棉 花 学 报 Cotton Science 2006，18(4)：213-217
Effect of Allelopathic Substance from Wheat Root Zones on the Growth of Cotton Seedling in Wheat-Cotton Interplanting System Abstract：Effect of allelopathic substance from wheat(Yumai 34) root zones in wheat-cotton interplanting system on the growth of cotton(Nucotn 33B) seedling was studied by conducting sand culture experiments. Allelopathic substance was extracted from 4 kg soil from wheat root zones by mixed impregnant，which was composed of Methanol，Acton and Ethyl acetiate by 1∶1∶1，and 50 g soil was extracted by 100ml mixed impregnant. Then the mixed impregnant was evaporated to dryness in a flash evaporator at less than 50 ℃ under a vacuum，the residue dissolved in Ethanol to 11 mL. Cotton seedling was cultured by 1/2 Hoagland-Aron nutrition solution contained 0.36mg·L-1 and 1.44mg·L-1 extracted in a green-house (13h light，white fluorescent lamp，26℃ and 11h dark，Compared humidity 60%.)，using 1/2 Hoagland-Aron nutrition solution which contained 0.4% Ethanol as control. Results showed that content of K in stem declined，CAT and SOD activity of cotton root was inhibited significantly，MDA content and comparative conductance of cotton seedling's root raised，and inhibit effect enhanced with concentration of abstracted substance raised. When the wheat seedling cultured in sand with 1/2 Hoagland-Aron nutrition solution (pH=6.5) grew to three-leaf stage，sand adhered to wheat root zone was collected and the cotton seedling were transplanted into. Data showed that the growth of cotton seedling was inhabited by residue of wheat root exudates，leaf area of cotton decreased and comparative conductance of cotton seedling's root was raised also. The weak growth of cotton seedlings in wheat-cotton interplanting system was possibly caused by allelopathy from wheat root exudates.
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