白羊草与达乌里胡枝子混播时其叶片叶绿素荧光特性对土壤水分变化的响应

Chlorophyll Fluorescence Characteristics of Bothriochloa Ischaemum with Periodical Soil Water Change when Intercropped with Lespedeza Davurica

[目的]研究半干旱黄土丘陵区白羊草群落优势种叶绿素荧光特性对土壤水分变化的响应,为进行水土保持林草措施合理配置提供科学依据。[方法]采用盆栽控制试验,设置7个组合比例(白羊草∶达乌里胡枝子,0∶12,2∶10,4∶8,6∶6,8∶4,10∶2和12∶0)和3种水分水平(高水HW,中水MW和低水LW),在拔节期、开花期与结实期将从高水分别降至中水(H-MW)和低水(H-LW)处理,并于水分变化后第0,2,4,6,8 d测定白羊草叶绿素荧光参数。[结果]最大光化学效率(可变荧光/最大荧光,Fv/Fm),实际光化学效率(ФPSⅡ)和表关量子传递速率(ETR)均随水分胁迫持续出现降低趋势,以结实期从高水处理降至低水处理下的降低幅度最显著;拔节期和开花期的Fv/Fm和ФPSⅡ显著高于结实期,且多数处理下的Fv/Fm大于0.750;H-MW和H-LW处理下土壤水分降低后非光化学淬灭系数(NPQ)在拔节期呈现升高趋势,而在开花期和结实期出现降低趋势,但光化学淬灭系数(qp)在3个生育期间呈相反变化趋势;土壤水分降低后第8 d,结实期的Fv/Fm和ФPSⅡ以H-MW显著高于H-LW,且大多数处理下12∶0组合比例的Fv/Fm,ФPSⅡ和ETR均显著低于其他组合比例处理。[结论]与达乌里胡枝子混播种植促进了土壤水分阶段降低条件下白羊草的叶片PSⅡ光化学活性。

[Objective] Chlorophyll fluorescence characteristics of Bothriochloa ischaemum in response to soil water periodical change were studied in order to provide a theoretical basis for the rational utilization of forest and grass measures for soil and water conservation in loess hilly regions. [Methods] Seven mixture ratios(B. ischaemum to Lespedeza davurica, 0∶12, 2∶10, 4∶8, 6∶6, 8∶4, 10∶2, and 12∶0) and three soil water regimes [HW 80%±5% of field capacity(FC), MW 60%±5% of FC, LW 40%±5% of FC)] were set in the pot experiment, and soil water content was reduced separately from HW to MW(H-MW) or from HW to LW(H-LW) during the heading period, flowering period, and mature period, respectively. Chlorophyll fluorescence parameters of B. ischaemum were measured at 0, 2, 4, 6, and 8 days after soil water reduced. [Results] Maximum photochemical efficiency(maximam fluorescence/variable fluorescence, Fv/Fm), active photochemical efficiency(ФPSⅡ) and apparent electron transport rate(ETR) showed decreasing trends with the water stress decrease, and those values decreased much more under H-LW-3. Fv/Fm and ФPSⅡ in the heading period or the flowering period were signicantly higher than in the mature period, and the Fv/Fm was larger than 0.750. Non-photochemical quenching(NPQ) showed increasing trends in the heading period and flowering period, and decreasing trends in the mature period, but the photochemical quenching(qp) showed opposite trends during the growth period. After 8 days of soil water reduction, Fv/Fm and ФPSⅡ in the mature period under H-MW were signicantly higher than under H-LW, and Fv/Fm, ФPSⅡ, and ETR in the 12∶0 mixture ratio were signicantly lower than in others under most water treatments. [Conclusion] The application of mixture planting enhanced the PSⅡ photochemical activity of B. ischaemum when intercropped with L. davurica under periodically decreasing soil water conditions.