Báo cáo lâm nghiệp: "Effect of water stress on potassium distribution in young seedlings of maritime pine (Pinus pinaster"

Chia sẻ: Nguyễn Minh Thắng | Ngày: | Loại File: PDF | Số trang:5

Thêm vào BST

Báo xấu

58
lượt xem 3
download

Download Vui lòng tải xuống để xem tài liệu đầy đủ

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Effect of water stress on potassium distribution in young seedlings of maritime pine (Pinus pinaster...

Chủ đề:

Bình luận(0) Đăng nhập để gửi bình luận!

Lưu

Nội dung Text: Báo cáo lâm nghiệp: "Effect of water stress on potassium distribution in young seedlings of maritime pine (Pinus pinaster"

Effect of water stress on potassium distribution in young seedlings of maritime pine (Pinus pinaster Ait.) A. Lamant 2 1 A. Nguyen 1 Laboratoire dAm6lioration des Arbres Forestiers, Pierroton, 33610 Cesfas, and INRA, 2 Laboratoire de Biologie et Physiologie Végétales, (CNRS UA568), Universit6 de Bordeaux 1, des Facult6s, 33405 Talence, France av. lings of the Tamjoute population compared Introduction seedlings of the Landes population. to One possible adaptational response of plants with respect to drought is osmotic adjustment (Kramer, 1980). At low water Materials and Methods potential, the maintenance of turgor is needed to sustain cell enlargement. Two Seedlings were grown on an aerated nutrient cellular processes may be involved in tur- solution (Seillac, 1960). The intensity of light gor maintenance: variation in cell wall was 30 W with a 14 h photoperiod, a rela- , 2 m- ’ elasticity and/or accumulation of intracellu- tive humidity of 45/70% day/night and a temperature of 24/22°C. Water deficit was lar solutes. Actually, without any informa- applied only to roots by a step-wise addition of tion on the volumetric modules of elastici- PEG (polyethylene glycol) to the solution (-0.1 ty, most authors ascribe the maintenance MPa/12 h or 24 h). The different final degrees of turgor to an increase of intracellular of water stress were: -0.03 (nutrient solution without PEG); -0.2, -0.5 and -0.8 MPa. K+ solutes. The cation potassium, which is contents were determined by emission spectro- the major osmotic component in plant photometry. cells, is often thought to be a possible Measurements of K· transport from roots to osmoregulator (Wyn Jones and Gorham, shoots were performed according to the method 1983). detailed by Jeschke and Jambor (1981). A set of 20-25 plants, previously water-stressed as In this paper, two populations of mari- described above were placed in labeled ( Rb+) 86 time pine (Pinus pinaster Ait.), a drought- PEG solutions (so=400 1lCi 86Rb+!mM-! K+). sensitive one (’Landes’ from France) and Experiments were run at 23-25°C in the dark a better adapted one (’Tamjoute’ from so that the fluxes were not disturbed by stoma- tal regulation. Samples of 2-4 plants were regu- Morocco) were compared for potassium larly harvested at intervals fromt=0 to t= 30 h content and migration to the aerial parts. and 2 replicates of the experiment were per- In a previous study (Nguyen and Lamant, formed. Tracer contents in the aerial parts were 1989), a more intense osmoregulation converted into meq of K+ and expressed on a was found in root apices of young seed- root fresh weight basis in order to limit the effect
of variation in the absorptive surface. Roots variation as a function of time, the slope being the expression of the migration to the aerial accumulated labeled K+ and, after 5-6 h, the absorbed K+ shoot contents showed a linear parts.
Results used to evaluate the differentiated K+ re- sponse of the two populations of pine; they illustrate the relations between the Variation in K content with + applied water dry weight of a sample and its K content. + deficits An accumulation of K+ was found in roots of the Moroccan seedlings, while the Potassium concentrations varied signifi- contents were maintained for the French in roots: expressed on a tissue cantly only plants. water content basis, an increase of +30 mM (-0.5 MPa treatment) was observed for both populations; expressed on a dry Potassium migration to the aerial parts matter basis, potassium contents de- creased with the water deficit treatments. These responses are the result of 3 simul- Under well-watered conditions (-0.03 MPa treatment), K migration to the aerial parts + taneous variations: accumulation of dry matter in roots with water stress (Nguyen was two times higher for the Landes popu- lation. (Fig. 2). However, the translocation and Lamant, 1989), water loss and varia- decreased with water stress, while it was tion in the K+ content. Fig. 1a and b (in- spired by the work of Hajji (1979)) were maintained for the Tamjoute population.
increase of +30 mM means that the varia- Discussion and Conclusion tion of osmotic potential due to K is only + The examination of variations in the K+ of about -0.07 MPa. However, the intra- content under water stress showed that cellular distribution of potassium has to be the potassium amount per root remained considered: other experiments (Nguyen, constant for French seedlings, while it 1986) showed that the osmotic contribu- increased for Moroccan seedlings, and the tion of K seemed to be quite significant in + evolution of dry matter was similar for both the cytoplasmic compartment. populations. A slightly lower water loss It is interesting to note that the variation found for the Tamjoute population was in potassium translocation closely paral- (Nguyen and Lamant, 1989): this would lels the height growth performances of 2 mean that the increase of +30 mM was yr old seedlings subjected to different only the result of root tissue dehydration in watering conditions (Fig. 3). The question French seedlings, while the same in- is raised as to the contribution of a re- crease in Moroccan seedlings integrated a duced supply of potassium to the lower part of the K supply resulting in better tis- + growth under water stress. Pitman and water status. sue Cram (1977) found that the rate of K + analysis, the active According to this export from the root to the shoot in barley contribution of K is underlined. With the seedlings was proportional to the relative hypothesis that the cation is homoge- neously distributed in the plant cell, an growth rate.
A. (1986) Effets d’une contrainte Nguyen The control of K+ export to the aerial racinaire sur de jeunes plants de pin hydrique parts could be localized at 2 boundaries in maritime. Ph.D. Thesis, Université de Bordeaux the root: 1) the ion secretion mechanism I, France into xylem vessels and 2) the net K up- + Nguyen A. & Lamant A. (1989) Variation in take from the substrate at the plasmalem- growth and osmotic regulation of roots of water- ma of cortical and endodermal cells. The stressed maritime pine provenances. Tree Physiol. 5, 123-133 K+ accumulation with water stress found in Moroccan seedling roots and some pre- Pitman M.G. & Cram W.J. (1977) Regulation of ion content in whole plants. In: Integration of liminary studies tend to favor the second Activity in the Higher Plant. Symp. Soc. Exp. possibility. Biol. XXXI (Jennings D.H., ed.). Cambridge Uni- versity Press, Cambridge Sarrauste N. (1982) Phothosynth6se, respira- tion et rbpartition de mati6re sbche de jeunes References plants de pin maritime appartenantsept pro- et conduits selon deux traitements venances hydriques. DEA Thesis, Universit6 de Paris VII, Hajji M. (1979) Effet du sel sur la croissance et France I’alimentation min6rale du laurier-rose. Physiol. g. , V6 17 - 517 24 Seillac P. (1960) Contribution à I’étude de la nutrition du pin maritime: variations saison- Jeschke W.D. & Jambor W. (1981) Determina- nibres de la teneur des pseudophylles en azote, tion of unidirectional sodium fluxes in roots of potassium et acide phosphorique. Ph.D. Thesis, intact sunflower seedlings. J. Exp. Bot. 32, Universit6 de Bordeaux, France 1257-1272 Wyn Jones R.G. & Gorham J. (1983) Osmo- Kramer J.P. (1980) Drought, stress and the ori- regulation. In: Encyclopedia of Plant Physiolo- gin of adaptations. In: Adaptation of Plants to gy. New Ser. Vol. 12C (Lange O.L. et aL, eds.). Water and High Temperature Stress. (Turner N.C. & Kramer P.J., eds.), pp. 7-20 Springer-Verlag, Berlin, pp. 35-58