Effects Of Transgenic Resistant-pest Cotton On Soil Fertility Quality

Scientists had culivated successfully transgenic resistant-pest cotton since early 1990s and transgenic resistant-pest cotton was one of transgenic plants which had been released quickly and commercially in global agricultural area. Transgenic resistant-pest plants can release transgene proteins through their residues,root exudates and pollens, and these proteins are bound rapidly to soil active particles and persisted in soil.Simultaneity, compared to conventional cotton,some chemical composition of transgenic resistant-pest plants have been changed because of the insertion of foreign transgenes.These differentia may lead to affect on the natural degradaion of transgenic resistant-pest plants in soil.With the large scale release of transgenic resistant-pest plants ,it needs urgently to understand their influence to the soil fertility ,then to soil ecosystem safety.Based on the cotton farmland of the Chinese Agriculture Academy of Science Institute(Henan, Anyang), identical soil type which has been planted traditional(non-transgenic)cotton and 5th year transgenic resistant-pest cotton and 10th year transgenic resistant-pest cotton has been researched. According to cotton's different vegetal period, we gathered the cotton field surface layer soil (0 - 20cm) on November 13 and 2005, April 3, 2006 and July 17, 2006 and October 16, 2006. We analysed the chemical and physical properties and the biological activities of the soil samples in the laboratory in order to research the effects of transgenic resistant-pest cotton on the soil fertility. Moreover, the population and number of the soil animals were investigated in three blocks cotton field by 5-spots. Meantime, through feeding earthworms(Eisenia foetida) by two kinds of leaves of transgenic resistant-pest cotton and traditional cotton in order to research the effects of transgenic resistant-pest cotton on the earthworm. The results were as below.1. There were no significant differences in the soil caly content , pH, organic matter,N/P/K total quantity and effective quantity in farmland planted with conventional cotton and transgenic resistant-pest cotton .2. There are positive effects for soil microbiological properties ( soil enzymes activitiesthe) in farmland planted with transgenic resistant-pest cotton ,compared to conventional cotton . soil dehydrogenase and catalase activities in the transgenic resistant-pest cotton were increased significantly. For example, the soil dehydrogenase activities in the 5th transgenic resistant-pest cotton and the soil catalase activities in the 10th transgenic resistant-pest cotton was higher than that in the conventional cotton. 3. There were no significant differences in the quantity of soil small invertebrates (belong to zoological properties of soil fertility quality ) in farmland planted with transgenic resistant-pest cotton ,compared to conventional cotton . however,it is the less dominant taxons of soil small invertebrates in farmland planted with transgenic resistant-pest cotton ,compared to conventional cotton . There were inconsistent effects of transgenic resistant-pest cotton on Simpson,Shannon-wiener diversity Indexes or Pielou evenness Index of the soil small invertebrates comparison with the conventional cotton.4. There weren,t negative effects on reproducation and growth of earthworms (Eisenia foetida)after 201 days under lab experimental feeding by the cotton leaves of transgenic resistant-pest cotton (zhong41)and conventional cotton(zhong35). At the same time, there was no significant diffences in SOD activity of earthworms in most investigating time.there were no significant diffences in the soil matrx nutrient content except for the available K after feeding experiment.5. There isn,t significant decrease in the siol fertility quality of the farmland planting 10th transgenic resistant-pest cotton. The effects of conventional cotton and transgenic resistant-pest cotton at the different periods of growth on some soil fertility indexes were investigated. There were no significant differences in the soil total phosphorus content and enzyme activities. However, the soil caly content, total nitrogen and total potassium were reduced in the later periods of cotton growth. The soil pH and the organic matter content were increased in in the later periods of cotton growth. The available N/K were highest in the intermediate periods of cotton growth,and the available P was lowest in the earlier period of cotton growth. These have provided a lot of experience for the scientific management of cotton growth.