Linking nutrient strategies with plant size along a grazing gradient: Evidence from Leymus chinensis in a natural pasture

St udying the changes in nutrient use strategies induced by grazing can provide insight into the process of grassland degradation and is important for improving grassland quality and enhancing ecosystem function. Dominant species in meadow steppe can optimize their use of limiting resources; however, the regulation of nutrient use strategies across grazing gradients is not fully understood. Therefore, in this study, we report an in situ study in which the impact of grazing rates on nutrient use strategies of Leymus chinensis, the dominant plant species in eastern Eurasian temperate steppes, was investigated. We conducted a large randomized controlled experiment(conducted continuously for five years in grassland plots in a natural pasture in Ha ilar, eastern Mongolia Plateau, China) to assess the effects of grazing rate treatments(0.00, 0.23, 0.34, 0.46, 0.69, and 0.92 adult cattle unit(AU) ha–1) on L. chinensis along a grazing gradient and employed a random sampling approach to compare the accumulation, allocation, and stoichiometry of C, N, and P in leaves and stems. Ou r findings demonstrated the follows:(i) The height of L. chinensis decreased with an increase in the grazing gradient, and the concentrations of C, N, and P significantly increased;(ii) the accumulation of C, N, and P per individual was negatively correlated with the concentration of aboveground tissues, suggesting that there was a tradeoff in L. chinensis between nutrient accumulation and concentration at the individual scale;(iii) the leaf-to-stem ratio of C, N, and P accumulation increased with grazing intensity, indicating a tradeoff in nutrient allocation and plant size at the individual plant level; and(iv) grazing rates were negatively correlated with the ratios of C:N and C:P in the stem; however, these ratios in leaves significantly increased with grazing intensity. Our findings suggest that L. chinensis in meadow steppe adapts to grazing disturbance through tradeoffs between plant size and nutrient use strategies. Moreover, our results imply that grazing produces a compensatory effect on nutrient use efficiency between the stems and leaves of L. chinensis.     

植物营养遗传性

不同植物存在营养基因型差异,因而具有不同营养特点,表现在不同植物对养分需求的种类、数量和养分代谢方式等存在差异。植物营养特性差异的研究,目前主要集中在根际动态过程的研究上,包括根系分泌物和根际微生物两方面。植物营养遗传性,在育种工作、土宜研究、环境保护等方面的应用具有广阔前景。     

农药经营市场存在的问题及治理对策

通过对当前农药经营市场现状和存在的主要问题的分析,提出了农药市场的有效治理对策。     

不同养分管理措施下萝卜的产量效应和养分利用效应比较

采用田间小区试验方法,比较了优化施肥和农民常规施肥两种不同的养分管理模式下当地主栽萝卜品种的产量及养分吸收利用效应。结果表明:在当地土壤肥力条件下,与农民常规施肥相比,氮(N)、磷(P2O5)、钾(K2O)养分量分别减施16.3%,59.5%及14.3%,根据萝卜生育特性进行运筹的优化施肥处理萝卜产量没有显著变化,萝卜养分累积量随生育期的变化趋势也未受到明显影响,但缺氮、磷、钾的PK、NK、NP处理均会显著降低萝卜产量及养分累积量,氮对萝卜产量及氮、磷养分的累积量影响最大,磷次之,钾最小,对萝卜植株钾养分累积量的影响则以氮最大、钾次之、磷最小。与农民常规施肥相比,优化施肥更有利于地下部磷钾养分的积累,氮、磷、钾肥表观利用率分别提高了21.4%,63.1%及41.1%,氮、磷、钾肥料偏生产力分别显著增加了27.3%,151.1%和18.8%,氮、磷肥的农学效率分别显著增加了17.9%,145.6%,且优化施肥处理在肥料投入成本降低33%的情况下收益增加了2776元/hm2。由此可见,根据土壤地力和萝卜养分需求特性进行的优化施肥处理在保证产量的基础上,可显著提高经济效益和生态效益。     

植物转基因技术的实用化标准和策略

从实用角度出发，综合评述了植物转基因技术的研究现状和发展趋势；探讨了植物转化系统的实用化标准：提出了植物遣传转化研究各个方面（包括组织培养、基因转移、转化体筛选、基因表达等）存在的问题和发展策略。     

Analysis on potential approaches to utilize genic male sterility in plant hybrid breeding

The exploitation of plant heterosis is an effective approach to increasing the food production. The heterotic hybrid varieties in major crops such as rice, cotton, and wheat can show more than 20% yield advantage over best conventional ones under the same cultivation conditions. The difficulties in breeding elite male sterile lines and the inconveniences for commercial hybrid seed production are hampering the development of hybrid crops breeding.     

不同钾营养对厚皮甜瓜生长发育及光合特性影响的研究

试验测定了无土栽培营养液中不同钾水平对甜瓜生长发育及叶片光合特性的影响。结果表明 :当 K2 =2 3 4mg/L时 ,甜瓜植株生长较好、叶片光合速率较强并长时间保持较高水平。当钾水平较低 (K1 =1 1 7mg/L)或较高 (K3=3 5 1 mg/L)时 ,植株生长势较弱、叶片净光合速率较低。同时叶绿体微观结构也有不同变化 ,当施钾 K2 =2 3 4mg/L时叶绿体呈扁圆形 ,基粒较多 ,叶绿体结构正常。钾过多 (K3=3 5 1 mg/L)叶绿体有少量片层结构失常且基粒结构不明显。     

浅谈读者投诉及投诉管理策略

图书馆的流通窗口一直是读者投诉的焦点,对此图书馆应积极面对,查原因找差距,及时向读者反馈意见;同时还要采取措施,提高服务质量。     

Dicamba resistance: enlarging and preserving biotechnology-based weed management strategies

The advent of biotechnology-derived, herbicide-resistant crops has revolutionized farming practices in many countries. Facile, highly effective, environmentally sound, and profitable weed control methods have been rapidly adopted by crop producers who value the benefits associated with biotechnology-derived weed management traits. But a rapid rise in the populations of several troublesome weeds that are tolerant or resistant to herbicides currently used in conjunction with herbicide-resistant crops may signify that the useful lifetime of these economically important weed management traits will be cut short. We describe the development of soybean and other broadleaf plant species resistant to dicamba, a widely used, inexpensive, and environmentally safe herbicide. The dicamba resistance technology will augment current herbicide resistance technologies and extend their effective lifetime. Attributes of both nuclear- and chloroplast-encoded dicamba resistance genes that affect the potency and expected durability of the herbicide resistance trait are examined.     

Biofumigation: An alternative strategy for the control of plant parasitic nematodes

Plant-parasitic nematodes wreak havoc on the yield and quality of crops worldwide. Damage from these pests is estimated to exceed US$100 billion annually but is likely higher due to misdiagnosis. Nematode damage may be catastrophic, but historically the solution has been damaging as well. Use of the synthetic nematicide methyl bromide(MBr) poses risks to the environment and to human health. Biofumigation, the use of plant material and naturally produced compounds to control pests, is an increasingly feasible method of pest management. The process acts through the growth or incorporation of plant material into the soil, that, over the course of its degradation, releases glucosinolates that break down into nematotoxic isothiocyanates. These secondary plant metabolites exist naturally in commonly grown plants, most of which belong to the Brassicaceae family. Research endeavors have increasingly explored the potential of biofumigation. The reaction of target pests, the selection of biofumigant, and ideal environments for efficacy continue to be evaluated. This review seeks to provide a cost and benefit assessment of the status of biofumigation for the control of plant-parasitic nematodes as an alternative to conventional methyl bromide usage.     

贵州不同区域尺度植烟土壤养分特征及其养分管理初探

以6个烟叶主产县、2个烟叶主产地区及全省的植烟土壤5个养分指标为对象,研究贵州不同区域尺度的植烟土壤养分特征及烟叶养分管理。结果表明,县级尺度间的植烟土壤养分平均含量差异较大,地级尺度间的植烟土壤养分平均含量差异缩小。含量变幅呈相反趋势,省级尺度的含量变幅最大,地级尺度间的含量变幅下降,县级尺度内的含量变幅最小。县级尺度间的植烟土壤养分分布频率差异最大,地级尺度间的分布频率差异缩小。根据不同区域尺度的土壤养分特征,对县级尺度的烟叶氮素及省级尺度的磷、氯素养分管理进行了初步探讨。     

Gender and resource management: Households and groups, strategies and transitions

Rural families must constantly negotiate their livelihoods by obtaining access to natural resources, labor, capital, knowledge, and markets. Successful negotiation leads to enhanced family well-being and sustainable use of natural resources. Unsuccessful negotiation threatens family survival, threatens sustainable use of natural resources, and reduces bio-diversity. These negotiation processes are mediated by gender relations. The ideas of negotiation and of survival strategies outlined here provide a framework within which the articles of this issue can be situated. The articles are the result of research on gender and natural resource management conducted in Latin America, Asia, Africa, and North America. Each experience illustrates the consequences for natural resources and family well being when they have voice and when they do not have voice in household decisions. This revised version was published online in June 2006 with corrections to the Cover Date.     

植物营养液对棉花增产效果的研究

试验结果表明:植物营养液可使棉花成熟吐絮提前13-15d,结铃率提高4.11-4.96个百分点;皮棉产量比对照增加18.57-24.15%,达差异极显著水平;同时可使棉花的单铃重、百粒重、衣指、衣分和纤维长度等品质性状有明显的改进。     

不同养分投入对设施番茄产量、品质和植株、土壤养分含量的影响

采用盆栽试验的方法,以番茄品种“普罗旺斯”为材料,研究高肥力土壤不同养分投入对设施番茄产量、品质及植株、土壤养分含量的影响。结果表明：适当增加磷肥投入能够提高番茄产量,适当增加钾肥投入能够改善番茄品质,综合分析,P3处理单株产量最高,口感与营养品质好,单株产量比CK1、CK2分别提高22.85%、77.85%,Vc含量比CK1、CK2分别提高6.68%、21.42%,糖酸比分别提高了21.06%、17.93%。但高肥力土壤,氮磷钾施用量高会造成植株、果实和土壤中氮磷钾养分累积,同时抑制中微量元素吸收。     

微地形土壤养分空间变异特征及养分管理研究

选取安徽省郑蒲港新区作为研究区域,运用地理信息系统与地统计学相结合的方法,选取土壤有机质、p H、全氮、碱解氮、有效磷、速效钾作为研究对象,选择不同的插值模型,并分析了各土壤要素的空间变异特征。结果表明,受到土地平整和施肥等人为因素影响,地形因子(高程、坡度)对土壤养分的影响程度较小,研究区河流隔开采样数据出现空间不连续,采用区域分块插值的核平滑方法插值模型最为稳定,更加符合研究区实际情况,不会出现为满足假设条件而出现系数为负的插值方程。研究区5种土壤元素均呈现南北低中间高的趋势,土壤速效钾和有效磷的变异系数较高,碱解氮和有机质变异性较弱,p H变异性最弱。占研究区90%以上的土壤4种养分元素均土壤有机质含量均处在中上水平以上,只有占研究区面积的19.66%和72.30%的碱解氮,分别处在中上、中下水平,研究区面积的61.6%和35.67%的p H分别处于酸和弱酸级水平。     

浅谈农药污染途径及防控对策

介绍了农药对大气、水环境、土壤、农林作物的污染途径,简述了农药对人类生存安全的潜在危害,并提出了农药污染的防控对策。     

Integrated pest management and plant health

Crop production and livelihoods of smallholder farmers are often threatened by crop insect pests and diseases worsening the insecurity of food.  Globalization has rapidly increased the introduction and threats of invasive pests.  Climate change results in a changed suitability of landscapes to pests, further increasing the threat and uncertainty of their impact.  Providing innovative technologies for sustainable pest management to smallholder farmers is urgently needed for food security and eliminating poverty.  The most devasting diseases and insect pests to major crops such as rice, wheat, maize and potato contribute to the largest yield losses in the world.  Under the support of the Food and Agriculture Organization (FAO), Chinese plant protection scientists, in collaboration with experts of different regions, carried out a specific project to prioritize top crop diseases and insect pests that affect smallholder farmers’ production globally.  After evaluation by relevant global experts, top 10 crop diseases and insect pests have been assessed as six crop diseases and four insect pests, namely cereal blast disease, potato late blight, wheat rust disease, Fusarium head blight, maize lethal necrosis disease, banana Fusarium wilt (TR4), rice planthopper, wheat aphid, whitefly, and oriental fruit fly.  Integrated pest management (IPM) guidelines for the identified diseases and insect pests have been formulated, and will be shared through a global knowledge platform.  To share the knowledge with more researchers, the IPM of four major diseases including cereal blast disease, Fusarium head blight, maize lethal necrosis disease and potato late blight were further reviewed and presented in this special focus.  The first case study is cereal blast disease caused by fungal pathogen Magnaporthe oryzae (Zhang et al. 2022), which is a destructive filamentous fungus that infects many plants including most economically important food crops, rice, wheat, pearl millet and finger millet (Chakraborty et al. 2021; Hossain 2022).  Different pathovars of M. oryzae often infect different host plants with high specificity.  The rice blast disease caused by the Oryza pathotype (MoO) of M. oryzae can result in 10–30% yield loss in rice-growing countries, posing a major threat to rice production, especially in the small-scale farming system (Mutiga et al. 2021).  The Triticum pathotype (MoT), causing wheat blast disease, was first found in Brazil in 1985.  It has now spread to other countries in South America, and also Asian countries such as Bangladesh (Islam et al. 2016).  Wheat blast disease can result in an average yield loss of 51% in the affected field, becoming one of the most fearsome wheat diseases (Islam et al. 2020).  Because of low fungicide efficacy against the blast diseases and lack of availability of resistant varieties, control of rice and wheat blast diseases is difficult.  A combination of management strategies including early detection and utilization of biopesticides was proposed (Zhang et al. 2022), providing some helpful insights for fighting these devasting cereal blast diseases.  The second case study is the fusarium head blight (FHB) caused by FHB pathogens, which are mainly the Fusarium graminearum species complex (Chen et al. 2022).  FHB is one of the most important diseases that affects wheat production worldwide (Summerell 2019).  In general, a severe FHB epidemic occurred every four or five years in the most of wheat production regions.  Since 2010, the outbreaks of FHB have become more frequent in China.  Besides causing yield loss in affected crop field, FHB also produces mycotoxin contaminating the harvested grains, which are harmful to humans and livestock (Stepien and Chelkowski 2010).  According to the economic importance and toxicity of FHB, F. graminearum is considered as one of the world’s top 10 fungal phytopathogens (Dean et al. 2012).  Breeding resistant cultivars has been considered as the most effective strategy against FHB (Wegulo et al. 2015).  Rational use of chemical pesticides, and potential biopesticides, and good agronomic practices are also important components in the IPM programme for FHB.   The third case study is the maize lethal necrosis disease (MLND), which is a relatively new viral disease on maize (Zhan et al. 2022).  The MLND is caused by the co-infection of maize chlorotic mottle virus (MCMV) and one of cereal-infecting potyviruses, and the symptoms on maize include leaf necrosis, premature aging, small cobs and even plant death (Redinbaugh and Stewart 2018).  First reported in Americas in 1970s and 1980s, the MLND has now spread to more than fifteen countries in the Americas, Asia and Africa (Wangai et al. 2012).  The outbreaks of MLND in several Asian and African countries caused devastating damage to maize production with large impacts on smallholder farmers (Mahuku et al. 2015).  Integrated management of MLND involves effective detection methods such as serological methods, nucleic acid-based methods, and next-generation sequencing.  The practices, such as using certified seeds, sanitary measures, crop rotation, and tolerant or resistant varieties, have been considered as the effective, economical and eco-friendly approach to prevent and control MLND.The fourth case study is the potato late blight (PLB) disease (Dong and Zhou 2022).  PLB, caused by the fungal-like oomycete pathogen Phytophthora infestans, is a devastating disease worldwide that led to the infamous Irish potato famine of the 1840s.  Besides the primary host potato, P. infestans also infects other solanaceous plants such as tomato, petunia and nightshade.  These infected plants can become pathogen inoculum to potato (Kirk et al. 2003).  Originated from Central Mexico or South America, this disease has spread to almost all major potato-producing countries including the United States, Canada, China, and India (Fry et al. 2015).  Up to now, PLB remains the most important biotic constraint to potato production worldwide and presents a major threat to global food security, especially for under-developed areas that heavily depend on potato as the major source of food (Cucak et al. 2021).  Careful agronomic practices, such as using pathogen-free seed, serve as the good start for the successful management of PLB.  Chemical fungicides remain the most effective means to control the pathogen.  However, these chemical fungicides should be used more scientifically to avoid over-dosage and high cost.  Some potential environmental-friendly biopesticides have been identified (He et al. 2021).  Additionally, new technologies which may bring some innovative solutions to control PLB are also proposed.  The desert locust (Schistocerca gregaria), the most destructive migratory insect pest in the world, was also selected in the special focus (Li et al. 2022).  Desert locust is an omnivorous insect, feeding on more than 300 various host plants including many cultivated crops and wild plants (Li et al. 2021).  Formation of desert locust swarms and the outbreak of desert locusts are induced by a combination of environmental stimuli.  During its outbreak and migration, desert locust can cause serious damage to cultivated crops, such as cotton, alfalfa, beans, wheat, barley, corn, flax, tobacco, tomato, potato, and melons, posing a major threat to food security and rural livelihoods.  Since the 20th century, there have been 15 outbreaks of the desert locust, affecting about 30 million km² of Africa and Asia continents and the lives of 850 million people in 65 countries (Ceccato et al. 2007; Divi 2020).  Studies demonstrate the correlation between poor early childhood health and the desert locust swarm outbreak (Kien and Nguyen 2022).  To date, much research has been conducted regarding the ecology and management of desert locusts.  Climate change resulted in more favorable conditions, which is a major factor contributing to the recent outbreak of desert locust in 2020 (Peng et al. 2020).  A critical component of preventive management programs is being able to locate significant infestations rapidly.  The FAO provides forecasts, early warning and alerts on the timing, scale and location of invasions and breeding through its global Desert Locust Information Service (DLIS).  Integrated management of desert locust, mainly including physical control methods, chemical insecticides, microbial pesticides, and biocontrol methods, are summarized in ths review (Li et al. 2022).  Occurrence of plant diseases and insect pests have been worsened by climate change in many aspects.  Prevention of yield loss of major crops is critical for achieving global food security.  Not only the IPM strategies should be adopted, but also the inter-government cooperation should be encouraged to share knowledge, information and innovative solutions, and to jointly tackle with challenges caused by transboundary pests.  All these efforts are needed to achieve the United Nations Sustainable Development Goals (SDGs) of 2030 Agenda for Sustainable Development.     

植物核酸营养素在葡萄生产中的应用

以8年生葡萄品种为试材,采用叶面喷施方法,研究了植物核酸营养素对葡萄生育的影响。结果表明,植物核酸营养素时葡萄黄叶转绿,叶片增厚、枝条成熟和提高果实品质等方面效果明显;平均单粒重比时照增加18．1％,可溶性固性物含量平均提高2．0％．每667m2产值平均提高24．5％;投入产出比为1：19。