根茎萌发与幼苗期的虉草水分生态幅

Water ecological amplitude of Phalaris arundinacea at rhizomatic germination and seedling stage

关键词:  虉草, 土壤水分含量, 根茎, 萌发, 幼苗期, 水分生态幅

Key words:  Phalaris arundinacea, soil water content, rhizome, germination, seedling stage, water ecological amplitude

摘要:

为揭示虉草根茎萌发和幼苗期的水分生态幅,该研究通过盆栽控制试验,设置8个水分梯度:(2 ± 0.5)%、(10 ± 0.5)%、(15 ± 0.5)%、(20 ± 0.5)%、(25 ± 0.5)%、(30 ± 0.5)%、(40 ± 0.5)%(水分饱和)和淹水(2 cm),通过萌发率、各形态指标和生理指标对虉草水分生态幅进行了探讨。结果表明:(1)土壤水分含量过低和过高都会降低虉草根茎萌发率。(2)随土壤水分含量的增加,虉草幼苗株高和地上生物量都呈现先上升后下降的趋势,两者并呈指数函数关系y = 0.203 8e^{0.048 6x}(R² = 0.803)。(3)虉草通过调整自身结构特点,降低个体大小、减少叶片数量和叶面积来适应胁迫环境,土壤水分含量为10%～30%时虉草含水率能保持相对稳定的水平。虉草的光和色素(Chl a、Chl b、Car)和相对叶绿素(SPAD)含量均随土壤水分含量的增加呈现出先上升后下降的趋势,Chl a/b则相反,呈先下降后上升趋势。(4)Chl/Car各组之间差异不显著。综合上述研究,利用高斯模型分析得出虉草的水分生态幅为7.48%～52.20%,最适水分生态幅为18.99%～40.60%。

Abstract:

We carried out an indoor culturing experiment to cultivate Phalaris arundinacea using rhizome to explore water ecological amplitude at rhizomatic germination and seedling stage. We exposed P. arundinacea to C1(2 ± 0.5)%, C2(10 ± 0.5)%, C3(15 ± 0.5)%, C4(20 ± 0.5)%, C5(25 ± 0.5)%, C6(30 ± 0.5)%, C7(40 ± 0.5)%(water saturation)and C8 flooding(2 cm)for 60 d, and determined the germination rate and various physiological indexes and morphological indexes. The results were as followes:(1)Rhizomatic germination rate of the plants was lowered by drought or excessive saturated of soil water content, but the rhizome still had stronger drought-resistance than seeds. Plant height and aboveground biomass increase firstly and then decreased with the increase of soil water content. The relationship between the plant height and aboveground biomass could be described as an exponential function: y = 0.203 8e^0.0486x(R² = 0.803 2).(2)The plants could adapt to the stress environment by adjusting the structural features, reducing the size, and decreasing the leaf number and the leaf area. Leaf length, leaf width, leaf number and leaf area showed the similar trend of increasing firstly and then decreasing with the increase of soil water content. When the soil water content ranged between 10%-30%, the water content of plant were able to maintain stability, and then increased with the increase of soil water content.(3)Chl a, Chl b, Car and SPAD contents in young shoots followed the same trend in variation, increasing firstly and then decreasing with the increase of soil water content. But Chl a/b content decreased firstly and then increased, did no differ much in the eight treatments.(4)There is no significant difference of Chl/Car in these treatments. In drought or excessive saturated of soil water content, the plants adjusted the distribution of Chl a and Chl b, raised Chl a /b, maintained Car /Chl, in order to maintain the regular photosynthesis process. Based on the above analysis, quantitive analysis on rhizomatic germination rate, morphological indexes and physiologic indexes by Gaussian Model, it is clear that the water ecological amplitude of P. arundinacea for rhizomatic germination and seedling stage was 7.48%-52.20%, and the optimum water ecological amplitude was 18.99%-40.60%.