Effects Of Bt Rice Straw Extract On Growth And Defense Enzyme Activity Of Vegetables Planted In Winter

Bacillus thuringiensis?Bt?rice is genetically modified to express insecticidal crystal protein from bacterium B.thuringiensis that is toxic to some lepidopteran pests.Straw returning is one of the major pathway through which Bt proteins release into the soil.The effect of Bt rice straw on vegetables planted in winter is a worthy scientific research.The experiment includes two parts,we used non-Bt rice?Tianyouhuazhan?,homozygous Bt rice?T775?and heterozygous Bt rice?F₁ of T775 hybrid?straw.Straw extracts were diluted into various concentrations(10,20 and 40 g·L^-1)for the treatment.One of is lab experiment:straw extracts(0,10,20and 40 g·L^-1)process the seeds of Pakchoi,flowering Chinese cabbage and lettuce.After 1 week,we recorded the germination rate of Pakchoi,flowering Chinese cabbage and lettuce seeds.Simultaneously,we determined the seedling dry weight,root length,shoot height.Another is pot experiment:straw extracts(0,10,20 and 40g·L^-1)process the plants of Pakchoi,flowering Chinese cabbage and lettuce every 3days.During the second weeek,the fourth week and the sixth week,we measured plant height of Pakchoi,flowering Chinese cabbage and lettuce Simultaneously,we determined dry weight aboveground and belowground part,defense enzymes?peroxidase[POD],superoxide dismutase[SOD]and catalase[CAT]activity?changes in both leaves and roots and chlorophyll content in leaves.In the hope of further providing theoretical basis for the ecological risk assessment of Bt rice.The main results are as follows.?1?Compared to 0 g·L^-1,heterozygous Bt rice straw extract at the highest concentration significantly decreased the seed germination rate of Pakchoi,increased the dry weight of Pakchoi,as well as non-Bt rice and heterozygous Bt rice straw extract significantly inhibited root elongation of Pakchoi.In the growth period,rice?non-Bt rice,homozygous Bt rice and heterozygous Bt rice?straw extract signicantly increased the aboveground dry weight of Pakchoi.Non-Bt rice,homozygous Bt rice and heterozygous Bt rice significantly decreased POD activity in root.Compared to non-Bt rice straw ertract,homozygous Bt rice straw extract increased height of seedling and plant,aboveground dry weight,enhanced leave and root CAT activity.Heterozygous Bt rice straw extract decreased germination of Pakchoi,inhibited POD activity.?2?For flowering Chinese cabbage,compared to 0 g·L^-1,heterozygous Bt rice straw extract at higher concentration significantly inhibited root enlongation.Non-Bt rice,homozygous Bt rice and heterozygous Bt rice under different concentrations significantly increase the dry weight of flowering Chinese cabbage.In the growth period,rice?non-Bt rice,homozygous Bt rice and heterozygous Bt rice?straw extract did not affect the growth of flowering Chinese cabbage.Non-Bt rice and homozygous Bt rice straw extract significantly increased the CAT activity in leaves,decreased POD activity in root.Heterozygous Bt rice straw extract significantly increased the CAT activity in leaves and in root,decreased the POD activity in leaves.Compared to non-Bt rice straw ertract,homozygous Bt rice and heterozygous Bt rice straw extract increased dry weght and the length of root,increased CAT activity both in leaves and roots,decreased POD activity in roots.?3?Compared to 0 g·L^-1,rice?non-Bt rice,homozygous Bt rice and heterozygous Bt rice?straw extract did not affect the seed germination of lettuce,significantly increased the dry weight and promoted shoot growth.Non-Bt rice straw extract at low concentration promoted root elongation of lettuce,homozygous Bt rice at the highest concentration inhibited the root elongation of lettuce.Non-Bt rice,homozygous Bt rice and heterozygous Bt rice straw extract did not affect the affect plant height,aboveground dry weight of lettuce,significantly increased underground dry weight of lettuce in the growth period.Non-Bt rice straw extract significantly decreased CAT activity in leaves.Hmozygous Bt rice straw extract increased SOD activity in leaves and SOD,CAT activity in root,decreased CAT in leaves.Heterozygous Bt rice straw extracts significantly decreased CAT activity in leaves.Compared to non-Bt rice straw ertract,homozygous Bt rice straw ertract inhibited root enlongation,underground dry weight,while enhanced SOD and CAT activity.Heterozygous Bt ricestraw extract decreased undergrounddry weight,POD activity in root of lettuce.Above of all,compared to non-Bt rice straw extract,two varieties of Bt rice straw extract had different effects on growth and defense enzymes activity of Pakchoi,flowering Chinese cabbage.and lettuce,because of different material and detection index.Compared to non-Bt rice straw extract,homozygous Bt rice straw extract promoted the growth of Pakchoi and flowering Chinese cabbage,strengthen CAT activity of Pakchoi,flowering Chinese cabbage and lettuce,inhibited root enlongation and decreased underground dry weight of lettuce,decreased root SOD activity of flowering Chinese cabbage.Heterozygous Bt rice straw extract decreased gernimiaton of Pakchoi,underground dry weight of lettuce,decreased POD activity of Pakchoi and lettuce,root SOD activity and POD activity of flowering Chinese cabbage.