The interactive effects of irradiance and photoperiod on Chara vulgaris L.: concerted responses in morphology, physiology, and reproduction

Abstract

Both the single and interactive effects of irradiance and photoperiod on a worldwide charophyte species, Chara vulgaris L., were investigated in a greenhouse experiment. Under high light intensity, plants exhibited shortened shoot, compact canopy and low Chl a/Caro. In contrast, elongated shoot, expanded canopy and low Chl a/Chl b corresponded to low light intensity. In addition, both ash mass ratio and relative growth rate (RGR) were positively related to light intensity. The effect of photoperiod on plants was relatively complex. Although photoperiod did not affect morphological characters, an increased photoperiod significantly decreased Chl a/Chl b and Chl a/ Caro ratios. Two-way analysis of variance (ANOVA) analysis indicated that significant interaction of irradiance and photoperiod was present on ash mass ratio, RGR, Chl a/Chl b, Chl a/Caro and Chl (a + b)/Caro ratios. The high RGR found for 50% sunlight, L:D 16:8 (50/16) conditions along with the significant interaction of irradiance and photoperiod on RGR indicated that the effect of irradiance was more important than photoperiod for plant growth. And finally, both irradiance and photoperiod had positive effects on the emergence of sex organs (#$) and the maturation of oospores, except that increased photoperiod did not accelerate the maturation of oospores. In summary, for both plant growth and reproduction, C. vulgaris was able to acclimate morphologically and physiologically to different irradiance levels and photoperiods. This study can partly explain the broad geographic distribution of C. vulgaris.

The mitigating effect of calcification-dependent of utilization of inorganic carbon of Chara vulgaris Linn on NH4-N toxicity

“…Chara vulgaris Linn, a polymorphic charophyte, has a broad, world-wide distribution between 70°N and 50°S and is prone to accumulate lime and form apparently non-banded encrustation on the stems (Anadón et al, 2002), with more than 60% of ash mass ratio under 50% of sunlight (Wang et al, 2008).…”

Morphological and reproductive differences among three charophyte species in response to variation in water depth

“…PG indicates the occurrence of sexual reproduction and PO indicates the maturation of oospores. A total of 4 or 5 apices (length: 3 to 5 cm) of 0.06 g of total fresh weight for each replicate were selected and extracted in 6 ml N,N-dimethylformamide (DMF) in order to determine pigment concentration (Wang et al 2008). Therefore, the harvested plant did not significantly affect the total DW.…”

“…Charophytes are bottom dwellers (Chambers & Kalff 1987a,b) and the responses of their stems to low light and high water levels have been well documented in previous studies. For example, charophytes can morphologically adapt to either high water levels or low light availability by elongating their stems toward the water surface (Andrews et al 1984a, Casanova 1994, Casanova & Brock 1999a, Blindow & Schütte 2007, Wang et al 2008. Conversely, acclimation of charophytes to low water levels or high light intensity can result in stunted stems, impacted apices, and in creased branchlet growth toward the apex as a way to protect the gametangia (Schneider et al 2006, Wang et al 2008, Schneider et al 2015.…”

“…For example, charophytes can morphologically adapt to either high water levels or low light availability by elongating their stems toward the water surface (Andrews et al 1984a, Casanova 1994, Casanova & Brock 1999a, Blindow & Schütte 2007, Wang et al 2008. Conversely, acclimation of charophytes to low water levels or high light intensity can result in stunted stems, impacted apices, and in creased branchlet growth toward the apex as a way to protect the gametangia (Schneider et al 2006, Wang et al 2008, Schneider et al 2015. Charophytes can also photosynthetically acclimate to different amounts of light by regulating pigment content and pattern (Andrews et al 1984b, Czeczuga 1986, Schagerl & Pichler 2000, Küster et al 2000, 2005, Wang et al 2008.…”

“…For example, the occurrence of sexual reproduction and maturation of oospores are stimulated by decreased water level (Casanova 1994, Casanova & Brock 1999a, Asaeda et al 2007) and increased light intensity (Wang et al 2008). For some charophyte species with bulbils (vegetative, starch-rich organs), the proportion of bulbils (PB) by total dry weight depends on water depth (Casanova 1994) and light intensity, including light used for photosynthesis and traits that are related to photo-inhibition for protection from ultraviolet (UV) radiation (de Bakker et al 2001).…”