| The continuous cropping obstacles can lead to significant reduction the peanut production and quality, deterioration of soil physical and chemical properties, soil fertility decline, disease worse. The study of mechanism of peanut continuous cropping obstacle, prevention and control measures improve the peanut yield and quality, and promote the sustainable development of the peanut industry,which has very important significance.Through the analysis of the test related to the physiological and biochemical indexes, screening out of peanut continuous cropping resistant germplasm resources and application of peanut continuous cropping resistant breeding, is one of the effective prevention and control of peanut continuous cropping obstacle.The objective of the experiment was to study the effect of peanut continuous cropping on soil microbial quantity, soil enzyme activity, soil nutrient content and dry matter yield, wich research on continuous cropping soil of peanut cultivars variety Guuihua17 and wild species A.correntina rhizosphere soil microbial species, quantity, the change of the soil enzyme activity and soil nutrient content. The paper studied the effects of different phosphorus and potassium application rate on photosynthetic characteristics and yield of peanut wild species A.correntina and cultivated variety Guihua22. The chlorophyll content, net photosynthetic rate and dry matter production of peanut function leaf were detected. The study was to analyze peanut root exudates and study the allelopathic effects of peanut root exudates. Putative phosphate and potassium transporter gene were cloned in A.correntina and Guihua17 with RT-PCR method in this study.The results were showed as follows:1 The soil for physical and chemical change, change of biological properties of peanut wild species is smaller than peanut cultivars variety under the condition of continuous cropping.The results showed that the quantities of fungi and bacteria significantly increased and actinomyces quantity significantly reduced in the two peanut varieties of rhizosphere soil along with the increasing length of continuous cropping,the decline in A.correntina. is smaller than Guihua 17.Compared with the control,two different peanut varieties of continuous cropping soil available nutrients content reduced along with the increasing length of continuous cropping. Compared with the control, the soil urease, invertase and acid phosphatase activity enzyme activity of Guihua 17 had dropped with the increasing length of continuous cropping.The soil urease, invertase and acid phosphatase activity enzyme activity of A.correntina had a fall and then rise tendency in various stages. The change of soil hydrogen peroxide enzyme activity was irregular in the two varieties.Correlation analysis showed that two peanut varieties of urease, invertase and acid phosphatase had markedly positive correlation with bacteria, actinomyces and soil nutrient content,it could be used as evaluation index of soil fertility.On the contrary, there was a negative correlation relationship with fungi.2 The photosynthetic production of peanut wild species affected by p, k application rate are relatively small, phosphorus and potassium use efficiency of peanut wild species is higher than peanut cultivars varietyThe results showed that the phosphorus and potassium treatments could significantly improve chlorophyll content, transpiration rate, Leaf stomatal conductance,dry matter weight and photosynthetic rate of Guihua22. Compared with Guihua22,and reduce the osmanthus leaf intercellular CO2 concentration.There’s no significant effect of different phosphorus and potassium application on photosynthetic characteristics and dry matter accumulation in A.correntin.Compared with Guihua22, there’s higher levels of chlorophyll and photosynthetic rate at 96 d and 120 d after planting in A.correntin. There’s small response to the change of plant phosphorus and potassium content and phosphorus and potassium use efficiency under different phosphorus and potassium treatments in A.correntin. A.correntina had a good photosynthetic physiological basis. The test results provided a theoretical basis for forther development and utilization of A.correntina.3 The relative expression levels of Phosphate transporter gene of peanut wild species was lower than peanut cultivars variety under low phosphorus stress in the roots.Phosphate and potassium transporter gene were obtained.Homology analysis shows that they shares high similarity with high affinity phosphate and potassium transporter proteins from other plants,which indicates that proteins may play a key role in phosphate and potassium transport of peanut.The methods of quantitative real- time PCR were performed for further research.The relative expression levels of P31 and P32, P51 and P52,K61 and K62 detected by quantitative real- time PCR exhibited up- regulation under low phosphorus stress and potassium stress in the roots, and expression patterns were shown differently between A.correntina and Guihua17.The expression of P31 and P32, P51 and P52 was up-regulated by phosphate starvation. The expression of K61 and K62 was not different between A.correntina and Guihual7 by potassium starvation.These transporter proteins may play a role during the process of transport phosphate and potassium. The relative expression levels of Phosphate and potassium transporter gene of peanut wild species was lower than peanut cultivars variety under low phosphorus stress and potassium stress in the roots.4 The root secretion and its allelopathy were shown differently between peanut wild species and peanut cultivars variety, plant growth of peanut wild species was inhibited by allelochemicals less than cultivated.Compounds extracted from peanut root exudates in water culture and soil were identified and allelopathy,wich were studied by GC-MS analysis and biologicall test. The peanutroot exudates included organicacide,alcohol,ester,acetone,aldehyde,pheyl, hydrocarbon and so on.Contrast with control,the influence of the peanut root exudates did not show significant allelopathyinhibition.Benzaldehyde,4-ethylbenzoic acid which was found to be the major component in peanut root exudates,was used to test the bioactivity. Treatments of H20,1×10-5mol/L,1×10-4mol/L,1×10-3mol/L concentration were applied to test their effects on early development of peanut.The results showed that 1×10-5mol/L concentration of benzaldehyde,4-ethylbenzoic acid and ferulic acid had less impact on stem length,root length, dry weight of root and shoot.Contrast with control, 1×10-3mol/L and 1×10-4mol/L concentrationof benzaldehyde,4-ethylbenzoic acid and ferulic acid reduced peanut seedling growth to varying degrees,wich existed significant differences (P<0.05);In addition to the low concentration treatment (1×10-5 mol/L) of benzaldehyde increase slightly the SOD activity, POD activity and MDA content in A.correntina and the SOD activity, POD activity in Guihua22,the SOD activity, POD activity and MDA content of different concentrations of benzaldehyde, 4-ethylbenzoic acid and ferulic acid showed rising trend to varying degrees in two peanut varieties.Tow peanut varieties of high concentrations of benzaldehyde treatment (1×10-3 mol/L) reached significant level (P<0.05) in addition to SOD activity, of A.correntina In conclusion, there were allelophathic substances in peanut root exudates, which was one of the causes of problems associated with allelopathy.To sum up, the long-term continuous cropping make the quantities of fungi and significantly increased, bacteria and actinomyces quantity significantly reduced in the two peanut varieties of rhizosphere soil along with the increasing length of continuous cropping,the decline in A.correntina. is smaller than Guihua 17.. Compared with Guihua22, there’s small response to the change of plant phosphorus and potassium content,phosphorus and potassium use efficiency under different phosphorus and potassium treatments in A.correntin. The relative expression levels of Phosphate transporter gene of peanut wild species was lower than peanut cultivars variety.Plant growth of peanut wild species was inhibited by allelochemicals less than cultivated.The test results provided a theoretical basis for forther development and utilization of A.correntina. |
