脱硫石膏改良盐碱土对水稻叶绿素荧光特性的影响

为揭示脱硫石膏改良盐碱土对水稻叶绿素荧光特性的影响,以水稻品种吉特605为试验材料,以不采用任何改良技术为对照(CK),设计4种脱硫石膏改良盐碱土技术集成模式,分别在水稻出苗期、分蘖期、孕穗期和灌浆期连续2年监测土壤电导率(EC)和pH值,测定水稻叶片叶绿素荧光参数和叶绿素含量,分析4种集成模式的改良效果。结果表明,随着处理时间的延长,与CK相比,各技术集成模式下土壤EC和pH值均极显著降低,水稻叶片叶绿素荧光参数Y、ETR、F_m、F_v/m等均显著增加(P<0.05),F_o呈下降趋势。除F_o、qP与叶绿素相对含量(SPAD)和叶片叶绿素含量(LCC)之间无显著相关性外(P>0.05),其他叶绿素荧光参数与SPAD和LCC之间均呈极显著正相关(P<0.01),其中NPQ与LCC之间相关系数最大,为0.771。各技术集成模式下qP的2年均值在4个生育时期均无显著差异(P>0.05),模式D和E下SPAD的2年均值均显著高于CK,模式E下LCC的2年均值也较CK显著升高。在各生育时期,各技术集成模式下叶绿素荧光诱导动力学曲线均表现出相同的变化趋势,但曲线中各特征点出现的时间不同,峰值也不同;随着技术集成模式的优化,斜率逐渐增大,各个特征点的相对可变荧光强度值均呈递增趋势。通过主成分分析,在水稻出苗期、分蘖期、孕穗期和灌浆期均提取到2个主成分,累积贡献率分别为96.285%、93.491%、91.285%和95.104%。利用隶属函数与权重对4种技术集成模式进行综合评价,获得了可综合评价改良效果的D值,排名依次为E>D>C>B>CK,说明模式E,即脱硫石膏22.5 t·hm^-2+改良剂7.5 t·hm^-2+有机肥30.0 t·hm^-2+黄沙30.0 t·hm^-2改良盐碱土的效果最佳。在此基础上,结合合理的灌排措施可有效缓解盐碱土对水稻幼苗的伤害,明显提高水稻叶片的叶绿素含量和光合电子传递效率,减轻盐碱胁迫对水稻生长过程中PSII系统的损伤。本研究结果为脱硫石膏改良盐碱土种植水稻提供了理论依据和技术保障。

Effects of Saline-alkali Soil Improved by Desulfurized Gypsum on Chlorophyll Fluorescence Characteristics of Rice

In order to reveal effects of saline-alkali soil improved by desulfurized gypsum on chlorophyll fluorescence characteristics in rice, a rice variety Jite605 was used as material, four combinations of integrated technology were designed, and no soil ameliorants application was used as control. Simultaneously, soil EC and pH, chlorophyll fluorescence parameters and chlorophyll content in rice leaves were measured in two consecutive years at rice seedling, tillering, booting and grain filling stages, and the modified effects of four integrated modes were analyzed. The results showed that with the extension of treatment time, compared with the control, the soil EC and pH values were significantly decreased under different modified combinations. The chlorophyll fluorescence parameters Y, ETR, F_mand F_v/m of rice leaves increased significantly (P<0.05) and F_o showed a decreased trend. Except for the original fluorescence (F_o), photochemical quenching coefficient (qP), there were significant positive correlations between SPAD, leaf chlorophyll content (LCC) and other chlorophyll fluorescence parameters (P<0.01), among which the correlation coefficient between NPQ and LCC was the largest, which was 0.771.The two-year average value of qP in each technology integrated modes had no significant difference in these four growth stages (P>0.05). The two-year average value of SPAD in mode D and E were significantly higher than A(CK) and LCC in mode E, and was also significantly higher than A(CK). At different growth stages, the chlorophyll fluorescence induction curves of each integrated modes showed the same trend, but the time of each characteristic point in the curve appeared differently and the peak value was different. As the improved modes optimized, the slope and the relative variable fluorescence intensity values of each feature point increased gradually. Through principal component analysis, two principal components were extracted at the seedling, tillering, booting and grain filling stages, and the cumulative contribution rates were 96.285%, 93.491%, 91.285% and 95.104%, respectively. An objective comprehensive evaluation value (D value) of the comprehensive evaluation improvement effect was obtained using membership function with index weight method. The ranking followed the order of E>D>C>B>A(CK), indicated that the mode E had the best effect to improve saline-alkali soil. On this basis, combining with reasonable irrigation and drainage measures can effectively alleviate the damage of saline-alkaline soil to rice seedlings, significantly improve the chlorophyll content and photosynthetic electron transport efficiency of rice leaves, and reduce the damage of PSII during rice growth under saline-alkali stress. The results provide a theoretical basis and technical guarantee for planting rice using the desulfurized gypsum to improve saline-alkaline soil.