Effects of Spraying Plant Extract Mixture on Growth and Development and Diseases of Flue-cured Tobacco

[Objective]The paper was to study the effects of plant extract mixture on growth and development,photosynthetic indexes and disease control of flue-cured tobacco.[Method]Using field test method,a total of five treatments were designed in the test,including T1(control,conven-tional pesticide control),T2(conventional pesticide control+spraying plant extract mixture at 15 and 30 d post transplanting),T3(conventional pesticide control+spraying plant extract mixture at 15,30 and 45 d post transplanting),T4(conventional pesticide control+spraying plant extract mixture at 15,30,45 and 60 d post transplanting),and T5(conventional pesticide control+spraying plant extract mixture at 15,30,45,60 and 75 d post transplanting).In addition,flue-cured tobacco in treatments T2-T5 were sprayed with antiviral agent once at 30 d post transplanting,and sprayed with quality promoting agent at 30 and 75 d post transplanting,respectively.[Result]The agronomic traits and photosynthetic indexes of all treatments were improved by spraying plant extract mixture,and those in T5 treatment were the best.Spraying plant extract mixture had significant control effect on brown spot;the disease index in T5 treatment was the lowest,and the control effect was the best.The results showed that spraying plant extract mixture promoted the growth and development of flue-cured tobacco,reduced the disease index of brown spot,and improved the quality of tobacco leaves.[Conclusion]Spraying plant extract mixture has positive effect on growth and development and disease control of flue-cured tobacco.

Influence of evenness on the litter-species richness-decomposition relationship in Mediterranean grasslands

Aims Human impacts on natural ecosystems induce changes in their functioning through alterations in species richness,composition and evenness of plant communities.Most litter diversity–decomposition processes studies have only manipulated species richness,ignoring the role of evenness.Here,results from a field litterbag experiment are presented to test whether changes in evenness of species distribution in litter mixtures affected the strength of the litter-species richness–decomposition relationship.Methods Ten herbaceous species abundant in Mediterranean grassland communities and representative of different genera and functional groups were used.Species richness was directly manipulated to produce litter mixtures of three and six plant species,as well as litter of each individual species used.Each level of species richness was replicated several times such that each repeat had a different species composition.Three-and six-species litter mixtures were also treated to vary in evenness(three levels).Decomposition rate was assessed by percentage dry weight loss over the 90 days of the experiment.Important Findings Decomposition rate was positively related to the linear increase in litter-species richness and was affected by the composition of the litter-species mixture.Decomposition rates differed significantly between evenness treatments and moreover,the strength of the positive relationship between litter-species richness and decomposition rate decreased notably in the low-evenness treatment.The effects of evenness on decomposition rate,at different richness levels,were partially explained by the differences in the initial litter mixture’s carbon-to-nitrogen ratio within them.This study reveals that shortterm decomposition rate is positively affected by both components of Mediterranean grassland litter-species diversity.