Response of soybean genotypes to different irrigation regimes in a humid region of the southeastern USA

Studies on irrigation scheduling for soybean have demonstrated that avoiding irrigation during the vegetative growth stages could result in yields as high as those obtained if the crop was fully irrigated during the entire growing season. This could ultimately also lead to an improvement of the irrigation water use efficiency. The objective of this study was to determine the effect of different irrigation regimes (IRs) on growth and yield of four soybean genotypes and to determine their irrigation water use efficiency. A field experiment consisting of three IR using a lateral move sprinkler system and four soybean genotypes was conducted at the Bledsoe Research Farm of The University of Georgia, USA. The irrigation treatments consisted of full season irrigated (FSI), start irrigation at flowering (SIF), and rainfed (RFD); the soybean genotypes represented maturity groups (MGs) V, VI, VII, and VIII. A completely randomized block design in a split-plot array with four replicates was used with IR as the main treatment and the soybean MGs as the sub-treatment. Weather variables and soil moisture were recorded with an automatic weather station located nearby, while rainfall and irrigation amounts were recorded with rain gauges located in the experimental field. Samplings for growth analysis of the plant and its components as well as leaf area index (LAI) and canopy height were obtained every 12 days. The irrigation water use efficiency (I_WUE) or ratio of the difference between irrigated and rainfed yield to the amount of irrigation water applied was estimated. The results showed significant differences (P < 0.05) between IR for dry matter of the plant and its components, canopy height, and maximum leaf area index as well as significant differences (P < 0.05) between MGs due to IR. Differences for the interaction between IR and MG were significant (P < 0.05) only for dry matter of pods and seed yield. In general, seed yield increased at a rate of 7.20 kg for each mm of total water received (rainfall + irrigation) by the crop. Within IR, significant differences (P < 0.05) on I_WUE were found between maturity groups with values as low as 0.55 kg m⁻³ for MG V and as high as 1.14 kg m⁻³ for MG VI for the FSI treatment and values as low as 0.48 kg m⁻³ for maturity group V and as high as 1.02 kg m⁻³ for maturity group VI for the SIF treatment. We also found that there were genotypic differences with respect to their efficiency to use water, stressing the importance of cultivar selection as a key strategy for achieving optimum yields with reduced use of water in supplemental irrigation.     

柑橘黄龙病对沙田柚树体特性和果实品质的影响

柑橘黄龙病（Citrus Huanglongbing,简称HLB）是柑橘的毁灭性病害,柑橘感染后不仅导致叶片黄化,影响果实品质,而且会使树势减弱直至植株死亡。本研究以感染黄龙病和健康沙田柚[Citrus maxima (Burm.) Merr. cv. Shatian Yu]为材料,对比分析黄龙病树（HLB⁺）和健康树（HLB^-）在叶片形态特征、果实品质、矿质元素等方面的差异,旨在掌握黄龙病对沙田柚树体和果实的影响,为促进柑橘黄龙病的防控提供理论参考。沙田柚黄龙病植株与健康植株相比,叶片面积减少28.13%,叶绿素a、叶绿素b和类胡萝卜素分别降低40.38%、44.00%和40.47%;果实外观着色异常且果实偏小,平均单果重下降45.62%,果皮变薄,种子败育增多,果实维生素C升高26.44%,达到显著水平,并且不同组织的多个元素发生显著变化。与健康植株相比,黄龙病叶片N和Ca元素分别减少19.00%和49.72%,果肉N元素减少18.00%,而果皮和果肉Ca元素显著升高;病树根、叶片、果皮和果肉S元素均显著低于健康树。病树叶片B和Cu元素分别降低了35.07%和54.45%,果皮Cu元素显著降低了42.96%,果肉Zn元素显著升高了41.30%。黄龙病严重影响了沙田柚叶片形态和果实品质以及矿质元素代谢,应高度重视提高沙田柚果园的黄龙病防控管理水平。     

Genistein and Daidzein Concentrations and Contents in Seedling Roots of Three Soybean Cultivars Grown under Three Root Zone Temperatures

Daidzein and genistein are plant-to-bacterium signal compounds involved in soybean nodule formation. They can induce nod gens expression in Bradyrhizobium japonicum. The objective of this study was to determine whether the production of signal molecules was affected by low root zone temperatures (RZTs) in a manner that varied among soybean cultivars. Daidzein and genistein concentrations of soybean seedling roots were measured at three RZTs by high performance liquid chromatography (HPLC). The results indicated that daidzein content and concentration per plant were higher at 15 and 17.5°C than those at 25°C. AC Bravor had higher daidzein contents and concentrations than did Maple Glen and KG20. At 17.5°C. KG20 had higher genistein content and concentration levels than Maple Glen, and no difference existed for the two cultivars at 15 and 25 C. Daidzein contents and concentrations of Maple Glen and AC Bravor increased with harvest time. However, for cultivar KG20, the content and concentration decreased at 19 days after inoculation. Genistein contents and concentrations of the three cultivars increased under each RZT up to the last harvest. There was an interaction between soybean cultivar and RZT for root genistein and daidzein contents and concentrations. The content and concentration of daidzein in soybean seedling roots were much higher (more than five times) than those of genistein.     

RTM-GWAS方法应用于大豆RIL群体百粒重QTL检测的功效

【目的】为全面解析大豆重组自交系群体中调控百粒重性状的QTL体系,将限制性两阶段多位点全基因组关联分析方法（RTM-GWAS）和不同定位方法进行比较、优选,为后续候选基因体系探索及分子标记辅助育种设计提供依据。【方法】利用以科丰1号和南农1138-2为亲本衍生的重组自交系群体NJRIKY的427个家系,通过由全基因组39 353个SNP构建的3 683个SNPLDB标记及3个环境下的百粒重表型数据,选用复合区间作图法（CIM）、基于混合线性模型的全基因组关联分析方法（MLM-GWAS）和RTM-GWAS3种方法检测百粒重QTL,通过QTL数目和总的表型变异解释率比较检测功效,挑选最佳定位结果进行NJRIKY群体中的百粒重遗传体系解析。通过候选基因体系的功能注释,挖掘调控大豆百粒重的生物学途径。【结果】科丰1号与南农1138-2的百粒重差异较大,多环境平均数分别为9.0和17.9 g,遗传变异系数为12.4%,遗传率为85.4%,适用于百粒重性状的遗传解析。比较3种方法定位结果表明RTM-GWAS方法表现最佳,检测QTL数目最多（57个）,解释表型变异最多（70.78%）。而CIM仅检测到14个QTL,解释了56.47%的表型变异,MLM-GWAS仅定位到6个QTL,解释了18.47%的表型变异。RTM-GWAS共检测到57个QTL,分布在19条染色体上,表型变异解释率为0.03%—7.57%,其中41个QTL覆盖了已报道的来自30个双亲群体的81个百粒重QTL,16个QTL为新发现位点,包含一个表型变异解释率大于3%的大效应位点Sw-09-2。此外,检测的57个QTL中有20个位点与环境存在互作效应。这57个QTL构成了影响NJRIKY群体百粒重性状的遗传体系。通过SNPLDB标记与预测基因内的SNP进行χ²检验,共筛选到36个候选基因,其中4个候选基因来自大效应QTL,剩余32个候选基因来自小效应QTL。通过GO注释发现这些候选基因功能注释丰富,其中13个候选基因与籽粒发育直接相关,剩余的候选基因功能丰富,包含转运、转录调节因子等,表明不同生物学途径的基因共同调控NJRIKY群体中百粒重性状的表达。【结论】3种定位方法中,高效的RTM-GWAS方法检测到较为全面的NJRIKY群体的百粒重QTL,更适用于双亲RIL群体的QTL定位。不同功能的候选基因共同调控了复杂的百粒重性状的表达。     

莲雾黑腐病病原菌的鉴定及其生物学特性研究

通过病害症状观察、分离菌致病性测定,以及分离菌株的形态和培养性状观察、rDNA-ITS序列分析将从莲雾果实上分离到的菌株FJAT-9860鉴定为可可毛色二孢菌Lasiodiplodia theobromae.菌株FJAT-9860在PDA培养基上菌落最初为白色,后逐渐变为灰色到黑色.分生孢子为单细胞,无色透明,椭圆形至圆形.ITS序列分析表明,菌株FJAT-9860与Lasiodi plodia theobromae strain亲缘关系最近,同源性为99％.该菌株最适生长温度为25℃,最适生长pH值为8.0,不同碳源对菌株FJAT-9860的生长影响不同,最佳碳源为甘露醇.     

VAM真菌对大豆幼苗抗旱性的影响

通过盆栽方法研究了干旱胁迫下接种泡囊丛枝菌根真菌(VAM真菌)摩西球囊霉(Glomusmosseae)对大豆[Glycine max (L.) Merr.]幼苗叶片质膜抗氧化系统、叶片渗透调节物质含量及叶片色素含量的影响.结果表明,干旱胁迫下,与未接种VAM真菌相比,接种VAM真菌可以缓解因干旱胁迫造成的大豆叶片内超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的下降,显著提高类胡萝卜素含量,缓解游离脯氨酸(Pro)的积累、提高可溶性蛋白质(SP)含量,提高可溶性糖(SG)的转运速度,抑制叶绿素(Chl)的分解.     

不同产地百尾参挥发性成分比较研究

[目的]分析比较不同产地百尾参的挥发性成分。[方法]采用有机溶剂-水蒸气蒸馏法及气相色谱质谱联用技术提取并比较分析不同产地百尾参的挥发性成分。[结果]从贵州安顺和凯里百尾参中分别鉴定出68和40种挥发性成分,分别占总峰面积的99.01%和98.96%;两个不同产地的百尾参挥发性成分中,含27种共有成分,但各成分的含量不同。[结论]两个产地百尾参的挥发性成分在数量及含量上有一定的差异。     

沙田柚F-box蛋白基因的克隆及序列分析

采用生物信息学方法,对沙田柚[Citrus maxima(Burm.)Merr.cv.Shatian Yu.]F-box蛋白基因编码的蛋白质从序列特征、理化性质、跨膜结构域、高级结构及功能域等方面进行了预测和分析。结果表明,该基因全长为1 427 bp(Gen Bank登录号为KR363148),开放阅读框(ORF)全长为1 101 bp,共编码366个氨基酸,编码蛋白质的分子质量43.09 ku,理论等电点5.15。沙田柚F-box蛋白基因编码蛋白含有一个植物F-box蛋白家族的保守结构域,为亲水性非分泌不稳定蛋白,不跨膜运动,共有30个可能的磷酸化位点。氨基酸序列分析表明,其编码的氨基酸与甜橙(Citrus sinensis,KDO71185)和克莱门柚(Citrus clementina,XP_006425495)F-box蛋白的同源性分别为99%、98%。系统进化树表明,沙田柚F-box蛋白基因与与甜橙(Citrus sinensis,KDO71185)和克莱门柚(Citrus clementina,XP_006425495)亲缘关系很近,属于同一进化分支。     

蟛蜞菊抽提物对花生蚜忌避及毒杀作用

用不同浓度蟛蜞菊甲醇抽提物对花生蚜选择性和非选择性忌避作用进行测定,并采用喷雾法进行蟛蜞菊抽提物对花生蚜的毒杀试验。结果表明:在选择性忌避试验中,蟛蜞菊抽提物对花生蚜具明显的忌避作用,最高忌避率达90.1％,而在非选择性忌避试验中忌避作用中等;2.5 g/L浓度蟛蜞菊抽提物喷雾处理花生蚜,第5天死亡率达93.7％,第1,3,5天致死中质量浓度(LC50)分别为1.4,1.2,0.9 g/L。蟛蜞菊抽提物有开发利用的价值。     

栾树离体幼胚成苗技术研究

通过栾树离体幼胚可以产生愈伤组织和再生植株。外植体消毒时,最适宜的方法是先去种皮再消毒,消毒时间酒精处理30 s,升汞处理9 min;用1 mg·L-1的GA3对外植体进行预处理,可以促进幼胚的无菌萌发;6BA有利于幼胚的快速成苗,最佳激素浓度为2 mg·L-1,2,4D有利于产生愈伤组织,最佳激素浓度为2 mg·L-1,5 mg·L-1的6BA与2,4D易导致外植体褐化、坏死;在使用AC时,要考虑到AC的无选择吸附性,应加大使用附加物的浓度或降低AC的使用量。