Photosynthetic Efficiency in Aroeira and Cedro After the Application of Salicylic Acid

The objective of this research was to quantify the photosynthetic efficiency of Cedrela fissilis and Schinus terebinthifolius seedlings after application of salicylic acid for eight weeks. The experimental design was completely randomized, composed of four treatments, with five replicates of 20 seedlings each. The treatments consisted of increasing doses of the salicylic acid solution: 0, 100, 200, 300 mg L. The solution was composed of salicylic acid, deionized water and adjuvant and applied with hand sprayer, weekly for 2 months. The parameters evaluated after the application of the acid consisted of the rate of CO2 assimilation, leaf transpiration, stomatal conductance and internal CO2 concentration, as well as water use efficiency, intrinsic water use efficiency and instantaneous carboxylation efficiency. In seedlings of Schinus terebinthifolius there was a reduction of the photosynthetic parameters and consequently a better use of water as the doses of the plant growth regulator were increased. In the seedlings of Cedrela fissilis the dose of 200 mg L resulted in greater CO2 fixation per molecule of water lost and in this sense, it can be inferred that the increase in the doses of salicylic acid improved the photosynthetic efficiency, but the use of water was lower. Thus, for both species, lower doses are more recommended because there must be a balance between the fixed amount of CO2, the plant generated from photoassimilates and the amount of water lost, in order not to generate a negative potential in the plant metabolism.


Introduction
The use of native wood species adds great commercial and social value to the environment in which they are inserted. In this sense, it is of great interest to increase the production of large scale and better quality seedlings. Thus, studies focusing on the potential, uses, establishment, development, practices and management in the nursery and in the field should be developed (Gonçalves et al., 2012

Materia
The resear 54°05′67″ region is C distributed during the  We used 400 seedlings of Schinus terebinthifolius (aroeira) and 400 seedlings of Cedrela fissilis (Cedro) obtained from Itaipu Binacional and the Environmental Institute of Paraná (EIP). The three month seedlings were propagated in 120 cm 3 plugs filled with a mixture of local soil and humus (NITOSOLO RED Eutroferric of very clayey texture), in a ratio of 3:1.
Prior to the treatments, seedlings underwent acclimatization in a protected shadehouse for approximately 30 days between August and September. During that period, the seedlings were fertilized with 3 mL of nutrient solution in order to provide macro and micronutrients required in the growing phase (Table 1).  Treatments wer applied weekly for 2 months from September 26 until November 14. The solution consisted of SA, deionized water and adjuvant (Agral®), 30 mL to 100 L -1 of water. We used a hand sprayer between 6 and 8 am. Irrigation consisted of three shifts of 15 minutes each in addition to weeding.
Measurement included photosynthetic potential, measured by gas exchange, CO 2 assimilation rate (A), leaf transpiration (E), stomatal conductance (g s ) and internal CO 2 concentration (Ci) in leaves fully expanded and photosynthetically active using a IRGA (Li-6400 XT). Measurements were carried out on cloudy days from 9 to 11 a.m, in order to obtain greater uniformity in relation to the climatic conditions for the analyzes.With artificial saturated light of 1,200 μmol m -2 s -1 and CO 2 concentration at 380 μmol, under a constant temperature of 25 °C.
At the end of the test, the chlorophyll content was determined by the Arnon method (1949), in leaves located in the middle third of the plants (photosynthetically active), 14.0 cm 2 of leaf area were removed and packed in Falcon tubes of 15.0 cm 3 precoated with foil and filled with 10 ml of 80% acetone.
The results were submitted to the Bartlett and Shapiro-Wilk tests in order to test the homogeneity and normality followed by the analysis of variance. When appropriated we tested treatment means using Dunnett test and comparison between SA doses the control treatment (0 mg L -1 ).

Results and Discussion
SA may induce morphological, biochemical or physiological alterations such as the increase in the content of photosynthetic pigments under normal or stressful conditions in plants (Singh & Usha, 2003;Khodary, 2004). Several studies have demonstrated the importance of exogenous application of SA to various metabolic functions in plants, whether physiological, ecological or biochemical. These responses have not been fully clarified, mainly because both the characteristics of the species and the climatic factors can influence the responses to the use of this inducer (Pál et al., 2014). proportional t re 3.15; 3.14; 3 % ( Figure 5).