乳源木莲天然林群落种间联结的研究

应用方差比率(VR)、卡方(χ2)检验、联结系数(AC)、点相关系数PCC和r等指标对乳源木莲群落中乔木层、灌木层物种各种对的种间联结性进行研究,结果表明:23个乔木层种群在总体上存在显著的正联结,且乳源木莲、拉氏栲、栲树等优势种与其它树种形成种对正联结的比例均比负联结的大,表明其它大部分树种易与这些优势种群混生,形成相对稳定群落.灌木层23个种群间的总体联结性也表现出正联结,并达到显著水平.     

Cucumis hystrix Chakr.×黄瓜种间杂种F1及其双二倍体细胞遗传学特性及花粉育性研究

研究了野生种Cucumis hystrix(2n=2x=24)与栽培黄瓜C. sativus L.(2n=2x=14)种间杂种F1(2n=2x=19)及其双二倍体(2n=4x=38)自交S1～S4代的细胞遗传学特征及花粉育性.结果表明减数分裂中期Ⅰ,杂种F1代花粉母细胞(pollen mother cell,PMC)染色体主要以单价体存在,染色体构型为16.75 Ⅰ+0.5Ⅱ+0.25Ⅲ+0.13Ⅳ;双二倍体染色体构型以二价体为主,伴随着自交,平均每个PMC所含二价体比例逐渐增加,非二价体配对比例减少.四分体时期,F1代不能形成正常的四分孢子,主要以多分孢子形态存在;双二倍体以四分孢子为主,并随着自交世代的增加,其比例增高.花粉育性观察发现,随着自交世代的增加,双二倍体花粉育性呈增高趋势.以上结果暗示,双二倍体在遗传上逐渐趋于稳定;双二倍体PMCs在后期Ⅰ和Ⅱ普遍含有落后染色体、染色体桥及染色体不均等异常现象,可能是导致其花粉育性较低的原因.     

Changes in particulate and mineral-associated organic carbon with land use in contrasting soils

Soil organic carbon(SOC) is the largest terrestrial carbon(C) stock, and the capacity of soils to preserve organic C(OC) varies with many factors,including land use, soil type, and soil depth. We investigated the effect of land use change on soil particulate organic matter(POM) and mineral-associated organic matter(MOM). Surface(0–10 cm) and subsurface(60–70 cm) samples were collected from paired sites(native and cropped) of four contrasting soils.Bulk soils were separated into POM and MOM fract...     

Genome-Wide Association Study of Nitrogen Use Efficiency and Agronomic Traits in Upland Rice

Genome-wide association study (GWAS) was performed for 16 agronomic traits including nitrogen use efficiency (NUE) and yield-related components using a panel of 190 mainly japonica rice varieties and a set of 38 390 single nucleotide polymorphism (SNP) markers. This panel was evaluated under rainfed upland conditions in Madagascar in two consecutive cropping seasons with two contrasted nitrogen input levels. Using another set of five grain traits, we identified previously known genes (GW5, GS3, Awn1 and Glabrous1), thus validating the pertinence and accuracy of our datasets for GWAS. A total of 369 significant associations were detected between SNPs and agronomic traits, gathered into 46 distinct haplotype groups and 28 isolated markers. Few association signals were identified for the complex quantitative trait NUE, however, larger number of quantitative trait loci (QTLs) were detected for its component traits, with 10 and 2 association signals for nitrogen utilization efficiency and nitrogen uptake efficiency, respectively. Several detected association signals co-localized with genes involved in nitrogen transport or nitrogen remobilization within 100 kb. The present study thus confirmed the potential of GWAS to identify candidate genes and new loci associated with agronomic traits. However, because of the quantitative and complex nature of NUE-related traits, GWAS might have not captured a large number of QTLs with limited effects.     

Release of glucose from dissolved and mineral-bound organic matter by enzymatic hydrolysis

Sorption of dissolved organic matter (DOM) by poorly crystalline minerals during their formation may protect large amounts of carbon in soils from mineralization. We investigated the bioavailability of carbohydrates in DOM and after co-precipitation with short-range ordered aluminosilicates. Carbohydrates originated from soil solutions collected in situ at two depths of a Dystric Cambisol, and from litter extracts. Quantification of substrate-specific degradability was achieved by the addition of β-glucosidase at an optimal concentration and subsequent determination of glucose release. Depending on DOM composition, 0.6–41.4 mg g⁻¹ C⁻¹ of glucose was enzymatically released from dissolved carbohydrates. Co-precipitated carbohydrates were partially accessible, resulting in a glucose release of 0.7–5.2 mg g⁻¹ C⁻¹. Restricted enzymatic depolymerization due to co-precipitation may contribute to accumulation of easily degradable substrates in soils.     

浙江北部岛礁周围海域鱼类优势种及其种间关系的初步研究

本文用定量张网渔获物组成资料，研究了浙江北部岛礁周围海域鱼类的群聚生态学。着重分析了优势种的区域及逐月和年间变化，以及优势种时空分布上的关系，还对鱼类群聚的食物关系进行了探讨。     

Viability of diploid and triploid larvae of Siberian sturgeon and bester hybrids

The aim of the present study was to produce Acipenser baeri× (Huso huso×Acipenser ruthenus) hybrids in a diploid and triploid state and to study their viability in comparison with the A. baeri from the fish farm stock. A heat shock (37°C) in the 18th minute after fertilization was applied to induce triploidy. The survival rate and the ploidy level of the hybrids obtained were studied. The mortality of triploid hybrids was approximately twice as high as the mortality of diploid hybrids. No significant difference in the survival rate between Siberian sturgeon and their diploid hybrid with bester was noted. Cytogenetic analysis was performed by preparing chromosomes from the gill epithelium. The results showed that all studied fish from the heat‐shocked group were triploid.     

广东省海洋牧场发展现状、问题与对策

【目的】健全的农业保险体系对规避或分散农业经营风险、推动农业现代化发展起着重要作用, 探究农业保险与农业现代化之间的耦合协调以及灰色关联性,对加快实现农业高质量发展至关重要。【方法】 基于 2010—2019 年山东省农业保险与农业现代化的相关数据,运用耦合协调度模型,揭示两大体系之间的耦合 互动关系,并采用灰色关联法分析农业保险对农业现代化发展的影响。【结果】山东省农业保险和农业现代化 的综合发展指数均呈上升态势;农业保险与农业现代化的耦合协调程度由严重失调逐渐趋好到优质协调状态, 耦合度由 2010 年的 0.329 上升至 2019 年的 0.875,改善明显;农业保险体系各指标与农业现代化总体指标的灰 色关联度较高,均在 0.7 以上,其中农险保费收入在财产险保费收入的占比、农险保费收入深度以及农险保费收 入与农业现代化的关联性较高,是主要的影响因素。【结论】提出完善市场化的农业保险机制和提升服务管理 水平、加大农业保险宣传力度和扩大农险覆盖面、推动农业保险与农业现代化融合协调发展等对策建议。     

棉籽大小与形状关联标记发掘及候选基因筛选

棉籽在油脂、饲料加工等领域具有重要用途,且影响纤维产量和品质。为发掘棉籽性状遗传位点与候选基因,利用419份具有丰富遗传变异的棉花品种资源构成的自然群体,在2个年度鉴定其棉籽性状,结合群体重测序SNP基因型进行全基因组关联分析。结果发现,供试群体棉籽长度、宽度、长宽比、面积与周长等性状存在较大遗传变异,变异系数3.91%~9.55%;有7个SNPs在2年同时被检测到与棉籽大小和形状关联,有23个SNPs在1年与3个以上棉籽相关性状关联,其中D11染色体D11∶50561153在2年与粒宽、面积和周长关联,D12染色体D12：56031535在2年与粒长、面积和周长关联;同时,D05染色体在2年检测到4个与籽粒长宽比显著关联SNPs,A07染色体检测到10个与粒长、周长和面积关联SNPs,且单倍型间相关性状差异极显著。进一步分析发现,关联位点附近存在21个候选基因随棉花胚珠发育进程表达量呈现增加趋势,其中Gh_D05G0148编码乙烯调控反应的EBF蛋白（EIN3-binding F-box protein）,该基因在棉花开花后1~35 d的胚珠中优势表达,且以开花后10 d表达量最高;同时,候选基因Gh_D05G0144编码胚珠发育相关YABBY转录因子,该基因在棉花开花后20~35 d的胚珠中表达量较高,推测与棉籽后期发育有关。以上结果为棉籽多性状同步改良提供了选择标记与基因,为实现纤维和棉籽性状同步遗传改良奠定了基础。     

策勒黑羊GDF9和BMP15基因多态性与产羔数关联分析

为了鉴定策勒黑羊BMP15和GDF9中的多态位点,并与产羔数性状进行关联分析,对相同饲养条件下81只具有产羔记录的策勒黑羊BMP15和GDF9基因完整ORF区进行测序。结果显示,在两个重要候选基因中共存在16个多态位点。GDF9基因有7个SNPs（分别为g.41769976G＞A、g.41769833G＞A、g.41769898G＞A、g.41769246A＞G、g.41769008T＞C、g.41769002A＞G）和g.41769723 TCAA缺失,其中：g.41769833G＞A 位点AA型比GG型平均多0.22只（P＜0.05）,其余6个突变位点均与产羔数不存在显著相关（P＞0.05）。BMP15基因存在9个突变位点：g.50986052C＞A、g.50985229A＞G、g.50985162T＞C、g.50985071C＞T、g.50983056C＞G、g.50982538T＞C、g.50981129A＞G、g.50980656T＞C和g.50981170T＞A,且这9个SNP位点与产羔数均不存在显著相关（P＞0.05）。结果可为策勒黑羊种群的保种育种提供理论参考。