氮素形态对紫花苜蓿盛花期生长及结瘤固氮的影响

在完全营养液条件下,采用砂培法,研究了3种氮素形态配比NO3--N,NH4+-N和NO3--N∶NH4+-N为1∶1和0、105、210mg/L 3个氮素水平对紫花苜蓿盛花期生长及结瘤固氮的影响。结果表明:不同形态氮素处理下紫花苜蓿的株高、生物量、根瘤数、根瘤重、固氮酶活性和全氮含量均显著高于CK。同一氮素水平下,株高表现为NO3--N和NH4+-N混合培养下效果最好,NO3--N培养下次之,NH4+-N培养下最低;生物量、根瘤数、根瘤重、固氮酶活性和全氮含量NO3--N和NH4+-N混合培养下效果最好,NH4+-N培养下次之,NO3--N培养下最低;茎叶比则是NO3--N培养下最大,NH4+-N培养下次之,NO3--N和NH4+-N混合培养下的最低,各氮素形态处理间差异显著(P0.05)。随着氮素水平的增加,各形态配比下紫花苜蓿的株高、生物量、根瘤数、根瘤重、固氮酶活性和全氮含量呈现增加的变化趋势,茎叶比呈现减小的变化趋势。NO3--N+NH4+-N的浓度为210mg/L时,紫花苜蓿的株高、生物量、根瘤数、固氮酶活性和全氮含量取得最大值,茎叶比取得最小值,根瘤重则在NO3--N+NH4+-N的浓度为105mg/L时取得最大值,紫花苜蓿在混合态氮培养下生长最好。     

仲裁协议研究

仲裁协议是合同中订立的仲裁条款和以其他书面方式在纠纷发生前或者纠纷发生后达成的请求仲裁的协议。目前,我国《仲裁法》对仲裁协议的形式要求仅仅是书面形式。随着科学技术尤其是电子通讯技术的发展,可实现合意目的的手段呈现出多样化趋势,不再仅限于传统的书面形式和签字。为适应仲裁发展的需要,在我国司法实践中,也出现了放宽对仲裁协议书面形式限制的倾向。在此,文章就对仲裁协议形式的扩大解释提出一些建议。     

人工增温条件下不同氮素形态比对重齿风毛菊气体交换及其群落生物量的影响

在青藏高原三江源区草地上,以开顶式温棚模拟增温,在其内部施用不同形态氮素(硝态氮和氨态氮)比例的氮肥,对重齿风毛菊(Saussurea katochaete)的光合速率、叶绿素荧光及其群落总生物量进行研究,旨在为人工管理草场施肥提供指导。结果表明:重齿风毛菊的光合速率随硝态氮比例增加而下降,气孔导度则增加。其他气体交换参数没有规律性变化。光系统II(PSII)光化学量子产量(Φ_PSII)在硝态氮比例为0%时最大,非光化学瘁灭(NPQ)则随硝态氮比例增大而增大。重齿风毛菊所在群落的总生物量在硝态氮和氨态氮比例平衡时达到最大。结果表明不同比例氮素施肥会对青藏高原草甸植物的净光合速率和群落总生物量产生影响。     

鲁南砂姜黑土及其有机无机复合体中无机磷的组成和分布

采用石灰性土壤无机磷分级法研究了不同肥力砂姜黑土无机磷的组成与分布。结果表明，砂姜黑土及其有机无机复合体中无机磷以磷酸＝钙盐和闭蓄态磷酸盐为主，分别占无机磷总量的２７％－４８％和２６％－３７％。土壤无机磷中的Ｃ２－Ｐ，Ｃａ８－Ｐ，Ａｌ－Ｐ，Ｆｅ－Ｐ均与速效磷存在着显著的正相关，并且随着土壤肥力水平的提高，其含量亦随之增加。土壤无机磷主要集中分布于〈５μｍ粒级的有机无机复合体中，各种形态无机磷的含量     

Renibacterium salmoninarum bar forms: characterization, occurrence, and evidence of a host response to a R. salmoninarum infection

Unique-staining Renibacterium salmoninarum (Rs) cells, termed bar forms, first observed in a coho salmon, Oncorhynchus kisutch (Walbaum), in 1983, could not be cultured, making their characterization difficult and significance obscure. They can be detected only by the fluorescent-antibody technique (FAT) and their numbers estimated only by a quantitative FAT (QFAT). Data collected over a 10-year period showed that bar forms were observed only in vivo and appeared associated with a host response. Bar forms were observed in 10 salmonid species from five countries and in fish from < 1 g to spawning adults. They were observed in 50.1% of kidney smears prepared from 10,061 Rs positive chinook, O. tshawytscha (Walbaum), coho, and Atlantic salmon, Salmo salar L. Bar forms were shown to be Rs cells based on absorption studies, their reaction with an Rs-specific FAT and enzyme-linked immunosorbent assay, and a transition from 'typical' Rs cells to bar forms in naturally and experimentally infected fish. Bar forms were determined to be non-virulent, damaged or dead Rs cells, based on fluorescence and electron microscopy observations, the inability to culture them, and mortality data. Bar forms appeared to represent visual markers of recovery from an Rs infection.     

氮素形态对小麦中后期的生理效应

利用水培研究了冬小麦品种小偃22营养与生殖并进生长阶段不同氮素形态对小麦叶片和根系内含氮物质、生理特性及对小麦成熟后生物量的影响. 为此目的, 营养液中加入了不同比例的硝态氮、铵态氮及尿素. 结果表明: 在铵、硝态氮比例为50∶50时, 叶面积最大, 叶片叶绿素含量最高, 根系活力最强; 小麦成熟后地上部生物量和经济产量     

NH_4~+-N与NO_3~--N不同配比对菠菜生长及食用品质的影响

为探究氮素形态对菠菜生长和品质的影响,试验采用盆钵培养的方法,在总氮浓度为15 mmol/L的条件下,设置了5种NO_3~--N与NH_4~+-N配比(分别为100:0、75:25、50:50、25:75和0:100),测定了5种铵硝配比条件下菠菜生长与品质相关指标。结果表明:与NH_4~+-N相比,NO_3~--N更有利于菠菜生长与Vc积累。适当增加NH_4~+-N比例后,Vc含量虽显著降低,但对菠菜的生长却无显著影响,并可显著降低可食用部分硝酸盐含量。因此,为了提供高产、低硝酸盐的优质菠菜,笔者认为适宜的NO_3~--N?NH_4~+-N为50:50。     

An Effect of Various Nitrogen Forms Used as Fertilizer on Lupinus albus L. Yield and Protein, Alkaloid and α-Galactosides Content

The influence of various forms of nitrogen supplied to the ground as N₂, NH, NO, [NH + NO], –NH₂, and Nd (N‐deficiency) on Lupinus albus L. cvs. Butan (sweet) and Bac (bitter) yield and protein, alkaloid and α‐galactoside biosynthesis in their seeds were studied. The experiments were performed in a greenhouse on perlite using, in all cases, the same dose of P, K, Mg and micronutrients (B, Zn, Mn, Cu, Mo, Fe). The Nd treatment contained only macro‐ and micronutrients without any nitrogen support. We found that different nitrogen forms used as a fertilizer had a significant influence on the development and yield structure of both lupin cultivars. It was found that the plants developed most favourably when nitrogen was supplied as N₂ and [NH + NO]. For the other forms, the anomalies like necrosis, chlorosis, leaves with small surface of assimilation were noticed. However, these observations were not always reflected by all parameters of yield structure. The forms of nitrogen had a pivotal influence on yield of generative and vegetative parts of lupin. Moreover, significant differences in protein, alkaloid and α‐galactoside content in seeds were observed.     

长期秸秆与氮磷肥配施对土壤钾素形态的影响

以山东省黄河冲积平原低肥力潮土为供试土壤,经18a盆栽土培定位试验后,采用化学形态分析方法对土壤的钾素形态进行了研究。结果表明,长期秸秆还田并配施适量的化肥,能明显提高潮土缓效钾和速效钾的释放效应,对矿物钾的有效化也有一定效果。在秸秆还田量分别为2250、4500、6750kg/hm2范围内,土壤水溶性钾、非特殊吸附钾、特殊吸附钾、非交换钾与秸秆还田量呈显著正相关;与矿物钾呈显著负相关。长期秸秆还田土壤钾素年度变化规律：非交换钾、特殊吸附钾呈逐年上升趋势;水溶性钾、非特殊吸附钾、矿物钾呈逐年下降趋势。     

镉胁迫下不同品种烟草镉化学形态分布研究

为研究镉胁迫下不同品种烟草积累和忍耐镉的差异及机制问题,以烟草品种‘RG17’、‘贵烟11号’、‘Xanthi’为试验材料,采用土培试验方法对不同品种烟草镉化学形态分布特征进行了研究。结果表明,烟草根、茎、叶镉的各形态含量随土壤镉浓度的增加而增加,根部FHAC分配比率最高,占绝对优势,茎FHAC降低,FNaCl增加,而叶片FNaCl分配比率最高,占绝对优势,且随着镉浓度的加大,根、茎、叶镉的各形态分配比率有接近的趋势。同样各形态分配比率因品种而异,根部‘Xanthi’FHAC分配比率最高,而FW、FNaCl分配比率低;叶内FNaCl分配比率‘Xanthi’高于其他品种,而FW分配比率低,随着镉浓度的增加,这种趋势更加明显。推断高积累型烟草根内镉形成难溶于水的磷酸盐有利于其对镉的积累,而与蛋白质络合,从细胞质转移到液泡可能是烟草耐性品种忍耐镉的主要机制之一。