| Applications of nanotechnology and nanomaterials in agriculture provide a new strategy and an alternative methods for diseases prevention and agricultural sustainable development.Nanochitin extracted from shrimp original chitin by acidic hydrolysis showed nanosized whiskers with cationic nature and high biological properties.Nanochitin whisker suspension(NCS)possesses properties of nontoxicity,renewability,biocompatibility,biodegradability,higher surface area,crystallinity and polycationic properties,which could be widely applied in biomedicine,nanocomposites,cosmetics,water treatment,foods,and others.However,nanochitin as a comprehensive bionanomaterial has not yet been systematically studied in agriculture utilization.This study is to explore antifungal activities and mechanism of nanochitin whiskers and it mixtures against wheat crown rot and wheat take-all,and will provide a theoretical basis for applications in agriculture.The main rfindings were as following:1.Characterization of nanochitin whiskers: detained by acidic hydrolysis,the particles were crystalline rod-like whiskers and well-dispersed in aquous solution and showed a colloidal suspension.The effective diameters of 95% particles that measure by dynamic light scattering were about 150 nm,the zeta potential was +50.4 m V,the concentration was 0.2-0.6%(w/v).2.Antifungal activity of NCS in vitro:(1)0.03%,0.003%,0.001%,0.0003%(w/v)of NCS showed significantly inhibitory effects on mycelial growth of F.pseudograminearum and F.graminearum;(2)0.00005-0.006%(w/v)of NCS showed certain levels of inhibition on mycelial growth of Phytophthora capsici,Colletotrichum capsici and Rhizoctonia solani;(3)0.03%,0.003%,0.001%(w/v)of NCS showed significantly inhibition on conidial formation of F.pseudograminearum and F.graminearum;(4)the inhibitory rate of 0.0003% NCS on G.graminis var.tritici was approximate 22.10%.The mixture of nanochitin with fludioxonil demonstrated synergistic effect on the antifungal activity of G.graminis var.tritici and reached same efficacy under the half dosage of chemical fungicide as nanochitin individual.3.Effects of NCS and its combination with fungicides on plant height,dry weight,and chlorophyll contents in leaves during seedling stage:(1)nanochitin individual as a coating agent had no significant effect on plant height of the wheat seedlings;(2)0.001%,0.009%,0.018%(w/v)of NCS alone significantly increased the biomass(dry matter)of wheat;(3)seedlings treated with 0.001%,0.003%,0.009%(w/v)of NCS and its mixed with tebuconazole A2,compare with treatments of A2 and control,showed greener,more robust and a dwarf effect;(4)by treated with 0.001%,0.003%,0.009%(w/v)of NCS alone,the contents of chlorophyll a and chlorophyll b and the total chlorophyll of wheat seedlings were significantly higher than those of the blank control group,and were significantly different from those of CK,same as the treatments of 0.003%,0.009%(w/v)NCS mixed with A2.4.Synergistic effects of NCS with chemicals fungicides: Whether as a seed dressing agent or a spraying treatment,nanochitin with tebuconazole showed a great synergistic effects in wheat crown rot control.5.Effects of NCS on defensive enzyme activities in wheat: 0.003% of NCS could increase SOD enzyme activity,PPO activity,and PAL enzyme activity in wheat leaves at certain period of time.In short,nanochitin whiskers have a great antifungal activity on soil-borne pathogenic fungi,especially in a range of concentrations of 0.001% to 0.005%(w/v);nanochitin whiskers have a strong potential to protect wheat from wheat crown rot and take-all diseases and reduce the use of chemical fungicides in wheat plantations;nanochitin could also increase the biomass accumulation,improve the chlorophyll content of leaves,stimulate defense enzyme activities,elicit plant defense system.These results suggested that nanochitin have great potential to control fungal diseases by stimulating resistance system of plant. |
PDF Full Text Request