不同氮素水平下CO_2倍增对转Bt棉花氮素代谢的影响

Effects of doubled atmospheric CO_2 concentration on nitrogen metabolism of tra nsgenic Bt cotton under different nitrogen fertilization levels.

通过开顶式CO2气室研究了盛蕾期转Bt棉花新棉33B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200mgN.kg-1)和CO2浓度倍增(750和375μl.L-1)的生理生态响应。结果表明:CO2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CO2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33B在低氮条件下,GS活力随大气CO2浓度的升高而显著增加;大气CO2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CO2浓度的升高而显著提高;大气CO2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CO2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CO2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CO2环境下),应进一步加强转Bt棉花的氮肥优化管理。

By using open-top chambers, this paper studied the physiological and ecological responses 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 CO2 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 CO2 concentration promoted the height- and stem growth and the biomass production of the two cultivars 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 CO2 concentration but increased significantly under doubled N fertilization level, while the GSA of 33^B was significantly higher under doubled CO2 concentration and low nitrogen fertilization level. Both the doubled CO2 concentration and the doubled nitrogen fertilization level increased the leaf nitrate reductase activity （NRA） of 33^B significantly, and the NRAof DP5415 also had a significant increase under doubled CO2 concentration. Doubled CO2 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 COs concentration and N fertilization level. All the results suggested that under doubled CO2 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 CO2 condition, optimized N fertilization should be made.