宁夏南部山区秸秆覆盖对春玉米水分利用及产量的影响

为研究秸秆覆盖在宁南山区对春玉米生长及其土壤水分的影响,在宁夏彭阳县对三种不同秸秆覆盖处理方式进行了试验研究。对比分析了不同覆盖措施下春玉米的生长状况、产量及水分利用效率变化的关系。结果表明:采用秸秆覆盖方式可使春玉米的株高、穗位高、穗长、生物产量及经济产量等指标得到显著提高,土壤的蓄水保墒性能增强,水分利用效率提高,增产增效明显;与传统方式相比,整秸秆覆盖可使春玉米的产量及水分利用效率分别提高3.5%及16.5%。     

Up in smoke: I. Smoke-derived germination cues for postfire annual,Nicotiana attenuata torr. Ex. Watson

Some postfire annuals with dormant seeds use heat or chemical cues from charred wood to synchronize their germination with the postfire environment. We report that wood smoke and polar extracts of wood smoke, but not the ash of burned wood, contain potent cue(s) that stimulate germination in the postfire annual plant,Nicotiana attenuata. We examined the responses of seeds from six populations of plants from southwest Utah to extracts of smoke and found the proportion of viable seeds that germinated in the presence of smoke cues to vary between populations but to be consistent between generations. With the most dormant genotypes, we examine three mechanisms by which smoke-derived chemical cues may stimulate germination (chemical scarification of the seed coat and nutritive- and signal-mediated stimulation of germination) and report that the response is consistent with the signal-mediated mechanism. The germination cue(s) found in smoke are produced by the burning of hay, hardwood branches, leaves, and, to a lesser degree, cellulose. Moreover, the cues are found in the common food condiment, liquid smoke, and we find no significant differences between brands. With a bioassay-driven fractionation of liquid smoke, we identified 71 compounds in active fractions by GC-MS and AA spectrometry. However, when these compounds were tested in pure form or in combinations that mimicked the composition of active fractions over a range of concentrations, they failed to stimulate germination to the same degree that smoke fractions did. Moreover, enzymatic oxidation of some of these compounds also failed to stimulate germination. In addition, we tested 43 additional compounds also reported from smoke, 85 compounds that were structurally similar to those reported from smoke and 34 compounds reported to influence germination in other species. Of the 233 compounds tested, 16 proved to inhibit germination at the concentrations tested, and none reproduced the activity of wood smoke. By thermally desorbing smoke produced by cellulose combustions that was trapped on Chromosorb 101, we demonstrate that the cue is desorbed between 125 and 150°C. We estimate that the germination cues are active at concentrations of less than 1 pg/seed and, due to their chromatographic behavior, infer that a number of different chemical structures are active. In separate experiments, we demonstrate that cues remain active for at least 53 days in soil under greenhouse conditions and that the application of aqucous extracts of smoke to soil containing seeds results in dramatic increases in germination of artificial seed banks. Hence, although the chemical nature of the germination cue remains elusive, the stability of the germination cues, their water-solubility, and their activity in low concentrations suggest that these cues could serve as powerful tools for the examination of dormant seed banks and the selective factors thought to be important in the evolution of postfire plant communities.     

A new method using feature extraction for identifying paddy rice species for quality seed selection

The purpose of this work was to explore a new feature extraction method for classifying paddy seeds using a feature extraction algorithm to achieve the area ratio, horizontal–slant and front–rear angles and find whether the proposed features have high discriminating power. Another objective was to find the smallest feature set that can ensure highly accurate recognition of seeds. A total of a 100 image features were extracted, and features having significant discriminating power were identified based on the analysis of variance (ANOVA). From the 100 features, 14 features were found to have high discriminating power and from these features, six were selected as the proposed features. Experimental results show that the proposed features and removal of redundant features enhanced the discriminating power of the feature set, and that the proposed features have an excellent discriminating property for seeds. The presented features resulted in the highest classification accuracy (98.8%) when compared to other methods.     

霍泉灌区作物需水量实时预报

采用联合国粮农组织最新推荐的修正Ｐｅｎｍａｎ公式分析计算了霍泉灌区长系列参考作物的腾发量及其变化规律,在此基础上提出了该灌区冬小麦、夏玉米需水量预报模型．分析了预报模型中参数Ａ０的变化规律,并在预报过程中进行调整．运用实测资料检验表明,修正后的模型在逐日作物需水量预报中更符合实际,具有比较高的精度．     

基于SVM区域构造的复杂中文版面分析

针对现有的版面分析算法对参数的敏感性以及弱适用性等缺陷,提出基于SVM区域构造的复杂中文文档版面分析算法。该算法通过选取最能代表区域字符特征的连通区(种子连通区)作为测试的第一特征,利用具有强学习和泛化能力的支持向量机实现区域构造,在构造的区域中运用投影快速判断文档阅读顺序。实验结果表明,该方法具有更好的适应性,对复杂的中文版面有满意的分析结果。     

基于确定模式的伪单跳变测试矢量生成技术

提出了一种基于确定模式的伪单跳变测试矢量生成方法,它是在折叠计数器确定模式的基础上,采用LFSR编码折叠计数器种子,通过选定的存储折叠距离来控制测试模式,使得产生的测试矢量之间实现伪单跳变。由于是在确定模式基础上进行的研究,没有改变原来的测试矢量,所以故障覆盖率不会改变,却大大降低了测试功耗。这样既保证了高故障覆盖率,又解决了不同种子所生成的测试矢量之间的重叠冗余。研究结果不仅表明该方案具有很好的数据压缩率,而且证明了该方案的有效性。     

中医针灸领域术语自动抽取研究

针对中医针灸领域术语的构成特点,该文建立了一种基于规则的领域术语抽取算法模型,该模型首先对中医针灸领域术语种子集进行有限次的迭代,生成中医针灸领域术语构件集;然后,以术语构件集为领域词典,采用最大向前匹配算法对中文针灸医学文献中的句子进行切分,并抽取候选术语;最后,利用语言规则对候选术语进行过滤处理,筛选出中医针灸领域专业术语。分别以关键字集和中医词典为种子集进行实验,开式测试的F值分别达到76.96%和35.59%。
     

生物农药防治玉米土传性病害药效的测定

采用美国生产的ＢＧ－２、Ｓｏｉｌｇａｒｄ两种生物农药和国内生产的生物型种衣剂（ＺＳＢ）对玉米茎腐病和纹枯病苗期和成株期的防治试验表明：两种生物农药均可在一定程度上防治茎腐病菌在苗期引起的根腐病,其中ＢＧ－２对镰孢菌的防治效果高达５５．１４％;Ｓｏｉｌｇａｒｄ对腐霉菌的防治效果达５５．５７％。ＢＧ－２对纹枯病的防治效果比ＺＳＢ好。田间试验表明：ＺＳＢ对纹枯病比对茎腐病的防治效果好。１：４０的种子包衣量为最佳。粉锈宁与ＺＳＢ混用比单独粉锈宁拌种防治茎腐病的效果好。     

玉米纹枯病病菌侵染过程研究

研究了纹枯病菌侵入玉米叶鞘的显微和超微过程,结果表明：在接种病菌后１２～２４ｈ,病菌通过表皮、乳孔和自然孔口３种途径侵入寄主,其中以表皮直接侵入为主。侵染垫是病菌主要侵入结构。接种１２ｈ,可在叶鞘表面形成少量近圆形的侵染垫。接种２４ｈ,则有大量侵染垫形成,侵染垫下可见侵入钉直接侵入寄主表皮。接种２４ｈ后叶鞘组织细胞内可见大量侵入的菌丝。     

玉米黄酒发酵条件的优化

以玉米碴为原料,分别选用UV－48黑曲霉和啤酒酵母为发酵菌种,通过对接种量、培养温度、pH值以及发酵周期的研究,确定以玉米为原料制作黄酒的最佳发酵条件为：最适接种量为糖化菌10％,酵母菌1％;最适发酵温度为15－18℃;最适pH值为4.5-5.5,最适发酵周期为16－19d。