Báo cáo lâm nghiệp: The effects of transplanting stress on photosynthesis, stomatal conductance and leaf water potential in Cedrus atlantica Manetti seedlings: role of root regeneration

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Báo cáo lâm nghiệp: "The effects of transplanting stress on photosynthesis, stomatal conductance and leaf water potential in Cedrus atlantica Manetti seedlings: role of root regeneration"The effects of transplanting stress on photosynthesis,stomatal conductance and leaf water potentialin Cedrus atlantica Manetti seedlings:role of root regeneration 2 KaushalJ.M. Guehl G. Aussenac 1 1 P.1 Laboratoire de Bioctimatologie et Ecophysiologie Foreshore, Station de Sylviculture et Production,INRA, Centre de Nancy, Champenoux, 54280 Seichamps, France, and2 Department of Forestry and Natural Resources, Punjab Agricultural University, Ludhiana,141 004 IndiaIntroduction El Nour, 198i3), considered separately, have been shown to be affected signifi- cantly by transplanting. However, a satis-Artificial forest stand establishment may factory rationale for studying effects ofbe achieved either with container-grown transplanting should also include valuableseedlings or with bareroot planting stock. information on the possible linkages be-Since growing seedlings in containers tween these processes and the inter-may lead to abnormal root development relationships with root regeneration afterafter transplanting (Aussenac et aL, 1988), transplanting.renewed attention should be given tobareroot planting. transplanting is accompanied Bareroot Materials and Methodsby specific transplanting stress, that may alead to substantial plant mortality or re-duced growth, due to the disturbance of One yr old seedl’ings were transplanted from athe functional continuity at the soil-root nursery to a glasshouse in polyethylene bagsinterface (Sands, 1984), or to mechanical (16 x 60 cm) containing sphagnum peat and were maintained well-watered. One yr later, indamage to roots caused by lifting the October 1985, half of the plants were lifted fromplants from the nursery beds (Chung and the bags, stored for 20 h at 20°C, 100% relativeKramer, 1975). humidity and in darkness, and then planted again in similar bags. The other half (control Physiological processes, such as C0 2 plants) were maintained in the initial bags. Theassimilation and translocation (Stupendick carbon dioxide (Jones, 1985). In an A vs c plot, these 2 limita- days 2, 9, 16, 23 andthen 30 after trans- on i tions are represented by the supply (Su) andplanting. demand (D) functions, respectively (see Fig. 2). In experiment 2, seedlings were transplantedin minirhizotrons. The plants were given optimalfertilization and the root systems were main-tained at 20°C in order to promote root regen- Resultseration. Assimilation rate measurements androot observations (number of growing roots androot elongation) were made just before trans- 1 Experimentplanting (day 0) and then weekly from day 7 today 49 after transplanting. In the transplanted seedlings, a marked Gas exchange measurements were made and parallel decline in both C0 assimila- 2with a classical open system under standard tion and stomatal conductance occurredenvironmental conditions. In experiment 1,intercellular C0 concentration (c values were 2 ) i from day 0 to day 9 after transplantingcalculated from the A and g data, which per- s (Fig. 1a and b); afterwards the declinemits assessment of the extent to which changes continued, but was less pronounced. Theof A following transplanting are due to reduced control plants presented a decreasingdiffusional supply of C0 to the mesophyll or to 2 trend of gas exchange, but the declinedecreasing mesophyll photosynthetic capacity less than in for the transplanted plants was accompa- significantly pronouncedwas nied by an almost constant c (Fig. 2), thusthe transplanted plants. Predawn needle i indicating that, despite the parallel evolu-water potential (Fig. 1c) was affe ...