Relationship between grain filling duration and leaf senescence of temperate rice under high temperature

High temperature during grain filling period has been reported to decrease the grain filling duration, leading to the lower grain weight and yield of rice. Two experiments in the phytotron and field were carried out to test the hypothesis that the leaf senescence of rice plants may determine the grain filling duration under high temperature. In the phytotron experiment in 2008, rice plants of a japonica cultivar “Ilpumbyeo” were subjected to three minimum/maximum (mean) temperature regimes of 11/19 (15), 17/25 (21), and 23/31 °C (27 °C). In the field experiment, rice seedlings of the same rice cultivar were transplanted on May 6th and June 19th in 2009 and the mean temperatures during the grain filling period were 24.4 and 21.9 °C, respectively. Both experiments revealed consistently that high temperature increased the rates of grain filling and leaf senescence while it reduced the durations of them. However, grain filling was terminated earlier than complete leaf senescence, the time gap being greater at higher temperature. In addition, the fraction of dry matter partitioning to the leaf sheath + culm resumed to increase following the termination of grain filling under high temperature, indicating that leaves were still maintaining photosynthetic capacity and supplying assimilates into the other plant tissues except grain even after the termination of grain filling. These findings suggest that an early termination of grain filling in temperate rice under high temperature was not resulted from the lack of assimilate owing to the early leaf senescence but from the loss of sink activity owing to the earlier senescence of panicle.     

Effect of catheter size and injection rate of contrast agent on enhancement and image quality for triple‐phase helical computed tomography of the liver in small dogs

Rapid contrast injection is recommended for triple‐phase helical computed tomography (CT) of the liver. However, a large‐gauge catheter is needed for faster contrast injection and this is not practical for small breed dogs or cats. The purpose of this crossover group study was to evaluate applicability of a lower injection rate with a small‐gauge (G) catheter for triple‐phase hepatic CT in small dogs. Triple‐phase CT images were acquired for six beagle dogs using three protocols: an injection rate of 1.5 ml/s with a 24 G catheter, 3.0 ml/s with a 22 G catheter, and 4.5 ml/s with a 20 G catheter. Enhancement of the aorta, portal vein, and hepatic parenchyma was measured in each phase (arterial, portal, and delayed) and image quality was scored subjectively by two observers. Injection duration, time to scan delay, and time to peak enhancement were also recorded. Contrast injection duration decreased with a higher injection rate (n = 6, P ≤ 0.01), but time to peak enhancement and time to scan delay were not significantly affected by injection rates and catheter sizes. Contrast injection rate did not significantly affect aortic, portal, and hepatic enhancement. In addition, separation between each phase and quality of images was subjectively scored as good regardless of injection rate. Findings from the current study supported using an injection rate of 1.5 ml/s with a catheter size of 24 G for triple‐phase hepatic CT in small dogs (weight < 12 kg).     

基于AquaCrop模型的小地区气候变化对小麦产量的影响

为了研究甘肃省高台县气候变化对小麦(Triticum aestivum L.)产量的影响,对该地区50 a的气象因素变化进行了分析,并且利用Aqua Crop作物模型模拟不同年份小麦的生产潜力。结果表明,年平均气温、年平均最高气温、年平均最低温度均呈增长趋势,增长幅度为0.021 5、0.012 4、0.014 5℃/a,总降雨量也呈增长趋势,增长幅度为0.220 2 mm/a,而日照时间呈降低趋势,降低幅度为1.328 8 h/a,并拟合得到了相应的线性趋势公式。该地区小麦生产潜力较低,平均模拟产量为5 807.5 kg/hm~2,不同年份间小麦产量差异极显著,并且从气候变化因素分析了该地区小麦产量变化的原因。     

基于高密度遗传图谱的玉米籽粒灌浆特性遗传解析

【目的】灌浆是玉米籽粒形成的重要生理过程,直接决定了籽粒的最终产量。了解玉米籽粒灌浆特性相关性状对粒重形成的作用,解析灌浆特性的遗传基础,为玉米高产育种实践提供指导。【方法】以中国玉米骨干自交系黄早四(HZS)、旅28(Lv28)为亲本构建的包含172个家系的重组自交系(recombination inbred line,RIL)群体为试验材料。首先,利用Logistic模型与Richards模型,进行玉米籽粒灌浆过程拟合度的比较分析。其次,利用方差分析、相关性分析及回归分析分别比较亲本籽粒灌浆特性的差异,研究群体中不同灌浆特性相关性状的关系及其对百粒重的贡献。然后,利用GBS方法,对群体进行基因型分型,选择亲本间多态性标记,构建遗传图谱。最后,利用完备区间作图法(inclusive composite interval mapping,ICIM)进行灌浆特性与生育期相关性状的QTL分析。【结果】籽粒灌浆一般呈现慢-快-慢的变化趋势,可分为缓增期、快增期以及减缓期3个阶段。通过比较不同灌浆模型的拟合度发现,基于Richards模型的预测值与表型值间的决定系数显著高于Logistic模型。比较亲本间灌浆特性的差异发现,黄早四的平均灌浆速率为旅28的1.28倍,但旅28的灌浆持续时间为黄早四的1.07倍,亲本之间在灌浆特性方面差异明显。群体表型相关性分析发现,除缓增期灌浆持续时间(T1)外,其他灌浆特性相关性状均与百粒重(HKW)存在显著的正相关关系。回归分析发现,快增期灌浆持续时间(T2)与灌浆速率(G2)可分别解释百粒重表型变异的57.50%和30.00%。利用多态性SNP标记构建了全长为1 471 c M,标记间平均遗传图距为1 c M的遗传图谱。多个环境下共检测到26个灌浆特性相关QTL、3个百粒重相关QTL及14个生育期相关的QTL,分布在玉米除第7染色体外的其他染色体上,LOD值介于3.27—9.05,单个QTL贡献率为5.97%—21.16%。同时,利用联合环境分析发现,控制不同性状的QTL定位在染色体相同或相近的位置,形成了多个分布于玉米基因组bin 1.05、bin 2.03、bin 4.05、bin 4.06、bin 7.04、bin 9.04的QTL富集区域。其中,在位于bin 4.05(48.24 Mb—135.73 Mb)和bin 9.04(110.40 Mb—114.73 Mb)的区间之内,共定位到多个仅与灌浆速率相关的主效QTL。【结论】Richards模型能够更好地模拟玉米籽粒的灌浆过程。在灌浆特性相关性状中,快增期灌浆速率与灌浆持续时间对于玉米粒重的增加具有重要作用。单环境检测发现,灌浆持续时间相关位点仅能在单环境中得以检测,表现为环境敏感类型。联合环境分析发现,在bin 4.05和bin 9.04区间内分别检测到仅与灌浆速率相关的主效QTL,可作为玉米籽粒灌浆研究的重点区域。     

聊城大学几种常见木本植物开花物候观测研究

对聊城大学几种木本植物的形态特征、物候期、生长规律、开花习性进行了研究,结果表明：温度和光照是影响开花物候的两大主要因素,不同木本植物的开花时间不同,同一种类单株开花时间因树龄和树势而异,短时间的温度异常对开花物候影响不显著。在所观测的不同木本植物间最早与最晚发芽日期可差10d,最早与最晚盛花日期可差50d,其中桃树的始芽期和始花期最早,石榴树的最晚.     

古浪县近51年气候变化特征

利用古浪县1959—2009年的气温、降水、日照时数资料,采用趋势分析方法,对年平均气温、年降水量、年日照时数变化趋势进行分析研究。结果表明:古浪县近51年的年平均气温呈上升趋势,冬季增温最明显;近51年来降水量趋势变化不大,春、夏、冬季降水量有增加趋势,秋季降水则呈减少趋势;日照时数呈上升趋势,春、秋2季呈增加趋势,而夏、冬2季呈减少趋势。     

NaCl和KCl不同浓度与处理时间对樱桃番茄产量和品质的影响

通过向营养液中分别添加NaCl和KCl,在2种EC值(4.0、8.0 mS/cm)和3种处理时间(10、20、30 d)下,对比研究2种盐胁迫对番茄产量和果实品质的影响。结果表明:NaCl比KCl处理更能提高番茄果实的VC含量,其中EC值为4.0 mS/cm的NaCl处理30 d与EC值为8.0 mS/cm的NaCl处理10 d的2种处理的果实中VC含量最高;可溶性固形物的含量在处理后都有不同程度的提高,在EC值为4.0 mS/cm情况下,NaCl处理和KCl处理的提升率差异不明显,当EC值增大至8.0 mS/cm后,KCl处理比NaCl处理的提升率更大;盐胁迫降低了果实的糖酸比,在相同处理下,除EC值为4.0 mS/cm、时间为30 d的处理外,KCl处理的下降率大于NaCl处理;盐胁迫使得番茄的单株产量减少,NaCl处理和KCl处理下降幅度最小都发生在EC值为4.0 mS/cm、处理时间为10 d时,分别为33.8%和5.5%;另外,相同处理条件下,NaCl处理的单株产量下降率明显大于KCl处理。为了改善番茄果实品质,建议采用EC值为4.0 mS/cm的NaCl或KCl营养液对番茄在开花后进行盐胁迫处理10 d。     

Calculation method for sunshine duration in canopy gaps and its application in analyzing gap light regimes

Understory light is essential to the growth and survival of plants, yet the light varies temporally and spatially within forest gaps. Measurement of understory light levels using light sensors is both time and labor intensive. Sunshine duration (SD) has a strong correlation with solar radiation and has been the variable most widely used for estimating solar radiation. The power of SD-based methods for estimating solar radiation lies in its ability to quickly estimate light levels. Although several calculation methods for SD within canopy gaps are available, all the methods oversimplify canopy gaps by classifying them as cylindrical or ellipsoid and thus have a relatively low level of accuracy. In this study we developed a calculation method for SD at any given point within natural canopy gaps and we used SD to estimate solar radiation within 12 canopy gaps on Mt. Taibai in China based on the Angström-Prescott model. We then evaluated the SD-based solar radiation by the total and direct solar radiation derived from a gap light index based on hemispherical photographs (HP). Finally, we analyzed the spatial-temporal characteristics of light levels within these 12 gaps by using the solar radiation derived from SD at hundreds of simulated points in each gap. Our results showed that (1) SD-based solar radiation was not statistically different from HP-based direct solar radiation and had a strong linear correlation with HP-based total solar radiation; (2) growing-season daily mean solar radiation within the 12 gaps varied from 0.08 to 13.28 MJ m⁻² day⁻¹ with an average of 4.13 MJ m⁻² day⁻¹; (3) solar radiation had a positive correlation with the ratio of the square root of the canopy gap area to the mean canopy height. This relationship was significant but solar radiation had no correlation with the canopy gap area; (4) among most gaps solar radiation was greatest in May while potential SD was longest in June 2008. From these results we can conclude that the SD-based method for estimating solar radiation developed in this study can quickly and accurately estimate light levels at any specified point within canopy gaps. SD-based solar radiation appears to be a good choice for studies on the spatial-temporal characteristics of gap light levels.     

长期冻存对昆虫细胞系SL2和NIH-SaPe-4活性的影响

对2种双翅目昆虫细胞系(黑腹果蝇胚细胞系SL2以及麻蝇胚细胞系NIH-SaPe-4)38个月长期液氮深低温保存效果进行了研究,通过对冻存时间和保护剂对2种细胞系冻后活力、圆度以及恢复时间影响的测定,比较了3种不同配方冻存保护液的效果。结果表明:2种昆虫细胞系冻后活性均随着冻存时间的增长而逐渐降低。长期冻存期中,使用90%胎牛血清(FBS)+10%二甲基亚砜(DMSO)冻存SL2效果较好,NIH-SaPe-4使用10%DMSO即可满足冻存的需要,而无需额外添加高浓度FBS。甘油不适用于这2种昆虫细胞系的长期保存。