长效尿素释氮过程及增产效果研究

长效尿素是氮肥新品种。通过1989、1990两年试验和大面积施用调查,发现长效尿素与普通尿素相比可抑制脲酶活性五十天左右,在施用前期,土壤脲酶活性低于对照区,尿素残余量高于对照,后期则相反,作物的叶绿素和氨基酸总量增加;增产效果明显,亩增产玉米40公斤,大豆10公斤,甜菜150公斤,亩纯增益分别为14.8,18.8和16.8元,经济效益显著。     

脲酶抑制剂醌氢醌对小白菜光合特性和氮代谢的影响

以醌氢醌为脲酶抑制剂,小白菜(B.chinensis Var.communis)为试材,进行小区试验,研究了不同用量的醌氢醌对小白菜光合特性和氮代谢的影响,结果表明:适量醌氢醌能使小白菜叶片的气孔导度增大,胞间CO2浓度降低,净光合速率提高,蒸腾速率降低;使小白菜叶片硝酸还原酶活性、谷氨酸脱氢酶活性、谷酰胺合成酶活性、总氮含量、蛋白质含量提高,游离氨基酸含量降低。小区试验醌氢醌用量以3.0-6.0 g/m2为宜。     

水貂乳酸脱氢酶(LDH)同工酶凝胶电泳分析Ⅱ

用不连续聚丙烯酰胺凝胶电泳分离水貂LDH同工酶,除了膈肌外,其它五种组织都显示出泳动率明显差别的五个区带。从多次实验结果中求出水貂LDH同工酶相对迁移率。又用高pH系统圆盘电泳分离水貂LDH同工酶,观察到水貂LDH_4和LDH_5可分离出不同数目的亚带。膈肌LDH_5可分离出五条亚带发现各种组织LDH_4和LDH_5出现亚带数不等,具有明显组织特异性。亚带分布不具有A基因突变后所产生规律性的结果,所以认为水貂LDH同工酶亚带的产生可能是亚基翻译后化学修饰的结果。同时做了水貂LDH同工酶热稳定性和尿素抑制作用实验。并提出水貂膈肌LDH_5对尿素抑制作用不敏感性的实验结果。     

大豆多糖固化脲酶胶黏剂填料的制备工艺研究

用吸附法检测大豆多糖固定化脲酶,得出最佳反应温度为60～70℃,pH为5.5～6.5。结果显示,大豆多糖亲水性能稳定,固化后是良好的胶黏剂填充材料。     

脲酶抑制剂NBPT对马铃薯幼苗生长的影响

研究了脲酶抑制剂NBPT与尿素配合施用对马铃薯生长过程中土壤尿素残留量和对马铃薯幼苗生长的影响。试验表明,NBPT能有效抑制土壤中脲酶活性,延缓尿素水解。其中,NBPT添加浓度为1%～1.5%时马铃薯幼苗生长最好;处理后第4天,UI1.0和UI1.5处理的土壤尿素残留量分别比对照提高了92.37%和88.36%。添加NBPT处理的水解时间比对照(U)推迟了2d;在试验范围内,单独施用NBPT不会对马铃薯幼苗产生显著不利影响;添加NBPT对马铃薯生长有很好的促进作用,与地上部分相比,对根系的促进作用更大。施用NBPT的最佳有效浓度范围为1.0%～1.5%。     

竹叶提取液对黄豆脲酶活性的影响

[目的]研究竹叶提取液对黄豆脲酶活性的影响。[方法]根据尿素溶液加入竹叶提取液后pH值的变化,判断竹叶提取液对脲酶活性的影响。[结果]竹叶水浸液和乙醇提取液对脲酶都有抑制作用,但乙醇提取液的抑制效率高于水浸液。乙醇提取液与微波辅助乙醇提取液相比,微波辅助乙醇提取液能明显降低黄豆脲酶的活性,故竹叶提取液对黄豆脲酶具有抑制作用。并且竹叶提取液随着用量的增加,抑制效果呈正相关系。[结论]该研究为茶多酚作为工业新型脲酶抑制剂的研究和生产提供一定的参考依据。     

Ammonia volatilization following surface application of urea to tilled and no-till soils: A laboratory comparison

Broadcasting of urea to agricultural soils can result in considerable losses by NH₃ volatilization. However, it is unclear if the impact of this practice on NH₃ emissions is further enhanced when performed on no-till (NT) soils. The objective of this study was to compare NH₃ volatilization following broadcasting of urea to NT and moldboard plowed (MP) soils. Intact soil cores were taken shortly after harvest from NT and MP plots of three long-term tillage experiments in Québec (Canada) and stored for 4.5 months prior to incubation. Urea (14 g N m⁻²) was applied at the soil surface and NH₃ volatilization was measured for 30 d using an open incubation system. Mean cumulative NH₃ losses were greater (P < 0.001) in NT (3.00 g N m⁻²) than in MP (0.52 g N m⁻²). Several factors may have contributed to the higher emissions from the NT soils. Urease activity in the top 1 cm of soils was on average 4.2 times higher in NT than in MP soils. As a result, hydrolysis of urea occurred very rapidly in NT soils as indicated by enhanced NH₃ emissions 4 h after application of urea. The presence of crop residues at the surface of NT soils also decreased contact of the urea granules with the soil, possibly reducing adsorption of NH₄⁺ on soil particles. Lower volatilization on the MP soils may also have partly resulted from a fraction of urea granules falling into shallow cracks. Field trials are needed to confirm our finding that NT soils bear greater potential for NH₃ volatilization following surface application of urea than MP soils.     

Use of urea coated with natural products to inhibit urea hydrolysis and nitrification in soil

Laboratory incubation experiments were conducted with uncoated urea or urea coated with dementholized oil (DMO), pitch (the mint oil discard), terpenes (the products of menthol mint oil), or dicyandiamide (DCD) to study the retardation of urea hydrolysis and nitrification in soil. Two levels (0.5 and 1 %) of coating were tested. Urea was applied at a rate of 200 mg kg⁻¹ of dry weight of soil. The urea hydrolysis and nitrification processes were inhibited by all three natural products. All the three natural products viz., DMO, terpenes, and pitch significantly retarded urease activity of soil.     

秸秆腐解对不同氮肥水平土壤脲酶活性的影响

本文利用黑龙江大学呼兰校区秸秆还田试验为平台,探讨秸秆还田后不同施氮量下土壤脲酶活性的动态变化特征,明确农田黑土玉米秸秆腐解下土壤氮素含量与脲酶活性的关系。试验以秸秆腐解和不施秸秆为主区,不同氮肥水平(纯N)(0、135kg/hm2、180kg/hm2、225kg/hm2)为副区,测定了土壤全氮、碱解氮及脲酶活性,试验结果表明：两种秸秆处理的土壤脲酶活性变化趋势均随玉米生育期的延长增加,在拔节期达到最高后降低;与无秸秆处理相比,在施氮量为180kg/hm2、225kg/hm2秸秆腐解处理可显著提高土壤脲酶活性(p&;lt;0.05),而施氮量为0、135kg/hm2时虽提高了脲酶活性,但未达到显著水平(p&;gt;0.05);土壤碱解氮、土壤全氮的变化趋势与土壤脲酶活性的变化趋势一致,均为随施氮水平的增加而增加;相关分析显示,土壤脲酶活性与土壤全氮、碱解氮呈极显著正相关。     

杀灭菊酯对亚热带果园红壤脲酶活性的生态毒理效应

通过模拟方法,系统研究杀灭菊酯对亚热带果园红壤脲酶活性的影响。结果表明:杀灭菊酯对土壤脲酶活性表现出先激活后抑制趋势,处理前3 d土壤脲酶活性升高,处理3 d后土壤脲酶活性受到抑制,7 d后低于对照水平;激活、抑制程度与处理浓度呈正相关。底物(尿素)浓度饱和前,土壤脲酶活性随尿素浓度增加而升高。模型U=β0 β1×C能较好拟合土壤脲酶活性(U)和尿素浓度(C)、杀灭菊酯浓度(C)之间关系,揭示出土壤酶促反应过程存在吸附-解吸的机制,证实不同肥力土壤脲酶活性受杀灭菊酯影响差异较大,高肥力土壤对土壤脲酶活性具有一定的缓冲作用,受杀灭菊酯影响较小。