Interactive Effects of Nitrogen Source and Salinity on Growth Indices and Ion Content of Indian Mustard

ABSTRACT

The interactions between salinity and different nitrogen (N) sources nitrate (NO₃ ^?), ammonium (NH₄ ⁺), and NO₃ ^? + NH₄ ⁺ were investigated on Indian mustard (Brassica juncea cv. RH30). Treatments were added to observe the combined effect of two salinity levels (8 and 12 ds m^{? 1}) and three nitrogen sources (NO₃ ^?, NH₄ ⁺, and NO₃ ^? + NH₄ ⁺) on different growth parameters and mineral composition in different plant parts, i.e., leaves, stem, and root. Salinity has been known to affect the uptake and assimilation of various essential nutrients required for normal growth and development. Different growth parameters, i.e., leaf area, dry weight of different plant parts, absolute growth rate (AGR), relative growth rate (RGR), and net assimilation rate (NAR) declined markedly by salinity at pre-flowering and flowering stages. All growth indices were less sensitive to salinity (12 d s m^{? 1}) with the nitrate form of nitrogen. It is pertinent mention that a high dose (120 kg ha^{? 1}) of nitrogen in ammonium form NH₄ ⁺, acted synergistically with salinity in inhibiting growth. Plants fed with combined nitrogen (NO₃ ^? + NH₄ ⁺) had an edge over individual forms in ameliorating the adverse effects of salinity on growth and yield. Under salt stress, different nutrient elements such as N, phosphorus (P), potassium (K⁺), and magnesium (Mg^{2 +}) were decreased in different plant parts (leaves, stem, and root). The maximum and minimum reduction was observed with ammoniacal and combined form of nitrogen, respectively, while the reverse was true of calcium (Ca^{2 +}), sodium (Na⁺), chloride (Cl^?), and sulfate (SO₄ ^2?) at harvest. Nitrogen application (120 Kg ha^{? 1}) in combined form had been found to maintain highest concentrations of N, P, Mg^{2 +}, and Ca^{2 +} along with reduced concentrations of Na⁺, Cl^?, and SO₄ ^{2 ?}. However, reverse was true with ammoniacal form of nitrogen.     

大刺鳅催产效率与积温的相关性研究

[目的]为大刺鳅的规模化繁殖、生产和增殖保护提供科学依据.[方法]通过注射催产激素对亲鱼进行催产,在一定水温(24～27℃)条件下对亲鱼进行人工挤卵,分析积温对大刺鳅产卵量、受精率和孵化率的影响.[结果]不同积温对大刺鳅的人工繁殖效率的影响非常大.若积温高于1 101.0℃ ·h或低于985.5℃·h,均不利于大刺鳅的繁殖;当积温介于1 027.5 ～1 046.0℃·h时,大刺鳅产卵量超过600粒/尾,受精率超过90％,孵化率超过80％.[结论]在进行大刺鳅人工繁殖时,应尽量控制催产积温在1027.5～1046.0℃·h.     

Enhancement of revegetation on construction fill by fertilizer and topsoil application: Effect on mycorrhizal infection

The influence of topsoil and fertilizer application on denuded road construction sites was evaluated to assess its contribution to improvement of vegetation re-establishment. the study sites were within a mixed hardwood and conifer forest on crushed, unweathered subsurface material with low fertility and low biological activity. Topsoils were removed from the site, stockpiled and reapplied to the site after construction. the effect of topsoil amendment on plant growth, soil fertility, mycorrhizal infection and an index of microbial biomass were measured in field and greenhouse experiments. Plant growth on the topsoil amended field plots were greatly increased relative to treatments with fertilizer but no topsoil. Three years after establishment, dry weight production on the plots without topsoil treatment was about 40 per cent of the plots treated with topsoil. Greenhouse experiments were designed to compare fresh, dried and stockpiled topsoil. These experiments indicated that storage of the harvested topsoil for five months in a stockpile had minor effects on plant growth, soil fertility, mycorrhizal infection and microbial biomass. Topsoil volumes had to exceed 20 per cent of the total soil volume to achieve statistically significant benefits and higher ratios showed greater benefit. the percentage of mycorrhizal infection was greatest in topsoil treatments without fertilizer. the addition of fertilizer increased growth but reduced the percentage of roots forming mycorrhizae. When the total weight of infected roots was calculated, however, infection was found to be greatest with a moderate level of fertilizer (equivalent to approximately 27 kg N ha⁻¹ and 39 kg P ha⁻¹), and was less in both higher fertilizer treatments and in unfertilized treatments. Topsoil amendment increased microbial biomass nitrogen but fertilizer treatment did not.     

银量法与凯氏定氮法测定氯化胆碱含量的比较与分析

对银量法和凯氏定氮法检测氯化胆碱含量的效果进行比较,结果表明:对未掺假的氯化胆碱产品,这两种检测方法都能准确地测定结果。银量法不适合掺有水溶性氯化物的样品测定;凯氏定氮法不适合掺有某些含氮化合物的样品测定。