The role of lignin and cellulose in the carbon-cycling of degraded soils under semiarid climate and their relation to microbial biomass

A high level of biological degradation is usually observed in soils under semiarid climate where the low inputs of vegetal debris constraint the development of microbiota. Among vegetal inputs, cellulose and lignin are dominant substrates but their assimilation by the microbial community of semiarid soils is yet not understood. In the present study, ¹³C-labeled cellulose and ¹³C-labeled lignin (75 μg ¹³C g⁻¹ soil) were added to two semiarid soils with different properties and degradation level. Abanilla soil is a bare, highly degraded soil without plant cover growing on it and a total organic C content of 5.0 g kg⁻¹; Santomera soil is covered by plants (20% coverage) based on xerophytic shrubs and has a total organic C content of 12.0 g kg⁻¹. The fate of added carbon was evaluated by analysis of the carbon isotope signature of bulk soil-derived carbon and extractable carbon fractions (water and sodium-pyrophosphate extracts). At long-term (120 days), we observed that the stability of cellulose- and lignin-derived carbon was dependent on their chemical nature. The contribution of lignin-derived carbon to the pool of humic substances was higher than that of cellulose. However, at short-term (30 days), the mineralization of the added substrates was more related to the degradation level of soils (i.e. microbial biomass). Stable isotope probing (SIP) of phospholipid fatty acids (PLFA-SIP) analysis revealed that just a minor part of the microbial community assimilated the carbon derived from cellulose and lignin. Moreover, the relative contribution of each microbial group to the assimilation of lignin-derived carbon was different in each soil.     

黑龙江省农业高校科技信息服务协同模式探索

黑龙江省农业高校为现代化大农业建设做出了巨大贡献,创新和完善了以农技推广中心、国营农场、农业合作组织为纽带的科技信息服务协同模式。通过对技术产品研发、培训教育和技术咨询等服务内容的研究,分析其采用项目带动、典型示范、科教培训、技术入股、教育网络联盟的多元结合方式,并在基础环境、业务制度、组织人才和资金等方面采取了有力的保障措施。     

旱作滴灌铺膜播种农机化技术集成与应用

为解决因水资源缺乏导致的粮食减产问题,开原市大力推广旱作滴灌铺膜播种农机化技术。详细介绍该技术的主要内容、关键环节及培训情况,并综合分析该技术的经济效益、社会效益和生态效益,为该技术在开原市推广应用提供有益借鉴。     

秋种马铃薯高产栽培技术

经过多年多点示范,总结出高山秋种马铃薯高产栽培技术。即秋种马铃薯以选择排灌水方便的沙壤土或黄壤土为宜,忌与茄科作物连作;8月上中旬,采用单垄双行双三角形播种,密度5.25万~6.00万株/hm2;合理施肥,注意防治病虫害。     

辽宁省科技特派行动高端人才支撑体系存在的问题和完善措施

高端人才的缺乏以及人才素质问题已经成为制约辽宁科技特派行动的主要因素。分析科技特派行动高端人才支撑体系在运行机制、体系构建及内外部协调等方面存在的问题,提出具体的完善措施。     

浅析农业技术推广组织标准体系构建

该文在分析我国农业技术推广组织存在问题；在农技推广中的作用，标准化工作的意义以及标准化现状的基础上，提出构建农业技术推广组织标准体系，为农业技术推广组织标准化工作提供了支持。     

Effects of biofloc under different carbon sources and protein levels on water quality,growth performance and immune responses in black tiger shrimp Penaeus monodon (Fabricius, 1978)

A 75‐day 2 × 3 factorial experiment was conducted to evaluate the effect of two levels of dietary protein (32 and 40%) and two different carbon sources (rice flour–R and molasses‐M), and without carbohydrate (control–C) in black tiger shrimp Penaeus monodon juveniles (3.37 ± 0.04 g) at 100 nos. m^?3 in 100 L fibre reinforced plastic tanks. Biofloc volume and total suspended solid were higher in molasses added groups (32 + M and 40 + M) followed by rice flour (32 + R and 40 + R) and controls (32C and 40C). Molasses and rice flour addition significantly reduced (P < 0.01) the total ammonia–N compared to controls. The highest Vibrio, Bacillus and Lactobacillus counts were recorded in 40 + M, 32 + M and 32 + R respectively. Among the treatments, significantly higher (P < 0.01) final body weight was recorded in 40 + R (8.5 ± 0.3 g), 40 + M (7.8 ± 0.3 g) and 32 + R (7.5 ± 0.4 g) compared to control groups, 32C (6.1 ± 0.3 g), 40C (6.4 ± 0.3 g) and molasses added group, 32 + M (5.7 ± 0.4 g). Rice flour supplementation significantly increased (P < 0.01) the total haemocyte count (×10⁶ cells mL^?1) in 32 + R (45.7 ± 3.7) and 40 + R (44.3 ± 3.1) compared to controls, 32C (27.3 ± 3.4) and 40C (25.8 ± 0.9). Similarly, higher superoxide dismutase, catalase, serum protein and glucose were recorded in the rice flour added groups, 40 + R followed by 32 + R. Among the treatments, the highest level of prophenoloxidase (OD 490 nm, 0.3 ± 0.0) and survival after challenge with Vibrio harveyi (55.6%) was observed in 32 + R. The study elucidates that rice flour addition produces optimum level of biofloc with better growth and immune responses compared to molasses and control. Furthermore, rice flour addition at 32% protein level could replace 40% protein feed.     

韩国稻作技术创新与转型

随着社会经济的发展及农业劳动力的转移,韩国水稻种植方式发生了转型。从上世纪70年代末期开始,韩国水稻机插秧比例快速上升,手插秧比例下降,到90年代基本实现了水稻种植的机械化;省工节本的直播稻产量受不确定因素影响较大,且稻米品质不如机插秧和手插秧,其种植面积出现了波动,现只占韩国水稻种植面积的4%左右。本文介绍了韩国水稻机插秧、湿润直播和旱直播技术的作业流程。     

猕猴桃叶片叶绿素含量高光谱估算模型研究

【目的】研究猕猴桃叶片叶绿素含量的高光谱估算方法,为猕猴桃长势的遥感监测提供理论依据。【方法】以陕西杨凌蒋家寨村2018年不同生育期(初花期、幼果期、膨果期、壮果期、果实成熟期)的猕猴桃叶片为研究对象,分别测定其高光谱反射率和叶绿素含量(SPAD值),分析原始光谱和5个常见的植被指数(归一化植被指数、归一化叶绿素指数、改进的叶绿素吸收反射率指数、MERIS地面叶绿素指数、土壤调整指数)与叶绿素含量之间的相关关系,提取各生育期的特征波段,分别建立基于特征波段和植被指数的单波段叶绿素含量一元线性估算模型。利用主成分分析对原始光谱数据进行降维,将得到的主成分得分作为随机森林模型的输入变量,建立基于多波段信息的叶绿素含量多元估算模型,并对模型进行精度验证和分析。【结果】不同生育期猕猴桃叶片光谱反射率变化趋势基本一致,整体趋势为可见光波段反射率低,近红外波段反射率高;在可见光波段,光谱反射率随着叶绿素含量的升高而降低;在近红外波段,光谱反射率则随着叶绿素含量的增加而升高。通过相关性分析可知,初花期、幼果期、膨果期、壮果期、果实成熟期原始光谱的特征波段分别为729,548,707,707和712 nm,估算模型决定系数(R~2)分别为0.18,0.85,0.54,0.85和0.82,其中初花期估算模型未通过显著性检验,其余生育期均通过极显著性检验。在5个常用植被指数中,初花期与叶绿素含量相关性最高的是归一化叶绿素指数(NPCI),但是估算模型决定系数R~2只有0.1,未通过显著性检验;其他生育期与叶绿素含量相关性最高的是MERIS地面叶绿素指数(MTCI),所建立的估算模型拟合效果好,预测精度高。基于主成分分析和随机森林回归建立的不同生育期猕猴桃叶片叶绿素含量估算模型的R~2在0.91～0.98,均通过极显著性检验,其拟合效果和预测精度远高于单波段一元线性回归和基于植被指数的一元线性回归模型,是估算猕猴桃叶片叶绿素含量的最优模型。【结论】基于主成分分析的随机森林模型包含了更完整的波段信息,对不同生育期猕猴桃叶片叶绿素含量具有较好的预测能力。     

DMDC前处理对巨峰冰葡萄酒发酵及其品质的影响

【目的】研究二甲基二碳酸盐(DMDC)杀菌技术对巨峰冰葡萄酒发酵过程及品质的影响,为DMDC应用于巨峰冰葡萄酒发酵加工提供理论依据。【方法】在糖质量浓度分别为350和400 g/L的浓缩葡萄浆醪中,分别添加250 mg/L DMDC和200 mg/L亚硫酸盐进行杀菌处理,比较2种杀菌处理方法对巨峰冰葡萄酒发酵期间可溶性固形物、总糖、还原糖、酒精度、pH、总酸、挥发酸、花色苷等理化指标及酒体感官评分的影响。【结果】处理前,当糖质量浓度分别为350和400 g/L时,其对葡萄醪的微生物菌落总数无显著影响。与处理前相比,DMDC处理能降低葡萄醪的菌落总数、霉菌和乳酸菌菌落数,优于亚硫酸盐处理;DMDC处理使葡萄醪的酵母菌菌落数降低至检测限之下,而亚硫酸盐对酵母菌只有微弱的杀菌作用。当糖质量浓度为400 g/L时,DMDC处理的可溶性固形物、总糖、还原糖质量浓度均高于亚硫酸盐处理,且二者之间差异显著;当糖质量浓度为350 g/L时,DMDC与亚硫酸盐处理之间的可溶性固形物、总糖、还原糖质量浓度无差异显著。在整个发酵过程中,当糖质量浓度分别为350和400 g/L时,DMDC处理的酒精度、pH均高于亚硫酸盐处理,DMDC处理的花色苷质量浓度低于亚硫酸盐处理,但二者总酸质量浓度差异不大。在发酵前期,各处理组的挥发酸质量浓度无显著差异(P0.05);在发酵后期,当糖质量浓度为400 g/L时,DMDC和亚硫酸盐处理的挥发酸质量浓度均较高。由感官评价结果可知,DMDC处理能改善巨峰冰葡萄酒的口感,酒体颜色呈桃红色;亚硫酸盐处理巨峰冰葡萄酒的口感较差,酒体颜色呈紫红的宝石色。【结论】用250 mg/L DMDC对葡萄浆醪进行处理可能成为一种有效控制发酵冰葡萄酒品质的杀菌前处理方式。