荞麦品种改良与产业发展现状及趋势分析

根据国内外荞麦生产现状及存在的问题,对未来荞麦产业发展、品种改良方向及品种选育技术进行了讨论。近年来,世界范围内荞麦种植面积稳中有升,荞麦消费量呈增加趋势,但荞麦生产中普遍存在生产条件差、产量低、品种改良难和不适宜机械化生产等问题,因此广适、高效、优质和高产等特性是荞麦品种改良的目标,传统杂交技术与分子育种技术的结合是未来荞麦品种改良的主要手段。     

混合盐胁迫对马蔺幼苗根系构型及生长量的影响

为探讨不同种类盐胁迫对马蔺幼苗生长状况的影响,采用室内培养的方法,研究总质量浓度为0.3%的NaCl、NaHCO₃单盐溶液及其不同配比的混合盐溶液胁迫对马蔺(Iris lactea var. chinensis)幼苗生长量、地上部干鲜重比值、地下部干鲜重比值以及根系构型的影响。结果表明,随着胁迫时间的延长,0.3%NaCl溶液对叶数和株高增长量的影响最小,其次为3种混合盐溶液,各处理在第14天时株高增幅达到最大。经0.3%NaHCO₃处理后的幼苗地上部干鲜重的比值为空白对照的2.17倍,地下部干鲜重则为空白对照的56.61%,随着混合溶液中NaHCO₃浓度的上升,地上部干鲜重比值表现出上升的趋势,地下部干鲜重比值则表现出下降的趋势。经35天处理后,0.3%NaHCO₃胁迫的马蔺幼苗根系总长、根系表面积较对照均显著下降,降幅分别为39.73%、26.08%,而各处理间的根系体积却无显著差异。研究结果显示,0.3%NaHCO₃溶液对马蔺幼苗的胁迫作用最强,2种单盐对根系的胁迫作用强于混合盐胁迫,而0.3%NaCl溶液对生长量的胁迫作用最弱。     

蒺藜苜蓿转录因子MtMYB的克隆、表达分析及拟南芥转化

MYB转录因子家族基因具有保守的DNA结合域,是植物最大的转录因子家族之一,广泛参与植物的代谢调控,在植物生长发育和胁迫响应等方面发挥重要作用。为改良品种性状和提高生产实践能力,本研究采用RT-PCR法克隆蒺藜苜蓿MYB转录因子基因MtMYB,其编码区长255 bp,编码84个氨基酸。生物信息学分析表明,该基因编码蛋白与其他物种MYB蛋白具有很高的同源性,其中与红三叶同源性最高。荧光定量结果表明,MtMYB基因在蒺藜苜蓿叶片中的表达量最高。MtMYB基因在外源IAA、6-BA的诱导下,总体都呈现先上升后下降的趋势。同时本研究成功构建35S::MtMYB的植物表达载体,并通过转基因技术将其转化至拟南芥中,PCR检测表明,MtMYB已成功整合至转基因拟南芥基因组中。RT-PCR检测表明,MtMYB能够在转基因拟南芥中正常转录。本研究为进一步探明MtMYB基因的功能提供了数据参考和实验材料。     

Dietary fishmeal levels affect the volatile compounds in cooked muscle of farmed large yellow croaker Larimichthys crocea

A comparative study on the volatile compounds in cooked muscle of wild and farmed large yellow croaker (LYC) was conducted. The two farmed LYC groups were fed with diets containing 44% (CF) and 25% (LF) of fish meal (FM) respectively. Results showed that 48 volatiles, including aldehydes, alcohols, ketones, hydrocarbons, aromatics, acids, esters, furans and miscellaneous compound, were detected in cooked fillets. The LF group had significantly lower amounts of total aldehydes and ketones, higher content of miscellaneous compound in cooked fillets than that in the CF and wild groups (p < .05). Compared with the wild group, the LF group had significantly lower amounts of total alcohols, acids and esters, while the CF group had significantly lower amounts of total aldehydes, higher content of total ketones in cooked muscle (p < .05). According to the principal component analysis (PCA), some volatiles (propanal, nonanal, etc.) could be considered as sensitive indicators to classify cooked muscle samples. In conclusion, differences in the volatiles in the cooked muscle between the wild and farmed LYC have been found. Low level of dietary FM (25%) changed the volatile profiles in cooked fillets of farmed LYC. A PCA may be useful to screen potential volatiles to classify cooked muscle samples in this study.     

基于灰色-BP神经网络模型的多情景交通用地需求预测——以长江中游城市群为例

为探索科学预测区域交通用地需求的合理途径,指导国土空间规划编制中交通用地规模的划定,拟通过灰色-BP神经网络模型识别主要社会经济影响因素,以长江中游城市群为例,在预测其远景交通用地需求规模的同时,基于城市群发展的阶段特征选取典型城市群样本设置3类情景,对不同情景下的交通用地需求分别进行预测。结果表明:1)城镇化水平、产业结构高度化程度和劳动力资源禀赋是当前影响长江中游城市群交通用地需求的主要社会经济因素。2)通过系统仿真试验对比不同方法的交通用地需求预测结果,可以发现基于灰色-BP神经网络模型的预测方法精度较高,误差较小,该预测方法对于区域交通用地规模的预测具有一定的适用性。预测得到的长江中游城市群2020和2030年交通用地需求分别为31.22万和49.07万hm2。3)不同情景下长江中游城市群交通用地需求预测结果存在明显差异,底线情景可作为划定交通用地规模的底限,一般情景可作为基准,极限情景可作为红线,长江中游城市群交通用地合理规模应以基准为参考,介于底线和红线之间。     

黄河未来输沙量态势及其适用性对策

[目的] 探索黄河输沙预测的新思路，预估黄河未来输沙态势与输沙量水平，为黄河流域生态治理规划提供参考。[方法] 结合黄河流域水土保持生态修复现状，采用单累积曲线法、滑动平均及频率分析方法，分析1950—2019年黄河主要来沙区间的实测输沙量变化特征及其未来态势。[结果] 1950—2019年黄河输沙量呈现阶梯式减少。1950—2019年黄河中游各站累积实测输沙量随时间的变化可用“左半抛物线”表征。黄河输沙量自1997年以来已进入相对稳定态势，目前已达企稳状态；黄河潼关站未来年输沙量在90%频率下为1.00×10⁸ t左右，在10%频率下为5.00×10⁸ t左右，未来多年平均输沙量为1.40×10⁸ t。[结论] 为了维持黄河输沙量低稳状态，提升水土保持措施质量与标准，补齐“后水土保持”短板，构建完善的水沙关系调控体系，维持黄河下游河道冲淤平衡，是黄河流域生态保护与高质量发展的保障。     

Integrating meteorological factors for better understanding of the urban form-air quality relationship

Landscape Ecology - Understanding the urban form-air quality relationship is essential to mitigate intra-urban air pollution and to improve urban ecology. However, few studies considered urban form...     

内冷油腔振荡冷却仿真方法研究

为了得出一种较为通用的活塞内冷油腔仿真分析方法,采用数值仿真研究方法,从湍流模型、多相流模型、压力速度耦合算法以及油腔几何模型进行油腔CFD仿真分析方法的研究。通过对比分析仿真所得的平均机油填充率、机油分布、壁面平均换热系数和换热系数分布,得出在进行活塞油腔CFD模拟时,标准k-ε湍流模型可以更为经济地进行流动传热计算。可保证计算模拟精度的多相流模型CLSVOF计算结果周期间变化更小,计算结果稳定。活塞油腔瞬态仿真计算时,压力速度耦合算法PISO计算得出的流动换热结果精度更高,收敛速度和达到计算稳定的速度更快,模拟所得流动传热情况更接近实际。全油腔模型模拟效果相对于简化模型效果更好。通过对油腔各壁面区域换热系数随曲轴转角变化的分析得出:振荡过程极大增强了顶面和底面的换热,油腔内壁面中顶部壁面周期平均换热系数最大;底部壁面换热系数变化趋势与顶部壁面变化趋势基本相反,这是由机油分布以及振荡规律决定的;由于侧部壁面未收到机油强烈的冲击,换热系数随曲轴转角变化相对较平缓。     

穗期高温对玉米子粒灌浆生理及产量的影响

为揭示玉米穗期高温胁迫对子粒灌浆生理及产量的影响,以耐热型玉米品种郑单958和热敏感型玉米品种先玉335为试验材料,研究了第9片叶完全展开至抽雄期高温对玉米子粒灌浆特性、淀粉合成酶活性、激素含量和产量的影响。结果表明,穗期高温处理,郑单958和先玉335的产量分别比对照降低了11.14%和25.40%;2个品种的粒重和灌浆前期的灌浆速率降低,到达最大灌浆速率的时间延迟,灌浆速率最大时的生长量减小,活跃灌浆期延长;灌浆前期子粒淀粉合成酶活性降低;高温对先玉335的影响明显高于对郑单958。高温处理后,2个品种子粒中的生长素、玉米素核苷和赤霉素含量变化趋势一致,均表现为灌浆初期降低,灌浆后期升高,脱落酸含量表现则相反。     

Summer drought decreases Leymus chinensis productivity through constraining the bud,tiller and shoot production

Extreme drought events can directly decrease productivity in perennial grasslands. However, for rhizomatous perennial grasses it remains unknown how drought events influence the belowground bud bank which determines future productivity. Ninety‐day‐long drought events imposed on Leymus chinensis, a rhizomatous perennial grass, caused a 41% decrease in the aboveground biomass and a 28% decrease in belowground biomass. Aboveground biomass decreased due to decrease in both the parent and the daughter shoot biomass. The decreases in daughter shoot biomass were due to reductions in both the shoot number and each individual shoot weight. Most importantly, drought decreased the bud bank density by 56%. In addition, drought induced a bud allocation change that decreased by 41% the proportion of buds that developed into shoots and a 41% increase in the buds that developed into rhizomes. Above results were supported by our field experiment with watering treatments. Thus, a 90‐day‐long summer drought event decreases not only current productivity but also future productivity, because the drought reduces the absolute bud number. However, plasticity in plant development does partly compensate for this reduction in bud number by increasing bud development into rhizomes, which increases the relative allocation of buds into future shoots, at the cost of a decrease in current shoots.