均值变点及分叉比确定最佳汇流阈值的对比

DEM为水文分析提供了更加多样化的研究分析途径。研究以ASTER GDEM为数据源,利用均值变点和水道分叉比综合对比分析不同区域的水文特征和流域地貌特征,对比不同区域在最佳阈值提取的河网差异及彼此间流域河道分叉比的特征。试验结果表明:清溪河样区和杏子河样区的最佳汇流阈值分别为1500和1300,其所对应的河网密度分别为0.63和0.68;不同的流域内取相同的汇流阈值时河道的分叉能力相同或相近,但河道的数目上有较大的区别。这两者的结合可以在今后的地形分析中提供必要的理论依据。     

基于DEM的东江湖风景区水文分析研究

DEM(Digital Elevation Model)是流域分析的主要数据源,提供了丰富的地质地貌、水文信息。详细介绍了利用DEM数据提取水文特征的方法,包括洼地填充、水流方向、汇流累积量、水流长度和水文分析。以东江湖流域为例,采用ArcGIS软件的Hydrology模块提供的D8算法以确定水流方向,通过汇流累积量的计算和相关阈值的设定,提取东江湖水文特征。结果表明,研究区最大水流长度为113651 m;采用该算法模拟的流域数字水系与水利部门提供的地形数据基本相符,真实反映了研究区水系的空间分布规律,为进一步研究东江湖流域的植被生态环境演变提供基础数据和参考。     

基于DEM 的重庆长江流域水系分维估算

摘要：基于数字高程模型,本文利用ArcGIS9.3的水文分析模块,根据不同的集水面积阈值, 提取了重庆长江流域河网信息,通过网格法计算了相应的水系分维。根据集水面积阈值与水系分维的相互关系, 确定该流域水系分维值为1. 036,经计算得到的河网特征以及流域信息与实际河流水系特征及流域信息基本吻合。     

黄秋葵多糖超声波辅助提取工艺优化及其对·OH体外抗氧化活性研究

以黄秋葵干果荚为原料,选用超声辅助手段对提取其多糖工艺进行优化。采用单因素试验探讨了超声温度、超声时间、液料比和超声功率对黄秋葵干果荚多糖提取得率的影响,在此基础上进行正交试验以确定最佳工艺条件。研究结果表明,提取黄秋葵干果荚多糖的最佳工艺条件为超声温度60℃,超声时间25 min,液料比40:1(mL:g),超声功率90 W,在此条件下提取的黄秋葵干果荚多糖平均得率为3.53%(m/m);制得的RPS对·OH的清除率随着其质量浓度的增加而增大,IC_(50)值为2.41±0.07 mg/mL,表现出较好的体外抗氧化活性。     

不同施肥处理对茶叶春梢内含成分的影响

通过在茶园中使用三种有机肥料及5个梯度施肥用量对比试验，测定茶叶春梢内含物质变化。结果表明，EM生物有机肥的最佳施肥量为200 kg/667 m²,酵素菌生物有机肥的最佳施肥量为300 kg/667 m²,油枯肥的最佳施肥量为200 kg/667 m²;当施肥量为150 kg/667 m²、200 kg/667 m²、250 kg/667 m²时，最佳肥料均为EM生物有机肥；当施肥量为300 kg/667 m²时，最佳肥料为酵素菌生物有机肥。在所有处理下，除油枯肥150 kg/667 m²处理，酚氨比略高于8,其余处理酚氨比都低于8,适宜加工绿茶。     

基于点云构建干热河谷典型冲沟DEM的参数优选—以析取克里格插值方法为例

为了探索析取克里格插值算法中的插值参数对构建DEM精度的影响,以云南元谋干热河谷典型冲沟为例,基于野外实测点云数据,改变析取克吕格插值中的核函数、搜索点数、搜索方向和光滑因子参数构建DEM,运用交叉检验和验证数据集检验评价DEM插值精度。研究结果表明：（1）在不同的核函数中,Stable 函数的插值效果最佳;（2）搜索点数为2~5 个是最佳的选择;（3）在搜索方向的对比中,有方向搜索比无方向搜索误差小,且四方向比八方向的误差小;（4）当光滑因子≥0.8 时,DEM插值精度的误差明显增大。通过对析取克里格插值参数的优选,在研究样区构建出0.08 m的高精度DEM,为该区域的冲沟研究提供资料。     

一种高质量的数字高程模型（DEM）建立方法 ——ANUDEM法

建立高质量的数字高程模型（DEM）是正确计算坡度、坡向、提取流域地形特征、进行水文分析的前提，因而在研究土壤侵蚀、植被建设和土地利用规划与评价中都具有重要意义。ANUDEM采用迭代有限微分内插技术和地形强化算法，自动去除伪下陷点和生成输入数据错误文件，便于查错改善DEM质量，并减少了去除伪下陷点的编辑或DEM的后处理过程。本文以黄土高原丘陵沟壑区典型小流域为例，利用大比例尺（1:10000）数字化地形图，利用ANUDEM建立DEM，从DEM光照模拟图、回放等高线、提取水系、坡度等方面对建立的DEM的质量进行了评价。研究表明，ANUDEM建立的DEM表面光滑；回放等高线与原等高线符合度高，能更准确地表现地形起伏；由其提取的坡度准确；水系连续完整与地形图上河流一致，适宜水文分析，是一种建立高质量DEM的优良方法。     

基于DEM的河网水系分形特征研究——以常德市桃源县为例

为了给流域的治理实践及理论研究提供基础性数字地形信息,以常德市桃源县为例,利用ArcGIS软件的水文分析扩展模块,探讨了DEM的制作处理,获取了研究区域水流流向、汇流累积量、河网水系等流域特征信息,同时用计盒维数和Horton定理2种水系分维数估算方法来估算水系分维数。结果表明：（1）运用DEM和ArcGIS的水文分析模块提取的水系连续完整,且与实际水系特征吻合性较好,是一种进行流域水文分析的优良方法;（2）利用DEM提取水系的分维值,与原水系分维值基本一致,说明利用DEM提取水系分维值的方法具有可行性;（3）根据分维值可以判定研究流域地貌处于幼年期,此时水系尚未充分发育。     

响应曲面法优化核桃青皮色素提取工艺的研究

以核桃青皮为原料,以提取的色素在510 nm处的吸光值为考察指标,在单因素试验的基础上,采用Plackett-Burman试验和响应曲面法优化核桃青皮色素的超声辅助-醇提工艺。结果表明,乙醇体积分数、液料比和提取温度是影响核桃青皮色素提取效果的三个主要因素;核桃青皮色素提取的最佳工艺条件为:乙醇体积分数40%,液料比20∶1(m L/g),提取温度70℃,超声功率150 W,提取时间80 min;所得模型预测值与验证试验的实际值相近,色素的平均吸光值为0.64,平均提取率为2.32 mg/g,说明对核桃青皮色素提取工艺的分析结果可靠、精密度高、重现性好,可用于实际工业化生产。     

龙牙楤木芽多糖提取与脱色工艺的研究

以龙牙楤木芽为试材,在单因素试验的基础上,以多糖提取率为响应值,通过Box-Behnken试验设计和响应面分析,对龙牙楤木芽多糖提取工艺进行优化;以脱色率和多糖保留率为考察指标,利用正交试验优化活性炭脱除龙牙楤木芽多糖中色素的工艺。结果表明,龙牙楤木芽多糖的最佳提取工艺参数为:提取温度84℃,提取时间5 h,液料比26∶1(m L/g),在该工艺条件下龙牙楤木芽多糖平均提取率为5.87%。采用粉末活性炭用量0.6%(m/m)、p H 4.0、温度60℃、时间60 min工艺条件进行脱色处理,平均脱色率达94.08%、多糖保留率为68.15%。     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Relation between wheat-rye crossability and seed set of common wheat after pollination with other species in the Hordeae

Summary Cultivars of common wheat (Triticum aestivum L. em. Thell.) of high wheat-rye (Secale cereale L.) crossability set more seed with pollen of other related species than did wheats of low wheat-rye crossability. This was found to be true for pollen parents from the genera Triticum, Aegilops, Secale, Agropyron and Elymus.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

Inheritance of fruit colour in a wild Russian red raspberry seedling

Summary A new gene, i, from a self-incompatible wild Russian Rubus idaeus seedling is described. The gene i interacts with the fruit colour gene T, Tii plants having apricot instead of red fruits, and spines, leaves and stems pigmented to varying degrees. A deficit of apricot-fruited seedlings in progenies segregating for i could be explained by linkage between i and the self-incompatibility S locus with a crossover value of approximately 26.7%.Segregations for spine colour in crosses and backcrosses of the Russian seedling with two green-spined (ttII) raspberries selected for their yellow fruit colour, showed that both the latter carried the spine colour intensifier gene P. This suggests that earlier authors were incorrect in attributing the apricot fruit colour developed by some tt plants to a pleiotropic effect of P.     

Flag Leaf Senescence, as Evaluated by Numerical Image Analysis, and its Relationship with Yield under Drought in Durum Wheat

Senescence was evaluated at different stages of the grain‐filling period in eight durum wheat varieties using numerical image analysis (NIA). The varieties were grown under early, severe drought conditions on the high plains of Sétif in Algeria. After flowering, three different irrigation treatments were applied. Treatment effect was small, while a genotypic effect was noted for most of the senescence parameters. Senescence correlated to biomass, while the maximal rate of senescence, V_smax, correlated to thousand‐kernel weight. The potential of the method of numerical image analysis for monitoring flag leaf senescence, detecting genotypic variability and selecting genotypes with delayed senescence is discussed.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Cowpea (Vigna unguiculata): Genetics,genomics and breeding

Cowpea, Vigna unguiculata (L.), is an important grain legume grown in the tropics where it constitutes a valuable source of protein in the diets of millions of people. Some abiotic and biotic stresses adversely affect its productivity. A review of the genetics, genomics and breeding of cowpea is presented in this article. Cowpea breeding programmes have studied intensively qualitative and quantitative genetics of the crop to better enhance its improvement. A number of initiatives including Tropical Legumes projects have contributed to the development of cowpea genomic resources. Recent progress in the development of consensus genetic map containing 37,372 SNPs mapped to 3,280 bins will strengthen cowpea trait discovery pipeline. Several informative markers associated with quantitative trait loci (QTL) related to desirable attributes of cowpea were generated. Cowpea genetic improvement activities aim at the development of drought tolerant, phosphorus use efficient, bacterial blight and virus resistant lines through exploiting available genetic resources as well as deployment of modern breeding tools that will enhance genetic gain when grown by sub‐Saharan Africa farmers.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Screening for resistance to take-all in wheat,triticale and wheat-triticale hybrid lines

Summary Fifteen triticale and wheat-triticale hybrid lines were evaluated for resistance to the take-all fungus Gaeumannomyces graminis var. tritici and compared with five wheat and two rye lines in inoculated field and pot trials. The triticale and wheat-triticale hybrid lines varied in rye chromosome number and degree of resistance expressed. One line, Venus with seven pairs of rye chromosomes consistently showed levels of resistance intermediate between wheat and rye. A trend was observed where increasing rye chromosome content led to greater resistance but exceptions showed that variation within triticales could not be ascribed to rye chromosome content alone.