Abstract
Some charophyte species reproduce sexually by oospores and vegetatively by bul- bils, and the proportion of branch whorls that contain reproductive organs can be used as quanti- tative measures of the degree of sexual reproduction. We examined inter-specific differences in the proportion of bulbils (PB) by total weight and the proportion of branch whorls containing gametangia (PG) or oospores (PO), as well as morphological and physiological differences among 3 charophyte species (Chara vulgaris Linnaeus, Chara braunii Gmelin, and Nitella gracilens Morioka) responding to variation in water depth (0.5, 1, 1.5, 2, and 3 m) in an outdoor experiment. A 2-way ANOVA contrasting species and water depth revealed that shoot elongation and the chlorophyll a to carotenoid (chl a/caro) ratio were primarily affected by water depth. However, variation among species contributed more than water depth to the differences in weight, sexual reproduction (PG and PO), and the chl a/chl b ratio. Additionally, variation among species con- tributed almost equally to the differences in PB that occurred among different water depths. Both Chara species extended their shoots and increased their PB in response to increasing water depth (from 0.5 to 1.5 m). However, deeper water (2 and 3 m) led to elongated shoots as well as decreased PB, PG, and PO. For N. gracilens, elongated shoots with increased water depth (from 0.5 to 3 m) occurred at the expense of both vegetative (decreased PB) and sexual reproduction (reduced PG and PO).
Highlights
Light is a critical factor for charophyte growth and reproduction (Spence & Chrystal 1970, Spence 1976, 1982, Stross et al 1988, 1995)
For some charophyte species with bulbils, 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
C. vulgaris flourished at depths of 1.5 to 2 m, but were interspersed with vascular plants in deep water (2 to 3 m)
Summary
Light is a critical factor for charophyte growth and reproduction (Spence & Chrystal 1970, Spence 1976, 1982, Stross et al 1988, 1995). 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. Charophytes can morphologically adapt to either high water levels or low light availability by elongating their stems toward the water surface 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)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
