[Objective] The paper was to study the algicidal effect of water-soluble extracts of Chinese chive under different environmental conditions, so as to provide reference for further study and development of new algicidal substances. [Method] The effects of water-soluble extracts of Chinese chive on the growth of Microcystis aeruginosa under different pH, light and aeration conditions were compared and studied. [Result] The growth inhibition rate of water-soluble extracts of Chinese chive on M. aeruginosa was greater than 90% under different pH conditions. With the growth of M. aeruginosa, the culture liquid with different initial pH was finally tended to 9-9.5. The growth inhibition rate of water-soluble extracts of Chinese chive on algae cell increased with the prolongation of culture time within the light intensity range of 1 000-4 000 lx. The inhibition effect of water-soluble extracts of Chinese chive on M. aeruginosa under low light intensity（1 000 lx）was better than that under high light intensity, the best light intensity for growth was not conducive to the exertion of allelopathic effect. Meanwhile, aeration condition was more conducive to the inhibition effect of water-soluble extracts of Chinese chive on the growth of M. aeruginosa. [Conclusion] pH, light and aeration conditions all affected the inhibition effect of water-soluble extracts of Chinese chive treated by high temperature on M. aeruginosa. Understanding the effect of these environmental factors on algicidal effect of allelochemicals could provide reference for further study and development of new algicidal substances.
K＋ is the most abundant cation in plant cells and plays an important role in many ways.K＋ uptake of plant has respect to its salt resistant capacity.There are two categories of channel transportation for plants to uptake K＋,one is through K＋ channels and the other is through nonselective cation channels（NSCCs）.The transmembrane localization of K＋ may change membrane potential（MP）.In this paper,three wheat varieties with different salt tolerance were selected and the MP was measured by microelectrode during K＋ uptake.The results showed that the effects of K＋ uptake on MP through K＋ channels or NSCCs were distinct.K＋ influx through K＋ channels led to MP hyperpolarization,while K＋ influx through NSCCs resulted in depolarization.Diverse MP alteration of wheat varieties with different salt tolerance was mainly due to NSCCs-mediated K＋ uptake.Compared with the salt-tolerant wheat,the MP hyperpolarization during K＋ uptake of saltsensitive wheat was much more evident,probably because of the cation outflux through NSCCs during this process.
WANG Yu-qianWANG Xiao-liSHAN Yu-huaSHENG Hai-junFENG Ke
[Objective] The aim was to study the antialgal activities of allelochemical extracts from three terrestrial plant species.[Method] The allelochemicals were extracted from the leaves of Magnolia grandiflora,Sophora japonica f.pendula and Buxus sinica （Rehd.et Wils.） Cheng by alcohol extraction,n-hexane,ethyl acetate and n-utanol phase.Furthermore antialgal activities of all components were determined.[Result] The active substances of M.grandiflora mainly existed in n-hexane and n-butanol phases.The active substances of S.japonica mainly existed in n-hexane phase,while the active substances of B.sinica mainly existed in ethyl acetate and aqueous phase.All the active substances showed significant antialgal activity （50% inhibition） after culture for 1 d except aqueous phase of B.sinica.In addition,inhibition rates of the tested phases increased with the increasing of culture duration and testing concentrations.The inhibition rates were over 90% against the growth of M.aeruginosa after culture for 7 d.The n-hexane and n-butanol phases of M.grandiflora exhibited the best antialgal activity,over 96% inhibition rate at the concentration of 25 μg/ml,which was significantly higher than those of the other components,furthermore it could cause shrinkage and obvious surface inanition of Microcystis aeruginosa.[Conclusion] The n-hexane and n-butanol phases of M.grandiflora have the best inhibition activities on the growth of Microcystis aeruginosa,so they are worthy of further study.
Plants need to be efficient in nutrient management, especially when they face the temporal nutrient defficiencies. Understanding how crops respond to nitrogen （N） starvation would help in the selection of crop cultivars more tolerant to N deficiency. In the present work, the physiological responses of two wheat cultivars, Yannong 19 （YN） and Qinmai 11 （QM）, to N starvation conditions were investigated. The two cultivars differed in biomass and N rearrangement between shoots and roots during N starvation. QM allocated more N to roots and exhibited higher root/shoot biomass ratio than YN. However, tissue measurement indicated that both cultivars had similar nitrate content in leaves and roots and similar remobilization rate in roots. Microelectrode measurement showed that vacuolar nitrate activity （concentration） in roots of QM was lower than that in roots of YN, especially in epidermal cells. Nitrate remobilization rates from root vacuoles of two cultivars were also identical. Moreover, vacuolar nitrate remobilization rate was proportional to vacuolar nitrate activity. During N starvation, nitrate reductase activity （NRA） was decreased but there were no significant differences between the two cultivars. Nitrate efflux from roots reduced after external N removal and QM seemed to have higher nitrate efflux rate.
[Objective]In order to investigate the antialgal activities and species of the allelochemicals in Magnolia grandiflora leaves.[Method]The antialgal substances against Microcystic aeruginosa from the extracts of Magnolia grandiflora leaves were separated,purified and identified based on the activity test,using silica gel column chromatography,gel column chromatography and GC-MS method and combining the algae inhibition experiment.[Result]The maximum inhibition rate of the extracts of Magnolia grandiflora leaves on Microcystic aeruginosa growth was 97.4% with the concentration of 8 g/L.A large amount of antialgal substances were found in the n-butanol extracts of Magnolia grandiflora and had very good inhibition effects on Microcystic aeruginosa,which were mainly small molecule substances such as alcohols,ketones and esters.[Conclusion]A new idea on developing new algal inhibitors had been provided.
