Báo cáo lâm nghiệp: "Leaf number, water stress and carbon nutrition effects poplar leaf growth on"

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Leaf number, water stress and carbon nutrition effects on poplar leaf growth J.P. Gaudillère Laboratoire de Chimie Biologique et de Photophysiologie, INRA, 78850 Thivervaf, France Introduction tion effects on the number and the mean size of epidermal poplar leaves. The final area of a leaf is described by the number and the mean size of epidermal cells. Water stress, nitrogen, light and Materials and Methods temperature have been demonstrated to affect foliage development. These factors act at different levels in the process of leaf Plant production production. The main susceptible physio- logical mechanisms are cell division and The experiments were carried out on Populus euramericana var. 1214. Cuttings grew on peat differentiation in the apex and in the un- and mineral nutrients were supplied as low folding leaf. It has been shown that carbon solubility fertilizer (Osmocote, 18/11/10}. Plants nutrition has a very significant effect on were watered daily with tap water. Growth the duration of the cell division phase. conditions were: metal halide lamps (200 pmol When the leaf begins to export carbon, M light period: 16 h, day and night tem- ); 1 S 2 - perature and humidity: 20°C and 70%. cell divisions end (Dale and Milthorpe, 1983). Plant-water relations also play a major role through their effects on cell Anatomical measurements expansion (Lockhart, 1965). Cell divisions are less affected by water stress (Clough Areas of attached leaves were measured by the dot grid method (Bouchon, 1975). The number and Milthorpe, 1975). and the size of epidermal cells were measured These experiments were designed to on prints (Austin et al., 1982) at the final har- availability and carbon nutri- specify water vest. * resent address: Stationi1o Dh B/ónót!lo 1fBICA RP131 i Pnnt-ei France. P Dr..oco.ont !r/rI,.r::H:!CO’ f coin. * c Bl Vtsg!tale, INRA, BP 131, 13140 p F r"n"" or7nn de l lV’lia A 3 4n -in-KA v q Physiologie Pont-de-la-Maye,
enrichment was carried out in a gas-tight Experimental conditions growth chamber with the same other growing conditions. CO! concentration was controlled Long-term stress was obtained by lowering the and monitored with an IRGA and the hourly daily watering to 10% of the amount of tran- spired water at the beginning of the experiment. C0 uptake or evolution was computed (La- 2 After 20 d, full watering was applied. C0 pierre et al., 1983). 2
Results tering, cell divisions and expansion started again. Newly expanded leaves presented the same anatomical characteristics as Leaf number (LN) effect the control (Figs. 2 and 3). Under our growth conditions, the final leaf of successive leaves on control Effect of carbon nutrition area plants increased until a constant value of 200 (± 10) cm (Fig. 1The number of , 2 A 40% increase in the photosynthetic C0 2 cells per leaf increased with LN (Fig. 2). assimilation rate of the trees was produ- The mean cell size was lower in preex- ced by C0 enrichment (600 p of the ) 1 - H 2 isting leaves than in the bud (Fig. 3; LN air. The final leaf area was highly stim- 1-7). Newly initiated leaves had initially ulated by this treatment (Fig. 1The main large epidermal cells (LN 8-25). Then a growth component affected by the in- regular decrease of the mean leaf area crease of the carbon nutrition was the was observed. number of cells per leaf, which doubled (Fig. 2). The mean size of the cells was Water stress effect not affected (Fig. 3). Reduction of watering provoked water Leaf growth was inhibited until stress. rewatering. The final leaf size was very Discussion significantly decreased (Fig. 1). This decrease was entirely explained by the mean size of the cells (Fig. 3). The num- Water stress and carbon nutrition signi- ber of cells per leaf (Fig. 2) was hardly ficantly change the final area of leaves. It affected by the treatment. With the rewa- is well known that the water supply
reduces the expansive growth of leaf cells References (Cleland, 1971) and that water stress reduces the final size of the epidermal Austin R.B., Morgan C.L., Ford M.A. & Bhagwat cells (McCree and Davies, 1974). The S.G. (1982) Flag leaf photosynthesis of Triti- present results show that poplar leaves cum aestivum and related diploids and tetra- follow the pattern. The size of same mean ploids species. Ann. Bot. 49, 177-189 the cells mainly reduced by water was Bouchon J. (1975) Precision des mesures de Carbon nutrition stress. specifically comptage de points. Ann. Sci. superficies par changes the number of epidermal cells. It For. 32, 131-134. be concluded that cell divisions in an can Cleland R. (1971) Cell wall extension. Annu. expanding leaf are limited by the carbon Rev. Plant Physiol. 22, 197-222 supply. In control plants, a regular in- Clough B.F. & Milthorpe F.L. (1975) Effect of crease in the size of the newly initiated water deficit on leaf development in tobacco. Aust. J. Plant Ptiysiol. 2, 291-300 leaves was observed. It could be ex- plained by an increased carbon availability Dale J.E. & Milthorpe F.L. {1983) General fea- with the number of leaves of the young tures of the production and growth of leaves. In: The Growth and Functioning of Leaves. tree. The importance of this C0 effect 2 (Dale J.E. & Milthorpe F.L., eds.), Cambridge could be justified, considering that it University Press, Cambridge, pp. 151-178 increases the photosynthetic activity of Lapierre C., Gatidill6re J.P., Guittet E., Rolando growing leaves. Autotrophy of expanding C. & Lallemand J.Y. (1983) Enrichissement leaves in poplar has been demonstrated photosynthetique en carbone 13 de lignine de (Larson et aL, 1980) and carbon nutrition peuplier: caracterisation pr6liminaire par acido- stimulation could be particularly significant lyse et RMN 1 Holzforschung37, 217-224 3C. by stimulating autotrophic carbon supply Larson P.R., lsebrands J.G. & Dickson R.E. in young leaves. (1980) Sink to source transition of Populus leaves. Ber. Dtsch. Bot. Ges. 93, 79-80 Lockhart J.A. (1965) An analysis of irreversible plant cell elongation. J. Theor. Biol. 8, 264-276 Acknowledgments McCree K.J. & Davies S.D. (1974) Effect of This work was supported by the CNRS water stress and temperature on leaf size and contract: Physiologie de la Croissance et du on size and number of epidermal cells in grain D6veloppement des V6g6taux ligneux. sorghum. Crop lici. 14, 751-755