Germination Speed Index Research Articles

Physiological quality of sunflower seeds under water stressed conditions

Water is one of the factors that most influences the seed germination process; however, its excess can cause injuries to cell membranes due to rapid imbibition. On the other hand, water restriction limits seed germination, promoting a reduction in cell water potential that disrupts physiological and metabolic reactions. Thus, the objective of this study was to evaluate the physiological quality of sunflower seeds subjected to water stress induced by polyethylene glycol 6000 (PEG 6000). The experimental design used was completely randomized, consisting of six treatments consisting of osmotic potentials (0; -0.3; -0.6; -0.9; -1.2; and -1.5 MPa) simulated with aqueous solutions of PEG 6000. Germination, radicle protrusion, first count, germination speed index, abnormal seedlings, shoot length, and root length were evaluated. Water stress induced by PEG 6000 solutions affects the physiological quality of sunflower seeds, being proportional to the reduction of osmotic potential. Germination and seed vigor decrease under water stress conditions from an osmotic potential of -0.4 MPa, with the most negative potentials (-1.2 and -1.5 MPa) preventing seed germination.

Production and Quality of Radish Seeds with Sulfur in Top Dressing and Organic Compost at Planting Fertilization

Aims: This study evaluates the effects of top dressing sulfur (S) fertilization, with and without organic compost before planting, on radish seed production and quality. Study Design: Eight treatments were studied in a factorial scheme (4 x 2): four S doses in top dressing fertilization (0, 60, 120, 180 kg ha-1 of S), with or without organic compost (50 t ha-1) in fertilization before seeding. Place and Duration of the Study: The experiment was carried out in the São Manuel Experimental Farm (22°46’ South, 48°34’ West, 740 m above sea level) in the School of Agriculture (FCA) of the Sao Paulo State University (UNESP) located in São Manuel, SP, Brazil. Radish sown happened in April, and harvest and seed analysis occurred in October 2017. Methodology: Radish seeds were manually harvested (188 days after being sown), cleaned, and dried. Evaluations of seed production per plant, weight of 1000 seeds, and seed quality (germination (%), germination first count, germination speed index, and dry weight of normal seedlings) were performed. Results: Applying organic compost increased radish seed production and the weight of 1000 seeds. Where no organic compost was applied, the higher the S dose, the greater the seed production per plant. With organic compost fertilization, the highest seed production and the weight of 1000 seeds were obtained with top dressing fertilization with 68 kg ha-1 of S. Germination and germination speed index were not affected by either factor, organic compost fertilization or S dose. Where no organic compost was applied, the higher the S dose, the lower the leachate level in the electrical conductivity test. Conclusion: The radish base fertilization with organic compost plus top dressing S fertilization (68 kg ha-1) is indicated for radish seed production.

Selenium treatment enhances the germination and growth of corn seedlings

Early seedling development and germination are vital phases in the life cycle of plants, as optimal germination contributes significantly to crop yields. Selenium (Se), an essential micronutrient for several organisms, including plants, plays a crucial role in improving germination and early seedling growth. Seed priming treatment is presented as a promising alternative to improve these aspects. This study aimed to evaluate the impact of priming treatment with different concentrations of selenium on germination and seedling development of Criollo maize. Two maize varieties were used and five selenium concentrations (0, 25, 50, 75 and 100 µM L-1) were tested. The results indicated that concentrations of 50 and 75 µM L-1 selenium had a noticeable positive effect on variables such as germination percentage, germination rate, germination potential and germination speed index. However, higher concentrations (100 µM L-1) showed consistently lower results, suggesting a negative impact on the germination process and initial seedling development.

Methodology of the accelerated aging test in tiny tomato seeds (solanum lycopersicum var. cerasiforme)

The objective of this study was to study whether the variations in the performance of the accelerated aging test, in terms of exposure time and temperature involved in the test methodology, performed in the traditional way or in saturated salt solution, would result in an efficient combination to evaluate the physiological quality of seeds tiny tomato (Solanum lycopersicum var. cerasiforme). The seeds were submitted to the tests of total germination, germination speed index, first germination count, substrate emergence, seedling length, seedling dry matter, cold test, electrical conductivity and variations in the conduction of the accelerated aging test. The treatments (36, 38, 40 and 42 ºC) x exposure time (24, 36, 48 and 72 hours) x procedures (traditional and saline) were used, with four replications each lot. The averages were compared by the Tukey test at 5% probability. The simple correlation coefficient (r) between the accelerated aging test results and the emergence test of substrate seedlings was also determined. The traditional accelerated aging test in the combinations of 24 hours at 36 °C and the accelerated aging test with saline in the combinations of 72 hours at 36 °C showed sensitivity for the evaluation of the physiological potential of tiny tomato seeds. For both accelerated aging tests, the temperature of 36 °C was efficient for the evaluation of the physiological potential of tiny tomato seeds.

Pinecone failure, hydrogel, fertilizer and volume of containers in the production of araucaria seedlings

The objective of this work was the evaluation of initial growth and quality of araucaria seedlings under the influence of alterations to different proprieties of the substrate. Four different experiments were installed, comparing volume of tubes, concentrations of controlled release fertilizer (FLC), proportion of crushed pinecone failures (substrate characteristics were also evaluated) and the effect of hydrogel concentrations in seedlings derived from different mother trees. The evaluations were carried out 10 months after sowing, varying according to the experiment, and were comprised of height, diameter, height/diameter ratio (h/d), survival rate and germination speed index. The seedlings developed inside the larger tubes (280 cm3) averaged higher in height, diameter and h/d ratio. The 6 g L-1 dose of fertilizer generated higher averages for all analyzed variables. The addition of pinecone failure to the substrate improved some physical attributes such as density, total porosity and aeration space, however it worsened the attributes related to water availability in the substrate. As for the growth of seedlings, the addition of pinecone failure did not change the height, diameter and h/d ratio. The use of hydrogel (3 g L-1 and 6 g L-1) generated better results for height. It is recommended the use of 180 cm³ tubes and 6 g L-1 of the contloed release fertilizer. Pinecone can be used in the substrate, as well as hydrogel as a additional resource.

Effects of Different Priming Treatments on The Germination and Growth of Okra (Abelmoschus esculentus L.)

The study was designed to overcome the low germination of okra seed and to assess the effects of different seed priming treatments on okra (Abelmoschus esculentus) seedlings, which were encompassed nine treatments: control, hydro priming, SMP-sand metrix priming, H2SO4 - 40%, H2O2 - 2%, NaCl - 3%, KCl - 3%, CaCl2 - 3%, and KI - 1%. A randomized complete block design was used with three replications. Germination percentages, germination speed index (GSI), seedling vigor index (SVI), and relative growth rate (RGR) were measured. The highest germination percentage (89.77%) and GSI (9.6) were observed with (H2O2 - 2%). T3 (H2SO4 - 40%) exhibited the highest SVI (0.7), indicating robust seedling health. Additionally, H2O2 - 2%. demonstrated the longest root and shoot length (11.7 cm and 14.2 cm, respectively) and highest seedling fresh weight (0.87 g). Treatment with H2SO4 - 40% displayed the highest dry weight (0.18 g). Notably, H2O2 - 2% treatment significantly enhanced germination and growth compared to the control. These findings underscore the potential of seed priming, particularly H2O2 - 2%, in enhancing okra seedling growth and development, offering valuable implications for crop productivity and establishment.

Seed germination and seedling structure of inga vera willd. (Fabaceae)

The preservation and sustained use of native species require basic botanical studies, especially those that deal with seed germination and seedling. Inga vera is a fruit-bearing species that typically occurs in the Atlantic Forest and riparian forests. The germination of its seeds and the morphoanatomy of its seedlings were the objects of this work. Seeds and reproductive branches were collected at the Caiuá Ecological Station, municipality of Diamante do Norte, Paraná, Brazil. Germination experiments were carried out in chambers with controlled temperature and photoperiod. From the germination tests, the percentage and germination speed index, average germination time and germination uniformity coefficient were calculated. The highest percentage and rate of germination occurred when the seeds were kept at 25°C. The seeds confirmed a recalcitrant characteristic, with reduced germination, after 20 days of storage. The seedlings were developed in a greenhouse, and are phanerocotylar with reserve cotyledons and bifoliolate eophylls. Part of the root and the reduced hypocotyl exhibit a root-stem transition region. The cotyledons have a homogeneous mesophyll and a starchy reserve. The epicotyl has a stem nature. Eophylls show dorsiventral mesophyll. Inga vera has a morphology similar to other investigated species of the genus and typical occurrence of closed primary vegetation.

Biometry and physiological potential of Pterogyne nitens Tull. Seeds as a function of different substrates

The Pterogyne nitens Tul., popularly known as "amendoim-bravo," belongs to the Fabaceae family and can be used in the recovery of degraded areas and in the restoration of riparian forests. The objective of this study was to biometrically characterize the seeds of "amendoim-bravo" and study the influence of substrates on the physiological potential of the seeds. For biometric characterization, eight replicates of 100 seeds were used to determine length and width. In the germination test using a completely randomized experimental design, the seeds were distributed in five different substrates: paper towel in roll form, between blotting paper, on top of blotting paper, between sand, and commercial substrate, at a regulated temperature of 30°C in a Biochemical Oxygen Demand (B.O.D) chamber. The first germination count (PCG), germination speed index (IVG), root length, shoot length of seedlings, dry root mass, and shoot mass of seedlings were analyzed. Evaluating the first germination count and germination index, the paper towel roll substrate showed superiority with 96% and 98%, respectively, statistically differing from the other treatments. The value for germination speed index also highlighted the use of the paper towel roll (6.347). Regarding mean time, mean speed, and synchrony, the best results were also achieved with the paper towel roll substrate. Pterogyne nitens Tul. seeds have an average length of 11.52 mm and a width of 6.35 mm. For evaluating physiological potential, the use of the paper towel roll substrate is recommended.

Physiological potential of canola seeds and its relationship with electrical conductivity

The objective of this work was to evaluate the electrical conductivity test to estimate the physiological potential of canola seeds, aiming to establish an efficient methodology for its execution. The experimental design was completely randomized with hybrids and 4 replications (lot 1 – Hyola 571 CL; lot 2 – Hyola 433; lot 3 – Hyola 76; lot 4 – Hyola 401; lot 5 – Hyola 61 and lot 6 – Hyola 50). Physical quality (degree of moisture and weight of a thousand seeds) and physiological quality (germination, first germination count, germination speed index, seedling emergence, emergence speed index, root length, shoot length and total, seedling dry mass). For the electrical conductivity test, variations in water volume (25, 50, 75 ml), number of seeds (25, 50, 75 and 100 seeds) and exposure time (1, 3, 6, 9.12 and 24 hours). Four replicates of each lot were evaluated. The electrical conductivity test was efficient for evaluating the physiological potential of canola seeds, with combinations of 50 or 75 seeds immersed in 75 ml of deionized water, for periods of 6 and 9 hours, providing better stratification of lots.

Selenium Seed Priming and Biostimulation Influence the Seed Germination and Seedling Morphology of Jalapeño (Capsicum annuum L.)

The priming of seeds is shown as a viable technique to improve germination, the growth of the radicle and plumule, and the seedling vigor index, which gives rise to seedlings with higher quality and tolerance to environmental growing conditions. Sodium selenite (Na2SeO3) and selenium nanoparticles (nSe) were used as priming media and postgermination biostimulation in seeds of jalapeño pepper, in concentrations of 1, 5, 10, 15, 20, 25, 30, 35, 40, and 45 mg L−1 for the two Se species, and control treatment. This research aimed to determine the priming response of jalapeño pepper regarding the germination percent, germination speed index, radicle length, plumule length, fresh weight, and seedling vigor index. The stimulation and phytotoxicity thresholds were also computed. The results showed a percentage of germination greater than 80% in all concentrations evaluated. Most variables of jalapeño pepper presented stimulation responses at Na2SeO3 doses lower than 5 mg L−1 and nSe doses lower than 15 mg L−1. The higher daily germination was favored by nSe on the fifth day compared to the sixth day of Na2SeO3; in addition, the higher cumulative germination occurred on the sixth day with nSe and on the eighth day with Na2SeO3. The use of low Na2SeO3 concentrations positively favors germination and the morphological traits of the shoots. Likewise, the use of Se in nanometric form was friendlier, that is, the degree of tolerance to Se was higher.

Physical and physiological aspects in cocoa seeds influenced by fruit maturity stage

The determination of the harvest time is one of the crucial aspects to consider for obtaining high-quality seeds, which can be established based on the fruit maturity stage. Therefore, the objective of this study was to evaluate the quality of seeds from cocoa clones based on the fruit maturity stage, aiming to determine the ideal harvest time. The experimental design used was completely randomized in a 4 x 4 factorial scheme, with four maturity stages based on the visual coloration of the fruit exocarp (green, semi-green, semi-ripe, and ripe) and four clones (SJ02, CEPEC 2006, PH16, and CCN51). After extraction from the fruits, the seeds underwent analysis, including assessment of physical aspects (length, width, water content, and dry matter) and physiological aspects (germination, germination speed index, seedling emergence, and electrical conductivity). The biometric results showed low influence of the maturity stages, not being sufficient to define the ideal harvest stage. The ripe stage (yellow-orange exocarp) for the studied clones enabled obtaining cocoa seeds with higher quality, generally indicating it as the ideal harvest time.

Physiological performance of brassinolide-conditioned green soybean seeds

Factors associated to biotic and abiotic stresses, such as high temperatures and prolonged droughts, can induce premature plant maturation and, thus, lead to the formation of green seeds. This is major issue for the soybean (Glycine max (L.) Merrill) production chain, due to low physiological seed quality. Although seed conditioning can improve seed germination and vigor, little is known on the use of the brassinolide (BL) phytohormone during this process in green soybean seeds. This study, therefore, aimed to elucidate BL conditioning effects on green soybean seeds. A BL stock solution was prepared and cultivar AS 3680 IPRO seeds were conditioned at 0.0, 0.2, 0.4, 0.6 and 0.8 μM BL concentrations followed by drying until reaching original water contents. Seed conditioning effects were investigated by assessing germination and accelerated aging test results, seedling shoot, and root lengths, electrical conductivity, germination speed index and dry seedling mass. Gas exchanges and chlorophyll a fluorescence parameters were determined in seedlings 15 days after sowing. Seed germination and vigor were superior when conditioned with 0.6 and 0.8 μM BL. Photosynthetic rates, effective quantum yields of PSII photochemical energy conversion and electron transport rates were improved in seeds treated with 0.4, 0.6 and 0.8 μM BL. Brassinolide-conditioned seeds exhibited histochemical reserve tissue differences and greater lipid and protein accumulation compared to the control group. These findings demonstrate that green soybean seed BL treatment can increase the quality and subsequent physiological development in soybean seedlings.

Phytotoxicity and cytogenetic action mechanism of leaf extracts of Psidium cattleyanum Sabine in plant bioassays.

The search for more environmental friendly herbicides, aiming at the control of agricultural pests, combinated with less harmfulness to human health and the environment has grown. An alternative used by researchers is the application of products of secondary plant metabolism, which are investigated due to their potential bioactivities. Thus, species belonging to the Myrtaceae family are potential in these studies, since this family is recognized for having high biological activity. A species belonging to this genus is Psidium cattleyanum, which has a medicinal effect and its fruits are used in human food. Thus, the objective of this research was to evaluate and compare the phyto-cyto-genotoxicity of aqueous and ethanolic leaf extracts of the specie P. cattleyanum, from plant bioassays, as well as to identify the main classes of compounds present in the extracts. For this, the extracts were prepared, characterized and biological tests were carried out by evaluating, in seeds and seedlings of lettuce and sorghum, the variables: percentage of germination, germination speed index, root growth and aerial growth; and in meristematic lettuce cells the variables: mitotic phases, mitotic index, nuclear alterations and chromosomal alterations. Flavones, flavonones, flavonols, flavononols, flavonoids, alkaloids, resins, xanthones and anthraquinone glycoside were characterized in the ethanolic extract. Both evaluated extracts, in the highest concentration, inhibited the initial plant development. All treatments caused alterations in the mitotic phases and inhibited mitotic index. In addition, the treatments promoted an increase in nuclear and chromosomal alterations. The mechanism of action presented was aneugenic, clastogenic and determined in epigenetic alterations. The ethanolic extract was more cytotoxic, since it had a more expressive effect at a lower concentration. Despite the cytotoxicity of the extracts under study, they promoted alterations at lower levels than the glyphosate positive control.

Physiological quality of seeds of arabic coffee cultivars stored for a period of two years.

The rapid loss of viability, coupled with the difficulties and limitations in conserving coffee seeds, are some of the challenges that nurseries are currently facing. Thus, the objective of this work was to analyze the physiological quality of stored Arabica coffee seeds from cultivars recommended for planting in Brazilian mountainous regions. Seeds from 10 Arabica coffee cultivars were used: Catucaí-785/15, Catucaí-2SL, Catucaí-24/137, Japan, Arara, Acauã, Catuaí IAC-81, Mundo Novo IAC-379/19, Catuaí IAC-62, and Caturra IAC-479. The seeds were collected in the Arabica coffee seed production field, in the municipality of Marechal Floriano-ES. They were subsequently processed and dried in the shade, at room temperature, until reaching a humidity of 35 ± 1%, analyzed and stored in a natural laboratory environment (25 ± 2 °C), for 24 months. The following were analyzed: seed water content, germination, germination speed index, electrical conductivity and potassium leaching. The experimental design used was completely randomized, with ten cultivars, two storage times, with four replications of 25 seeds. Storing arabica coffee seeds for 24 months results in a drop in the germination percentage. Stored seeds of the Catucai 24/137 and Arara cultivars showed germination percentages similar to those of newly harvested seeds. Seeds of the Catuai IAC-62 cultivar maintain vigor during storage. The stored seeds of the Caturra IAC-476 and Japi cultivars showed a reduction in physiological quality. Electrical conductivity and potassium leaching tests are efficient in identifying seeds in an advanced state of deterioration. Seeds of Arabica coffee cultivars stored for 24 months, under the conditions of the present study, produce abnormal seedlings.

Tempo de imersão em ácido sulfúrico para superar a dormência de sementes de batata-doce

ABSTRACT To increase genetic variability, sweet potato needs to be sexually propagated in breeding programs. However, its seeds have a hard and thick integument, requiring some dormancy breaking method. Chemical treatment of seeds allows greater efficiency of the relationship between seeds obtained in crosses and those that germinate, providing genotypes to be tested for their potential, aiming at developing a new commercial cultivar. Thus, the objective of this study was to identify the effects of immersion times of seeds in sulfuric acid (98%) on the germination and initial growth of sweet potato seedlings. The seeds were immersed for five different times: 0 (control), 20, 40, 60, and 80 min. The experiment was carried out in a completely randomized design with ten repetitions consisting of 25 seeds each experimental plot. The germination percentage, germination speed index (GSI), dry mass of whole seedlings, and length of the largest root and shoot of the seedlings were evaluated. The germination percentage and GSI increased with immersion time until 53.30 min, with maximum estimated values of 85.39 and 25.10%, respectively. For the parameters dry mass of whole seedlings, length of the largest root, and shoot length, increases were observed up to 55.00, 37.63, and 44.44 min, respectively. In conclusion, the immersion of sweet potato seeds in sulfuric acid (98%) for 53 min is ideal for breaking dormancy and providing better conditions for the initial development of seedlings.

Fitness costs on herbicide-resistant Digitaria insularis (L.) Fedde germination.

Digitaria insularis poses a significant challenge in weed control due to its perennial habit, dense clumping growth, and the widespread presence of herbicide-resistant biotypes. Our research investigates whether single or multiple herbicide resistance biotypes of D. insularis experience fitness costs, specifically affecting their germination. To determine the resistance factor, a dose-response curve was employed using glyphosate and haloxyfop-P-methyl herbicides separately in a completely randomized design (CRD) with four replicates per dose (nine doses total). Shoot dry mass was measured at 100 days after herbicide application (DAA), with control assessments performed at 14, 28, and 42 DAA. Subsequently, a separate CRD experiment examined the germination rate as a function of temperature and photoperiod for each biotype. This factorial scheme tested six temperatures across three biotypes (susceptible and two resistant types) under three light exposure periods (0, 8, and 12 hours). Germination percentage and the germination speed index (GSI) were calculated for 14 days, with counts of healthy seedlings recorded daily. Statistical analysis confirmed the resistance/susceptibility of the biotypes based on the dose-response curve. For the susceptible and simple resistance biotypes, the most favorable temperatures for germination were 20, 30 and 40 °C, at which the highest germination percentages and a higher germination speed index were observed. On the other hand, for the biotype with multiple resistance, the temperatures of 25, 30 and 35 °C were more favorable, promoting superior results in both parameters studied.

Effect of treatment with thiamethoxam and cyantraniliprole on the germination and storage of forest tree seeds

ABSTRACT: Seed predation is a problem that limits the use of direct sowing of tree species, and it is necessary to develop studies involving products used in seed treatment. The objectives of this study were to evaluate the effects of treatment with insecticides on the storage and germination of seeds of six forest species. Seeds were treated with thiamethoxam and cyantraniliprole and germinated on paper and sand substrates at 25 °C under constant light. For storage, the seeds were treated and analyzed at 0, 3 and 6 months. For both tests, the following variables were evaluated: germination, mortality, hard seeds, abnormal seedlings, average length of shoot and primary root, and germination speed index (GSI). For Senna multijuga, treatment with insecticides had no effect. Peltophorum dubium and Enterolobium contortisiliquum showed positive effects of the treatments on seedling vigor and development, while Guazuma ulmifolia displayed a negative effect on primary root length. Bowdichia virgilioides and Hymenaea courbaril seeds were sensitive to the treatments. It is possible to treat and store P. dubium and E. contortisiliquum seeds with thiamethoxam for up to six months.

Abordagem molecular em genitores elites de mamoeiro com foco na qualidade fisiológica das sementes

Abstract: Papaya seeds have natural barriers (phenolic compounds, seed structure and genetic factors) that make their germination difficult. And the use of seeds is the main means of propagating the species, whether for commercial cultivation, maintenance of germplasm or selection of genetic materials. Thus, the use of seeds with physiological quality (germination, normal seedlings and germination speed) is fundamental to the production of vigorous plants. However, few studies have been developed with the aim of evaluating and improving seed quality. From this perspective, the study aims to evaluate the quality of seeds in genetic materials widely used to obtain new genotypes, in order to identify superior materials and possible crosses between those that have high physiological seed quality. For this purpose, 44 genotypes were analyzed by molecular characterization, via microsatellite markers (observed and expected heterozygosity, number of alleles, information index, fixation index, inbreeding coefficient, genetic structure and genetic dissimilarity via UPGMA grouping), as well as determining physiological quality of the seed (germination speed index, percentage of germination and abnormal seedlings). Among the genotypes, 10 have germination above 60%, a high rate of germination speed and a low percentage of abnormal seedlings, and can be used in crosses to improve seed quality. The dissimilarity analysis was able to highlight the dissimilarity between the accessions of the Solo and Formosa groups. The use of the dissimilarity coefficient and the number of shared alleles made it possible to identify 18 possible crosses promising to improve the quality of papaya seeds.

Atividade fitotóxica dos extratos aquosos de Apeiba tibourbou Aubl. e Curatella americana L. na germinação de sementes de Lactuca sativa L.

ABSTRACT Allelochemicals have been used as an alternative to pesticides and inhibit the action of pathogens or stimulating the growth of other plants. This study aimed to analyze the phytotoxic potential of the species Apeiba tibourbou Aubl. (Malvaceae) pau-de-jangada and Curatella americana L. (Dilleniaceae) lixeira on the germination of Lactuca sativa L. seeds (Asteraceae). Aqueous extracts of A. tibourbou and C. americana leaves at different concentrations were applied on L. sativa seeds for seven days. The species studied have the potential to control the germination of lettuce seeds treated with lixeira and pau-de-jangada extracts, especially in terms of germination speed index and average germination time. The extracts of both species have phytotoxic potential for controlling germination.

Thermal optima for seed germination of 30 tree species from Central Amazonia: a comparison of approaches and a new proposal

This study compared the seed germination of 30 tree species from Central Amazonia using a wide temperature range (5-40°C with 12 hours of light daily). Seeds were submitted to pre-germination treatments, whenever necessary, sown on vermiculite or germitest paper, and normal seedling development was assessed until stabilisation. With the same data set, seeds' optimal germination temperature (Topt ) was determined by comparing the following approaches: (i) 2-step, the temperature with the highest germination and the shortest time to seed population reach 50% of germination was chosen; (ii) the highest Germination Speed Index (GSI); (iii) using the formula developed by Olff and collaborators (Olff's approach); (iv) three species were evaluated with Covell's approach; and (v) new formulas for Topt calculation are proposed, based on germination success and five different variables of germination rate (Cipriani's approach). Comparing the results, Topt differed between 0.6-10.0°C. GSI and 2-step indicated generally higher values than Olff's formula. The minimum and maximum Topt differences between Cipriani's approaches were between 0.1-2.2°C. Our study showed that Toptshould be determined for each species as, even the 30 Amazonian tree species of the same habitat, Topt ranged between 22.5 and 32.5°C.