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Leaf dynamics in growth and reproduction of Xanthium canadense as influenced by stand density.

Ogawa T, Oikawa S, Hirose T - Ann. Bot. (2015)

Bottom Line: Stand density may influence leaf dynamics through its effects on light gradient and on plant growth and reproduction.In the vegetative phase of plant growth, the light gradient strongly controls leaf longevity, whereas later the effects of branching and reproductive activities become stronger and over-rule the effect of light environment.As leaf N supports photosynthesis and also works as an N source for plant development, N use is pivotal in linking leaf dynamics with plant growth and reproduction.

View Article: PubMed Central - PubMed

Affiliation: Department of International Agricultural Development, Tokyo University of Agriculture, Tokyo 156-8502, Japan.

No MeSH data available.


Leaf- and plant-level nitrogen productivity (NP; A), mean residence time (MRT; B) and nitrogen use efficiency (NUE; C) of Xanthium canadense plants grown in an open (6·25 plants m−2, white) or in a dense stand (59·2 plants m−2, grey). NP × MRT = NUE. Leaf-level variables are from Table 8; plant-level variables are from Table 1. Error bars denote ± 1 s.d. ***P < 0·001, **P < 0·01, *P < 0·05, + P < 0·1, nsP ≥ 0·1.
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mcv114-F3: Leaf- and plant-level nitrogen productivity (NP; A), mean residence time (MRT; B) and nitrogen use efficiency (NUE; C) of Xanthium canadense plants grown in an open (6·25 plants m−2, white) or in a dense stand (59·2 plants m−2, grey). NP × MRT = NUE. Leaf-level variables are from Table 8; plant-level variables are from Table 1. Error bars denote ± 1 s.d. ***P < 0·001, **P < 0·01, *P < 0·05, + P < 0·1, nsP ≥ 0·1.

Mentions: Nitrogen plays a crucial role in photosynthetic production (Evans, 1989; Hikosaka and Terashima, 1995). Most plant N is allocated to green leaves (e.g. Hocking and Steer, 1983; this study), and most leaf N to chloroplasts (Evans and Seemann, 1989; Makino et al., 2003). There is a correlation between N uptake and dry mass growth (e.g. Hirose, 1978) as well as between leaf N and photosynthetic capacity (Field and Mooney, 1986; Evans, 1989). Then leaf N use in photosynthetic production and plant N use in dry mass production both are important for understanding plant functioning in a given environment. Hirose (2011) re-analysed the data on N use in a perennial Solidago altissima and an annual Amaranthus patulus stand (Hirose, 1975), in which higher NUE in S. altissima than in A. patulus was explained by a higher MRT in the former. Extensive recycling of N between above- and below-ground parts as well as between new and old leaves accounted for the higher MRT of plant N in the perennial system. At leaf level, a higher NUE in S. altissima was also explained by a higher MRT of leaf N (Hirose, 2012). NUE and NP are higher at leaf level than at plant level because N allocation to leaves is a fraction of N taken up from soil, and net dry mass production is a fraction of surplus production. MRT is lower at leaf level than at plant level because leaf turnover is higher than plant turnover due to the N recycling between leaf and other structures at plant level. The same was observed in the present study: NUE and NP were higher, and MRT was lower at leaf than at plant level (Fig. 3). However, a difference in MRT between stands was observed at plant level, but was not observed at leaf level. In contrast, a difference in NUE between stands was observed at leaf level, but was not observed at plant level. A difference in NUE at leaf level between stands reflects the difference in NP more than the difference in MRT. It is intriguing that the effect of different light climates on NUE via NP is more evident at leaf level than at plant level. This may be because the light environment influences photosynthetic productivity directly, and N allocation indirectly within a plant. Lower NP at leaf level (closely related to LNP) in the dense stand was compensated for by a higher allocation of N to leaf (LNR) at the plant level (Table 1). Thus, only a small difference was found in NP at plant level between the two stands.Fig. 3.


Leaf dynamics in growth and reproduction of Xanthium canadense as influenced by stand density.

Ogawa T, Oikawa S, Hirose T - Ann. Bot. (2015)

Leaf- and plant-level nitrogen productivity (NP; A), mean residence time (MRT; B) and nitrogen use efficiency (NUE; C) of Xanthium canadense plants grown in an open (6·25 plants m−2, white) or in a dense stand (59·2 plants m−2, grey). NP × MRT = NUE. Leaf-level variables are from Table 8; plant-level variables are from Table 1. Error bars denote ± 1 s.d. ***P < 0·001, **P < 0·01, *P < 0·05, + P < 0·1, nsP ≥ 0·1.
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Related In: Results  -  Collection

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mcv114-F3: Leaf- and plant-level nitrogen productivity (NP; A), mean residence time (MRT; B) and nitrogen use efficiency (NUE; C) of Xanthium canadense plants grown in an open (6·25 plants m−2, white) or in a dense stand (59·2 plants m−2, grey). NP × MRT = NUE. Leaf-level variables are from Table 8; plant-level variables are from Table 1. Error bars denote ± 1 s.d. ***P < 0·001, **P < 0·01, *P < 0·05, + P < 0·1, nsP ≥ 0·1.
Mentions: Nitrogen plays a crucial role in photosynthetic production (Evans, 1989; Hikosaka and Terashima, 1995). Most plant N is allocated to green leaves (e.g. Hocking and Steer, 1983; this study), and most leaf N to chloroplasts (Evans and Seemann, 1989; Makino et al., 2003). There is a correlation between N uptake and dry mass growth (e.g. Hirose, 1978) as well as between leaf N and photosynthetic capacity (Field and Mooney, 1986; Evans, 1989). Then leaf N use in photosynthetic production and plant N use in dry mass production both are important for understanding plant functioning in a given environment. Hirose (2011) re-analysed the data on N use in a perennial Solidago altissima and an annual Amaranthus patulus stand (Hirose, 1975), in which higher NUE in S. altissima than in A. patulus was explained by a higher MRT in the former. Extensive recycling of N between above- and below-ground parts as well as between new and old leaves accounted for the higher MRT of plant N in the perennial system. At leaf level, a higher NUE in S. altissima was also explained by a higher MRT of leaf N (Hirose, 2012). NUE and NP are higher at leaf level than at plant level because N allocation to leaves is a fraction of N taken up from soil, and net dry mass production is a fraction of surplus production. MRT is lower at leaf level than at plant level because leaf turnover is higher than plant turnover due to the N recycling between leaf and other structures at plant level. The same was observed in the present study: NUE and NP were higher, and MRT was lower at leaf than at plant level (Fig. 3). However, a difference in MRT between stands was observed at plant level, but was not observed at leaf level. In contrast, a difference in NUE between stands was observed at leaf level, but was not observed at plant level. A difference in NUE at leaf level between stands reflects the difference in NP more than the difference in MRT. It is intriguing that the effect of different light climates on NUE via NP is more evident at leaf level than at plant level. This may be because the light environment influences photosynthetic productivity directly, and N allocation indirectly within a plant. Lower NP at leaf level (closely related to LNP) in the dense stand was compensated for by a higher allocation of N to leaf (LNR) at the plant level (Table 1). Thus, only a small difference was found in NP at plant level between the two stands.Fig. 3.

Bottom Line: Stand density may influence leaf dynamics through its effects on light gradient and on plant growth and reproduction.In the vegetative phase of plant growth, the light gradient strongly controls leaf longevity, whereas later the effects of branching and reproductive activities become stronger and over-rule the effect of light environment.As leaf N supports photosynthesis and also works as an N source for plant development, N use is pivotal in linking leaf dynamics with plant growth and reproduction.

View Article: PubMed Central - PubMed

Affiliation: Department of International Agricultural Development, Tokyo University of Agriculture, Tokyo 156-8502, Japan.

No MeSH data available.