不同吸附特性的稻草生物炭对稻田氨挥发和水稻产量的影响

秸秆生物炭具有改善土壤生态环境、土壤蓄水保肥和减少温室气体排放等正效应,但其石灰效应会加大稻田氨挥发损失。为充分发挥生物炭吸铵特性,降低其石灰效应的不利影响,对不同热解温度(300、500、700℃)和酸化水平(pH值=5、7、9)稻草生物炭处理下的田面水NH_4~+-N浓度、氨挥发和水稻产量进行了研究。结果表明:偏酸性(pH值=5)、中性(p H值=7)生物炭处理在基肥期和分蘖肥期均能显著降低田面水NH_4~+-N峰值浓度(P0.05),降幅达16.90%～35.60%。全生育期稻田氨挥发损失占施氮量的15.14%～26.05%(2019年)、15.10%～19.00%(2020年)。稻田增施热解温度为700℃、酸化水平为5(p H值=5)的生物炭(C700P5)降氨效果最好,两年氨挥发分别显著降低22.93%、12.61%(P0.05)。高温热解配合偏酸性、中性生物炭(C700P5、C700P7)增产效果显著,增产率达9.92%～13.50%,结构方程模型表明,其增产原因是生物炭酸化处理降低了稻草生物炭的石灰效应,而热解温度调整提高了生物炭阳离子交换量(CationExchange Capacity,CEC),进而降低了田面水NH_4~+-N浓度和氨挥发损失,最终提高了水稻地上部氮素积累和水稻产量。研究可揭示不同热解温度和酸化水平制备的生物炭在稻田中的应用潜力,并为稻田合理施用生物炭和减少化肥施用量提供理论依据。     

Weed seedling emergence in contrasting fodder crop systems following 30 years of cultivation in the lowlands of Northern Italy

Five fodder crop systems of different intensity (ranging from a double annual crop of Italian ryegrass + silage maize to a permanent meadow) were adopted for 30 years in the lowlands of Northern Italy under two input levels, differing mainly in their provision of organic fertiliser (manure). Herbicides were used in the maize crops included in all systems, except the meadow. After 30 years, the weed seedbank of all systems and input levels were assessed by the seedling emergence technique on soil samples from each plot. The cropping systems determined the abundance and composition of the weed assembly. Relatively few, frequent species made up the majority of the emerged seedlings in all systems, and there was no relationship between the total number of emerged seedlings and the mean number of species recorded in the different systems. Arabidopsis thaliana and Oxalis corniculata were abundant in the annual double crop and in the 3- and 6-year rotations that also comprised the annual double crop. These weeds, however, were unlikely to represent a major threat to the crops, due to their vigour and growth period. The permanent meadow tended to greater weed biodiversity than the other systems. The application of manure favoured the seedbank of species such as Lolium multiflorum, Digitaria sanguinalis and A. thaliana. Weed communities in the different systems were mainly determined by herbicide application, (through the ability of weeds to avoid its effects, determined by the weed life history and emergence period) and manure application (with its possible dual effect of spreading weed seeds and favouring nitrogen-responsive weeds).     

Prevention and Controlling Effect of Intercropping on Pests and Diseases and Its Risk Control in Cotton Fields

Cotton is one of the major field crops which are seriously threatened by pests and diseases. In recent years, the ecological management of cotton pests and diseases with intercropping has become to be an interesting approach. Intercropping possibly increases the population of natural enemies and finally reduces the population density of pests as a result of changes in ecological structure and environmental conditions of farmland. Intercropping thus has been considered an important alternative in controlling pests and diseases. However, cotton field intercropping also has some limitations in controlling pests and diseases. Unreasonable intercropping system has many risks such as increasing labor input, increasing the difficulty of pests’ control, and aggravating pests and diseases. In this paper, the effects and the underlying mechanisms of cotton intercropping on cotton pests and diseases were reviewed. The possible risks and countermeasures used for ecological control of intercropping were also put forward, and the future and application of ecological management of cotton pests and diseases with intercropping were prospected.     

Effects of three methionine sources in diets on temporal B0AT1 and ASCT2 mRNA expression in different intestinal segments of cobia,Rachycentron canadum

A 4‐week feeding trial was conducted using five groups of hybrid grouper (61.15 ± 0.15 g) to explore the potential effects of three methionine (Met) sources. Five isonitrogenous and isolipidic diets were formulated that included a fishmeal (FM) diet; nonsupplemented (NS) diet; or NS diets with the addition of the L‐methionine (L‐Met), DL‐methionine (DL‐Met), or coated Met (Co‐Met) to obtain the same Met level as the FM diet. Fish were randomly distributed into sea cages (30 fish per cage). Weight gain and specific growth rate in the DL‐Met group and FM group were significantly higher than those in all other groups (p < .05). In the proximal and distal intestines, of the 20 gene and time combinations (10 per gene), there were 14 combinations (70%) in which there were no significant differences in gene expression levels between the FM and DL‐Met groups (p > .05). The main reason for the same growth effect between the DL‐Met and FM groups may be attributed to the synchronized absorption at most time points after feeding, which had similar expression patterns of B⁰AT1 and ASCT2 of the proximal and distal intestines between two groups.     

优质常规稻品种桂野丰的选育与栽培技术

桂野丰是广西农业科学院水稻研究所育成的感温型常规优质常规稻新品种。该品种粒型长,株型集散适中、剑叶直、分蘖力强、耐寒性较强、茎杆粗壮、抗倒力强、穗长适中、穗大粒多、着粒密、熟期转色好、有特殊的玉兰香味。米质达部颁2级,平均单产442.3~465.6 kg·hm^-2。2017年通过广西壮族自治区农作物品种审定委员会审定,适宜在广西桂北、桂中和桂南作早晚稻种植。     

徐州某规模猪场防疫措施的建立与实施——“五流”生物安全防控

非洲猪瘟在我国流行已有两年多的时间,尽管很多科研团队都在致力于非洲猪瘟疫苗的研发,但尚未有治疗措施和有效的疫苗来控制该病。因此现阶段“生物安全”是控制非洲猪瘟最为有效,也是唯一的方法。文章总结出目前规模化猪场常见的感染风险有“人员流动、物品流动、车辆流动、水源流动、猪群流动”(即“五流”),并提出严格控制“五流”的生物安全防控措施(即“五流”生物安全防控),以减少外界病原与猪只的接触,稀释病原浓度,降低病原载量,最大程度地降低规模化养猪场感染疾病的风险。为当前规模化猪场建立有效的生物安全措施提供参考。     

Bioactive Compounds in Wild Asteraceae Edible Plants Consumed in the Mediterranean Diet

Plant Foods for Human Nutrition - Three wild edible plant species belonging to the Asteraceae family, Crepis vesicaria L. (s.l.), Sonchus asper (L.) Hill s.l., and Sonchus oleraceus L., usually...     

云南、广西三七黑斑病病原链格孢菌的鉴定

正黑斑病是三七栽培生产中常见的一大病害,叶片受害产生近圆形或不规则水浸状病斑,常导致成株落叶、幼苗生长点及茎秆顶端腐烂枯死。其病原一般认为是链格孢属真菌人参链格Alternaria panax Whetzel~([1,2]),也有相关研究证明黑斑病病原为细链格孢Alternaria tenuis Nees~([3]),后定名为链格孢Alternaria alternata Keissl~([4])。本研究利用ITS序列和histone 3部分编码序列的PCR鉴定,结合形态学鉴定,分析三七主产区黑斑病菌的组成和分布情况及几种病原菌的致病力差异,以期为三七黑斑病防治提供理论依据。     

Effects of different variable sets on the potential distribution of fish species in the Amazon Basin

Estimating species’ potential distribution is one of the main objectives of macroecology, especially when sampling biases can affect knowledge on how environmental variables affect species distribution. Ecological niche models estimate species’ environmental niches from different variables and their occurrences. Using the presence-only data from eight Amazonian fish species, which inhabit rivers and streams, we aimed to (a) explore the effect of different sets variables on the spatial distributions of target species and (b) evaluate the predictive responses of MaxEnt to sets of variables with different degrees of complexity. MaxEnt has high flexibility in relation to the input data and its performance is influenced by a moderate number of adjustable parameters, allowing for high precision results when balancing underestimation and overestimation errors. We used environmental predictors in MaxEnt the principal components of climatic, topographic and edaphic variables as inputs. The combination of topographic and edaphic variables produced more precise and spatially restricted distribution ranges for all species when compared to those generated with climatic variables. All models reached high AUC values, especially for stream species. Modelled range sizes were broader for the river species, suggesting different tolerance thresholds and habitat preferences when compared to stream species. The complexity of the different variables sets did not affect MaxEnt's prediction capacity. However, for stream species, MaxEnt showed a greater predictive power. This work increases the knowledge with regards to the influence of different environmental predictors on the spatial patterns of the distribution of Amazonian fish.     

Selection efficiency of high inorganic phosphorus-low stachyose lines from soybean breeding populations of different genetic backgrounds

Reducing the antinutritional components of soybean (Glycine max) seed is necessary for producing animal feed with increased metabolizable energy and nutrient availability. The objective of this study was to evaluate marker-assisted and phenotypic selection for the high inorganic phosphorus (Pi) and low stachyose traits controlled by the Lpa and MIPS1 mutations in six breeding populations. Phenotypic selection for low phytate individuals carrying Lpa mutations using Pi was reliable, but the assay should include parental genotypes to construct thresholds before performing selections, as the effect of Lpa on Pi depends on genetic background. Phenotypic selection for low phytate individuals carrying MIPS1 using Pi should be complemented with sugar data because selection based solely on Pi may be inefficient, as this trait is not environmentally stable in MIPS1 germplasm. Marker-assisted selection for simple sequence repeat (SSR) linked to Lpa2 (Satt527, Satt561) depended on the pedigree of the population suggesting that perfect markers (e.g., single nucleotide polymorphism) should become the molecular tool for screening a large number of progenies with high efficiency.