3个单倍体诱导系的初步评价

为了评价3个诱导系,将诱导系与6个玉米组合杂交,分析了初步诱导率。结果表明：诱导系间的初步诱导率存在显著差异;美诱系的初步诱导率（6．52％）显著高于日诱系（3．89％）和高诱1号（3．21％）;基础组合间的初步诱导率差异不显著。     

通辽市玉米高产高效种植综合技术应用

通辽市玉米生产中普遍存在水肥资源利用率低、机械化程度低、技术到住率低、生产成本高、品质差或个别地区高产不高效等问题,为了更好地解决生产中存在的实际问题,结合市政府提出的吨粮田建设,主要采取六项有效增产技术。即：机械化宽窄行覆膜增密技术、土壤检测配方施肥技术、病虫害综合防治技术、氮后移增产技术、隔行去雄增产技术、深松深翻技术。通过上述六项关键技术的综合应用,大大提高玉米生产水平,真正实现农牧业增产、农牧民增收、农牧业现代化的目标。     

立枯丝核菌侵染玉米的研究

 用获自水稻及玉米的立枯丝核菌(Rhizoctonia solani Khn) AG-11A接种玉米发生典型纹枯症状,其致病力显著强于AG-4。玉米拔节期,上位叶鞘抗性较强,抽雄及抽丝期抗性减弱,下位叶鞘无论在拔节期或抽雄、抽丝期,均较上位叶鞘感病。接种玉米后8小时,形成侵染垫及附着胞,从这些结构上形成侵入钉侵入,AG-4侵染上位叶鞘时,常以菌丝直接穿透表皮或从气孔侵入。在去掉菌体的叶鞘表面,发现有周边光滑或稍破损的侵入孔。接种后12小时,在叶鞘细胞中发现菌丝,它们在穿过细胞壁进入邻近细胞时,明显变细。接种后16小时,新生出的菌丝从气孔成丛出现。     

Evaluating eddy covariance method by large-scale weighing lysimeter in a maize field of northwest China

Accurate determination of evapotranspiration (ET) is useful to develop precise irrigation scheduling. Although eddy covariance (EC) is a direct method which is widely used to measure ET, its performance in arid region of northwest China is not clear. In this study, ET measured by EC (ET_EC) was compared with that by large-scale weighing lysimeter (ET_L) during the whole growing season of maize in 2009. Energy balance ratio was 0.84 for daytime fluxes, indicating that lack of energy balance closure occurred, so daytime ET_EC was adjusted by Bowen-ratio forced closure method. Compared to the corresponding ET_L, half-hourly daytime ET_EC was underestimated by 21.8% without the adjustment and 4.8% with the adjustment. Furthermore, nighttime ET_EC was adjusted using filtering/interpolation method. Mean error between half-hourly nighttime ET_EC and ET_L decreased from 30.2% without the adjustment to 10.3% with the adjustment. After such adjustment of day and night measurements, daily ET_EC was underestimated by 6.2% compared to ET_L. These results indicated that the adjusted ET_EC well matched with the ET_L. Moreover, the discrepancy of adjusted total ET_EC and ET_L was decreased to 3.2% after subtracting the overestimated ET by lysimeter resulting from irrigation and heavy rainfall events. Thus, after appropriate adjustments of observations, eddy covariance method is accurate in estimating maize ET in the arid region of northwest China.     

基于核自适应滤波的无线传感网络定位算法研究

针对动态室内环境的变化及时变的接收信号强度(Received signal strength,RSS)对定位精度的影响,提出了一类基于核自适应滤波算法的农业无线传感器网络室内定位方法。核自适应滤波算法具体包括量化核最小均方(Quantized kernel least mean square,QKLMS)算法及固定预算(Fixed-budget,FB)核递推最小二乘(Kernel recursive least-squares,KRLS)算法。QKLMS算法基于一种简单在线矢量量化方法替代稀疏化,抑制核自适应滤波中径向基函数结构的增长。FB-KRLS算法是一种固定内存预算的在线学习方法,与以往的滑窗技术不同,每次时间更新时并不修剪最旧的数据,而是旨在修剪最无用的数据,从而抑制核矩阵的不断增长。通过构建RSS指纹信息与物理位置之间的非线性映射关系,核自适应滤波算法实现WSN的室内定位,将所提出的算法应用于仿真与物理环境下的不同实例中,在同等条件下,还与其他核学习算法、极限学习机(Extreme learning machine,ELM)等定位算法进行比较。仿真实验中2种算法在3种情形下的平均定位误差分别为0.746、0.443 m,物理实验中2种算法在2种情形下的平均定位误差分别为0.547、0.282 m。实验结果表明,所提出的核自适应滤波算法均能提高定位精度,其在线学习能力使得所提出的定位算法能自适应环境动态的变化。     

基于红外光声光谱的农作物秸秆导热系数定量分析

选用我国华北地区具有代表性的小麦、玉米、水稻秸秆样品,对比研究了偏最小二乘(PLSR)和高斯核支持向量机(RBF-SVR)分别构建单一和混合种类秸秆全波段定量分析模型的效果,探讨了红外光声光谱耦合化学计量学方法构建我国主要粮食作物秸秆导热系数定量分析模型的可行性。研究发现,小麦秸秆和水稻秸秆导热系数RBF-SVR非线性模型,以及玉米秸秆、混合种类秸秆的PLSR线性模型效果较优。进一步应用蚁群算法与上述最优建模方法相结合,构建了更加优化的小麦秸秆、玉米秸秆、水稻秸秆和混合秸秆导热系数模型,验证决定系数(R_p~2)分别为0.77、0.83、0.96和0.79,验证均方差(RMSEP)分别为0.007 8、0.015、0.005 9、0.014 W/(m·K),验证相对分析误差(RPD)分别为2.81、2.41、7.39和2.15。研究结果表明,红外光声光谱技术结合先进适用的化学计量学方法可实现我国主要粮食作物秸秆导热系数的快速定量分析,但混合秸秆模型预测精度仍需进一步提升。     

基于HOG特征的IKSVM稻瘟病孢子检测

为解决稻瘟病孢子的人工检测过程中主观性强、自动化程度低、效率低等问题,提出一种基于梯度方向直方图特征（HOG特征）的加性交叉核支持向量机（IKSVM）的稻瘟病孢子检测方法。该方法首先利用图像采集系统采集稻瘟病孢子图像,利用Gamma校正法调节图像的对比度,抑制噪声干扰;然后,提取孢子图像的HOG特征作为输入向量,输入到支持向量机中,构建加性交叉核支持向量机分类器;最后,通过训练得到稻瘟病孢子分类器。为测试所提出的HOG/IKSVM方法的综合性能,分别选用HOG/线性SVM方法与HOG/径向基核SVM（HOG/RBF-SVM）方法做对比试验。试验结果表明,HOG/IKSVM的检测率为98.2%,高于HOG/线性SVM方法的79%;在平均检测时间上,HOG/IKSVM方法的平均检测耗时仅为HOG/RBF-SVM方法的1.1%。说明该方法可以进行稻瘟病孢子室内检测识别。     

不同肥料配施对酸性土钙素活化及花生产量和品质的影响

为了揭示增施钙肥和不同肥料配施对沿海地区酸性土钙素增量及活化效应,于2015—2016年设置单施无机肥(CK_1)、无机肥/熟石灰配施(T_1)、无机肥—有机肥配施(CK_2)、无机肥—有机肥—熟石灰配施(T_2)、无机肥—有机肥—微生物肥配施(CK_3)、无机肥—有机肥—微生物肥—熟石灰配施(T_3)6个处理,研究了不同肥料配施对酸性土有效钙含量、花生植株性状、荚果产量和籽仁品质的影响。结果表明:CK_2和CK_3均在一定程度上提高酸性土中水溶性钙和交换性钙含量,0—20cm水溶性钙含量各生育期平均分别比CK_1提高48.13%和66.50%,交换性钙含量分别提高39.12%和60.88%。增施钙肥处理(T_1、T_2和T_3)能显著增加水溶性钙和交换性钙含量,但_T1处理对有效钙含量增加较少,而T_2和T_3处理增加幅度较大,其中T_3处理0—20cm水溶性钙和交换性钙含量各生育期平均比CK_3提高1.63,1.74倍,说明钙肥与有机肥和微生物肥配施能显著提高酸性土钙素活化度。不同肥料配施均提高了酸性土花生的主茎高、分枝数、主茎绿叶数、单株干物质重、叶面积指数和实收株数,增加了单株结果数和荚果饱满度,显著提高了荚果产量,并提高了蛋白质、总氨基酸和脂肪含量以及O/L值。其中T_3处理分别比CK_3、T_2、CK_2、T_1和CK_1增产14.38%,4.99%,18.31%,25.65%和52.52%,增产幅度最大,其籽仁品质也最优。增施钙肥并与有机肥和微生物肥配施能显著提高酸性土钙素活化度、有效钙含量、荚果产量和籽仁品质。     

糙米发芽前含水率提升工艺优化

糙米发芽前的吸水过程是导致籽粒裂纹的根本原因,制约着发芽糙米品质和口感。为降低发芽前糙米裂纹增率,探究了完整吸湿区间内各含水率水平糙米的最优吸湿速率。将糙米初始含水率至发芽含水率的完整区间分为若干子区间,在各区间内以不同加湿速率加湿至该区间目标含水率。探究各区间内裂纹增率的变化规律,建立裂纹增率与加湿速率变化规律的数学模型,以低裂纹增率为目标确定最优加湿速率。在此基础上,得出完整区间内以低裂纹增率及高效率为目标的加湿速率数学模型并试验验证。与前期分段加湿工艺相比,本优化工艺可降低发芽前糙米和发芽糙米裂纹增率(41.48±0.15)%和(43.67±0.26)%,糙米发芽率和γ-氨基丁酸含量增加(6.92±0.25)%和(25.03±0.18)%,为高品质发芽糙米的生产方法提供参考。     

Intensification of Upland Agriculture in Thailand: Development or Degradation?

The large scale conversion of extensive swidden agriculture to intensive market oriented production of maize in upland areas of South East Asia is a cause of environmental concern. This study investigates how intensive maize cultivation affects soil quality in an upland area of Northern Thailand by comparing commonly used indicators of soil quality in soils from maize fields used at various intensities. Relations between these indicators and concentration of permanganate oxidizable carbon (Pox‐C) – a low cost proxy for soil quality – are also examined. The extent, type and drivers of land use changes between 2002 and 2012 are investigated by classification of high resolution satellite images, interviews, participatory mapping and questionnaires. We document a widespread change from traditional swidden agriculture to intensive cultivation of maize that is mainly brought about by economcic and political drivers. We show that the concentration of Pox‐C in the top soil of the maize fields is closely related to common indicators of soil quality and to farmers' perceptions of soil quality. Most of the other soil quality indicators are negatively – albeit not significantly – related to intensity of maize cultivation. There is a strong negative correlation between intensity of maize cultivation and concentration of Pox‐C in the upper 5 cm of the soil where the Pox‐C concentration declines with a rate of 40 mg year under maize⁻¹. We conclude that Pox‐C is a sensitive indicator of effects of land use intensity on the soil and a useful integrative measure of soil quality. Copyright © 2016 John Wiley & Sons, Ltd.