%0 Journal Article %1 Garnieretal_99 %A Garnier, E. %A Salager, J. L. %A Laurent, G. %A Sonie, L. %D 1999 %J New Phytologist %K bibtex-import citeulikeExport %P 119--129 %T Relationships between photosynthesis, nitrogen and leaf structure in 14 grass species and their dependence on the basis of expression %V 143 %X The relationships between leaf structure, nitrogen concentration and CO2 assimilation rate (A) were studied for 14 grass species grown in the laboratory under non-limiting nutrient conditions. Structural features included leaf thickness and density, and the proportion of leaf volume occupied by different types of tissue (mesophyll, epidermis, vessels and sclerenchyma). Relationships were assessed for data expressed per unit leaf area and fresh mass. The latter was found to be closely related to leaf volume, which allowed us to use A per unit leaf fresh mass (Afm) as a surrogate of A per unit leaf volume. Assimilation rate per unit leaf area (Aa) was positively correlated with leaf thickness and with the amount of mesophyll per unit leaf area; the relationship with leaf nitrogen content per unit area was only marginally signicant. Afm was negatively correlated with leaf thickness and positively with fresh mass-based leaf organic nitrogen concentration. A multiple regression involving these two variables explained 81\% of the variance in Afm. The value of Afm was also signicantly related to the proportion of mesophyll in the leaf volume, but surprisingly the correlation was negative. This was because thin leaves with high Afm and nitrogen concentration had proportionally more mechanically supportive tissues than thick ones; as a consequence, they also had a lower proportion of mesophyll. These data suggest that, in addition to leaf nitrogen, leaf thickness has a strong impact on CO2 assimilation rate for the grass species studied

@article{Garnieretal_99, abstract = {{The relationships between leaf structure, nitrogen concentration and CO2 assimilation rate (A) were studied for 14 grass species grown in the laboratory under non-limiting nutrient conditions. Structural features included leaf thickness and density, and the proportion of leaf volume occupied by different types of tissue (mesophyll, epidermis, vessels and sclerenchyma). Relationships were assessed for data expressed per unit leaf area and fresh mass. The latter was found to be closely related to leaf volume, which allowed us to use A per unit leaf fresh mass (Afm) as a surrogate of A per unit leaf volume. Assimilation rate per unit leaf area (Aa) was positively correlated with leaf thickness and with the amount of mesophyll per unit leaf area; the relationship with leaf nitrogen content per unit area was only marginally signicant. Afm was negatively correlated with leaf thickness and positively with fresh mass-based leaf organic nitrogen concentration. A multiple regression involving these two variables explained 81\% of the variance in Afm. The value of Afm was also signicantly related to the proportion of mesophyll in the leaf volume, but surprisingly the correlation was negative. This was because thin leaves with high Afm and nitrogen concentration had proportionally more mechanically supportive tissues than thick ones; as a consequence, they also had a lower proportion of mesophyll. These data suggest that, in addition to leaf nitrogen, leaf thickness has a strong impact on CO2 assimilation rate for the grass species studied}}, added-at = {2019-03-31T01:14:40.000+0100}, author = {Garnier, E. and Salager, J. L. and Laurent, G. and Sonie, L.}, biburl = {https://www.bibsonomy.org/bibtex/23d33f6e696288284a77412a93dcde157/dianella}, citeulike-article-id = {1523704}, comment = {(private-note)Thick leaves were found to have a signicantly higher proportion of non-parietal mesophyll(i.e. mesophyll minus proportion of mesophyll occupied by cell walls but a lower proportion of `dense' tissues (i.e. sum of vessels plus sclerenchyma) than thin leaves Hypothesised Reasons for Amass - thickness relationships: Leaf organic-N concentration per unit fresh mass ([N]lfm) was lower in thick than in thin leaves (Fig. 5b). Since it was also positively and strongly related to A per unit fresh mass (Fig. 3d), this implies that Afm and leaf thickness were negatively related. This points to a lower concentration of the enzyme Rubisco in thick leaves (Field \& Mooney, 1986; Evans, 1989), which may limit their capacity for CO2 xation. Interestingly, the lower [N]lfm of thick leaves is seen with a higher proportion of non-parietal meso phyll (compare Figs 4a and 5b), indicating that the volume of mesophyll is not a good indicator of the volume of chloroplasts in the leaf. Leaf absorptance depends strongly on chlorophyll content per unit leaf area (Agust\"{i}¿½ et al., 1994; Syvertsen et al., 1995; Evans, 1998), but this does not seem to vary systematically with leaf thickness (Pammenter et al., 1986; Kebede et al., 1994). However, when expressed per unit mass, the average chlorophyll concentration is lower in thick than in thin leaves (Pammenter et al., 1986; Agust\"{i}¿½ et al., 1994; Kebede et al., 1994), and/or in leaves with a low specic leaf area (Poorter \& Evans, 1998). Since light absorption per unit mass was found to be positively related to chlorophyll a concentration (Agust\"{i}¿½ et al., 1994), on average, a unit mass or volume is likely to absorb less light in thick than in thin leaves. How this affects assimilation rate depends on the light gradients within the leaf (Vogelmann, 1993) and on the coupling between light absorption and CO2 fixation proles within the leaf (see e.g. Evans, 1999). E The path length of CO2 within the leaf is supposed to be longer in thick leaves, inducing a higher resistance to CO2 diffusion in the gaseous phase across the leaf (Parkhurst, 1994; Syvertsen et al., 1995; Evans \& von Caemmerer, 1996).}, interhash = {e75597c46d6b18784b91e3eeb0f39aef}, intrahash = {3d33f6e696288284a77412a93dcde157}, journal = {New Phytologist}, keywords = {bibtex-import citeulikeExport}, pages = {119--129}, posted-at = {2007-07-31 06:17:28}, priority = {2}, timestamp = {2019-03-31T01:16:26.000+0100}, title = {{Relationships between photosynthesis, nitrogen and leaf structure in 14 grass species and their dependence on the basis of expression}}, volume = 143, year = 1999 }