华南地区桉属树种改良工作存在问题及其对策

本文从我国桉属树种遗传改良工作存在问题着手,根据桉属的生物学特性,论述了育种策略、育种计划、杂种利用、种子生产基地、无性系林业等当前亟需解决的几个问题.强调遗传改良工作的成败取决于正确的育种策略和一个完整的育种计划.加强对基因资源的管理并进一步补充完善育种群体是育种工作者的主要工作领域.从整体出发,在不断扩大育种群体、提高遗传品质的同时,为生产提供更多、更好的种和苗.     

LYCD对南美白对虾抗氧化及吞噬活性的影响

在饲料中添加质量分数0.4%LYCD喂养南美白对虾Penaeus vannamei,可显著提高机体的抗氧化和SOD酶产生的能力,实验组内脏团SOD酶活性表现出极显著差异（P＜0.01）,肌肉SOD酶显著高于对照组;MDA的量显著降低,内脏团呈现极显著差异（P＜0.01）,肌肉呈现显著差异;同时LYCD还可使细胞吞噬指数明显增加（P＜0.01）.     

倒木基质对长苞铁杉种苗生长及生理特性的影响

以高腐烂(Ⅲ、Ⅳ、Ⅴ)等级的长苞铁杉倒木作为长苞铁杉种子萌发的基质和覆盖物,探讨倒木基质对长苞铁杉种子的萌发和幼苗生长的影响,以期为长苞铁杉的更新提供新的途径和思路。研究中选择直径>20 cm、Ⅲ~Ⅴ腐烂等级的长苞铁杉倒木为试验材料,分不同等级倒木与黄壤土按质量比例2:8、5:5、8:2、1:0、CK（对照,只有黄壤土）探讨倒木作为基质对长苞铁杉种子萌发的影响,以不同等级倒木按照覆盖住种子的不同覆盖厚度2.5、5、7.5、10 mm、CK（对照,只覆盖绵沙）研究倒木覆盖对长苞铁杉种子萌发的影响,结果表明,倒木基质对长苞铁杉种子发芽和幼苗生长均具有一定的促进作用。（1）第Ⅲ等级和第Ⅴ等级的倒木在木:土=5:5处理下种子发芽率与幼苗根长均显著高于其他配比处理。（2）第Ⅳ等级的倒木在木:土=8:2时长苞铁杉发芽率显著高于其他配比处理,在木:土=5:5处理显著影响长苞铁杉幼苗的根长和叶长;各腐烂等级(Ⅲ、Ⅳ、Ⅴ)的倒木在木:土=1:0处理下,长苞铁杉幼苗CAT活性、PPO活性、SOD活性均显著高于对照组(CK);第Ⅴ等级倒木对长苞铁杉幼苗POD活性影响显著。（3）第Ⅲ等级倒木覆盖7.5 mm处理下,长苞铁杉种子发芽率显著高于对照组(CK),覆盖5 mm处理下幼苗根长显著高于对照组(CK);不同腐烂等级(Ⅲ、Ⅳ、Ⅴ)倒木覆盖5 mm处理对长苞铁杉幼苗的叶长有显著影响;第Ⅲ等级倒木覆盖处理下长苞铁杉种子发芽率优于其他等级,但与对照组(CK)无显著差异。     

轮作及农艺措施对减轻向日葵列当危害的影响

向日葵列当对向日葵生产带来严重危害,目前向日葵生产中主要通过化学除草、选择抗性品种进行防除。通过合理轮作是减轻列当危害的有效手段,但是如何选择轮作作物、其防除效果如何并不清晰。采用向日葵连作重茬土壤进行盆栽试验,并进行田间调查,研究结果表明：向日葵与燕麦、小麦和马铃薯轮作均可不同程度地降低向日葵列当寄生率,其中向日葵—燕麦—向日葵轮作对列当耗减最多,与对照组（向日葵连作）相比列当寄生率降低30%。向日葵—燕麦—向日葵—燕麦—向日葵、向日葵—小麦—向日葵—小麦—向日葵轮作列当寄生率均低于50%,两者差异不显著,而显著低于向日葵—马铃薯—向日葵—马铃薯—向日葵轮作处理。田间调查结果显示向日葵的花盘直径与列当寄生数呈负相关,地膜覆盖对向日葵列当寄生影响不大。综合得出,燕麦是一种良好的向日葵列当诱捕作物,适合在内蒙古等食用向日葵主产区推广应用。     

Nitrogen Vertical Distribution and Status Estimation Using Spectral Data in Maize

Nitrogen (N) is often distributed in a vertical gradient and the symptom of N deficiency usually appears earlier in the lower leaves than in the upper ones. As for hyperspectral technology, identifying the sensitive leaves and the effective index are the two key factors for timely N topdressing. The results of this paper showed that the N contents in the lower leaves produced significant difference among different N rate treatments (a = 0.001) and showed an extremely significant relationship with soil nitrate nitrogen at 30 days after emergence. Taking the optimal treat as a reference, Nitrogen Stress Index (NSI) and Nitrogen Spectral Stress Index (NSSI) of the lowest two leaves could indicate plant N deficiency and guide nitrogen topdressing. NSI or NSSI could change regularly with the nitrogen stress degree and indicate the necessary amount of N topdressing. NSSI is relatively a better indicator since it comes from a fast, timely, uncontaminated, and nondestructive method.     

辽宁省水稻主栽品种稻曲病抗性鉴定与评价

为明确辽宁省水稻主栽品种对稻曲病的抗性水平,从而为抗病品种选育、品种合理布局提供科学依据,在2015-2019年对辽宁省200个水稻主栽品种设置3个播期,在田间病圃内采用自然诱发法对稻曲病进行抗性鉴定和评价。结果显示,不同年度间、同年度不同播期间,水稻品种间抗性差异明显,不同穗型水稻稻曲病发生程度不同,且显著差异。随着播期的推迟,稻曲病的发生程度明显下降,并且年度间变化趋势基本一致。200个供试水稻品种中表现高抗（HR）和抗病（R）品种分别为5个（占2.5%）和34个（占17.0%）,中抗（MR）和中感（MS）品种分别为34个（占17.0%）和53个（占26.5%）,感病（S）和高感（HS）品种分别为46个（占23.0%）和28个（占14.0%）。整体上,抗∶中∶感品种数的比值为19.5∶43.5∶37.0,结果表明辽宁水稻主栽品种稻曲病抗性较差。     

Variation of intra‐aggregate organic carbon affects aggregate formation and stability during organic manure fertilization in a fluvo‐aquic soil

The aggregate formation and stability are controlled by the dynamics of soil organic matters (SOM), but how it is related to SOM chemical composition within different‐sized aggregates is largely unknown during manure fertilization. In this study, the variations of intra‐aggregate organic carbon (OC), including intra‐particulate organic matter (iPOM) and mineral‐associated organic matter, were quantitatively and qualitatively analysed, and then, their effects on aggregate formation and stability were assessed under four treatments: control (CK), mineral fertilizer (NPK), reduced manure (30%M) and manure fertilizers (M). Manure application (M) significantly increased macroaggregate proportion, mean weight diameter (MWD), and OC contents within different‐sized aggregates compared to CK, NPK, and 30%M. The OC accumulation of macroaggregate in M was attributed to OC content increase in silt plus clay subfraction rather than iPOM with more labile organic groups; oppositely, in microaggregate it was located in the relatively stable fine iPOM. The macroaggregate formation and stability were controlled by the fine iPOM within macroaggregates, whose abundant polysaccharide‐C and aliphatic‐C after manure fertilization advanced the microbial growth except for Gram‐positive bacteria, which further promoted macroaggregate formation and stability. The free silt plus clay fraction also affected macroaggregate formation and stability, and its polysaccharide‐C derived from microorganisms or decomposing SOM was positively associated with MWD and macroaggregate proportion. Because polysaccharide‐C can be easily associated with mineral particles, further improving micro‐ or macroaggregation. We conclude that continuous manure fertilization could increase labile SOM accumulation within aggregates and then facilitate microbial growth, which collectively are responsible for aggregate formation and stabilization.     

白细胞介素18与有关疾病的研究进展

白细胞介素18(IL-18)是近年来发现的一种多效应细胞因子,除了具有免疫调节作用外,还与肿瘤性疾病、感染性疾病、变态反应性疾病、自身免疫病及肝病等密切相关。在疫苗佐剂、多肽性药物开发等方面具有潜在的应用前景。     

甜菜覆膜栽培高产生理基础的研究

本文介绍了3年的覆膜栽培实验研究,其结果表明:覆膜栽培,可为甜菜生育创造良好的土壤环境。生育前期提高土壤含水量10.7～27.4%;0～25厘米耕层积温增加684.1℃;0～20厘米耕层速效氮提高8.0～26.7%,速效磷提高12.4～18.8%,速效钾提高7.3～27.9%,甜菜提早出苗8天左右,较直播甜菜早11天左右,叶面积指数(LAI)3.0时达郁闭状态,持续期增多25天,LAI最大值达4.9,高于直播0.8。总光合势增加36.7%,光合速率增加CO_20.57毫克/分米~2时以上,生长中心提早5天以上转至根部。在块根增长期,根部干物质积累强度(1.9克/株·日)提高0.36倍,总光能利用率为:1.84%,较直播甜菜高0.45%。在同等栽培条件下,覆膜甜菜平均单产为3439.1公斤/亩,较直播增产31.8%。