Anionic Exchange Membranes as a Soil Test for Nitrogen Availability

Abstract

A better understanding of nitrogen (N) availability to crops remains an essential key for a productive and safe production system. The main objective of this study was to evaluate the potential of anionic exchange membranes (AEMs) as part of a soil‐testing procedure to predict in situ soil NO₃‐N availability for forage and corn produced in eastern Canada. The AEMs were buried in the surface horizon (0–15 cm) at four experimental sites for forage and at one site for corn. Treatments consisted of five NH₄NO₃ rates (0, 60, 120, 180, and 240 kg N ha^?1) in forage and of six anhydrous ammonia (0, 50, 100, 150, 200, and 250 kg N ha^?1) in corn production. In all sites, NO₃ ^? adsorbed on AEMs (NO_3AEMs) increased significantly with N fertilizer rates, indicating the ability of the AEMs to detect differences between N fertilizer treatments and to predict the soil N availability to crops. The NO_3AEMs fluxes were significantly related to soil NO₃‐N concentration as extracted by water or KCl (0.66≤R²≤0.95). Significant relationships between crop N uptake and NO_3AEMs were obtained (0.52≤R²≤0.94), suggesting that AEMs can be used as an index of soil N availability. Results indicated that AEMs provide a reasonably accurate evaluation of N availability to forage and corn. Because of their low cost, simplicity, and consistency over years, soils, and crops, AEMs could be efficiently used in soil N availability analysis.     

Analysis of cationic elements in liquid samples by x‐ray

Abstract

Plant analyses methods have expanded immensely to document plant mineral element deficiency and toxicity disorders and to note mineral element interactions. Experiments were conducted to determine the feasibility of using cation exchange papers for the extraction of cationic elements from solutions to be analyzed by x‐ray fluorescence. The cationic elements Al, Fe, Mn, Zn, and Cu were effectively extracted from solutions by one exchange resin paper disk if solutions were passed several times through the exchange resin paper. Calcium and Mg were extracted from solutions if two or three separate exchange papers were used, and K was not extracted from solutions with the use of up to five separate exchange papers. The relatively high concentrations of K in solutions and the relatively low exchange capacity of ion exchange resin papers apparently prevented the effective removal of K from solution. The detectability limits on the exchange resin disks by this technique were <2.8 μg Al, 0.5 μg Fe, 0.10 μg Mn, 0.10 μg Zn, and 0.08 μg Cu. Extraction of cationic elements from solutions for x‐ray analysis appeared practical and relatively rapid for Al, Fe, Mn, Zn, and Cu, less practical for Ca and Mg, and impractical for K.     

盐胁迫对油葵种子萌发和幼苗生长及离子吸收、分布的效应

研究了100～300mmol/L NaCl胁迫对油葵种子萌发、幼苗生长及其离子吸收、分布的效应.结果表明,油葵在种子萌发出苗阶段表现较强的耐盐性.100～300mmol/L NaCl胁迫对油葵萌发的影响主要表现为推迟出苗、不影响出苗率.但100～300mmol/L NaCl处理均显著抑制幼苗生长,干物质积累速率下降.Na 主要积累在茎秆、根部,叶片中较少.Cl-主要积累于茎秆和叶柄,叶片和根系中较少.盐胁迫下叶片、叶柄中K 含量显著增加,根系吸收SK,Na、叶柄和叶片运输TSK,Na均显著上升,表明油葵在离子吸收和向上运输过程中,对K 具有较强的选择性,这是油葵具有较强耐盐性的主要原因.     

离子注入技术及其在小麦育种中的应用

离子注入是一种新的诱变技术,已在作物诱变育种中发挥了重要作用.本文对离子注入引起变异的诱变机理及由此引起的生物体在生理生化、细胞学、分子遗传学等方面产生的各种生物效应进行了综述,同时对离子注入技术在小麦新品种选育、新种质创造以及介导外源基因导入等方面的应用做了分析,并对离子注入改良小麦的发展前景作了展望.     

兔卵母细胞孤雌激活方法的研究

对兔卵母细胞的孤雌激活方法进行探讨,为兔的体细胞核移植奠定良好的技术平台。体外成熟培养20～22h的兔卵母细胞随机分组,分别进行以下试验：采用不同脉冲电压、脉冲次数和脉冲时间,电激活兔卵母细胞,摸索最佳电激活参数;比较不同的激活方法处理免卵母细胞的效果,Ⅰ：Ion5min＋6-DMAP3h,Ⅱ：Ion5min＋CHX3h,Ⅲ：Ion5min＋6-DMAP联合CHX3h,Ⅳ：电激1次联合6-DMAP＋CHX3h;优化6-DMAP与CHX作用时间。结果显示：当电激参数为：电压40V／mm,脉冲时间20μs和脉冲次数3次时,兔孤雌胚的分裂率和囊胚率最高,可达80．64％和14．51％;采用第Ⅳ种方法激活兔的卵母细胞,胚胎的分裂率和囊胚率（80．64％,13．71％）均显著高于Ⅰ组（66．67％,8．6％）和Ⅱ组（43．21％,1．24%,P〈0．05）,略高于第Ⅲ组（77．59％,12．07％）;当兔孤雌胚分别在含6-DMAP和CHX的CM中培养1。h和3h时,1h处理组在分裂率（80．68％vs77．59％）和囊胚率（15．91％vs12．07％）上都略高于3h处理组。结果表明：兔卵母细胞经Ion处理5min,或先电激1次（参数为电压40V／mm,脉冲时间20μs,脉冲3次）,再用2mmol／L6-DMAP＋5mg／LCHX处理1～3h,均可获得较好的激活效果,有利于兔孤雌胚的发育。     

N离子注入对陆地棉发芽率和出苗率的影响

在3千电子伏(Kev)能量和四种不同的注入时间下,用N离子注入四个陆地棉品种干种子内,以估计不同品种承受能力和不同剂量对棉花出苗率和发芽率的影响。结果表明:PD系统的品种有较好的承受能力,而同一品种在四种剂量下的发芽率无显著的差异。     

离子注入引起银杏种子M1代染色体畸变的研究

本文报道了离子注入引起银杏Ｍ１代染色体畸变的结果。研究表明,Ｎ＋离子辐照银杏种子后,胚根细胞中出现了核异常和染色体畸变,显微观察发现有多核、染色体桥、游离染色体和落后染色体,畸变频率在０．８～ｌｌ．２％。随着辐照剂量的提高,畸变频率增大,畸变类型增多。发芽试验结果与染色体损伤结果相符。     

无性系培养技术在水稻遗传改良中的应用前景

概述了体细胞无性系变异发生的特点与其在水稻遗传改良中的应用状况,分析了体细胞无性系变异在实际应用中所存在的问题,并提出了加速水稻育种进程的新途径。     

利用花药培养加速离子束介导转基因水稻后代的纯合速度

利用花培加速玉米稻分离后代的纯化。从 1996年开始 ,对转基因玉米稻经多代选择仍“疯狂”分离的后代 ,进行花药培养 ,经两年的繁育种植 ,已获得株型较理想、性状稳定遗传的玉米稻花培株系 ,表明将花药培养方法与转基因技术相结合 ,对加速玉米稻分离后代的纯化是有效的     

离子注入水稻诱发当代损伤效应的研究

籼型转基因水稻种子为材料 ,用不同的离子种类、能量和剂量进行辐照 ,采用 3因子 3水平 9个处理的正交试验 ,调查离子束注入对诱变当代幼苗存活率及幼苗生长速度起主导作用的物理因子 ,以研究离子注入水稻诱发当代损伤的效应。结果发现 ,影响存活率效应最大的是注入离子的能量 ,以低能量 (15kev)的离子注入效果最佳 ;影响苗期生长的主效因子是注入离子的种类 ,以Ar+ 为最佳