NaHSO_3对油菜苗期光合特性及氮代谢的影响

Effects of NaHSO_3 on photosynthetic characteristics and nitrogen metabolism of rapeseed seedlings

为研究光合促进剂NaHSO3促进油菜叶片光合的作用机理,以甘蓝型油菜中双11号为材料,在水培条件下研究了不同浓度NaHSO3（0~0.08mmol·L-1）处理对五叶期幼苗生长发育、氮代谢及光合荧光特性的影响。结果表明,水培条件下,低浓度（0.02mmol·L-1）NaHSO3处理10d、15d和20d后植株株高均显著增加,分别比对照提高21.0%、28.4%和40.4%;鲜重和根长虽有增加但与对照相比差异不显著;高浓度（0.08mmol·L-1）NaHSO3处理10~20d后显著抑制植株根系长度,抑制率为15.1%~16.5%。不同NaHSO3浓度处理均显著增加了叶绿素b和总叶绿素含量,其中0.02mmol·L-1NaHSO3处理对叶绿素含量的促进作用最大,且只有该浓度处理会显著提高叶绿素a含量;NaHSO3处理油菜后,净光合速率、光饱和点和表观量子效率显著增加,光呼吸速率显著降低;最大光能转化率（Fv/Fm）和实际光能转化率（ΦPSⅡ）增加,非光化学猝灭系数（NPQ）降低;不同NaHSO3浓度处理均能增加硝酸还原酶（NR）和谷氨酰胺合成酶（GS）的活性,其中对NR的促进作用在0.02mmol·L-1达到最高。本研究结果表明,NaHSO3对光合速率的促进作用与光呼吸抑制无关,而是主要通过促进油菜叶片中叶绿素b含量增加,进而提高了光能吸收和传递效率,因此光合速率提高。

To understand the mechanism of NaHSO3 as a photosynthetic accelerator on rapeseed, the effects of NaHSO3 on growth, nitrogen metabolism and photosynthetic characteristics of Brassica napus cuhivar Zhuangshuang 11 were investigated in liquid solution added with NaHSO3 at the concentration of 0 -0.08 mmol/L. Results showed that with 0.02 mmol/L NariS03, plant height increased by 21.0% , 28.4% and 40.4% respectively after 10, 15 and 20 days. Their fresh weight and root length were also increased but not significantly different to the control. With 0.08 mmol/L NaHSO3, root length was significantly decreased by 15.1 - 16.5% after 10 - 15 days. Contents of chlorophyll b and total chlorophyll in rapeseed seedlings significantly increased under all concentrations of NaHSO3 treatments. Increase of chlorophyll a was observed only at 0.02 mmoL/L NaHSO3 treatment, and the highest contents of chlorophyll b and total chlorophyll were also achieved. After NaHSO3 treatment, photosynthetic rate （ Pn）, light saturation point （LCP） and apparent quantum efficiency （AQY） increased significantly, while photorespiration rate （ Rp）, intercellular concentration of CO2 （Ci） and transpiration rate （Tr） declined significantly. With a higher maximum light energy conversion rate （Fv/Fm） and actual light energy conversion rate （ФPSⅡ） and a lower non -photochemical quenching coefficient （NPQ）, the low concentration of NaHSO3 resulted in an increasing of the share of light energy which was used to describing photochemical transfer. The activity of nitrate reductase （NR） and glutamine synthetase （SR） increased after NaHSO3 treatment. In conclusion, NaHSO3 improved the photosynthesis through the increase of chlorophyll b content, which led to a higher efficiency of electronic absorption and transportation.