草莓果实中脱落酸受体基因FaABAR/CHLH表达变化及其影响因素分析

 为了探讨脱落酸调控草莓果实成熟的信号识别机制,以‘北农香’草莓花后1 ~ 4周的果实为试材,在克隆脱落酸受体基因FaABAR/CHLH的基础上,通过荧光定量PCR研究了果实发育过程中该基因表达量的变化及其影响因素。结果表明,草莓果实中脱落酸受体FaABAR/CHLH基因编码一个含有1 381个氨基酸的蛋白,且该蛋白含有一个金属离子螯合酶H亚基超家族保守区。在果实发育的前期（小绿、大绿和浅绿果期）,FaABAR/CHLH基因表达量维持较高水平;随着果实的加速褪绿,其表达量迅速降低,至白果期降到最低点;随着果实着色启动,其表达量又迅速上升。ABA和高pH能促进FaABAR/CHLH基因在转录水平上的表达,而蔗糖则抑制该基因转录水平。草莓果实中脱落酸受体基因FaABAR/CHLH表达水平的变化进一步揭示了ABA在调控果实成熟中的重要作用。     

pH值对胃蛋白酶原激活率影响的研究

采用 2 4头平均体重 5.2 5kg的 2 8± 1日龄断奶杜×长大杂交仔猪 ,分成 4个处理组 ,在玉米豆粕型基础饲粮 (对照组 )中分别添加 1 % Na HCO3、 0 .6% HCl、 2 .4 % HCl,饲养仔猪 3周后于晨饲后 1 h屠宰 ,测定胃内容物 p H和胃内容物中胃蛋白酶原激活率。结果表明 ,添加 1 % Na HCO3使胃内容物 p H值上升 ,而添加 0 .6% HCl、 2 .4 % HCl则使胃内容物 p H值下降 ,胃内容物 p H值越低 ,胃蛋白酶原激活越快。在体外试验中 ,随 p H值下降 ,胃蛋白酶原激活率呈三次曲线上升。上述结果表明 ,胃蛋白酶原激活率与 p H值有关 ,p H值越低 ,胃蛋白酶原激活率越高     

姬菇生物学特性的初步研究

研究了不同温度，PH和含水量对姬菌丝生长的影响。结果表明，30℃时菌丝生长快，随着温度的降低，菌丝生长速度递减，适宜菌丝生长的温度范围为25－30℃，PH7．5时菌丝生长最快，适宜菌丝生长的PH范围为6．0－7．5；适宜菌丝生长的培养料含水量为55％－70％，含水量60％时菌丝生长速度最快。     

不同覆土材料对鸡腿菇出菇性状和产量的影响

通过对不同覆土材料的化学成分和物理结构的测定，分析了不同种类覆土材料对鸡腿菇出菇性状和产量的影响，结果表明：孔隙度、最大持水量和营养成分较高的覆土材料——腐叶土有利于鸡腿菇产质量的提高，随着栽培时间的延长，覆扇叶土的覆土层的电导率呈上升趋势而pH值呈下降趋势较其它两种覆土材料明显。     

Methane oxidation in non-flooded soils as affected by crop production — invited paper

Methane is an important greenhouse gas, which contributes approximately 20% to global warming. The atmospheric CH₄ concentration is increasing rapidly, resulting from an imbalance between CH₄ production and consumption. The only known biological CH₄ sinks are soils where methanotrophic bacteria consume CH₄ by oxidizing it. For several reasons the CH₄ uptake potential, particularly of arable soils and grassland, is only partly exploited, as several agricultural practices have adverse impacts on the activity of the CH₄ oxidizing bacteria. The kind of land use in general has a remarkable influence with much higher oxidation rates under forest than under grassland or arable soil. Regular soil cultivation by ploughing and fertilization with ammonium or urea have been identified as main factors. Immediately after ammonium application the methanotrophic enzyme system is blocked, resulting in an inhibition of CH₄ oxidation. In addition to this short-term effect a long-term effect exists after repeated ammonium fertilization, which is most likely caused by a shift in the population of soil microbes. Crop residues affect CH₄ oxidation differently, depending on their C/N ratio: with a wide C/N ratio no effects are expected, whereas with a narrow C/N ratio strong inhibition was observed. Animal manure, particularly slurry, can cause CH₄ emission immediately after application, whereas in the long run farmyard manure does not seem to have adverse impacts on CH₄ oxidation. The methanotrophic activity decreased markedly with soil pH, although in many cases liming of acidified soils did not show a positive effect. Arable soils have a rather small pH range which allows CH₄ oxidation, and the inhibitory effect of ammonium can partly result from a concomitant decrease in soil pH. Reduced tillage was identified as a measure to improve the methanotrophic activity of arable land, set aside of formerly ploughed soil points into the same direction. Plant growth itself is not primarily responsible for observed effects on CH₄ oxidation, but secondary factors like differential pesticide treatments, changes in pH, or cultivation effects are more likely involved. Although for the overall CH₄ fluxes the oxidation processes in agricultural soils are of minor importance, all available possibilities should be exhausted to improve or at least preserve their ability to oxidize CH₄.     

pH、抗坏血酸对硫酸亚铁化学状态的影响

本研究对不同ｐＨ值下，不同抗坏血酸水平及不同时间内硫酸亚铁溶液中以不同化学状态存在的铁进行了定量分析和研究。结果表明，低ｐＨ有利于硫酸亚铁以溶解、离子化及二价形式存在，ｐＨ的升高则具有相反的作用，特别是随时间的延长更加明显。抗坏血酸的存在可以促进硫酸亚铁的溶解，促进其离子化以及保持离子态铁稳定地以二价形式存在，有效地防止了硫酸亚铁在高ｐＨ环境下的不溶及二价铁被氧化为三价铁。抗坏血酸的这些作用是通过其还原及络合作用实现的。     

智能滴灌施肥控制系统中 pH调节品质的优化

利用遗传神经网络,通过对其权值的训练,优化权系数和网络结构.由可测的输出变量,将诸多有关作物 pH值调节的扰动推算出来,实现最优控制.仿真结果表明它能使加酸施肥系统控制偏差不超过± 2%,优化了调节品质.     

温度和pH对面粉和硼润土粘合性能的影响

将面粉和硼润土2种粘结剂分别以4%添加到配合饲料中,经pH分别为4.00、5.20、6.20、7.45、8.00、9.00、10.00的缓冲液调制后制成颗粒,再分别在30℃、55℃和85℃的烘箱中干燥,最后测定各处理饲料在水中的稳定时间、沉降速度和粗蛋白溶失率。结果表明:随着烘干温度的升高,2种粘结剂粘合性能明显增强;当pH为4～6.2时,粘结剂粘合性能没有明显变化,但当pH>7.45时,随着pH的升高,2种粘结剂的粘合性有增强的趋势,粗蛋白的溶失率也明显降低。     

区分松材线虫病材与健康材的研究

通过对南京地区黑松、马尾松松材线虫病材的化学成分的研究，发展病材的主要化学成分与健康材相比无明显差异，但苯醇抽出物和乙醚抽出物含量却显著减少。病材乙醚抽出物含量的明显减少是松材遭受松材线虫侵袭的特征之一。在乙醚抽出物的组成上病材和健康材也存在差别，此外两者的ｐＨ值也不相同，因而可选用适当的指示剂通过显色反应加以区分。     

渗透压与pH值对常温保存山羊精液的影响

本文研究了山羊精液在高倍稀释（１：３０），常温（１３—１５℃）保存条件下，稀释液渗透压与ｐＨ值对精子存活时间的影响。试验选用两种稀释液，渗透压调为较高的３４１和３３９渗压毫克分子浓度与较低的２６３和２８０渗压毫克分子浓度，ｐＨ值分别调为６．５和７．０。结果表明：在渗透压类同的条件下，ｐＨ为６．５，精子总存活时数比ｐＨ为７．０时长（ｐ＜０．０１）。生存指数高（Ｐ＜０．０１）。在ｐＨ值相同的条件下，较高渗透压的稀释液保存效果好。渗透压与ｐＨ值对精子共同作用下，在ｐＨ６．５时，不论渗透压较高或较低，精子活力维持在０．３以上的时数为３０小时左右，而ｐＨ７．０时只有１６小时左右。较低渗透压使精子顶体完整率下降轻快（Ｐ＜０．０１）。