Hybridization and in vitro culture of an orchid hybrid Ascocenda ‘Kangla’

The present study focuses on hybridization program involving two species belonging to two different vandaceous genera, viz., Ascocentrum ampullaceum (Roxb.) Schltr. var. auranticum, a narrow endemic orchid of Manipur and Vanda coerulea Griff., an endangered orchid of Appendix I of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), to synthesize the primary hybrid genus with intermediate and improved characters in the F₁ generation. Observations on the crossability in the present bigeneric cross between V. coerulea and A. auranticum had been achieved with 60% success when V. coerulea was taken as female parent. Murashige and Skoog (MS) basal medium at half-strength was effective for the development of the hybrid seedlings of V. coerulea × A. auranticum followed by Vacin and Went (VW) and Knudson C (KC) media. The best response of seedling growth was observed on MS medium at half-strength supplemented with 2.3 μM kinetin + 0.5 μM α-naphthalene acetic acid with maximum shoot height (2.7 cm), leaf number (4.6) and root number (4.1) after 150 days of inoculation. The survival percentage and growth performance of the seedlings were found to be higher (80% survival) in potting substrate consisting of brick:charcoal in the ratio 2:1 mulched with moss (Sphagnum sp.) than in potting substrate consisting of brick:charcoal:tree fern in the ratio 2:1:1. The first flowering was observed in the hybrid seedlings of V. coerulea × A. auranticum after 2 years of transfer to the ex vitro environment. Morphologically, the flowers differed from that of the parents clearly showing the success of the hybridization experiment. Registration of the hybrid has been made with the Royal Horticultural Society with the nomenclature Ascocenda ‘Kangla’ (No. T128725).     

白雪公主水培试验研究

以天南星科植物白雪公主为试材,采用水培法经不同浓度的吲哚乙酸（IAA）处理,进行诱导水生根系试验,然后用诱导的水生根系材料进行营养液培养。结果表明：采用低浓度IAA、短时间浸泡处理可有效促进水生根系生长。20mg/L的IAA浸泡1d处理后的白雪公主插条表现出生根快、持续生根时间长、生根量多、根系长、生根率高等优点,是水培白雪公主插条最适宜的处理浓度。KC营养液最适合白雪公主的生长,各项生长指标都达到最佳。     

KC1‐extractable aluminium in highly weathered soils. Is it exchangeable?

Abstract

In a study involving 212 samples of surface and sub‐surface soils derived from basaltic, granitic, and metamorphic parent materials in the high rainfall region of north Queensland, Australia, the Al extracted with 1 M KC1 has been compared with ‘exchangeable aluminium’, defined as the difference between CEC and sum of basic exchangeable cations. It was concluded that for these highly weathered soils KCl‐extractable Al is exchangeable, and therefore that the sum of basic and acidic cations (ECEC) is a reliable measure of CEC at field conditions.     

基于分级变频高转矩软起动器的研究

研究了三相感应电动机分级变频软起动的控制方法，并采用三相电路对称分量法对各种组合的三相电源系统进行优选，进而提出了电机分级变频起动产生最大转矩的三相电源最优组合方式．在理论分析与仿真的基础上，完成了以16位单片机80C196KC为微处理器的分级变频高转矩软起动器的实验研究．实践表明，基于分级变频理论的软起动器能使电机以高转矩和较小起动电流平滑起动，且控制简单．负载试验结果与仿真结果基本吻合，证明了这种分级变频高转矩软起动理论的正确性和有效性．     

Influence of potassium chloride on desorption of cadmium sorbed on hydroxyaluminosilicate-montmorillonite complex

Cadmium adsorption and desorption on a synthetic hydroxyaluminosilicate-montmorillonite (HAS-Mt) complex were investigated in comparison with a montmorillonite (Mt) and hydroxyaluminum-montmorillonite (HyA-Mt) complex.

Kinetics studies of Cd adsorption on Mt, HyA-Mt and HAS-Mt complexes were conducted at pH 5.0, using a 10^-7 M Cd(NO₃)₂ solution in a solid to solution ratio of 100 mg to 100 mL. After 240 min reaction, 94, 88, 32% of the added Cd were removed from the solutions of the Mt, HyA-Mt, and HAS-Mt systems, respectively. Considering the magnitude of the cation exchange capacity of the clay and complexes, affinity of Cd ions was highest for the HAS-Mt complex.

Desorption experiment was conducted using 1 M KC1, 1 M KNO₃, and water. The desorption rate of Cd sorbed on the Mt was the highest, 90 and 59%, using KC1 and KNO₃, respectively, while, that on the HyA-Mt and HAS-Mt was around 30% and much lower than in the case of Mt, using both chemical reagents. Water could not desorb the adsorbed Cd at all. The difference in the desorption rate between KC1 and KNO₃ was due to the complex ion formation of Cd with the anionic species.

The adsorption of Cd by Mt varied with the nature of intercalated materials, namely, HyA and HAS. The extent of the desorption of Cd decreased due to intercalation of HAS and HyA. In the soil environment, Mt is commonly intercalated with HyA and/or HAS. Our data indicated that the formation of HyA- and HyA-Mt complexes should lead to Cd accumulation in soil environments. In addition, the application of potash (KC1) fertilizer would enhance the desorption of the Cd accumulated in soils.     

双向晶闸管的简易测试及在温控系统中的应用

介绍了使用万用表测试双向晶闸管电极、好坏、触发能力的方法;还介绍一种通过KC08过零触发双向晶闸管实现温度控制的电路,并分析了电路的工作原理．     

Micropropagation of Cymbidium Sleeping Nymph through protocorm-like bodies production by thin cell layer culture

Transverse thin cell layers (tTCLs) of protocorm-like bodies of two stages of PLBs (30 d and 60 d old) of Cymbidium Sleeping Nymph were used as explants to induce PLBs by using coconut water (CW) as a natural additive. 5% (v/v) CW supplemented to KC medium induced an average of 5 PLBs per responding tTCL of 30 d old PLBs with 83% of responding tTCLs. A low percentage of responding tTCLs were observed in 60 d old PLBs’ tTCLs. Anatomical and confocal microscopic studies traced the origin of PLBs to subepidermal layers of the tTCL. A significantly high percentage of shoot regeneration was obtained from PLBs formed on 1–10% (v/v) CW from tTCLs of 30 d old PLBs in comparison to PLBs induced on control after first subculture on KC medium (without CW). The induced PLBs regenerated into plantlets with velamenous roots and these plantlets were transferred to greenhouse conditions on cocopeat:perlite (9:1) with nearly 100% survival. Post-transfer performance of the plantlets was monitored. The results suggest tTCLs as potential explants (with respect to economy of precious hybrid materials) which can overcome the slow growth of hybrid PLBs and coconut water as a single natural additive for the mass multiplication of commercially important orchids.     

KClO3诱导东魁杨梅成花的生理效应

研究不同KClO3浓度对6年生东魁杨梅成花过程生理生化的影响,结果表明:喷施KClO3后东魁杨梅叶片细胞受到伤害处于胁迫状态,丙二醛含量和电解质渗漏率显著增加.KClO3浓度低于1 500 mg·L-1时,叶绿素a、叶绿素b以及总叶绿素含量均显著增加,SOD、POD和CAT活性显著提高,导致叶片光合能力显著上升;生理分化期叶片蛋白质含量明显上升,可溶性糖含量降低;而形态分化期蛋白质含量下降,可溶性糖含量显著上升,可溶性糖/蛋白质比值显著增加,从而促进东魁杨梅的花芽分化.KClO3浓度高于1 500 mg·L-1时,叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量均降低;SOD、POD和CAT活性降低;导致叶片光合能力、可溶性糖含量以及可溶性糖/蛋白质比值显著下降,从而抑制东魁杨梅的花芽分化.结论是喷施1 000～ 1 500 mg·L-1 KClO3可显著提高东魁杨梅的成花率.     

用VC++6.0和80C196KC单片机实现拖拉机仿真机组综合控制

介绍了拖拉机仿真机组控制系统的组成、作用和工作原理。它是一个由中央监控系统和多个子系统组成的、响应有滞后的分布式控制系统，对这样的控制系统，串行通信控制是一种有效的控制方法。在控制系统中，上下位机的信息交换通过串行口完成，可靠地传输控制信号和准确地执行控制命令是实现控制目的的关键。在VC＋＋6.0环境下利用MSComm控件，制定了具体的通信协议，编程实现了和80C196KC单片机串行通信的分布式综合控制。试验结果表明，控制效果很好，具有一定的实用意义。     

Conductimetric determination of soil urease activity

Abstract

A fast and sensitive method to determine urease activity in soils is described. It involves extraction of NH₄‐N with 1 N. KC1 : 0.01 N HC1 and measurement of NH₄ concentration by electroconductivity using a steady state flow system across a membrane. Sampling was done directly from the extracts with an automatic sampler at 40 samples per hour. The detection limit for NH₄‐N was below 0.05 ppm in the extract. Extracts could be stored at room temperature for 17 hours before measuring NH₄. No post‐treatment hydrolysis of urea occured.