Chlorophyll a fluorescence, gas exchange, growth and nutrient trait data of tree legume

<b>Introduction</b>A study of tropical forest restoration was conducted in a 3-ha plantation degraded area of the Balbina Hydropower Dam, in Amazonas State Brazil. Gas exchange Including photosynthesis and stomatal conductance; relative growth rate in diameter and root mass allocation; 21 chlorophyll <i>a</i> fluorescence (ChF) variables and photosynthetic pigments concentration and ratios dataset was collected 18 and 24-months after the experiment establishment. The initial treatments were considered as fertilized (high-nutrient) and unfertilized (low-nutrient) treatments for six tree legume species. During the experiment course the strong 2015/16 El Niño Southern Oscillation (ENSO) supported the data collection under drought conditions which is not common in the Amazon region (Jaquetti 2020). Thus one can evaluate the seasonality effects on the functional traits mentioned above. The species selected from the Fabaceae family were: the non-N₂-fixing <i>Cenostigma tocantinum</i>, <i>Senna reticulata</i>, <i>Dipteryx odorata</i>; and the N₂-fixing <i>Clitoria fairchildiana</i>, <i>Inga edulis</i> and <i>Acacia</i> sp. The high-nutrient (fertilized) treatment received multiple nutrient fertilization with macro and micronutrients during plantation and 2 additional amendments each year. More information on the species selected, fertilization regimes and environmental conditions of the experimental trial can be found in Jaquetti (2018). <b>Growth analysis</b>The relative growth rates of its diameter (RGR_D) and root mass fraction (RMF) data. was used from https://data.mendeley.com/datasets/fj55scwr3g/3<i><br><br></i><b></b><b>Functional traits</b>The east-oriented, healthy, sun-exposed and completely expanded leaves criteria was used. Leaves located in the middle third of the plant were selected for the photosynthetic pigment analysis, gas exchange and ChF measurements and foliar nutrient concentration. Functional traits data collection was performed in the wet period and drought periods approximately 18 and 24-months after the experiment establishment.<b></b><b> </b><b>Photosynthetic pigments</b>The photosynthetic pigments chlorophyll a (Chl a) and b (Chl b) and carotenoids (Car) were determined by spectrophotometry at 663 nm (Chl a), 645 nm (Chl b) and 480 nm (Car) (Ultrospec 2100 pro UV/visible, Amersham Biosciences, Cambridge, UK) in the Laboratory of Physiology and Biochemistry of INPA (Lichtenthaler and Wellburn, 1983). Prior to analysis the fresh material 0.1 g of was ground in 10 ml of 80% acetone with magnesium carbonate (MgCO3) and 10 ml of 100% acetone added following the initial grinding step. Ratios of Chl a/Chlb and Chl a + b/Car were calculated.<b>Photosynthesis measurements</b>Gas exchange including the net photosynthetic rate (<i>P</i>_n) and stomatal conductance (<i>g</i>_s) were measured between 8:00 and 11:30 h using a portable photosynthesis system (Li-6400, Li-Cor Inc., Lincoln, NE, USA) (Santos Junior et al. 2006). Measurements were performed with photosynthetic photon-flux densities (PPFD) of 0 and 2000 μmol m^-2 s^-1, and the foliar chamber adjusted for a CO₂ concentration of 400 ± 4 μmol mol^-1, temperature 31 °C ± 1 °C and water-vapor concentration of 21 ± 1 mmol mol^-1.<b>Chlorophyll <i>a</i> fluorescence</b>The dark-adapted chlorophyll <i>a</i> fluorescence data was collected with a portable fluorometer (Handy PEA, MK2-9600-Hansatech, Norfolk, UK) between 8:30 and 11:00 h. The leaves were 30 min dark-adapted and exposed to a 5 s excitation pulse of saturating light (3000 μmol m^-2 s^-1) using a wavelength of 650 nm. The performance index was calculated on absorption basis (<i>PI</i>_ABS) as described by Gonçalves et al. (2007).<b>Foliar nutrient concentration</b>Macro and micronutrients concentrations of leaves were determined in each treatment after oven-dried at 65 °C and ground before the analysis. The nitrogen (N) concentration (mass basis) phosphorus (P) concentration was was used from: https://data.mendeley.com/datasets/fj55scwr3g/3. The macronutrient potassium (K), calcium (Ca) and magnesium (Mg) and micronutrient iron (Fe) and zinc (Zn) concentration were determined using spectrophotometric atomic absorption (PerkinElmer 1100B, Inc., Waltham, MA, USA) (Embrapa, 2009).