Research Progress on the Growth-Promoting Effect of Plant Biostimulants on Crops

A Plant Biostimulant is any substance or microorganism applied to plants to enhance nutrition efficiency,abioticstress tolerance,and/or crop quality traits,regardless of its nutrient content.The application of Plant biostimulants(PBs)in production can reduce the application of traditional pesticides and chemical fertilizers and improvethe quality and yield of crops,which is conducive to the sustainable development of agriculture.An in-depthunderstanding of the mechanism and effect of various PBs is very important for how to apply PBs reasonablyand effectively in the practice of crop production.This paper summarizes the main classification of PBs;Thegrowth promotion mechanism of PBs was analyzed from four aspects:improving soil physical and chemical properties,enhancing crop nutrient absorption capacity,photosynthesis capacity,and abiotic stress tolerance;At thesame time,the effects of PBs application on seed germination,seedling vigor,crop yield,and quality were summarized;Finally,how to continue to explore and study the use and mechanism of PBs in the future is analyzedand prospected,to better guide the application of PBs in crop production in the future.

Elevational patterns of warming effects on plant community and topsoil properties: focus on subalpine meadows ecosystem

Climate warming profoundly affects plant biodiversity, community productivity, and soil properties in alpine and subalpine grassland ecosystems. However, these effects are poorly understood across elevational gradients in subalpine meadow ecosystems. To reveal the elevational patterns of warming effects on plant biodiversity, community structure, productivity, and soil properties, we conducted a warming experiment using open-top chambers from August 2019 to August 2022 at high(2764 m a. s. l.), medium(2631 m a. s. l.), and low(2544 m a. s. l.) elevational gradients on a subalpine meadow slope of Mount Wutai, Northern China. Our results showed that three years of warming significantly increased topsoil temperature but significantly decreased topsoil moisture at all elevations(P<0.05), and the percentage of increasing temperature and decreasing moisture both gradually raised with elevation lifting. Warming-induced decreasing proportions of soil organic carbon(SOC, by 19.24%), and total nitrogen(TN, by 24.56%) were the greatest at high elevational gradients. Experimental warming did not affect topsoil C: N, p H, NO_(3)^(-)-N, or NH_(4)^(+)-N at the three elevational gradients. Warming significantly increased species richness(P<0.01) and Shannon-Weiner index(P<0.05) at low elevational gradients but significantly decreased belowground biomass(P<0.05) at a depth of 0–10 cm at three elevational gradients. Warming caused significant increases in the aboveground biomass in the three elevational plots. Warming significantly increased the aboveground biomass of graminoids in medium(by 92.47%) and low(by 98.25%) elevational gradients, that of sedges in high(by 72.44%) and medium(by 57.16%) elevational plots, and that of forbs in high(by 75.88%), medium(by 34.38%), and low(by 74.95%) elevational plots. Species richness had significant linear correlations with SOC, TN, and C: N(P<0.05), but significant nonlinear responses to soil temperature and soil moisture in the warmed treatment(P<0.05). The warmed aboveground biomass had a significant nonlinear response to soil temperature and significant linear responses to soil moisture(P<0.05). This study provided evidence that altitude is a factor in sensitivity to climate warming, and these different parameters(e.g., plant species richness, Shannon-Weiner index, soil temperature, soil moisture, SOC, and TN) can be used to measure this sensitivity.

Effect of Plant Growth-Promoting Rhizobacteria at Various Nitrogen Rates on Corn Growth

Plant growth-promoting rhizobacteria (PGPR) colonize plant roots and promote plant growth by producing and secreting various chemical regulators in the rhizosphere. With the recent interest in sustainable agriculture, an increasing number of researchers are investigating ways to improve the efficiency of PGPR use to reduce chemical fertilizer inputs needed for crop production. Accordingly, greenhouse studies were conducted to evaluate the impact of PGPR inoculants on biomass production and nitrogen (N) content of corn (Zea mays L.) under different N levels. Treatments included three PGPR inoculants (two mixtures of PGPR strains and one control without PGPR) and five N application levels (0%, 25%, 50%, 75%, and 100% of the recommended N rate of 135 kg N ha&#8722;1). Results showed that inoculation of PGPR significantly increased plant height, stem diameter, leaf area, and root morphology of corn compared to no PGPR application under the same N levels at the V6 growth stage, but few differences were observed at the V4 stage. PGPR with 50% of the full N rate produced corn biomass and N concentrations equivalent to or greater than that of the full N rate without inoculants at the VT stage. In conclusion, mixtures of PGPR can potentially reduce inorganic N fertilization without affecting corn plant growth parameters. Future research is needed under field conditions to determine if these PGPR inoculants can be integrated as a bio-fertilizer in crop production nutrient management strategies.

Genetic Effects and Heterosis in Plant Height and Internode Traits of Japonica-Indica Hybrid Rice

[Objective] This study aimed to investigate the genetic effects and heterosis of plant height and internode traits of japonica-indica hybrid rice. [Methed] Incomplete diallel crosses were made between six japonica CMS lines and nine indica widecompatibility restorer lines; the genetic effects of plant height and internode traits of japonica-indica hybrid rice were analyzed using the additive-dominance genetic model. [Result] The ple, nt height, panicle length and the length of internode 1 of japonica-in- dica hybrid rice were mainly controlled by the additive effects; but the length of in- ternode 3, internode 4 and internode 5 were mainly controlled by dominance effects. Both the narrow sense heritability and broad sense heritability of plant height, panicle length, number of elongated internodes and length of most internodes reached signifi- cance level. The positive phenotypic correlation, genetic correlation, additive correla- tion and dominance correlation between plant height and panicle length, number of e- longated internodes and internode length were significant; and most of the other paired traits were significantly positively correlated. Heterosis analysis showed that the positive heterosis value over mid-parent and positive heterosis value over better- parent of the length of internode 3, internode 4, internode 5 and internode 6 reached significant level, and the heterosis value over mid-parent of plant height reached extreme significance level. [Conclusion] This study will provide reliable theoretical basis for the genetic improvement and heterosis utilization of plant height and internode traits in japonica-indica hybrid rice.

Analysis of Genetic Effects of Nuclear-Cytoplasmic Interaction on Quantitative Traits:Genetic Model for Diploid Plants

A genetic model was proposed for simultaneously analyzing genetic effects of nuclear, cytoplasm, and nuclear-cytoplasmic interaction （NCI） as well as their genotype by environment （GE） interaction for quantitative traits of diploid plants. In the model, the NCI effects were further partitioned into additive and dominance nuclear-cytoplasmic interaction components. Mixed linear model approaches were used for statistical analysis. On the basis of diallel cross designs, Monte Carlo simulations showed that the genetic model was robust for estimating variance components under several situations without specific effects. Random genetic effects were predicted by an adjusted unbiased prediction （AUP） method. Data on four quantitative traits （boll number, lint percentage, fiber length, and micronaire） in Upland cotton （Gossypium hirsutum L.） were analyzed as a worked example to show the effectiveness of the model.

Preliminary Report on Application Effects of Slow-release Formula Fertilizer in Tea Plants

In order to accelerate the construction of green production mode for tea in Hubei Province, improve the yield of tea and use efficiency of fertilizers, and improve the quality of tea, application effects of special slow-release formula fertilizer in tea plants were investigated in Wuhan. The results showed that compared with conventional fertilization, application of tea plant-specific slow-release formula fertilizer improved the yield of tea by more than 30%. The amino acid content in tea was increased by 21.05% and 30.82%, respectively, and the income was increased 27 696 （33.88%） and 27 624 （33.79%） yuan/hm2, respectively.

Effects of Pigment Indicators on the Color Expression of Leaves of the Colored-leaf Garden Plants

[Objective] In this study, the relationship between the pigments and the color expression of leaves of colored-leaf plants was discussed. [Method] The colors of leaf blades of 6 kinds of plants were analyzed with the Royal Horticultural Soci-ety Colour Chart. The chlorophyl content, carotenoids content and anthocyanin con-tent in leaf blades were determined. In addition, the color types of leaf blades, kinds of pigments, pigment contents and pigment distributions of 6 kinds of plants were compared. [Result] The chlorophyl contents ranked as Populus canadensis Moench （green leaves） 〉 Populus deltoids cv. Zhonghuahongye （purple green leaves） 〉 Populus euramericana cv. Quanhong （red leaves）; Acer palmatum Thunb. （green leaves） 〉 Acer palmatum cv. Atropurpureum （purple red leaves） 〉 Acer pal-matum Thunb. cv. Atropurpureum （red leaves）. The ranking of anthocyanin contents was just opposite. The chlorophyl content was negatively related to the anthocyanin content. The leaf color of plants is determined by various pigments. The more the chlorophyl is, the greener the leaf is. The more the anthocyanin is, the redder the leaf is. In the colored-leaf plants, the chlorophyl content represents about 80% of the content of pigments, the carotenoids content represents about 17%, and the an-thocyanin represents about 3%. There is a difference in the chlorophyl content be-tween colored-leaf plants and green plants. However, the relatively low chlorophyl content wil not hamper the normal life activities of colored-leaf plants. [Conclusion] We hoped to provide reference and basis for the production and landscaping of col-ored-leaf plants.

Mapping QTLs with epistatic effects and QTL×environment interactions for plant height using a doubled haploid population in cultivated wheat

Quantitative trait loci （QTLs） for plant height in wheat （Triticum aestivum L.） were studied using a set of 168 doubled haploid （DH） lines, which were derived from the cross Huapei 3/Yumai 57. A genetic linkage map was constructed using 283 SSR and 22 EST-SSR markers. The DH population and the parents were evaluated for wheat plant height in 2005 and 2006 in Tai＇an and 2006 in Suzhou. QTL analyses were performed using the software of QTLNetwork version 2.0 based on the mixed linear model. Four additive QTLs and five pairs of epistatic effects were detected, which were distributed on chromosomes 3A, 4B, 4D, 5A, 6A, 7B, and 7D. Among them, three additive QTLs and three pairs of epistatic QTLs showed QTL×environment interactions （QEs）. Two major QTLs, Qph4B and Qph4D, which accounted for 14.51% and 20.22% of the phenotypic variation, were located similar to the reported locations of the dwarfing genes Rhtl and Rht2, respectively. The Qph3A-2 with additive effect was not reported in previous linkage mapping studies. The total QTL effects detected for the plant height explained 85.04% of the phenotypic variation, with additive effects 46.07%, epistatic effects 19.89%, and QEs 19.09%. The results showed that both additive effects and epistatic effects were important genetic bases of wheat plant height, which were subjected to environmental modifications, and caused dramatic changes in phenotypic effects. The information obtained in this study will be useful for manipulating the QTLs for wheat plant height by molecular marker-assisted selection （MAS）.

Psychophysiological Effects of Bamboo Plants on Adults

The present study was conducted to clarify the psychophysiological relaxation effects of viewing bamboo on university students. Forty healthy Chinese participants enrolled in this study to clarify the psychophysiological relaxation effects of viewing bamboo. The effects of visual stimulation using a pot both with and without a bamboo were recorded by measuring the student＇s blood pressure, EEG and STAI. We observed that viewing bamboo plants resulted in significantly lower systolic（female, P 〈 0.001; male, P 〈 0.001; P 〈 0.05） and diastolic（female,P 〈 0.001; male, P 〈 0.001; P 〈 0.05） blood pressures, but no changes in the pulse rate（female, P = 0.09; male, P = 0.07; P 〉 0.05） were observed. The results of the EEG analysis indicated brainwave variation（all P 〈 0.05） and lower anxiety scores（P 〈 0.01） after 3 min of viewing bamboo compared with the control. These findings indicate that visual stimulation with bamboo plants induced psychophysiological relaxation effects on adults.

Synergistic effects of plant extracts and antibiotics on Staphylococcus aureus strains isolated from clinical specimens

Objective:This study has been done to evaluate the interaction between water extracts of Psidium guajava, Rosmarinus officinalis,Salvia fruticosa,Majorana syriaca,Ocimum basilucum,Syzygium aromaticum,Laurus nobilis,and Rosa damascena alone and then synergy testing of these extracts with known antimicrobial agents including oxytetracycline HCl,gentamicin sulfate,penicillin G,cephalexin and enrofloxacin.This study was conducted against five S.aureus isolates;one is Methicillin -resistant Staphylococcus aureus(MRSA) and 4 Methicillin - sensitive Staphylococcus aureus(MSSA).Methods:Evaluation of the interaction between plant extracts and different antimicrobial agents has been done using well - diffusion and microdilution methods. Results:The results of the conducted experiments using well - diffusion method demonstrate that these plants showed in vitro interactions between antimicrobial agents and plant extracts were additive,while using microdilution method showed synergistic effects with significant reduction in the MICs of the test antibiotics against these strains of S.aureus.This change in MIC was noticed in all plant extracts against test antibiotics including these plants showed weak antibacterial activity by well diffusion method.Synergism effect was occurred in both sensitive and resistant strains but the magnitude of minimum fold reduction of inhibitory concentration in resistant strains especially MRSA strain was higher than the sensitive strains.Coclusion:This study probably suggests the possibility of concurrent use of these antimicrobial drugs and plant extracts in combination in treating infections caused by S.aureus strains or at least the concomitant administration may not impair the antimicrobial activity of these antibiotics.

Plant growth-promoting rhizobacteria(PGPR)and its mechanisms against plant diseases for sustainable agriculture and better productivity

Plant growth-promoting rhizobacteria(PGPR)are specialized bacterial communities inhabiting the root rhizosphere and the secretion of root exudates helps to,regulate the microbial dynamics and their interactions with the plants.These bacteria viz.,Agrobacterium,Arthobacter,Azospirillum,Bacillus,Burkholderia,Flavobacterium,Pseudomonas,Rhizobium,etc.,play important role in plant growth promotion.In addition,such symbiotic associations of PGPRs in the rhizospheric region also confer protection against several diseases caused by bacterial,fungal and viral pathogens.The biocontrol mechanism utilized by PGPR includes direct and indirect mechanisms direct PGPR mechanisms include the production of antibiotic,siderophore,and hydrolytic enzymes,competition for space and nutrients,and quorum sensing whereas,indirect mechanisms include rhizomicrobiome regulation via.secretion of root exudates,phytostimulation through the release of phytohormones viz.,auxin,cytokinin,gibberellic acid,1-aminocyclopropane-1-carboxylate and induction of systemic resistance through expression of antioxidant defense enzymes viz.,phenylalanine ammonia lyase(PAL),peroxidase(PO),polyphenyloxidases(PPO),superoxide dismutase(SOD),chitinase andβ-glucanases.For the suppression of plant diseases potent bio inoculants can be developed by modulating the rhizomicrobiome through rhizospheric engineering.In addition,understandings of different strategies to improve PGPR strains,their competence,colonization efficiency,persistence and its future implications should also be taken into consideration.

Synergistic combination of arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria modulates morpho-physiological characteristics and soil structure in Nitraria tangutorum bobr.Under saline soil conditions

Nitraria tangutorum Bobr.,a typical xero-halophyte,can be used for vegetation restoration and reconstruction in arid and semiarid regions affected by salinity.However,global climate change and unreasonable human activity have exacerbated salinization in arid and semi-arid regions,which in turn has led to the growth inhibition of halophytes,including N.tangutorum.Arbuscular mycorrhizal fungi(AMF)and plant growth-promoting rhizobacteria(PGPR)have the potential to improve the salt tolerance of plants and their adaptation to saline soil environments.In this study,the effects of single and combined inoculations of AMF(Glomus mosseae)and PGPR(Bacillus amyloliquefaciens FZB42)on N.tangutorum were evaluated in severe saline soil conditions.The results indicate that AMF and PGPR alone may not adapt well to the real soil environment,and cannot ensure the effect of either growth promotion or salt-tolerance induction on N.tangutorum seedlings.However,the combination of AMF and PGPR significantly promoted mycorrhizal colonization,increased biomass accumulation,improved morphological development,enhanced photosynthetic performance,stomatal adjustment ability,and the exchange of water and gas.Co-inoculation also significantly counteracted the adverse effect of salinity on the soil structure of N.tangutorum seedlings.It is concluded that the effectiveness of microbial inoculation on the salt tolerance of N.tangutorum seedlings depends on the functional compatibility between plants and microorganisms as well as the specific combinations of AMF and PGPR.

A novel Effective Panicle Number per Plant 4 haplotype enhances grain yield by coordinating panicle number and grain number in rice

Increasing effective panicle number per plant(EPN)is one approach to increase yield potential in rice.However,molecular mechanisms underlying EPN remain unclear.In this study,we integrated mapbased cloning and genome-wide association analysis to identify the EPN4 gene,which is allelic to NARROW LEAF1(NAL1).Overexpression lines containing the Teqing allele(TQ)of EPN4 had significantly increased EPN.NIL-EPN4^(TQ) in japonica(geng)cultivar Lemont(LT)exhibited significantly improved EPN but decreased grain number and flag leaf size relative to LT.Haplotype analysis indicated that accessions with EPN4-1 had medium EPN,medium grain number,and medium grain weight,but had the highest grain yield among seven haplotypes,indicating that EPN4-1 is an elite haplotype of EPN4 for positive coordination of the three components of grain yield.Furthermore,accessions carrying the combination of EPN4-1 and haplotype GNP1-6 of GNP1 for grain number per panicle showed higher grain yield than those with other allele combinations.Therefore,pyramiding of EPN4-1 and GNP1-6 could be a preferred approach to obtain high yield potential in breeding.

Clonal Transgenerational Effects Transmit for Multiple Generations in a Floating Plant

Environmental conditions of a parent plant can influence the performance of their clonal offspring,and such clonal transgenerational effects may help offspring adapt to different environments.However,it is still unclear how many vegetative generations clonal transgenerational effects can transmit for and whether it depends on the environmental conditions of the offspring.We grew the ancestor ramets of the floating clonal plant Spirodela polyrhiza under a high and a low nutrient level and obtained the so-called 1^(st)-generation offspring ramets of two types(from these two environments).Then we grew the 1^(st)-generation offspring ramets of each type under the high and the low nutrient level and obtained the so-called 2^(nd)-generation offspring ramets of four types.We repeated this procedure for another five times and analyzed clonal transgenerational effects on growth,morphology and biomass allocation of the 1^(st)-to the 6^(th)-generation offspring ramets.We found positive,negative or neutral(no)transgenerational effects of the ancestor nutrient condition on the offspring of S.polyrhiza,depending on the number of vegetative generations,the nutrient condition of the offspring environment and the traits considered.We observed significant clonal transgenerational effects on the 6^(th)-generation offspring;such effects occurred for all three types of traits(growth,morphology and allocation),but varied depending on the nutrient condition of the offspring environment and the traits considered.Our results suggest that clonal transgenerational effects can transmit for multiple vegetative generations and such impacts can vary depending on the environmental conditions of offspring.

Potential seed germination-enhancing plant growth-promoting rhizobacteria for restoration of Pinus chiapensis ecosystems

Rhizosphere soil samples of three Pinus chiapensis sites were analyzed for their physicochemical properties,soil bacteria isolated and screened in vitro for growthpromoting abilities.Nine isolates that showed promise were identified to five genera Dyella,Luteimonas,Euterobacter,Paraburkholderia and Bacillus based on the sequences of16 S rRNA gene.All the strains were isolated from nondisturbed stands.These bacteria significantly decreased germination time and increased sprout sizes.Indole acetic acid and gibberellin production and phosphate solubilisation were detected.Results indicate that these biochemicals could be essential for P.chiapensis distribution and suggest the possibility that PGPR inoculation on P.chiapensis seeds prior to planting could improve germination and possibly seedling development.

Immunomodulatory effects of selected Malaysian plants on the CD18/11a expression and phagocytosis activities of leukocytes

Objective:To investigate the effects of 20 methanolic extracts from Malaysian selected plants on CD18/11 a expression and phagocytosis activity of leukocytes using flow cytometry analysis.Methods:The effects of methanolic extracts on CD18/11 a expression and phagocytosis of leukocytes were measured by labelling the cells with CD18-fluorescein isolhiocyanaie and ingestion labelled with Escherichia coli-fluorescein isothiocyanate and then analyzed using flow cytometer.Results:About 12 out of 20 methanolic extracts of selected Malaysian medicinal plants significantly(P≤0.05) inhibited the CD18/1 la expression of leukocytes at both concentrations of 6.25 μg/mL and 100 μg/mL in dose dependent manner.The most active inhibitory was shown in Citrus aurantifolia(Christm.) Swingle and Alpinia galangal(L.) Willd.at dosage 100ug/mL.Moreover,the Orthosiphon aristatus(Blume) Miq(O.aristatus).showed the highest stimulatory activity at the concentration of 100 μg/mL.Other than that,four plant extracts significantly(P<0.05) rose the phagocytosis activities of leukocytes in dose dependent manner.However,Annona muricata L.and O.aristatus showed the highest stimulated activities at the 100 pg/mL concentration.Conclusions:The results suggest that methanolic extracts of Cirrus aurantifolia.Alpinia gaiangal,O.aristatus and Annona muricata are able to modulate innate immune system and can potentially be recognized as therapeutic agents for modulating immune system.

Plant growth-promoting properties and anti-fungal activity of endophytic bacterial strains isolated from Thymus altaicus and Salvia deserta in arid lands

Endophytes,as crucial components of plant microbial communities,significantly contribute to enhancing the absorption of nutrients such as nitrogen and phosphorus by their hosts,promote plant growth,and degrade pathogenic fungal mycelia.In this study,an experiment was conducted in August 2022 to explore the growth-promoting potential of endophytic bacterial strains isolated from two medical plant species,Thymus altaicus and Salvia deserta,using a series of screening media.Plant samples of Thymus altaicus and Salvia deserta were collected from Zhaosu County and Habahe County in Xinjiang Uygur Autonomous Region,China,in July 2021.Additionally,the inhibitory effects of endophytic bacterial strains on the four pathogenic fungi(Fusarium oxysporum,Fulvia fulva,Alternaria solani,and Valsa mali)were determined through the plate confrontation method.A total of 80 endophytic bacterial strains were isolated from Thymus altaicus,while a total of 60 endophytic bacterial strains were isolated from Salvia deserta.The endophytic bacterial strains from both Thymus altaicus and Salvia deserta exhibited plant growth-promoting properties.Specifically,the strains of Bacillus sp.TR002,Bacillus sp.TR005,Microbacterium sp.TSB5,and Rhodococcus sp.TR013 demonstrated strong cellulase-producing activity,siderophore-producing activity,phosphate solubilization activity,and nitrogen-fixing activity,respectively.Out of 140 endophytic bacterial strains isolated from Thymus altaicus and Salvia deserta,104 strains displayed anti-fungal activity against Fulvia fulva,Alternaria solani,Fusarium oxysporum,and Valsa mali.Furthermore,the strains of Bacillus sp.TR005,Bacillus sp.TS003,and Bacillus sp.TSB7 exhibited robust inhibition rates against all the four pathogenic fungi.In conclusion,the endophytic bacterial strains from Thymus altaicus and Salvia deserta possess both plant growth-promoting and anti-fungal properties,making them promising candidates for future development as growth-promoting agents and biocontrol tools for plant diseases.

Stability and Ecological Effects of Main Plant Communities in Minqin Desert Area

[ Objective ] To elucidate the change trend in stability and ecological effects of plant communities in desert along with global wanning. [ Method ] The data of site-specific observation on five main plant communities at ten plots in Minqin desert area were used to analyze the stability and ecological effects of desert plant communities by using two indicators vegetation coverage and projective cover degree. [ Results ] The vegetation coverage of Artemisia arenaria and Ephedra przewalskii, and the projective cover degree of A. arenaria and man-made Haloxylon ammodendron forest decreased remarkably; and the vegetation coverage of Ni- traria tangutorum was also decreased to some extent. [ Conduslon] （1） The plant communities with poor vegetation coverage gives a relatively strong stability, while that with high vegetation coverage has a relatively poor stability; （2） the yearly precipitation is the determinant of vegetation coverage and projective cover deglee; （3） the ecological function is found to be most remarkable in per unit area N. tangutorum, followed by E. przewalskii and N. tangutorum ＋H. ammodendron, and least in per unit area A. Arenaria. The vegetation is sparse in desert and plant branches does not distribute regularly, thus the crown-based vegetation coverage can not reflect the actual surface coverage.

Effects of plant latex based anti-termite formulations on Indian white termite <i>Odontotermes obesus</i>(Isoptera: Odontotermitidae) in sub-tropical high infestation areas

In the present investigation various bioassays were conducted to evaluate the anti-termite efficacy of plant latex based formulations to control population of Indian white termite in subtropical soil. Results reveal that crude latex, its fractions and combinatorial fractions have shown very high toxicity against O. obesus. The LD50 values for different latex fractions of 24 h were in a range of 5.0-17.613 μg/mg while combined mixtures of Calotropis procera have shown synergistic activity against termites and caused comparably high mortality with LD50 1.987-6.016 μg/mg. The mortality rate was found dose and time dependent as it was found to be increased with an increase in dose and exposure period. In olfactometry tests, C. procera latex solvent fractions have shown significant repellency at a very low dose 0.010-0.320 μg/mg. Interestingly, solvent fractions have significantly repelled large numbers of worker termites due to volatile action of active components of latex and different additives. ED50 values obtained in crude latex were 0.121 μg/mg body weights while combinatorial formulations have shown ED50 in between 0.015-0.036 μg/mg. Statistical analysis of repelled and un-repelled termites gave a low Chi-square value (X2 value = 0.890) which is an indicator of independence of repellent action in randomly selected termite groups. In field experiments pre-soaked cotton threads impregnated with Calotropis procera crude latex were tagged around tree trunks of Tectona grandis provided a wider protection against O. obesus. By employing these pre-coated threads, termite infestation and tunneling activity were significantly decreased (p Calotropis procera possesses enough anti-termite potential against Indian white termite, O. obesus population. If used these, formulations may also provide wide a range of control against other kinds of pests including house hold, medical and veterinary. However, Calotropis procera latex based formulations can be recommended for effective control of termites in high infestation areas by applying spray, or in form of poison baits or as fumigant in pure form.

Effects of Eichhornia crassipes Growth on Aquatic Plants in Dianchi Lake

[Objective] The aim was to study the effects of Eichhornia crassipes as an invasive plant on aquatic plants in Dianchi Lake. [Method] Based on the determination of chlorophyll content of phytoplankton and submerged plant (Potamogeton pectinatus) in Dianchi Lake in different months, the effects of E. crassipes on aquatic plants in Dianchi Lake were studied, and the allelopathy effect of root culture solution of E. crassipes on Microcystis aquaticum was discussed. [Result] The growth of E. crassipes in Dianchi Lake reduced the chlorophyll content of phytoplankton and submerged plant (P. pectinatus), and it showed that E. crassipes had certain inhibitory effect on their growth; the culture solution of E. crassipes root inhibited M. aeruginosa growth obviously. [Conclusion] The study could provide scientific references for the prevention and control of ecological safety of E. crassipes.