龟纹瓢虫幼虫体内主要共生菌种类分析

共生菌和昆虫是互利共生的关系，它参与宿主生殖、代谢、解毒等生理过程。龟纹瓢虫为农田生态系统重要天敌昆虫，同时具有取食植物花粉的习性。为明确龟纹瓢虫体内共生菌的种类与群落结构，通过Illumina MiSeq平台对龟纹瓢虫幼虫体内共生菌的16S rDNA V3～V4区进行高通量测序，生物信息学方法分析共生菌的种类和多样性。结果显示，共获得3910个OTUs，长度为360～480 bp的序列占99.54%； OTU注释结果表明，龟纹瓢虫共生菌包括37个门，75个纲，143个目，261个科，605个属；变形菌门Proteobacteria（51.84%）、厚壁菌门Firmicutes（21.81%）、放线菌门Actinobacteria（11.35%）、蓝藻菌门Cyanobacteria（7.06%）、拟杆菌门Bacteroidetes（4.49%）为龟纹瓢虫幼虫的5个优势种群。在属水平上葡萄球菌Staphylococcus（16%）、不动杆菌属Acinetobacter（8.54%）、Paracocccus（4.93%）、假单胞菌Pseudomonas（3.59%）、Boechera gunnisoniana（3.34%）、棒状杆菌属Corynebacterium（2.18%）、阪崎肠杆菌Cronobacter（2.04%）、考克氏菌属Kocuria（1.50%）、链球菌属Streptococcus（1.15%）和芽胞杆菌Bacillus（1.11%）为优势菌群。本研究初步明确了龟纹瓢虫幼虫体内共生菌种群组成与结构，为通过共生菌提高龟纹瓢虫人工繁殖效率提供参考，同时为转基因植物对龟纹瓢虫的安全评价提供新的思路。     

Pseudomonas aeruginosa produces secondary metabolites that have biological activity against plant pathogenic Xanthomonas species

The bioactivity of compounds produced by Pseudomonas aeruginosa (LN strain), against three Xanthomonas species was investigated under greenhouse conditions and using electron microscopy. Chromatographic fractions EAP, VLC3, VLC4, VLC3d and VLC4f were tested against Xanthomonas axonopodis pv. malvacearum, X. axonopodis pv. phaseoli and X. axonopodis pv. citri by disc diffusion. Fractions with antibiotic activity were tested in vivo under greenhouse conditions and their bioactivity was evaluated. Scanning electron microscopy showed that VLC4f affects biofilm formation while VLC4f and VLC3d both affect cell morphology. The semi-purified fractions controlled bacterial diseases caused by Xanthomonas spp. when sprayed on plants under greenhouse conditions. The VLC4f fraction showed superior results in disease management, reducing the number of lesions on cotton and orange leaves by 94%, and reducing disease severity in bean leaves by 73%. The data suggest that the fractions were effective and have potential as an alternative to conventional bactericides in the control of plant diseases caused by Xanthomonas sp under greenhouse conditions.     

Effects of Nitrogen Application Rates on Soil Nitrogen Content,Nutrient Uptake and Utilization of Cotton in Low Fertility Fields

[Objective] The effects of nitrogen (N) application rates on cotton yield, nutrient uptake and utilization rate, soil available N and urease activity were investigated in low-fertility cotton fields of the Yellow River Basin. [Methods] Six N application rate treatments, 0, 90, 180, 270, 360 and 450 kg·hm^－2 (N0, N90, N180, N270, N360 and N450, respectively), were established using cotton CCRI 79 in the field during 2016 and 2017. The cotton yield, dry matter quality, N, phosphorus and potassium accumulation levels, N use efficiency, 0–100-cm soil layer ammonium and nitrate N contents, 0–100-cm soil layer urease activity and other indicators were investigated. [Results] (1) Compared with N0, the N treatments significantly increased seed cotton yield, except the N90 treatment in 2016. Two years of N360 treatments significantly increased the number of bolls per cotton plant, while no significant differences were found among the seed cotton yields with other N treatments. The N application rates had no significant effect on lint percentage. (2) Compared with N0, N applications significantly increased the cotton dry matter accumulation. The accumulation of N, phosphorus and potassium in cotton increased along with the N application rates in the 90–360 kg·hm^－2 range. The levels of N, phosphorus and potassium in N450-treated cotton decreased compared with N360-treated cotton. As the N application rates increased, the N agronomic efficiency and N fertilizer partial productivity of cotton decreased. When the N application rates exceeded 360 kg·hm^－2, the N physiological efficiency began to decrease, but there were no significant differences among treatments. (3) The nitrate N contents in the 41–80-cm soil layers of the treatments, except for N90, significantly increased compared with N0. The nitrate N contents in the 41–80-cm soil layers of N270-, N360- and N450-treated cotton were significantly increased compared with those of N0, N90 and N180. However, N applications had no significant effects on the ammonium N contents in the soil. (4) The soil urease activities increased when N application rates were less than 360 kg·hm^－2, and then decreased when the N application rates were greater than 360 kg·hm^－2. [Conclusion] The optimum N application rate was 277.0 kg·hm^－2. When the N application rates were greater than 360 kg·hm^－2, the nitrate N contents in the soil increased. However, the nutrient accumulation levels and the N fertilization efficiencies decreased, and the soil urease activities were inhibited. No obvious increase in cotton yield was observed.     

Extraction of Cotton Fiber DNA and Its Application in Traceability

[Objective] To address the questions of lacking monitoring system for origins of varieties, this study explored a DNA extraction method suitable for cotton fiber, aiming to establish an identification system that uses cotton fiber DNA as a medium to trace the authenticity and cultivar of cotton varieties. [Method] By improving and optimizing the extraction method, the DNAs of cotton fibers at different days post anthesis and lint from different years were extracted and used as templates for routine polymerase chain reaction (PCR) amplification. 13 pairs of simple sequence repeat(SSR) primers were selected for SSR-PCR amplification using the DNA of Lu 1127, Shikang 126 and Ruiza 816. [Result] The DNA extraction method can extract cotton fiber DNAs of different developmental stages and different years. With the development of fiber, although the extracted DNA content is reduced, it can still meet the needs of downstream experiments. The extracted cotton fiber DNAs can be subjected to conventional PCR amplification, the PCR amplified bands were clear; 13 pairs of cotton SSR primers were used for SSR-PCR amplification of cotton fiber DNAs of Lu 1127, Shikang 126 and Ruiza 816, and a clear polymorphic band could be amplified and easily distinguished. [Conclusion] This extraction method is suitable for extracting genomic DNA of cotton fiber, and is satisfied with conventional PCR amplification with SSR markers. It is confirmed that the cotton fiber DNA molecular markers are feasible for tracing the source of cotton varieties, and it is expected to provide technical support for ensuring the safety of cotton industry.     

Effects of Different AFD Treatments on Yield Formation and Fiber Quality of Cotton

[Objective] We examined the effects of spraying AFD (Agent of flower bud differentiation), a new plant growth regulator, on cotton yield formation and fiber quality. This study was designed to provide a scientific basis for chemical regulation. [Method] Six treatments of different AFD concentrations were used for this experiment. Cotton plant height, boll number, boll weight, seed cotton yield, and fiber quality were assessed to clarify the effects of chemical regulation on cotton at different concentrations. [Result] The results showed that cotton plant height was associated with AFD concentration while AFD was effective in inhibiting the cotton boll shedding ratio and significantly increasing the boll opening ratio. Furthermore, the boll number per plant and boll weight were significantly higher in plants sprayed with AFD at concentrations of 1 350^-1 800 mL·hm^－2 than in the control group and higher seed cotton yields were obtained. Different concentrations of AFD had no significant effect on cotton breaking strength, micronaire value, and breaking elongation. However, the highest AFD concentration had certain inhibiting effects on fiber length and uniformity index. [Conclusion] The use of chemical control via a suitable concentration of AFD had a significant effect on increasing cotton yield and little effect on fiber quality. The study of the mechanism by which AFD affects cotton traits is of great significance for cotton production.     

Effects of Removal of Redundant Buds and Topping of Fruiting Branches on Source-Sink Activity,Yield, and Fiber Quality of Cotton

[Objective] Removal of redundant buds and decapitation of fruiting branches are important pruning measures for cotton production. The effects of the two procedures on source–sink activity, yield, and fiber quality were studied to provide a scientific basis for a simplified pruning method. [Method] A field trial was carried out in bottomland of the Yellow River valley, Zhengzhou, Henan Province in 2014–2015 using cotton ‘Lumianyan 28’. Treatments consisted of removal of redundant buds, decapitation of fruiting branches, and removal of redundant buds and decapitation of fruiting branches in combination (RDR treatments). Redundant buds and tops of fruiting branches were retained in the control (CK). The source–sink size and activity, yield traits, fiber quality, and economic return were recorded. [Result] The RDR treatments increased the leaf area index and total dry matter accumulation, and increased the sink-source ratio at advanced growth stages compared with CK. In the middle growth period, the RDR treatments increased indoleacetic acid (IAA) content and superoxide dismutase (SOD) activity, and decreased abscisic acid (ABA) content in the leaf. Moreover, the RDR treatments increased IAA content and SOD activity, and decreased ABA content in seeds of pre-summer bolls and summer bolls, whereas the IAA and ABA contents and SOD activity in fibers showed the opposite trend to that of seeds. The lint yield following removal of redundant buds, decapitation of fruiting branches, and combined removal of redundant buds and decapitation of fruiting branches was increased by 4.43%, 5.17%, and 9.31%, respectively, but no significant difference was observed among these treatments. Decapitation of fruiting branches had amore marked effect on yield than removal of redundant buds, and these two treatments applied in combination had a cumulative effect on yield. The RDR treatments had no significant effect on fiber quality. Decapitation of fruiting branches increased economic return, but removal of redundant buds reduced economic return, and the effect on economic return of removal of redundant buds and decapitation of fruiting branches in combination was inconsistent. [Conclusion] The RDR treatments generally improved the source–sink relationship, enhanced source and sink activity, and increased cotton yield. However, the increase in yield and economic benefits were less marked. We recommend simplified pruning techniques without removal of redundant buds and decapitation of fruiting branches for large-scale cultivation of cotton.     

Effects of Low Phosphorus Stress on Root Morphology and Physiological Characteristics of Different Cotton Genotypes at the Seedling Stage

[Objective] Phosphorus is one of three major required nutrients for cotton growth and development. A phosphorus deficiency will lead to retarded cotton growth, undeveloped roots, and the abscission of buds and bolls, which results in serious reductions in cotton yield and quality. While applied phosphorus is easily fixed in soils, it is mostly transferred to occluded P, which is not available to plants. Therefore, this study aimed to provide theoretical support for the study of response mechanisms to low phosphorus stress and the efficient phosphorus uptake and utilization of different cotton genotypes. [Method] The effects of phosphorus accumulation and utilization, leaf photosynthetic characteristics and root morphology of two genotypes of cotton (CCRI 79 and SCRC 28) were studied in hydroponic cultures having different phosphorus concentrations. [Result] CCRI 79 had higher phosphorus utilization rates of 90.92 mg·mg^－1 at the low phosphorus level (KH2PO4 1.0×10^－5 mol·L^－1) and 23.09 mg·mg^－1 at the high phosphorus level (KH2PO4 0.5 mol·L－1) compared with SCRC 28. When phosphorus was deficient, the total root length, total root surface area and total root volume of SCRC 28 increased by 13.05%, 18.78% and 10.50%, respectively, while the total root length, total root surface area and total root volume of CCRI 79 decreased significantly. [Conclusion] Here, we found that SCRC 28 had a root morphology and physiological characteristics that allowed it to adapt to low phosphorusstress, while CCRI 79 utilized phosphorus more efficiently.     

49份山西水地小麦品系的HMW-GS组成及品质分析

为了解在育种过程中各品系材料的品质状况,采用SDS-PAGE技术对选取的49份品系材料高分子量麦谷蛋白亚基的组成进行分析。结果表明：共发现8种等位变异和11种亚基组合类型。其中,Glu-A1位点出现2种亚基类型,以亚基1(83.67%)为主。Glu-B1位点出现4种亚基类型,以亚基14+15(42.86%)为主。Glu-D1位点出现2种亚基类型,亚基2+12(71.43%)和亚基5+10(28.57%)。对49份材料进行品质性状测定,并与各个亚基间做相关性分析。Glu-A1位点,亚基1的各个指标均高于亚基Null的指标。Glu-D1位点,亚基5+10的品质指标也高于亚基2+12。Glu-B1位点4种亚基在各个品质指标间均存在显著差异,亚基7+8对蛋白质含量、容重以及湿面筋的贡献最高,亚基17+18对沉淀值和最大抗延阻力的贡献最高,亚基7+9具有最长的稳定时间。     

行距对机采棉干物质积累及氮磷利用效率的影响

【目的】新疆棉花生产的主要环节均已实现机械化,但采摘环节仍大量使用人工,农机农艺不协调是导致机收比例低的主要原因。优化机采棉行距配置是实现农机农艺融合的有效途径,因此本研究通过设置不同的机采棉行距,探究其对棉花产量形成及养分利用的影响,为机采棉行距配置的优化提供理论依据。【方法】采用随机区组设计,选择生产中最佳密度,在密度一致基础上,设置"一膜三行"(S1,平均行距76 cm)、"一膜四行"(S2,平均行距57 cm)、"一膜六行"(S3,平均行距38 cm)3种行距,其中S3处理为常规机采行距(CK),研究行距对棉花干物质积累、分配以及对产量形成及氮、磷养分吸收利用的影响。【结果】不同行距下棉花干物质的积累符合Logistic生长函数模型。2年均值表明随着平均行距的降低,单株干物质积累总量降低43.3%,干物质最大积累速率降低(1.4 g·株-1·d-1),快速积累期起始时间从出苗后51.4 d逐渐推迟至62.5 d,但快速积累持续时长从19.7 d增加至35.1 d。增加行距显著提高单株成铃(0.9个),对铃重及衣分无显著影响,籽棉及皮棉产量显著增加16.7%和17.4%。行距对植株养分积累与分配有显著的影响,S1处理氮积累总量(907.0 kg·hm-2)、磷积累总量(58.3 kg·hm-2)、吐絮期经济器官氮分配率和磷分配率(N 55.7%和P2O569.1%)、每100 kg皮棉氮素吸收量(32.1 kg)均最高;而S3处理氮积累总量(664.5 kg·hm-2)、磷积累总量(38.9 kg·hm-2)最低,S2处理吐絮期经济器官氮分配率和磷分配率(N 48.5%和P2O560.3%)、每100 kg皮棉氮素吸收量(28.6 kg)最低。【结论】综合来看,一膜三行下植株养分指标及产量均优于其他行距,更适宜作为高效机采的行距。     

外源钙对低温胁迫下苹果花器官生理指标的影响

以二十年生苹果品种"红富士"为试材,采用人工气候室模拟低温冻害的方法,研究不同外源钙不同浓度对苹果花器官丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性及过氧化氢酶(CAT)活性的影响,并用隶属函数法进行抗寒性综合评价。结果表明:低温胁迫下不同外源钙各浓度处理MDA含量较对照降低了10.7%~53.6%,且均呈极显著差异;不同外源钙除28 mmol·L^-1 CaCO₃处理外各浓度处理均提高了SOD活性,除14 mmol·L^-1Ca(NO₃)₂处理外均与对照呈极显著差异;不同外源钙各浓度处理均提高了POD活性,除14、28 mmol·L^-1Ca(NO₃)₂处理外均与对照呈极显著差异;不同外源钙各浓度处理CAT活性较对照提高了8.7%~22.7%,且均与对照呈极显著差异。综上所述,丙二醛含量、过氧化氢酶活性、过氧化物酶活性和超氧化物歧化酶活性4个生理指标可作为苹果抗寒性的鉴定指标。通过隶属函数值分析表明21 mmol·L^-1CaCl₂处理后的苹果花器官抗寒性效果最佳。