| Effect of atmospheric CO2concentration on crop growth have already become one of global change studies. Culture experiment was used in this thesis, and conducted with two varieties of oilseed rape (Brassica napus L.)(X-2and X-6) under normal and deficiency nitrogen (N) application conditions. Effects of elevated CO2on growth and production, root morphological and physiological indexes, N absorption efficiency and N efficiency in oilseed rape were studied in thesis. It will provide scientific basis for investigating response of oilseed rape growth mechanism to atmospheric CO2concentration, N levels and varieties. The results showed that:1.Results of growth and metabolism indexes showed that, increased trend of plant height, root diameter, dry matter weight of above ground, contents of total soluble sugars and nitrate of stem and leaf, root cap rate were expressed under CO2enrichment condition, but decreased trend of nitrate reeducates activity and SPAD in leaves, free amino acid of stem and leaf were expressed. Effect of CO2enrichment on growth and metabolism of oilseed rape are closely related to N application levels, expressed with the above indexes were changes more under normal N application condition. Effect of CO2enrichment on growth and metabolism indexes were related to verities, Root diameter, root cap rate, dry weight, total soluble sugars increasing, free amino acid content, SPAD decreasing of X-6was higher than X-2, but nitrate content showed as contrary results.2.Root morphological and physiological characters of oilseed rape were determined. Results showed that the total volume, total weight,total absorption area and active absorption area of root system per plant were increased, and quantity of lateral root, total root length, root activity was decreased. Effects of CO2enrichment on root indexes were related to N level and varieties. Root indexes increasing of normal N application level was higher than deficiency N condition under CO2enrichment condition, but root indexes decreasing of normal N application level was lower than deficiency N condition. Responses of every indexes to N application levels in X-2was higher than X-6, expression with decreased range of root indexes in X-2was higher than X-6under N deficiency condition when CO2enrichment in atmospheric.3.Nitrogen absorption accumulation of rape were determined. The results showed that nitrogen accumulation of all organism in rape (except leaf)and nitrogen accumulation per plant increased and nitrogen content of all parts of rape trend to decrease due to the dry matter accumulation increasing was much greater than amount of nitrogen accumulation.Effects of CO2enrichment on nitrogen accumulation and nitrogen content were related to nitrogen level and varieties. Nitrogen accumulation and nitrogen content increasing were under normal nitrogen more than N deficiency and decreasing were on the contrary with CO2enrichment. When nitrogen accumulation and nitrogen content decreasing were X-2more than X-6under N deficiency with CO2enrichment.4.Nitrogen efficiency of rape were determined. The results showed that nitrogen use efficiency of all treatments increased and nitrogen absorption efficiency,nitrogen efficiency trend to increase with the elevation of CO2concentrations. Effects of CO2enrichment on nitrogen absorption efficiency were related to nitrogen level and varieties. Nitrogen absorption efficiency of all growing periods increased in X-6, decreased at bolting stage and flowering stage with deficiency N, increased at silique mature stage and no change at three stages with normal N in X-2with CO2enrichment. Effects of CO2enrichment on nitrogen efficiency content were related to nitrogen level and varieties. Nitrogen efficiency under elevated CO2concentration was higher than atmospheric CO2concentration,but Nitrogen efficiency at flowering stage under N deficiency was on the contrary. |
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