水稻土壤碱解氮与脲酶活性对不同氮素水平的响应

在常规栽培条件下,采用盆栽模拟试验方法,研究了土壤脲酶活性和碱解氮含量在不同施氮水平下随水稻生长的动态变化,结果表明:随着施氮量的增加,土壤碱解氮含量增加,高氮处理的含量最高;而脲酶活性则表现为中氮处理的整体水平高于高氮处理,施氮量在0~214.65 kg/hm2的范围内,脲酶活性随着氮素水平的升高而增强,两种水稻品种相比较,弯穗型不抗倒伏的秋光对氮素的敏感程度显著高于直立穗型抗倒伏的07425。     

除草剂中光合作用抑制剂的研究

文章阐述了除草剂中的几类光合作用抑制剂,其抑制途径与作用机理,以及除草剂中光合作用抑制剂的研究进展。     

马铃薯对氯苯胺灵的吸收规律研究

通过施用不同剂量的抑芽剂,并采取不同的捂盖时间,研究马铃薯对氯苯胺灵的吸收规律,确定最佳的捂盖时间。结果表明,随着抑芽剂施用量的增大,马铃薯中氯苯胺灵的含量也在增大;当抑芽剂的施用量相同时,随着捂盖时间的增加,马铃薯对氯苯胺灵的吸收量也在增加,捂盖5d后,马铃薯对氯苯胺灵的吸收量达到最大值。因此,对于施用抑芽剂的马铃薯,最佳捂盖时间可定为5d。     

紫花芸豆胰蛋白酶抑制剂的分离和纯化

[目的]从紫花芸豆中分离纯化胰蛋白酶抑制剂。[方法]以紫花芸豆为材料,采用脱脂、酸抽提、热变性、硫酸铵分级沉淀及离子交换层析和凝胶过滤层析等方法,分离纯化胰蛋白酶抑制剂。[结果]胰蛋白酶抑制剂经PAGE和IEF电泳显示单一条带。凝胶过滤法测定其表观分子量约为59kD。SDS电泳结果显示它有3个亚基,分子量分别为34、16、15kD。等电聚焦法测定其等电点为5．25。动力学的方法检测PVTT与胰蛋白酶发生不可逆抑制作用。[结论]离子交换层析和凝胶过滤层析法能快速地分离纯化紫花芸豆中的胰蛋白酶抑制剂。     

黑眶蟾蜍皮肤白蛋白的纯化及胰蛋白酶抑制活性

[目的]探讨黑眶蟾蜍皮肤白蛋白的纯化及胰蛋白酶抑制活性。[方法]通过离子交换层析和凝胶过滤层析,从黑眶蟾蜍皮肤中得到其白蛋白,命名为BufomA-skin。65nmol／L的BufomA-skin分别与30nmol／Ltrypsin在25℃不同保温时间（0．25—24h）下测定胰蛋白酶抑制活性,计算剩余酶活力。[结果]BufomA-skin为单链蛋白,分子量约为66．7kDa。但在非还原状态下,50～66kDa条带呈弥散样。该蛋白有抑制胰蛋白酶水解小肽底物的活性,但对其他丝氨酸蛋白酶如凝血酶、糜蛋白酶、弹性蛋白酶及枯草杆菌蛋白酶无抑制。BufomA-skin与胰蛋白酶保温24h后,胰蛋白酶活性无恢复。[结论]黑眶蟾蜍皮肤白蛋白具有稳定的胰蛋白酶抑制活性,在黑眶蟾蜍防御天敌捕食的过程中发挥重要作用.     

长坡尾矿坝植物修复过程中土壤脲酶活性变化

采集广西南丹县长坡矿尾矿坝0~20 cm表土,测定了土壤pH、有机质、碱解N含量和脲酶活性。采用数理统计的相关分析方法,探究重金属污染区的植被自然恢复和植物修复过程中,土壤脲酶活性与土壤肥力水平的关系,为重金属污染区土壤的生态恢复提供理论依据。结果表明:长坡尾矿坝土壤有机质含量较低,土壤肥力状况仍然较差。土壤脲酶活性与土壤碱解氮含量之间呈正相关,与土壤有机质含量相关性不大。在尾矿坝植被自然恢复过程中,五节芒、苔草、割鸡芒等植物根际土脲酶活性的平均值相对较高,而狗牙根、类芦根际土的脲酶活性相对较低。如果不引进外来物种,只选择该尾矿坝上自然生长的植物作为生态恢复的物种,五节芒、割鸡芒和苔草等植物应作为优先选择的物种,类芦、狗牙根等植物可作为第2阶段修复的物种。     

左伏3号山楂的组织培养和常温离体保存研究

以伏山楂品种＂左伏3号＂为试验材料,进行组织培养和常温离体保存研究。结果表明：左伏3号启动培养的最佳培养基是MS＋6-BA1.0 mg.L-1＋IAA0.08 mg.L-1,成活率达到93.3%;继代培养的最佳培养基是MS＋6-BA0.8 mg.L-1＋NAA0.01 mg.L-1,繁殖系数达到5.5;生根培养在1/2MS＋NAA0.5 mg.L-1上生根率（31.7%）最高,移栽可成活。0.4～2.0 mg.L-1的PP333不适宜左伏3号的常温离体保存,而CCC 40 mg.L-1和ABA2.0 mg.L-1比较适合。     

土壤中脲酶和磷酸酶对百草枯的响应

[目的]为评价百草枯对土壤环境质量的影响提供依据。[方法]取河南工业大学校区草地0~30 cm土样,过筛混匀。分别用0(对照)、100、200、500、1 000μg/g百草枯溶液处理土样,然后在25℃条件下恒温培养,培养2、6、12、20、30、45、60 d时测定土样脲酶和磷酸酶的活性。[结果]百草枯对土壤脲酶活性有抑制作用,且浓度越大抑制作用越强,100μg/g百草枯处理20 d对土壤脲酶活性的抑制率为4.5%,而1 000μg/g百草枯处理2 d对土壤脲酶活性的抑制率可达60.45%;百草枯对土壤磷酸酶活性具有先抑制后刺激作用,500μg/g百草枯处理30 d后土壤磷酸酶的活性为对照的126%。[结论]百草枯可在较大程度上影响土壤脲酶和磷酸酶的活性。     

Inhibitory action of Cerrado plants against mammalian and insect α-amylases

A total of 185 hexanic, dichloromethanic, ethanolic and hydroethanolic extracts from 24 species of Cerrado plants, were tested against Zabrotes subfasciatus, Acanthoscelides obtectus, and human saliva α-amylases. Twelve crude extracts presented inhibition rates greater than 80% against digestive α-amylases of the insect pest Z. subfasciatus, at a concentration of 1 mg mL⁻¹. These extracts were also tested against A. obtectus and human saliva α-amylases to verify their affinity and specificity of action. The hydroethanolic Kielmeyera coriacea stem bark extract presented a strong inhibitory potential, with IC₅₀ values of 110 μg mL⁻¹ for Z. subfasciatus and 272.12 μg mL⁻¹ for A. obtectus, in addition to a 97.09% reduction in enzyme activity of human saliva α-amylases at 125 μg mL⁻¹. The hexanic Aspidosperma macrocarpon root wood extract totally inhibited the activity of Z. subfasciatus α-amylases, reduced the enzyme activity of A. obtectus by 14.69% at 1 mg mL⁻¹, but did not alter the activity of human saliva α-amylases, thus characterizing greater inhibition affinity and specificity. The results suggest that the application of plant extracts against insect α-amylases represent a promising biotechnological tool for development of new insect pest control strategies, with noticeable affinity and specificity of action against different target enzymes.     

Nitrification Inhibitor Effects on Nitrous Oxide Emission,Nitrogen Transformation,and Maize (Zea mays L.) Yield in Loamy Sand Soil in Thailand

The nitrification inhibitors (NIs) effects on soil nitrogen (N) fates and maize yields were investigated in a loamy-sand soil in Thailand. The treatments were chemical fertilizer (CF) and CF with dicyandiamide (DCD) or neem oil at two rates of 5% and 10%. Compared to the CF plot, DCD and neem oil reduced the cumulative nitrous oxide (N₂O) emission by the equivalent of 26% and 10%, respectively (P < 0.05). DCD and neem oil had a positive effect in slowing ammonium (NH₄⁺)-conversion and prolonging NH₄⁺-N in the soil with a maximum efficiency of 45% and 30%, respectively. NO₃^–N was higher in the NI plots (P < 0.05), but the effect was less pronounced later in the growing season. Adding the NIs increased maize yields and N uptake, but was only significant (P < 0.10) for neem oil. Results indicate that applying NIs is an effective method to mitigate soil N losses and enhancing N use efficiency in a tropical, agricultural field.