不同氮素水平下CO_2倍增对转Bt棉花氮素代谢的影响

通过开顶式CO_2气室研究了盛蕾期转Bt棉花新棉33~B及其对照亲本DP5415的生长势和氮素代谢特征对土壤氮素水平(100和200 mg N·kg~(-1))和CO_2浓度倍增(750和375μl·L~(-1))的生理生态响应.结果表明:CO_2浓度升高可显著提高2种棉花的株高和茎粗,增加生物产量;氮素水平提高可显著增加转Bt棉花的株高、茎粗,以及茎和蕾的鲜质量,而对亲本棉花DP5415的影响不显著;对照棉花DP5415的谷氨酰胺合成酶(GS)活力随大气CO_2浓度的升高而显著降低,随氮素营养的提高而升高,转Bt棉花新棉33~B在低氮条件下,GS活力随大气CO_2浓度的升高而显著增加;大气CO_2浓度升高及氮素营养的增加使盛蕾期转Bt棉花的硝酸还原酶(NR)活力显著增加,DP5415的NR活力也随大气CO_2浓度的升高而显著提高;大气CO_2浓度对2种棉花的亚硝酸还原酶(NiR)活力都有明显的抑制作用,其中,高CO_2浓度条件下,DP5415的NiR活力还随氮素营养的增加而显著下降.可见,大气CO_2浓度升高下,土壤氮素水平变化对转Bt棉花的生长势影响显著,但对其氮素代谢生理的影响较对照亲本棉花小.生产中(尤其是高浓度CO_2环境下),应进一步加强转Bt棉花的氮肥优化管理.

Abstract：

By using open-top chambers, this paper studied the physiological and ecological re-sponses of transgenic Bt cotton cv. 33~B and its parent line non-transgenic cotton cv. DP5415 in their growth potential and nitrogen metabolism to doubled CO_2 concentration (750 μl·L~(-1) vs.375 μl·L~(-1)) and nitrogen fertilization level (200 mg N·kg~(-1)vs. 100 mg N·kg~(-1)). Doubled CO_2 concentration promoted the height-and stem growth and the biomass production of the two eultivars significantly, whereas doubled N fertilization level only had significant positive effects on 33~B. The leaf glutamine synthetase activity (GSA) of DP5415 decreased significantly under doubled CO_2 concentration but increased significantly under doubled N fertilization level, while the GSA of 33~B was significantly higher under doubled CO_2 concentration and low nitrogen fertili-zation level. Both the doubled CO_2 concentration and the doubled nitrogen fertilization level in-creased the leaf nitrate reductase activity (NRA) of 33~B significantly, and the NRA of DP5415 also had a significant increase under doubled CO_2 concentration. Doubled CO_2 concentration had significant inhibitory effects on the leaf nitrite reductase activity (NiRA) of both 33~B and DP5415. The NiRA of DP5415 decreased significantly under doubled CO_2 concentration and N fertilization level. All the results suggested that under doubled CO_2 concentration, N fertilization level had significant effects on the growth potential of transgenic Bt cotton but lesser effects on its nitrogen metabolism, compared with the control non-transgenic cotton. Therefore, in the planting of transgenic Bt cotton, especially,under elevated CO_2 condition, optimized N fertilization should be made.

Effects of doubled atmospheric CO_2 concentration on nitrogen metabolism of transgenic Bt cotton under different nitrogen fertilization levels

By using open-top chambers, this paper studied the physiological and ecological re-sponses of transgenic Bt cotton cv. 33~B and its parent line non-transgenic cotton cv. DP5415 in their growth potential and nitrogen metabolism to doubled CO_2 concentration (750 μl·L~(-1) vs.375 μl·L~(-1)) and nitrogen fertilization level (200 mg N·kg~(-1)vs. 100 mg N·kg~(-1)). Doubled CO_2 concentration promoted the height-and stem growth and the biomass production of the two eultivars significantly, whereas doubled N fertilization level only had significant positive effects on 33~B. The leaf glutamine synthetase activity (GSA) of DP5415 decreased significantly under doubled CO_2 concentration but increased significantly under doubled N fertilization level, while the GSA of 33~B was significantly higher under doubled CO_2 concentration and low nitrogen fertili-zation level. Both the doubled CO_2 concentration and the doubled nitrogen fertilization level in-creased the leaf nitrate reductase activity (NRA) of 33~B significantly, and the NRA of DP5415 also had a significant increase under doubled CO_2 concentration. Doubled CO_2 concentration had significant inhibitory effects on the leaf nitrite reductase activity (NiRA) of both 33~B and DP5415. The NiRA of DP5415 decreased significantly under doubled CO_2 concentration and N fertilization level. All the results suggested that under doubled CO_2 concentration, N fertilization level had significant effects on the growth potential of transgenic Bt cotton but lesser effects on its nitrogen metabolism, compared with the control non-transgenic cotton. Therefore, in the planting of transgenic Bt cotton, especially,under elevated CO_2 condition, optimized N fertilization should be made.