be potential substitutes for existing time-consuming and expensive approaches to fight this newly emerged global threat.

    Zhaohui XUE, Fang WAN, Xin GAO, Wancong YU, Zhijun ZHANG, Jing LIU, Xiaohong KOU

    • Aqueous enzymatic extraction (AEE) is performed for oil extraction from Schizochytrium sp.

    • AEE process is optimized by response surface methodology.

    • Microalgal oil extracted by AEE has high contents of PUFA, tocopherols and phenolics.

    • AEEO exhibits considerable antioxidant activity as compared with SEO.

    Schizochytrium sp., a marine microalga, is a potential source of edible oil due to its short growth cycle and rapid lipid accumulation, especially of docosahexaenoic acid. An approach to isolate edible microalgal oil from Schizochytrium sp. using aqueous enzymatic extraction (AEE) was developed. Parameters were optimized by single-factor experiments followed by Box-Behnken design. Proteases were effective in extracting oil. The maximum free oil recovery (49.7%±0.58%) and total oil recovery (68.1%±0.94%) were obtained under optimum conditions of liquid-to-solid ratio of 4.8:1, a 2.5% enzyme concentration of papain and an extraction time of 2.2 h. There was a significant difference (P<0.05) in polyunsaturated fatty acid composition between microalgal oil obtained by AEE and by Soxhlet extraction, with the former having superior physiochemical properties and higher concentrations of bioactive components including total phenolic compounds and total tocopherols. These findings indicate a potential application of AEE for extraction of oil from Schizochytrium sp.

    Shufeng YAO, Jiali XU, Haibo ZHANG, Hong GAO, Shibin SHANG, Dan WANG

    • Ethyl acetate and 95% ethanol extracts from T. chinensis rhizomes gave great inhibition on six plant pathogenic fungi

    T. chinensis has potential to be a new natural fungicide resource

    T. chinensis has potential to be used for the preservation of agricultural and forestry products such as fruits and vegetables

    The antifungal effectiveness of extracts of five medicinal plant species was determined. The inhibitory activity of extracts of Eucalyptus tereticornis, Xanthium sibiricum, Artemisia argyi, Tupistra chinensis and Pyrola calliantha were evaluated against the mycelial growth of the plant pathogenic fungi Aspergillus niger, Botrytis cinerea, Penicillium digitatum, P. expansum, P. italicum and Rhizopus stolonifer. All plant extracts were prepared at 60°C using solvents (either water, 50% ethanol (v/v), 95% ethanol (v/v), ethyl acetate or petroleum ether). Fungicidal effects of all plants tested were confirmed. Different extracts from the same plant species gave different degrees of inhibition. All aqueous extracts had weak or no activity on all fungi tested. Ethyl acetate and 95% ethanol extracts from T. chinensis rhizomes gave greater inhibition and a broader spectrum inhibition than the other extracts. T. chinensis may have potential as a new natural fungicide and may be used for the preservation of agricultural and forestry products such as fruits and vegetables.

    Yong ZHOU, Linjuan OUYANG, Dahu ZHOU, Yicong CAI, Haohua HE

    • A total of 8 SOD genes from watermelon were identified and bioinformatically analyzed.

    • The SOD proteins from watermelon and other different plant species can be classified into five groups consistent with their metal cofactors.

    ClSOD genes exhibited distinctive tissue-specific and abiotic stress responsive expression patterns.

    Superoxide dismutase (SOD) is an important enzyme in the antioxidant system of plants and plays a vital role in stress responses by maintaining the dynamic balance of reactive oxygen species (ROS) concentrations. Genome-wide analysis of the SOD gene family in various plant species has been conducted but little is known about this gene family in watermelon (Citrullus lanatus). Here, eight SOD genes were identified in the watermelon genome and are designated ClCSD1-5, ClFSD1-2 and ClMSD according to their metal cofactors. Phylogenetic analysis shows that SOD proteins from various plant species can be classified into five groups and members in the same group possess the same metal cofactor and similar subcellular localizations. Expression analysis of the ClSOD genes indicates that they had tissue-specific expression patterns with high expression in different tissues including the leaves, flowers and fruit. In addition, the expression of ClSOD genes differed appreciably under salinity, drought and abscisic acid (ABA) treatments, indicating that they may be involved in ROS scavenging under different abiotic stresses via an ABA-dependent signaling pathway. These results lay the foundation for elucidating the function of ClSOD genes in stress tolerance and fruit development in watermelon.

  • NEWS
    Xiaofei LI, Ruipeng YU, Long LI
    Baohua CHU, Jia SUN, Huan DANG, Ziqing MA, Shuang ZHAO, Qingmei GUAN, Xuewei LI