基于水稻QTL定位分析预测单穗粒重最优基因型

选择符合需要的基因型个体是育种实践中的重要环节,而理想基因型的预测则又是其前提。本文以水稻“珍汕97B×明恢63”的F₁杂种（汕优63）所衍生的永久F₂群体为材料,对单穗粒重进行了QTL定位分析,并对不同环境下单穗粒重的最优株系（SL）和最优杂种（SH）的基因型及其遗传效应值进行了预测。结果表明,QTL定位分析共检测到9个与单穗粒重相关的QTL,其中7个具有环境互作效应;上位性是控制水稻单穗粒重遗传变异的一个重要的遗传组分。最优基因型预测显示,不同环境下最优株系（SL）与最优杂种（SH）的基因型及遗传效应值不同。在两个环境中,SH的遗传效应值都是最高的。因此,SH将能够充分挖掘单穗粒重的最大潜力。9个QTL全为杂合或全为纯合均不是最佳选择,预测得到的SH有近一半的QTL是纯合基因型。同时讨论了在育种中获得SL和SH的途径。     

密度和追肥时期对重穗型冬小麦品种L906群体辐射和光合特性的调控效应

密度和追肥时期对重穗型高产冬小麦的群体发展,冠层辐射和光合特性有明显的调节效应.随着密度增加,开花前的叶面积指数(LAI)、群体净光合速率(NCP)、群体叶源量(CLSC)提高,但生育后期衰减较快;密度过高导致群体透光率下降,消光系数增加,单茎受光量降低,冠层光环境恶化,后期旗叶的羧化效率降低;密度过低则导致生育前期漏光损失     

NCT对小麦衰老生理的影响

以新合成的NCT配制成不同浓度的水溶液，对灌浆初期的大田小麦进行叶面喷施，以喷清水作对照，并以与NCT相同浓度梯度的NAA水溶液作对比处理，测定了喷后不同时期小麦旗叶的相对电导率、叶绿素含量、超氧化物歧化酶（SOD）活力及丙二醛（MDA）含量。结果表明：NCT能延缓灌浆期SOD活力，使叶绿素含量降低，控制相对电导率和MDA含量的升高，并使小麦穗粒重和千粒重增加，其效果明显优于NAA。     

Effect of two wheat genotypes and Swedish environment on falling number, amylase activities, and protein concentration and composition

Variation in falling number, amylase activities, protein concentration and composition were investigated in two wheat cultivars grown in Sweden over two seasons, in four locations, with four N fertilizer rates, with and without fungicide treatment. The results showed that;

不同工况下Y型网式过滤器流场数值模拟分析

为探究网式过滤器的水力性能,充分了解网式过滤器内部最初流场、滤芯网面流量分布情况,应用计算流体动力学方法对网式过滤器3种入口流速(0.5、1.5、2.5 m/s)以及3种滤网目数(60、80、100目)对过滤器流场进行数值模拟。通过试验对模拟结果的可靠性进行验证,结果表明：过滤器的水头损失集中在出口侧滤芯上,该部分水头损失占总损失的87%;水流在腔体内可分为出口侧加速区、出口侧减速区、堵头回流区和漩涡区4部分;滤网面流量分布严重不均,高流量区域主要分布在出口侧,入口流速由0.5 m/s增至2.5 m/s过程中,网面最大与最小流量均相差3.3倍,滤网目数为60、80、100目时,网面最大与最小流量相差3.3、3.1、2.3倍,且滤网目数增至100目时,最大与最小流量位置向两侧偏移;堵头处死水区压力大、流速低,泥沙易于沉淀,建议扩大堵头容积以承接更多的泥沙;可以考虑增大腔体体积、改变腔体角度、在入口处设置导流片,从而改善流场分布;建议在滤网上增加环状片体,改善网面流量分布,从而提高过滤器的使用寿命以及过滤效率。     

基于改进YOLO的玉米幼苗株数获取方法

为快速准确获取玉米幼苗株数、评估播种质量、进行查缺补苗等管理,对YOLO算法进行改进,提出了一种基于特征增强机制的幼苗获取检测模型（FE-YOLO）,实现了对玉米幼苗株数的快速获取。该方法根据玉米幼苗目标尺寸和空间纹理特征,构建了基于动态激活的轻量特征提取网络,融合了多感受野和空间注意力机制。实验表明：FE-YOLO模型增强了幼苗空间特征、降低了网络复杂度,使模型的mAP和召回率分别达到87.22%和91.54%,每秒浮点运算次数和检测推理时间仅为YOLO v3的7.91%和33.76%。FE-YOLO能够实现无人机正射影像的玉米幼苗株数获取和种植密度估算,该模型复杂度低、识别精度高,能够为玉米苗期管理提供技术支持。     

玉米穗茎兼收割台切碎装置参数优化

针对玉米穗茎兼收割台的需求,设计了一种横置滚筒式茎秆切碎装置,并对其切碎性能及割台摘穗性能进行了试验研究。通过对切碎装置工作原理的分析,确定在拉茎速度与切碎滚筒转速比值一定的条件下,以机器作业速度、动刀切割前角、切碎滚筒转速为自变量,以玉米果穗损失率、籽粒破碎率、籽粒损失率、茎秆平均切段长度和几何标准差为试验指标,利用Box-Benhnken Design中心组合试验设计原理,进行了3因素3水平正交旋转组合田间试验,利用Design-Expert软件对试验结果进行了响应面分析和回归分析,得到试验指标与试验因素间的数学模型。试验结果表明：机器作业速度和切碎滚筒转速与5个试验指标有二次非线性关系,动刀切割前角仅与茎秆平均切段长度、几何标准差有二次非线性关系,因素的交互项中仅机器作业速度与切碎滚筒转速的交互项对籽粒破碎率、茎秆平均切段长度有显著影响。对切碎滚筒转速进行圆整,得到最优参数组合为：机器作业速度为1.35m/s,动刀切割前角为52°,切碎滚筒转速为1350r/min,此时果穗损失率为1.1%,籽粒破碎率为0.23%、籽粒损失率为0.74%、茎秆平均切段长度为30.73mm、几何标准差为1.28。与田间试验结果对比可知,回归模型有很好的可靠性。将最优组合试验结果与优化前的参数组合（机器作业速度为1.11m/s,动刀切割前角为53°,切碎滚筒转速为1657r/min）得到的结果进行比较可知：优化后较优化前果穗损失率降低0.4%,籽粒破碎率降低0.784%,籽粒损失率降低1.318%,茎秆平均切段长度缩短12.20mm,几何标准差减少0.34。优化后试验指标低于标准规定的指标值,满足设计要求。     

Screening of Ethiopian sorghum (Sorghum bicolor) landraces for their performance under Striga hermonthica ‐infested conditions

Striga hermonthica is a major constraint to sorghum production and productivity in sub‐Saharan Africa, Ethiopia, in particular. The objectives of this study were to evaluate the performance of 49 sorghum genotypes based on their reaction to S. hermonthica and investigate the relationships among yield and Striga resistance traits, including the Striga emergence count, area under Striga number progress curve, area under Striga severity progress curve, grain yield under infested, grain yield under non‐infested conditions and relative yield loss. The genotypes differed significantly in all measured parameters under Striga‐infested and non‐infested conditions. The genotypes ‘Birhan’, ‘Gubiye’, Wolegie, Zegerie, Nechmashila I, Woftel, Tetron and Eyssa were identified as promising ones based on grain yield and Striga‐related traits. On the other hand, the genotypes Jamyo, Bobie, Gedido, Mankebar and Zengada had moderate Striga numbers with low relative yield loss as compared with susceptible checks. The most promising variety, Zegerie, Mankebar and Zengada, out yielded the standard resistant checks ‘Birhan’ and ‘Gubiye’ under Striga infestation. Ward cluster analysis grouped the 49 sorghum genotypes in to four distinct clusters under Striga‐infested conditions. All members of clusters II and III showed the highest yielding group with the lowest to moderate Striga number, while cluster IV supported the lowest yield with the highest Striga number. Significant negative correlations were observed between yield‐ and Striga‐related traits. Highly significant and strong correlations were observed among Striga resistance indices, indicating that any of the Striga resistance parameters can be used as an indicator of resistance. The wide variations in grain yield among genotypes under Striga‐infested conditions would be invaluable genetic resources for production in Striga endemic areas of Ethiopia.     

Combined mutations in five wheat STARCH BRANCHING ENZYME II genes improve resistant starch but affect grain yield and bread-making quality

Increases in the proportion of amylose in the starch of wheat grains result in higher levels of resistant starch, a fermentable dietary fiber associated with human health benefits. The objective of this study was to assess the effect of combined mutations in five STARCH BRANCHING ENZYME II (SBEII) genes on starch composition, grain yield and bread-making quality in two hexaploid wheat varieties. Significantly higher amylose (∼60%) and resistant starch content (10-fold) was detected in the SBEII mutants than in the wild-type controls. Mutant lines showed a significant decrease in total starch (6%), kernel weight (3%) and total grain yield (6%). Effects of the mutations in bread-making quality included increases in grain hardness, starch damage, water absorption and flour protein content; and reductions in flour extraction, farinograph development and stability times, starch viscosity, and loaf volume. Several traits showed significant interactions between genotypes, varieties, and environments, suggesting that some of the negative impacts of the combined SBEII mutations can be ameliorated by adequate selection of genetic background and growing location. The deployment of wheat varieties with increased resistant starch will likely require economic incentives to compensate growers and millers for the significant reductions detected in grain and flour yields.     

王氏唇柱苣苔的离体培养及遗传稳定性

以王氏唇柱苣苔(Chirita wangiana)叶片为外植体进行组培离体快繁研究,并利用流式细胞术对组培苗进行遗传稳定性分析。结果表明:最佳初代诱导培养基为MS添加0.5 mg/L 6-BA+0.1 mg/L NAA;最适继代培养基为MS添加0.5 mg/L 6-BA+0.05 mg/L NAA;最适生根培养基为1/2 MS培养基添加0.5 mg/L IBA和15 g/L蔗糖,所有生根培养基获得的组培苗移栽驯化成活率达到92%以上。组织学切片检测表明,王氏唇柱苣苔叶片为外植体所形成芽体均为器官发生方式形成。流式细胞术检测表明,组培苗倍性没有变化,基因组大小与母本相比仅发生了1.86%的减少;染色体数目为2n=36,跟母本一致,植株形态特征上也无变异。研究结果可为王氏唇柱苣苔的园艺应用快速提供大量遗传稳定的种苗。