硫化氢对淹水平邑甜茶根系形态构型、叶片活性氧和光合特性的影响

以盆栽平邑甜茶为试材,分别将盆浸没于5种浓度硫化氢(H₂S)释放剂硫氢化钠(NaHS;0、0.02、0.05、0.1、0.2 mmol·L^-1)水溶液,以及添加有次牛磺酸(HT;H₂S清除剂)的NaHS水溶液中,10 d后调查根系形态构型、叶片活性氧生成和光合气体交换参数以及植株生长的变化.结果表明: 在淹水处理液中加入0.02～0.1 mmol·L^-1 NaHS,能增加土壤淹水时根系总长度、表面积、体积、直径、根尖数、分形维数、一级侧根数量和根系活力,降低叶片超氧阴离子(O₂^-·)生成速率和过氧化氢(H₂O₂)含量,提高叶片光合速率(P_n)、蒸腾速率(T_r)、气孔导度(g_s)、水分利用效率(WUE)和表观CO₂利用效率(CUE),还提高幼苗株高和植株生物量,其中NaHS在浓度0.1 mmol·L^-1 时作用效果最显著;当NaHS施用浓度达到0.2 mmol·L^-1或在0.1 mmol·L^-1 NaHS中加施次牛磺酸时,上述指标均降回到单纯淹水时的水平.这说明添加适量H₂S能够有效缓解土壤淹水对平邑甜茶根系生长的抑制,可以通过减少活性氧产生以及提高CUE,从而减轻淹水胁迫对叶片光合性能和植株生长的不利影响.

Effects of hydrogen sulfide on root architecture,leaf reactive oxygen and photosynthetic characteristics of Malus hupehensis under waterlogging

The root architecture, leaf reactive oxygen species and photosynthetic characteristics of potted Malus hupehensis seedlings were investigated after 10 days of waterlogging under five concentrations of hydrogen sulfide (H₂S) donor sodium hydrosulfide (NaSH,0, 0.02, 0.05, 0.1, 0.2 mmol·L^-1) and NaSH with scavenger hypotaurine (HT). The results showed that the root length, root surface-area, root volume, root diameter, root top number, fractal dimension, first lateral roots and root activity all increased, the leaf superoxide anion (O₂^-·) accumulation and hydrogen pero-xide (H₂O₂) content both decreased, the leaf P_n, T_r, g_s, WUE and CUE all raised, the plant height and biomass both increased when the 0.02-0.1 mmol·L^-1 NaHS were added to the waterlogging environment. Adding 0.1 mmol·L^-1 NaHS showed the best effects. All these parameters dropped back to the level of waterlogging alone when NaHS concentration was 0.2 mmol·L^-1 or HT was added to the 0.1 mmol·L^-1 NaHS solution. These suggested that applying an appropriate amount of H₂S could effectively alleviate the inhibition of soil waterlogging on the root growth of M. hupehensis and relieve the effects of waterlogging stress on photosynthesis and plant growth by reducing the production of reactive oxygen species and increasing CUE.