| Allelopathy is a new marginal area of research, and this field plays a vital role in the arrangement of crop cultivation system, farml and weed control, disease and insect prevention, and reduction of the barrier harm of the succession cultivation. Pugionium cornutum(L.)Gaertn is a biannial plant species in Cruciferae. It has important ecological value in fixing sand and preventing water loss and soil erosion, and also it is a kind of vegetable growing in desert area with high nutritional and medicinal values. This paper studied the allelopathic effects of different concentrations aqueous extracts from different parts of P. cornutum on seed germination and seedling growth of B.campestris, Eragrostis pilosa L., Amaranthus retroflexus Linn, Chenopodium album L., Setaira viridis L., and P. cornutum. The allelopathic mechanism to B.campestris was investigated with seedlings growing in the pots. The aqueous extracts were separated and identified the allelochemicals by GC-MS. The purpose of the research was to provide theoretical basis for the allelopathy research and to build up the planting patterns of P. Cornutum. The main results were as follows:1 Except for Eragrostis pilosa L., the aqueous extract with concentration>0.15g·mL-1 significantly inhibited the seed germination and seedling growth of Amaranthus retroflexus Linn, Chenopodium album L., and Setaira viridis L. The aqueous extract with concentration≤0.10g·mL-1 had positive effects on seed germination and seedling growth of Chenopodium album L. By synthetical effect, the allelopathic effects of aqueous extracts from the same part of P. cornutum on the four weeds were different, at high concentration, the order was Setaira viridis L.>Amaranthus retroflexus Linn>Chenopodium album L.>Eragrostis pilosa L.2 Pugionium cornutum had obvious autotoxicity with the effect of concentration.The inhibition effects on plant growth enhanced as the aqueous extracts concentration increased. As extract concentration≤0.10g·mL-1, the aqueous extracts had no obvious autotoxicity. However, the aqueous extract with concentration>0.15g·mL-1 had obvious inhibition effects. With the concentration of aqueous extracts increase, SOD and POD activity were inhibited, the MAD content increased. The autotoxicity of aqueous extracts was in the order of leaf>peel>branch.3 Aquatic extracts from leaf, peel, branch inhibited seed germination and seedling growth of B.campestris. Different concentrations aquatic extracts decreased chlorophyll content, soluble protein content and root activity of B.campestris seedling, inhibited superoxide dismutase(SOD)and peroidase(POD) activity of the B.campestris seedlings,, increased conductivity and MDA content of the seedlings. The allelopathic effect order of aqueous extracts from different organs of P. cornutum was leaf, peel, branch.4 Allelochemicals of P. cornutum was obtained from aqueous extracts. It was collected by XAD-4 resin, then XAD-4 resin was washed by different polar solvent, and separated step by step. Finally, we selected the allelopathic activity of the strongest component, separated by column chromatography, then allelochemicals were identified by GC-MS. The results showed that cinnamicacid,1,2-benzenedicarboxylic acid, salicylic acid and 2-hexadecen-l-ol,3,7,11,15-tetramethyl were the main allelochemicals from leaves, peels and branches of P. cornutum. For the three organs, peel contained the most allelochemicals in the aqueous extracts, followed by branch and leaf contain the least.5 Cinnamic acid,1,2-benzenedicarboxylic acid,2,3,5,6-tetramethyl, which were replaced by exogenous organic compound, were proved to inhibit plant growth. At concentration≤1.0×10-4 mol·L-1, the three compounds had relatively weak allelopathic eff-ects; At concentration 1.0×10-2mol·L-1, the three compounds significantly inhibited plant growth. By synthetical effect, three compounds all had inhibitory effects, and the order of inhibitory effects from strong to weak was:cinnamic acid>phenol,2,3,5,6-tetramethyl>1,2-benzenedicarboxylic acid. |
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