Defense Function Of Aromatic Plants Against Alfalfa Thrips

Alfalfa(Medicago sativa L.)is one of the excellent leguminous herbage which plays an important role in grassland husbandry production and grassland ecological construction.It is known as the "king of herbage" because of its high yield,high quality,high palatability,high adaptability and strong stress resistance.In this study,Medicago varia Martin.cv.Caoyuan No.3 was selected as the experimental material,and Odontothrips loti was selected as the pest.Artemisia frigida Willd.,Dracocephalum moldovica L.and Melilotus officinalis L.are the main aromatic plants.Under the treatment combination of Caoyuan No.3,Caoyuan No.3 + Artemisia frigida,Caoyuan No.3 + Dracocephalum moldovica and Caoyuan No.3 + Melilotus officinalis,the worm situation index of different treatment combinations of Medicago varia Martin.cv.Caoyuan No.3 and the migration trend of different plants selected by Thrips were measured.The main anti-insect chemical components of main aromatic plants against the harm of Thrips,such as Artemisia frigida,Dracocephalum moldovica and Melilotus officinalis,and the biomass and nutritional quality of Medicago varia Martin.cv.Caoyuan No.3 were tested.The main research results were obtained as follows:1.The migration distance of Thrips to Medicago varia Martin.cv.Caoyuan No.3was significantly greater than that to Artemisia frigida,Dracocephalum moldovica and Melilotus officinalis(P < 0.05).The migration distance from Thrips to Dracocephalum moldovica was the shortest.The worm situation index of Caoyuan No.3 +Dracocephalum moldovica treatment combination was significantly lower than that of Medicago varia Martin.cv.Caoyuan No.3 treatment and other treatment combinations(P< 0.05).2.The contents of thymol,ferulic acid,oxalic acid,3,4-dihydroxycinnamic acid and 4-hydroxycinnamic acid of aromatic plant Dracocephalum moldovica were significantly higher than those of Melilotus officinalis and Artemisia frigida(P < 0.05);The content of 1,2,4-phenyltrigenol in Dracocephalum moldovica and Melilotus officinalis was significantly higher than that in Artemisia frigida(P < 0.05).The content of dihydroxyacetone in Artemisia frigida was significantly higher than that in Dracocephalum moldovica.The chemical components of Lucinioside and phenyl-β-D-glucopyranoside were found in both Dracocephalum moldovica and Melilotus officinalis(P < 0.05).3.The dry-fresh ratio comparison test showed that the dry-fresh ratio of Caoyuan No.3 + Dracocephalum moldovica treatment combination was significantly higher than that of Medicago varia Martin.cv.Caoyuan No.3,Caoyuan No.3 + Artemisia frigida and Caoyuan No.3 +Melilotus officinalis treatment combination(P < 0.05);The results of biomass comparison experiment showed that the biomass of Caoyuan No.3 +Dracocephalum moldovica treatment combination was 80.68g/ pot,which was significantly higher than that of Caoyuan No.3 + Melilotus officinalis 75.24g/ pot,Caoyuan No.3 + Artemisia frigida 66.50g/ pot and Medicago varia Martin.cv.Caoyuan No.3 51.49g/ pot(P < 0.05).4.The combinations with crude protein content higher than 19% included Caoyuan No.3 + Artemisia frigida,Caoyuan No.3 + Dracocephalum moldovica and Caoyuan No.3+ Melilotus officinalis;The lowest acid detergent fiber was Caoyuan No.3 +Dracocephalum moldovica treatment combination(32.33%).The contents of Ca and P in Caoyuan No.3 + Dracocephalum moldovica treatment group were significantly higher than those in Caoyuan No.3 + Artemisia frigida,Medicago varia Martin.cv.Caoyuan No.3 and Caoyuan No.3 + Melilotus officinalis treatment group(P < 0.05);The RFV value was the largest in the combination of Caoyuan No.3 + Dracocephalum moldovica treatment.According to the comprehensive analysis of the chemical composition,migration trend of Thrips,insect situation index,dry-fresh ratio,biomass and nutrient composition of aromatic plants,It can be preliminarily speculated that the defense performance of Dracocephalum moldovica against Thrips is stronger than that of other aromatic plants.