Soil acidification induced by intensive agricultural use depending on climate

Journal of Soils and Sediments - Soil acidification is a major issue in agricultural ecosystems. However, how agricultural land uses shape the soil pH pattern and affect soil acidification on a...     

机插密度对盐碱地超级稻产量及钠钾离子吸收的影响

为筛选出江苏滨海盐碱地超级稻品种‘湘两优900’的适宜机插密度,研究了不同机插密度（高密度,T₁：25.0×10⁴穴/hm²;中密度,T₂：19.9×10⁴穴/hm²;低密度,T₃：16.6×10⁴穴/hm²）对水稻各指标的影响,并动态监测了土壤及田间水盐分的变化。结果表明：水稻种植能够显著降低土壤可溶性总盐含量,降幅可达28.68%;随机插密度变小,水稻单穴的分蘖数、干物质重能够显著提高,而群体的分蘖数和干物质重会相应的显著降低;水稻SPAD值在生殖生长期时,随密度下降呈增加的趋势,而叶面积指数在所有生育期均呈降低的趋势;机插密度下降能够显著增加单穴钠钾离子积累量和显著降低群体的钠钾离子积累。相关分析表明,不同机插密度水稻实际产量与单株钠离子积累量呈显著负相关,与群体有效穗数、群体干物质积累量呈显著正相关,与每穗总粒数、群体钾离子积累量呈极显著正相关。本试验条件下,江苏滨海盐碱地‘湘两优900’的适宜机插密度为25.0×10⁴穴/hm²。     

Nitrogen Deep Placement Combined with Straw Mulch Cultivation Enhances Physiological Traits,Grain Yield and Nitrogen Use Efficiency in Mechanical Pot-Seedling Transplanting Rice

To assess the effects of straw return coupled with deep nitrogen (N) fertilization on grain yield and N use efficiency (NUE) in mechanical pot-seedling transplanting (MPST) rice, the seedlings of two rice cultivars, i.e., Yuxiangyouzhan and Wufengyou 615 transplanted by MPST were applied with N fertilizer at 150 kg/hm² and straw return at 6 t/hm² in early seasons of 2019 and 2020. The experiment comprised of following treatments: CK (no fertilizer and no straw return), MDS (deep N fertilization and straw return), MBS (broadcasting fertilizer and straw return), MD (deep N fertilization without straw return), MB (broadcasting fertilizer without straw return). Results depicted that the MDS treatment significantly increased the rice yield by 41.69%?72.22% due to total above-ground biomass, leaf area index and photosynthesis increased by 54.70%?55.80%, 38.52%?52.17% and 17.89%?28.40%, respectively, compared to the MB treatment. In addition, the MDS treatment enhanced the total N accumulation by 37.74%?43.69%, N recovery efficiency by 141.45%?164.65%, N agronomic efficiency by 121.76%? 134.19%, nitrate reductase by 46.46%?60.86% and glutamine synthetase by 23.56%?31.02%, compared to the MB treatment. The average grain yield and NUE in both years for Yuxiangyouzhan were higher in the MDS treatment than in the MD treatment. Hence, deep N fertilization combined with straw return can be an innovative technique with improved grain yield and NUE in MPST in South China.     

浙江省主要养殖区凡纳滨对虾（Litopenaeus vannamei）红体病病原研究

对2012—2013年浙江省凡纳滨对虾( L itopenaeus vannamei)主要养殖区的红体病虾进行病原鉴定及其分子特征与耐药性研究,并与2011年的结果进行比较分析.结果表明：通过 Vitek 、16S rRNA 序列分析与病毒特异性聚合酶链反应,2012—2013年在红体病虾中同时检测出副溶血弧菌( V ibrio parahaemolyticus)与传染性皮下和造血组织坏死病毒( infectious hypodermal and haematopoietic necrosis virus , IHHNV ),而2011年在红体病虾中仅检测出副溶血弧菌,未检测出 IHHNV ;3年均未检测出桃拉综合征病毒( Taura syndrome virus , TSV)和白斑综合征病毒( white spot syndrome virus , WSSV ).基于 dnaE‐gyrB‐recA‐dtdS‐pntA‐pyrC‐tnaA 的多位点序列分型结果表明,副溶血弧菌分离株具有较高水平的分子多样性：2011—2013年各年的分离株均分属多个序列型( sequence type ,ST ),来自位于进化树不同亚枝、亲缘关系较远的不同克隆;2012—2013年的分离株经历了较高水平的分子变异,其中 ST918与 ST919为首次报道的副溶血弧菌新 ST ;2011年分离株与2012—2013年分离株的等位基因和序列型特征具有较大差异,ST414与 ST114分别代表2011年与2012—2013年红体病的优势 ST .2011—2013年的副溶血弧菌分离株均属于大流行群,并具有相同的毒力基因谱( tlh＋ tdh－ trh－ T3SS1＋ T3SS2－),tdh与 trh的缺失并未影响细菌的致病力.分离株对抗菌药物尤其是氨基糖苷类的耐药性呈现加重趋势.说明本次凡纳滨对虾红体病可能是多种致病因子共同作用的结果,亟须建立红体病病原监测体系,并探明细菌性病原与病毒性病原混合感染对致病性的影响及其互作机制,以提出综合防控方案.     

A portable soil nitrogen detector based on NIRS

As one of the most important soil nutrient components, soil total nitrogen (TN) content needs to be measured in precision agriculture. A portable soil TN detector based on the 89S52 microcontroller was developed, and a Back Propagation Neural Network (BP-NN) estimation model embedded in the detector was established using near-infrared reflectance spectroscopy with absorbance data at 1550, 1300, 1200, 1100, 1050, and 940 nm wavelengths. The detector consisted of two parts, an optical unit and a control unit. The optical unit included six near-infrared lamp-houses, a shared lamp-house drive circuit, a shared incidence and reflectance Y-type optical fiber, a probe, and a photoelectric sensor. The control unit included an amplifier circuit, a filter circuit, an analog-to-digital converter circuit, an LCD display, and a U-disk storage component. All six absorbance data as inputs were used to calculate soil TN content by means of the estimation model. Finally, the calculated soil TN content was displayed on the LCD display and at the same time stored in the U-disk. A calibration experiment was conducted. The soil TN content correlation coefficient (R ²) of the BP-NN estimation model was 0.88, and the validation R ² was 0.75. This result indicated that the developed detector had a stable performance and a high precision.     

有机肥及与化肥配施对水稻空育163品质的影响

为明确不同有机肥及与化肥配施对空育163品质的影响,采用随机区组设计进行试验研究。结果表明,基施腐植酸和甜叶菊有机肥有利于降低稻米垩白粒率、垩白度、蛋白质和直链淀粉含量,但对整精米率影响不大。甜叶菊有机肥和化肥配施处理食味评分值最高,与对照达显著水平。因此,基施甜叶菊有机肥375 kg·hm-2能明显改善空育163的外观和食味品质,可应用于优质米生产。     

降胆固醇能力强的耐酸耐胆盐乳酸菌的筛选及鉴定

对从发酵酸菜中分离的乳酸菌,进行降胆固醇能力强的乳酸菌的筛选和鉴定,并对其耐酸耐胆盐能力进行测定。从分离的乳酸菌中,筛选到一株胆固醇降解率达到52.21%的乳酸菌M16。M16菌株具有较强的耐酸耐胆盐能力,在p H 2环境中30℃培养2 h后活细胞数仍然可以达到4.5×106 CFU·m L-1,在1.0%胆盐的环境中培养4 h后活细胞数仍然可以达到1.0×106 CFU·m L-1。通过菌体形态、菌落特征和生理生化实验,将M16乳酸菌鉴定为乳杆菌属的乳酸菌。     

官司河流域7种林分枯落物及土壤层水文效应1）

为定量评估森林水源涵养能力,结合野外采样和浸水试验对官司河流域7种林分枯落物及土壤层水文效应进行比较。结果表明：林分枯落物蓄积量范围为4．49～13．19 t· hm－2,其中马尾松纯林最大,麻栎纯林最小;各林分枯落物最大持水深和有效拦蓄量均表现为未分解层大于半分解层,且纯竹林最大,分别为2．87 mm和9．77 t· hm－2。枯落物层持水量和吸水速率与浸水时间均显著。各林分0～30 cm土壤总孔隙度变化范围为37．1％～54．3％,竹林和松栎混交林的表层土壤有效持水量最大,分别为256．52、44．5 t· hm－2。纯竹林、松栎混交林持水效果较好,可作为水源涵养林得以推广。     

Physiological and related anthocyanin biosynthesis genes responses induced by cadmium stress in a new colored-leaf plant “Quanhong Poplar”

The worsening of Cadmium (Cd) pollution has intensified the urban ecological environment deterioration in the world. Purifying contaminated environment using the tall, colored-leaf woody plants has been proved as an aesthetically pleasing approach. However, the effects of Cd stress on colored-leaf woody plants have been little reported. Present hydroponic experiments were carried out to study the physiological and related anthocyanin biosynthesis genes responses to Cd stress in “Quanhong Poplar” plants. The experiments consisted of four Cd levels (0, 50, 100 and 150 μM). Leaves were sampled at 5, 10, 20, 30, 40, 50, and 60 days after the first treatment for detection of related enzyme activities and genes expression. The results showed that the plants treated with 100 or 150 μM Cd presented obvious toxicity symptom, i.e. the inhibition of growth and the decrease of chlorophyll and anthocyanin contents. However, plants growth was enhanced and the synthesis of chlorophyll, anthocyanin were promoted when the plants were subject to 50 μM Cd stress. Furthermore, the activities of relative enzymes as well as their genes expression were induced, which indicated that low concentration of Cd induced the anthocyanin accumulation in “Quanhong Poplar” plants, which suggested that using “Quanhong Poplar” to purify contaminated environment would be an aesthetically pleasing approach, which would not only remediate contaminated environments but also bring landscape effects.     

干旱胁迫对4个锦带花品种叶绿素及PSⅡ光化学活性的影响

为了明确干旱胁迫对四季锦带、红王子锦带、紫叶锦带和金叶锦带4个品种叶绿素质量分数和荧光参数的影响,采用田间持续干旱法,测定了各参数的变化曲线。结果表明：在干旱胁迫下,各品种叶绿素质量分数变化规律较一致,均呈不规则波动,其中四季锦带和金叶锦带、红王子锦带和紫叶锦带叶绿素质量分数曲线的变化趋势两两相似;胁迫显著降低了PSⅡ单位面积有活性反应中心数量RC／CSo、光化学性能指数PI,A,B,S值;荧光诱导曲线中K点相对可变荧光（Wk）和J点相对可变荧光（Vj）的值均较对照不同程度增加;暗适应下初始荧光Fo 值、PSⅡ最大光化学效率Fv／Fm 值均呈现下降趋势。总之,干旱胁迫下4个锦带花品种PSⅡ光化学活性受到不同程度的抑制,四季锦带对干旱的响应最强烈,其次是紫叶锦带和金叶锦带,红王子锦带最弱。