Study On The Interaction Of "Cotton·Plant Growth Regulator (DPC)·Aphis Gossypii"

Crop is an open system capable to maintain internal stability, which can feel the signals through their neurologic information delivery system, and regulate their growth and development by the plant hormones. Under the effects of Plant Growth Regulator, crop tissues and metabolism would change, the development and population of pests would also being effected directly or indirectly.The cotton growing area increases with the development of planting technology in Xinjiang. Plant high-density and short-height of cotton regulated by Plant Growth Regulator in technology system of "dwarfed, high-density, early and agricultural plastic mulching film". At the same time, some pests have caused serious damages to cottons under the Continuously Cropping of cotton. Aphis Gossypii is a major insect in field crops.Up to now, there is no relationship between population of Aphis Gossypii and cotton regulated by Plant Growth Regulator. It is not clear that DPC has effects to Aphis Gossypii and its population increased or decreased, Aphis Gossypii feeding with cotton treated by DPC. Xinluzao 44 was used in this paper to research the interaction among Aphis Gossypii, cotton and DPC.1 The Influences of Physiological and Biochemical Characteristics of Cotton by Different DPC TreatmentsThe contents of leaf chlorophyll, MDA, soluble sugar, soluble protein and free proline were detected after treated by different DPC contents, also the activities of POD, SOD and CAT. The results show that, (1)chlorophyll, free proline and soluble protein were higher than the control in early days, with the increased concentration of free proline and soluble protein when DPC content increased. But in the later period the chlorophyll and free proline were lower than CK; (2) MDA content in leaves has been lower than CK, decreased with increased DPC contents; (3) soluble sugar content didn't change; (4) in early days, SOD activity was higher than the control, while later lower; POD and CAT activities were lower the control, then higher than CK. Therefore, the proper concentration of DPC could increase the ability of cell resistance to osmotic pressure, enhance the capacity of cotton resistance to stress, and improve drought resistance of cotton leaves, also the photosynthesis.2 The Influences of Physiological and Biochemical Characteristics of Cotton by Different Aphis Gossypii populationsThe contents of leaf chlorophyll, MDA, soluble sugar, soluble protein and free proline were detected after treated by different Aphis Gossypii populations, also the activities of POD, SOD and CAT.The results show that after the Aphis Gossypii feeding, chlorophyll, soluble protein and proline contents decreased, indicating that the resulting mineral malnutrition, leading to inhibition of chlorophyll, protein and proline synthesis. The more Aphis Gossypii, the more increased MDA content, whereas inhibition of MDA production. When 200 aphids/plant reached, MDA was highest, decreasing membrane stability. It damaged the maximum degree of membrane, and enhanced accumulation of MDA in leaves of cotton, which greatly promoted the cotton leaf senescence and reduced the cold hardiness of cotton leaves. As the aphids feeding on plant sap, most sap were discharged by the form of honeydew, sometimes up to 90%, so aphid honeydew excretion and the excretion of frequency can be used as the feeding rate and digestive capacity of signs. Most honeydew were sugars and amino acids, which could be used to supply nutrition, so as to improve the soluble sugar content of cotton leaves. After a small amount of aphids fed plant sap, it could reduce the SOD, POD and CAT activities, but a certain number of aphids could enhance the SOD, POD and CAT activities.3 The Influences of Physiological and Biochemical Characteristics of Cotton by DPC and then by Different Aphis Gossypii populations treatmentThe contents of leaf chlorophyll, MDA, soluble sugar, soluble protein and free proline were detected after treated by DPC and then by different Aphis Gossypii populations, also the activities of POD, SOD and CAT.The results show that in the same DPC concentration, with the increase of Aphis Gossypii populations, the contents of soluble sugar and MDA increased, but the contents of leaf chlorophyll, free proline and soluble protein content decreased, also SOD, POD, CAT activities decreased. In the same aphid population treatment, with the increase of DPC concentrations, the contents of chlorophyll, free proline and MDA increased, and soluble sugar and soluble protein had no change. SOD activity increased, but POD and CAT activities decreased.4 The Effects of Aphis Gossypii Population Reproduction by Different DPC ConcentrationsAphis Gossypii's contact toxicity, repellent effect, adult longevity and reproductive capacity and population growth were studied by different DPC concentrations. The results show that there was no contact effect. Within the same time after treatment, the repellent effect on aphids was enhanced with the concentration gradient increased.48h repellent rate was 33.3% treated by concentration of 400mg·L-1; and 48h repellent rate was 18.2% treated by 25mg·L-1.In the same concentration, with the processing time, the repellent effect increased. On the seventh day,48h repellent was 66.4% treated by concentration of 400 mg·L-1; 48h repellent rate of 46.2% treated by 25mg·L-1. The first day, the Aphis Gossypii life span and reproductive capacity of adults were not inhibited.And life expectancy was reduced only by 400 mg·L-1. As time moved on, Aphis Gossypii adult life and reproductive capacity were tapered, indicating that Aphis Gossypii life and reproductive capacity of adult were affected with cotton growth time by DPC treatments. DPC also had good effects on Aphis Gossypii inhibition.