Study On Allelopathic Effec Of Alfalfa To Wheat

In order to investigate the allelopathic effect of alfalfa(Medicago sativa L) andthe relationship of water competition with the allelopathic effect under the droughtcondition, Root-exudates of alfalfa seedlings were extracted by dichloromethane,and identified by gas chromatography-mass spectrometry combined instrument(GC-MS), and the bio-characteristics of typical exudation which were3,5-di-tert-Butyl-4-hydroxybenzaldehyde were tested through germination experiment.The results reflected that root exudates of alfalfa mainly included straight-chainalkanes, cycloalkanes, alkenes, alcohols, methyl thiophenol, benzene, phenols, esters,heterocyclic aniline, naphthylamine, phenolic acids and polycyclic aromaticcompounds.Typical exudation3,5-di-tert-Butyl-4-hydroxybenzaldehyde was a kind ofallelochemical showsed stronger allelopathic effect on itself than on other crops.3,5-di-tert-Butyl-4-hydroxybenzaldehyde promoted sprouting of wheat at lowconcentrations(150×10-6mol／L), At high concentrations(450×10-6mol／L), but ithibited sprouting of the seedlings planted in sand more seriously than to the dry rootweight.When water supplied inadequate(45％,60％holding Water capacity of the soil),whether unicast or mixed sowing, wheat growth was inhibited in a pot experiment, thecompetition is greater than allelopathy. Under the condition of the sufficient watersupplied, multiple system is better than mono system on wheat growth,andallelopathic effect showed less negative effect yield havest under intercropping thanmono croping. Intercropping of alfalfa and wheat under the stress of the dryenvironment, competition is greater than allelopathy.Competing effect superiority allelopathic effect under under the condition of lownitrogen supplies. competing under under the condition of inferior allelopathiceffect strength nitrogen abundant. In Dingxi the experiment of Alfalfa and wheat interval zone, Wheat distanceinterval with the closer, the soil moisture content decreased slightly, Alfalfa and wheatto moisture competition is intense, Wheat dwarf is the more serious and allelopathicphenomenon more obvious. With the farther away from the sides of the border, alfalfaand wheat the same layer moisture content differences more obvious,when distanceis80cm differences highly significant。...