Effects of growth temperature and winter duration on leaf phenology of a spring ephemeral (Gagea lutea) and a summergreen forb (Maianthemum dilatatum)

Spring ephemeral herbs inhabiting deciduous forests commonly complete reproduction and vegetative growth before canopy closure in early summer. Effects of shading by early canopy closure on reproductive output and vegetative growth, however, may vary depending on the seasonal allocation patterns of photosynthetic products between current reproduction and storage for future growth in each species. To clarify the effects of sink-source balance on seed production and bulb growth in a spring ephemeral herb, Gagea lutea, we performed a bract removal treatment (source reduction) and a floral-bud removal treatment (sink reduction) under canopy and open conditions. Leaf carbon fixations did not differ between the forest and open sites and among treatments. Bract carbon fixations were also similar between sites but tended to decrease when floral buds were removed. Seed production was higher under open condition but decreased by the bract-removal treatment under both light conditions. In contrast, bulb growth was independent of light conditions and the bract-removal treatment but increased greatly by the bud-removal treatment. Therefore, leaves and bracts acted as specialized source organs for vegetative and reproductive functions, respectively, but photosynthetic products by bracts were flexibly used for bulb growth when plants failed to set fruits. Extension of bright period was advantageous for seed production (i.e., source limited) but not for vegetative growth (i.e., sink limited) in this species.

Section: Is Carbon Fixation Sink-limited?mentioning

confidence: 76%

How do sink and source activities influence the reproduction and vegetative growth of spring ephemeral herbs under different light conditions?

Sunmonu

Kudo

2014

“…These two species have perennial shoot axes (Yoshie 2008a). In contrast, the growth period of Maianthemum dilatatum (a species distributed in Murodo-daira) and Gagea lutea in the cool temperate region, both of which have annual shoot axes with a predetermined number of leaves, was shorter at cultivation temperatures of 25/20°C than 15/10°C (Yoshie 2008b). These results suggest that warm air temperatures lengthen the growth period of herbs with perennial shoot axes and, conversely, shorten the growth period of herbs with annual shoot axes and a predetermined number of leaves.…”

Section: Discussionmentioning

confidence: 98%

Vegetative phenology of alpine plants at Tateyama Murodo-daira in central Japan

Yoshie

2010

Self Cite

The vegetative phenology of 29 alpine species, including herbaceous and woody summergreens and evergreens, was investigated. Summergreen species initiated and completed leaf growth earlier than evergreen species. The green period of leaves in summergreen plants was determined largely by the time of growth initiation. Early initiation of growth in summergreen plants contributes to the increase in photosynthetic carbon gain. Early cessation of growth in summergreens is advantageous for the growth in the following year because it leads to an increase in stored photosynthates. The growth period of leaves and stems in alpine plants correlated with the time of growth initiation more strongly than with the time of growth cessation, indicating the importance of early growth initiation for the increase in plant growth. The growth period of leaves was positively correlated with the sum of leaf lengths and the number of leaves. Herbs with a long growth period of more than 50 days had perennial shoot axes not terminated by inflorescences, suggesting a relationship between the growth period and shoot habit. Two summergreen species were completely dead by mid-September, before the air temperature decreased below 0 degrees C. The remaining summergreen species died immediately after the air temperature decreased to -1.4 degrees C in late September.

“…In contrast, previous studies indicated that a warm temperature significantly shortened the leaf expansion period of temperate herbs that have a determinate growth habit. The expansion period was shorter at 20°C (approximately 11 days) than at 10°C (18 days) in Erythronium japonicum, a spring ephemeral (Yoshie and Fukuda 1994), and was also shorter at 25/20°C (17 days) than at 15/10°C (33 days) in Gagea lutea, a spring ephemeral and at 25/20°C (9 days) than at 15/10°C (12 days) in Maianthemum dilatatum, a summergreen geophyte (Yoshie 2008a). These results suggest that the increased expansion period of plants due to warm temperatures is a trait common to herbs with an indeterminate growth habit.…”

Section: Discussionmentioning

confidence: 89%

“…Increased temperature reduces the expansion period of individual leaves (e.g. Dennet and Auld 1980;Rawson and Dunstone 1986), thus the leaf expansion period of plants with a determinate growth habit is shortened with increasing temperatures (Yoshie and Fukuda 1994;Yoshie 2008a). Because plant growth and development are strong functions of temperature, warmer temperatures increase the rate of ontogenetic development and result in a substantial shortening of the shoot expansion period (the time to flowering) in determinate annual species (Morison and Lawlor 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have indicated that a long chilling treatment shortens the green period (Risser and Cottam 1967) as well as the expansion, mature, and senescent periods of individual leaves (Yoshie and Fukuda 1994;Yoshie 2008a) in spring ephemerals that develop determinate number of leaves. The shoots of spring ephemerals grow at a very slow pace under the ground surface during the unfavorable season (Muller 1978;Lapointe 2001;Lapointe and Lerat 2006), frequently sprouting before the snowmelt (Risser and Cottam 1968); however, they require chilling temperatures for normal sprouting and growth (Risser and Cottam 1967;Yoshie 2008a). These results suggest that the decrease in green period due to the long chilling treatment is partly caused by advancing endogenous developmental stages during the chilling treatment.…”

Section: Introductionmentioning

confidence: 99%

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Effects of growth temperature and chilling duration on leaf phenology of Fauria crista-galli subsp. japonica, an alpine snowbed geophyte

Yoshie

2010

Self Cite

I examined the effects of growth temperature and winter duration on the leaf phenology of Fauria crista-galli plants, which have an indeterminate growth habit. After a 220-day chilling treatment, the leaf expansion and green periods of plants maintained at 25/20°C were much longer than those of plants maintained at 15/10°C and of plants at the natural habitat obtained in a previous study. The results indicate that early growth cessation and early leaf senescence in the natural habitat are not only due to endogenous rhythm but determined to some extent by cool summer temperatures. When grown at 15/10°C, the green period of individual leaves and plants was much shorter after a long chilling treatment (220 days) than after a short chilling treatment (110 days). The plants sprouted during or immediately after the termination of chilling treatment, suggesting that the decrease in the green period results partly from an advance of endogenous developmental stages during the chilling treatment and that the timing of snowmelt potentially affects the time of leaf senescence in the natural habitat.