On the Use of Jack‐Knife Techniques in Systematic Sampling

We have proposed two general classes of ratio and product type estimators to estimate an unknown population parameter of a response variable y under systematic sampling strategy. Jack‐Knife technique is employed to make the classes almost/exactly unbiased and sampling variance of the proposed estimators are derived to the first order of approximation. The merits of the proposed estimators over other estimators are discussed in this paper.     

The Effects of Naphthalene Acetic Acid,Kinetin and Wound on the Callus Formation with Relation to the Biosyntheses of Tryptophan and Indole Acetic Acid in the Cotyledon of Mung Bean

The effects of the exogenous auxin——NAA, kinetin and wound on the callus formation of the cotyledon of mung bean (Phaseolus radiatus L.) with relation to the biosyntheses of endogeonous tryptophan (Trp) and IAA have been studied. The results indicate that wound plays an important role in the callus formation. The size of wounded surface is directly proportional to the proliferation of the callus tissue. The levels of free Trp and endogenous 1AA decreased in the initial period of the callus formation of mung bean cotyledon but increased in the later period. The substitution of L-Trp for NAA in the culture medium would play almost the same role in the callus proliferation. It has proposed that the exogenous phytohormones affect the biosyntheses of endogenous Trp and IAA, thereafter induce the callus formation. The wound has an important synergism with the phytohormones in this process.     

Effects of continuous leaf wetness on photosynthesis: adverse aspects of rainfall

Above-ground parts of Phaseolus vulgaris L. plants were treated with artificial misty rain (‘rain’) in a growth chamber to investigate the effects of leaf wetness on photosynthetic performance. The following results were obtained. (1) Stomata closed completely within 2 min of the onset of continuous ‘rain’ application and gradually opened to half the original aperture by 60 min. The rate of CO₂ exchange measured on such wet leaves changed in parallel with the changes in stomatal aperture and attained 60 to 70% of the control level by 1h. (2) The dependence of the rate of leaf photosynthesis, A, on the intercellular CO₂ concentration, c_i [A(c_i) relationship], examined in thoroughly dried leaves which had been treated with ‘rain’ did not change until after 4 h of treatment. However, leaves treated for 6h showed discernible decreases in A at high c_i (c_i>500μmolmol ^?1). The photosynthetic rate of leaves treated with ‘rain’ for 24 h was reduced at all c_i, and A at the ambient CO₂ concentration of 350μmolmol^?1 was 60 to 70% of that of the control level. The rate of photosynthesis did not recover even after 3 d of treatment of the plants in a dry environment. These results clearly indicate that leaf wetness causes not only instantaneous suppression of photosynthesis but also chronic damage to the photosynthetic apparatus. Potential effects of leaf wetness on photosynthetic performance in nature are also discussed.     

Homoserine dehydrogenase in Pisum sativum and Ricinus communis

Homoserine dehydrogenase was extracted from Ricinus communis and Pisum sativum. The kinetic parameters of the forward and reverse reactions were determined. In the forward reaction only the enzyme from Ricinus is inhibited by threonine. The response to K⁺ is different for the enzyme from the two sources.     

The Weak Cytokinins N,N′-bis-(1-naphthyl)urea and N,N′-bis-(2-naphthyl)urea may Enhance Rooting in Apple and Mung Bean

The present research investigates the possibility that 2 weak urea-type cytokinins, the N,N′-bis-(1-naphthyl)urea and the N,N′-bis-(2-naphthyl)urea, enhance adventitious root formation. The rooting activity was assessed using the stem slice test, the mung bean rooting test and the rooting of apple microcuttings. The two compounds influenced the adventitious rooting process differently as regards the bioassay used. In the stem slice test, in the presence of exogenous auxin, both compounds enhanced the rooted slice percentage. In mung bean shoots, the N,N′-bis-(1-naphthyl)urea enhanced the root formation at the lowest concentration used (0.01 μM) while the N,N′-bis-(2-naphthyl)urea enhanced rooting at higher concentrations. In the rooting test of apple microcuttings the N,N′-bis-(1-naphthyl)urea and the N,N′-bis-(2-naphthyl)urea slightly enhanced only the mean root number per microcutting.     

Lead uptake,toxicity and accumulation in <Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> plants

The effects of lead were investigated in bean plants (Phaseolus vulgaris L. cv. Zlota Saxa) grown hydroponically in nutrient solution and exposed to Pb(NO₃)₂ (0.1, 0.5, 1 mM) with or without equimolar concentrations of chelator ethylenediaminetetraacetic acid (EDTA). The roots treated only with Pb(NO₃)₂ accumulated up to 25 g(Pb) kg⁻¹(d.m.), during 4-d exposure. However, in bean plants exposed to 0.5 mM Pb + 0.5 mM EDTA or 1 mM Pb + 1 mM EDTA 2.5 times less Pb was determined. In bean plants treated only with Pb, less than 6 % of total lead accumulated was transported to the aboveground parts, while in the case of plants grown with Pb + EDTA, around 50 % of total Pb was transported to the shoots.     

水杨酸诱导普通菜豆镰孢菌枯萎病抗病性的研究

普通菜豆是人类主要食用豆类之一,其营养价值高、栽培面积大。镰孢菌枯萎病是普通菜豆典型的土传病害,给普通菜豆生产带来严重损失。水杨酸(SA)被认为是诱导植物抗病反应的重要信号分子之一,参与植物的过敏反应(HR)和系统获得性抗性反应(SAR)。本研究通过不同植物激素处理普通菜豆BRB-130,结果表明,SA处理普通菜豆叶片使植株根中SA的含量升高,并显著提高植株对枯萎病原菌FOP-DM01菌株的抗性。SA诱导普通菜豆根组织中苯丙氨酸解氨酶、过氧化物酶活性及过氧化氢的含量显著升高,从而诱导普通菜豆产生HR和SAR。因此,SA作为普通菜豆抗病信号途径中重要的化学激活因子,能够显著提高普通菜豆对枯萎病原菌的抗病性,为发展环境友好型化学农药提供新的思路。     

传统豆瓣酱微生物群落发酵演替规律及其功能分析

[目的]解析中国传统豆瓣酱发酵过程中的微生物群落演替规律和理化代谢物质变化,探讨不同发酵阶段影响豆瓣酱风味的核心功能微生物.[方法]采用高通量测序解析豆瓣酱发酵过程中的微生物群落结构和演替,并跟踪检测发酵过程中的理化代谢物质,然后分析微生物群落和理化代谢物质变化之间的相关性,最后在体外分离核心微生物并对其功能特性进行验...     

3-O-feruloyl-4-O-caffeoylquinic acid from coffee beans

A new phenolic ester was isolated from unroasted robusta coffee beans (Coffea canephora) by HPLC. The isolated compound was identified as an ester of caffeic acid and ferulic acid with quinic acid (3-O-feruloyl-4-O-caffeoylquinic acid) using ¹H NMR and mass spectroscopy.