木薯后期衰老对淀粉积累的影响

对新选056、南洋红、GR891、辐选01、华南124和新选048六个木薯品种生育后期抗衰老生理和淀粉积累特性进行研究。结果表明:不同木薯品种生育后期抗衰老生理与淀粉积累特性有明显差异,木薯后期茎叶生长状况对块根淀粉积累有明显影响,后期茎叶过早衰老或生长过旺对块根淀粉积累都不利。对抗衰老能力最强的是华南124,其次是辐选01和新选048,抗衰老能力最弱的是南洋红。其中新选056、南洋红、GR891、辐选01、华南124和新选048生育后期叶片过氧化物酶活性分别为383.93△OD470/gFw.min,279.33△OD470/gFw.min,405.20△OD470/gFw.min,445.97△OD470/gFw.min,364.43△OD470/gFw.min和202.20△OD470/gFw.min;丙二醛含量分别为0.0178μmol/gFW,0.0189μmol/gFW,0.0237μmol/gFW,0.0153μmol/gFW,0.0128μmol/gFW和0.0140μmol/gFW;可溶性糖含量分别为0.74%,0.70%,1.02%,0.84%,1.12%和1.30%;自由水/束缚水比值分别为3.07,4.77,6.85,3.64,2.57和3.11;块根淀粉含量分别为29.6%,25.8%,32.8%,32.7%,25.6%和28.9%。     

普通小麦和华山新麦草及其属间杂种F_1同工酶分析

用聚丙烯酰胺凝胶电泳法对普通小麦和华山新麦草及其属间杂种 F_1的三叶期叶片、拔节期叶片、剑叶、幼穗和幼根进行了酯酶同工酶分析。结果表明,不同器官及同一器官的不同发育时期酯酶同工酶酶谱表型有明显差异。普通小麦和华山新麦草就同一器官、同一发育时期相比,酶谱差异较大,佐证了普通小麦和华山新麦草间亲缘关系较远。     

高活力蛋清溶菌酶制备技术的研究

溶菌酶是一种无毒、无害、安全性较高的高盐基水解蛋白酶,在食品和医药领域有着广泛的用途。试验以蛋清为原料,通过阳离子交换树脂法提取高活力(纯度)溶菌酶。试验确定吸附与洗脱条件,蛋清与树脂的体积比为5∶1,搅拌时间为3.5h,洗脱液的离子强度为1mol/L,pH值为8.0,洗脱液经等电点沉淀和透析进一步分离纯化,所得浓缩液以110℃的进风温度和70℃的出风温度进行喷雾干燥得溶菌酶,产品活力为20650U/mg,水分含量为6.2%。     

Sources of resistance to head scab in Triticum

Multi-floret and single-floret injection inoculation methods were used to test 1076 accessions of Triticum for resistance to initial infection and resistance to pathogen spread within spike tissue respectively. The data obtained between years or inoculation dates were comparatively similar and were little influenced by climatic factors, especially humid condition. All the tested materials uniformly exhibited susceptibility to initial infection, but there were great differences in resistance to spread among species or cultivars. The diploid and tetraploid wheats were severely susceptible. Only 30 genotypes of common wheat of T. aestivum concv. vulgare showed high resistance to spread. The highest frequency of high spread resistance existed in these landraces which were distributed in Zhejiang, Hubei, Hunan, Jiangsu provinces and Shanghai City, Guizhou, Sichuan and Yunnan provinces ranked second. The majority of wheat landraces from Hebei, Shanxi, Shaanxi Province and Beijing City showed susceptibility or high susceptibility. No resistance was found in Tibetian wheats. This revised version was published online in July 2006 with corrections to the Cover Date.     

高F值寡肽及其生理功能

高F值寡肽是一种具有高支链氨基酸含量和低芳香族氨基酸含量组成的小肽混合物.由于它具有独特的氨基酸组成和重要的生理功能,日益受到食品和医药界的高度关注.对高F值寡肽及具有治疗或缓解减轻肝性脑病症状、改善手术后及卧床病人的蛋白质营养状况、抗疲劳、治疗苯丙酮尿症和解酒醉等生理功能进行综述,以供读者参考.     

多伦草原土壤理化性质在沙漠化过程中的变化

以典型生态脆弱区内蒙古多伦县为例,连续2 a进行了沙漠化对土壤理化性质的影响研究。结果表明,随着草原沙漠化的加剧,(1)土壤颗粒组成发生变化,黏粒含量趋于减少,砂粒增多。不同粒径对土壤团粒结构形成和保水保肥的贡献不同,黏粒的减少抑制了土壤的膨胀、可塑性及离子交换等物理性质。(2)土壤含水量下降。上层(0—20 cm)土壤含水量下降明显,随着沙漠化梯度的增加,表层土壤含水量下降速度加快,从而深层土壤含水量逐渐高于表层。(3)土壤容重呈上升趋势。容重的增加必然影响土壤中水分和空气的移动及植物根系的发育。不同深度的土壤容重与草原沙漠化也存在一定的关系,潜在阶段深土层(30—50 cm)的容重最小,而严重阶段表土层(0—5 cm)容重最小。(4)土壤有机质,C,N含量下降,方差分析显示各沙漠化梯度间均差异极显著。且土壤N的衰减要快于C。土壤C/N比呈增加趋势,说明伴随着土壤C,N的显著下降,质地变粗,植物N素供应不足更为突出。(5)土壤容重与土壤全N,C及黏粒含量的相关分析表明,细颗粒物多,有机质含量高,土壤容重即小,从而有助于提高土壤的稳定性,且5—10 cm土层的性质表现突出。(6)土壤的颗粒组成状况与土壤营养元素之间有着同增同减性,但黏粒与N的关系要密切于黏粒与C和C,N间的关系。因此土壤中细颗粒物的减少会导致N素的衰减十分明显,从而导致土壤稳定性降低。     

基于GIS的土壤适宜性评价方法研究与系统实现

以漳州市为研究区域,采用矢量数据结构模型,以评价因子图层叠加后生成的图斑作为评价单元,在组件式GIS开发工具SuperMap软件支持下,建立一种可以由用户任意选择进行适宜性评价的农作物对象,确定适宜性评价指标和评价标准的适宜性评价咨询系统.系统支持用户事先将不作评价的地物类型剔除,同时可以通过将用户在使用系统过程中建立的各种农作物生态指标库保存起来,从而使系统在用户的不断参与下更加方便实用.同时系统能够对收集的各类数据进行动态管理,具有相关的统计、分析和管理功能,可方便及时地为地区引进农作物新品种,并为农业生产结构调整提供依据.结合土壤适宜性评价系统的开发实践,对土壤适宜性评价的实现过程与方法进行了探讨.     

履带式稻(麦)联合收割机液压——机械式行走系统的研究

液压行走系统因其结构简单、操纵方便、转向灵活等特点已广泛在联合收割机中采用。该文分析了液压一机械式联合收割机行走系统的工作过程，并以某联合收割机为例，对液压行走系统的配置方案、液压元件的选型、液压系统主要参数的确定、液压系统的性能验算和实测等方面进行了研究。研究结果表明，此液压行走系统的设计是合理的、可行的，完全可以满足联收机实际使用条件和较恶劣的工况。这为我国联合收割机液压行走系统的设计和配置提供重要的参考价值。     

Tissue iron distribution and adaptation of iron absorption in rats exposed to a high dietary level of NaFeEDTA

Although it has been shown that iron absorption from NaFeEDTA, a promising iron fortificant, is effectively down-regulated in iron-loaded rats, effects of prolonged exposure to high dietary levels of NaFeEDTA are not well understood. The objectives of this study were to determine whether rats can adapt to a high dietary level of NaFeEDTA by down-regulating iron absorption, and to determine effects on tissue iron distribution, with or without an iron absorption inhibitor. Male Sprague-Dawley rats were exposed to diets supplemented with FeSO4 or NaFeEDTA at 1200 mg of Fe/kg of diet, with or without tea, for 27 days. Iron absorption measured by whole-body counting before and after exposure showed that rats adapted to the high dietary level of FeSO4 or NaFeEDTA by down-regulating iron absorption to a similar extent. However, nonheme iron concentrations in liver and spleen were about 35-50% lower, whereas the concentration in kidney was about 300% higher in rats fed NaFeEDTA, compared to rats fed FeSO4. Tea had no major impact on iron absorption or iron status, regardless of iron source. Our results showed that although iron absorption was down-regulated similarly, body iron distribution was markedly different between rats exposed to FeSO4 and those exposed to NaFeEDTA. Further studies are warranted to determine the effects of prolonged exposure to dietary NaFeEDTA on kidney iron accumulation and kidney function.     

半干旱黄土丘陵区不同植被类型的土壤水分特征及其稳定性

[目的]研究5种不同植被类型土壤水分动态特征,为区域内优化配植模式提供理论依据。[方法]以甘肃省定西市半干旱黄土丘陵区5种典型的植被类型为研究对象,使用土壤水分速测仪对2017,2018年0—200 cm土层土壤含水量进行观测,并对不同植被类型土壤水分特征及其稳定性进行分析。[结果]①不同植被类型土壤水分呈现出:山杏×侧柏混交林地(11.24%)退耕苜蓿草地(10.97%)自然荒地(10.66%)退耕林地(9.99%)柠条林地(9.55%)。②5种植被类型在0—200 cm土层依据有序聚类法可分为动态变化层(0—40 cm),利用层(40—100 cm)和弱利用层(100—200 cm)3个层次。在动态变化层(0—40 cm),土壤水分呈现出:自然荒地(14.23%)最高,柠条林地(11.04%)最低;在利用层(40—100 cm):退耕苜蓿草地(12.16%)最高,柠条林地(9.15%)最低;在弱利用层(100—200 cm):自然荒地(10.81%)最高,退耕林地(8.61%)最低。③不同植被类型土壤水分土层稳定性(变异系数)呈现出:退耕林地(19.9%)山杏×侧柏混交林地(21.3%)自然荒地(21.9%)退耕苜蓿草地(22.6%)柠条林地(23.6%)。④不同植被类型土壤水分时间稳定性(变异系数)呈现出:自然荒地(25%)退耕林地(25.2%)山杏×侧柏混交林地(26.5%)柠条林地(27.1%)退耕苜蓿草地(31.9%)。[结论]柠条林地土壤水分含量最低,在土层和时间上不稳定,山杏×侧柏混交林地较其他植被类型土壤水分含量更高,更具有稳定性。