Morphology and Allometry of Juvenile Açaí Palms Under Cultivation Conditions in Central Amazonia

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper investigates the morphological and developmental differences between two Amazonian açaí palm species, Euterpe oleracea and Euterpe precatoria, under controlled cultivation conditions in Central Amazonia. By examining key growth traits such as stem height, diameter, and leaf characteristics, the study identifies significant differences in growth performance and reproductive timing between the species. The findings highlight E. oleracea's faster growth and earlier onset of reproduction, making it a more viable option for commercial cultivation. The development of precise allometric models for estimating leaf area further contributes to optimizing cultivation practices, offering valuable insights for improving productivity and management of these economically important palms. Here are some suggestions to enhance the overall quality of the work.

Abstract

Explicitly state the primary aim of the study in the first sentence to immediately inform readers about the focus. For instance, you might start with: “This study aims to compare the morphological and developmental traits of two Amazonian açaí palm species, Euterpe oleracea and Euterpe precatoria, to refine genotype identification and improve production methods.”

Highlight the most significant findings and their implications for cultivation strategies more clearly. For example, you can mention, “The study identified key differences in growth and reproductive timelines between the species, which can inform targeted cultivation practices to enhance yield.”

Streamline the results to focus on the most impactful findings without excessive technical detail. Instead of listing every measured parameter, summarize the key differences and their importance. For example: “E. oleracea showed superior growth metrics and earlier reproductive onset compared to E. precatoria, underscoring the potential for differentiated management approaches to optimize production.”

Introduction

Strengthen the background by briefly discussing the historical significance of açaí palm species in Amazonian culture and economy. Highlight how their cultivation has evolved over time and the impact on local communities.

Although you mention limited investments in cultivation technologies, explicitly state the existing knowledge gaps regarding the morphological and developmental differences between the two species under controlled cultivation conditions.

Emphasize the practical implications of understanding morphological traits, such as how variations in leaf area, stem structure, and growth patterns can influence cultivation techniques. For instance, you could discuss how these traits inform decisions related to planting density, irrigation schedules, or harvesting strategies, directly connecting the research findings to potential agricultural applications.

Materials and Methods

While the current structure is detailed, organizing the section into more concise subheadings with clear descriptions will help readers follow the experimental setup easily. For example, use subheadings like "Study Site and Climate Conditions," "Soil Preparation and Planting Procedures," and "Nutrient Management and Pruning Practices" to guide readers through each stage of the methodology.

Briefly explain the rationale behind specific experimental choices, such as why the BRS Pará and Chumbinho cultivars were selected, the significance of using aged laying hen manure, and the choice of measurement tools like the CI-203 Portable Laser Area Meter. Providing these justifications will help readers understand the scientific basis behind each method.

Ensure all procedural details are sufficiently precise for replication. For instance, specify the exact protocols for phenotypic assessments, including the criteria for identifying nutritional deficiencies and the standards used for recording growth metrics. Explicitly mention any calibration steps or quality control measures taken for the measuring instruments, as these details are critical for other researchers attempting to replicate the study.Top of Form

Results and Discussion

Expand on the implications of the observed nutritional deficiencies in E. precatoria, particularly in the context of its lower reproductive performance and slower growth compared to E. oleracea. Discuss how the increased sensitivity to boron and potassium deficiencies might affect long-term productivity and what targeted interventions could mitigate these impacts, such as tailored fertilization schedules or soil amendments specifically designed for E. precatoria.

While the section provides valuable insights into the growth metrics of both species, emphasize how these morphological differences translate into practical agricultural benefits. For instance, discuss how the superior stem and leaf growth of E. oleracea can enhance its suitability for intensive cultivation, contrasting this with the potential challenges of managing E. precatoria in similar settings. Highlight how these traits could guide species selection for specific environments or cultivation goals.

Integrate a discussion on how leaf area directly influences photosynthetic capacity, light interception, and overall plant vigor. Explain the practical significance of the allometric models developed for estimating leaf area, such as their potential use in optimizing planting density, predicting growth responses to environmental stress, or assessing the impacts of different cultivation practices. This will help bridge the gap between physiological measurements and their practical application in improving açaí cultivation.

 

Conclusions

Write one logical paragraph for conclusion.

Expand the conclusions to connect the findings to broader implications, such as how the results can influence regional agricultural practices or impact local economies. Highlight the potential for E. oleracea to drive economic growth in Amazonian communities due to its faster growth and earlier reproductive phase, which can attract investment in açaí cultivation.

Based on the observed differences between the two species, provide specific recommendations for cultivation adjustments. For example, suggest exploring increased planting densities or tailored nutrient management protocols for E. precatoria to mitigate its slower growth and smaller leaf area, enhancing its productivity.

Clearly state the need for future research, such as developing cultivars of E. precatoria with improved growth traits or testing allometric models across different environmental conditions. Highlight how these research efforts could bridge the identified gaps, optimize cultivation, and improve the commercial viability of both species.Bottom of Form

Comments on the Quality of English Language

 Minor editing of English language required.

Author Response

Dear Reviewer #1,

We appreciate your constructive criticisms certainly contributed to the improvement of the document. We attended most of the points raised by the reviewers, modified others and addressed detailed answers. Other changes were inserted directly into the text and are highlighted with the track changes tool.

Comments 1: This paper investigates the morphological and developmental differences between two Amazonian açaí palm species, Euterpe oleracea and Euterpe precatoria, under controlled cultivation conditions in Central Amazonia. By examining key growth traits such as stem height, diameter, and leaf characteristics, the study identifies significant differences in growth performance and reproductive timing between the species. The findings highlight E. oleracea's faster growth and earlier onset of reproduction, making it a more viable option for commercial cultivation. The development of precise allometric models for estimating leaf area further contributes to optimizing cultivation practices, offering valuable insights for improving productivity and management of these economically important palms. Here are some suggestions to enhance the overall quality of the work.

Response 1: We are grateful for your valuable suggestions and studies presented related with our work.

Comments 2 (Abstract): Explicitly state the primary aim of the study in the first sentence to immediately inform readers about the focus. For instance, you might start with: This study aims to compare the morphological and developmental traits of two Amazonian açaí palm species, Euterpe oleracea and Euterpe precatoria, to refine genotype identification and improve production methods. 

Explicitly state the primary aim of the study in the first sentence to immediately inform readers about the focus. For instance, you might start with: This study aims to compare the morphological and developmental traits of two Amazonian açaí palm species, Euterpe oleracea and Euterpe precatoria, to refine genotype identification and improve production methods.

Highlight the most significant findings and their implications for cultivation strategies more clearly. For example, you can mention, The study identified key differences in growth and reproductive timelines between the species, which can inform targeted cultivation practices to enhance yield.

Streamline the results to focus on the most impactful findings without excessive technical detail. Instead of listing every measured parameter, summarize the key differences and their importance. For example: E. oleracea showed superior growth metrics and earlier reproductive onset compared to E. precatoria, underscoring the potential for differentiated management approaches to optimize production.

Response 2: The suggestion was accepted and corrected. "Two Amazonian species of açaí palm trees (Euterpe oleracea and Euterpe precatoria) are exploited in the commercial production of açaí pulp or juice. While E. oleracea benefits from developed cultivation technologies, E. precatoria lacks such advancements. Studies on the morphology and development of açaí palms under cultivation conditions can contribute to increasing the productivity of the species. The aim of this study was to carry out morphological characterization, assess growth and development in the juvenile phase of the plants, and obtain allometric models for E. precatoria and E. oleracea. Evaluations were conducted between 44 to 48 months post-planting. Allometric equations were formulated to accurately estimate leaf area. Results showed that E. oleracea begins reproduction earlier and exhibits greater growth in stem dimensions and leaf areas compared to E. precatoria, indicating that E. precatoria can be cultivated at higher planting densities. Allometric models, based on leaf length and width, effectively predicted individual leaf areas for both species, demonstrating their utility in optimizing cultivation strategies."

Comments 3 (Introduction): Strengthen the background by briefly discussing the historical significance of açaí palm species in Amazonian culture and economy. Highlight how their cultivation has evolved over time and the impact on local communities.

Although you mention limited investments in cultivation technologies, explicitly state the existing knowledge gaps regarding the morphological and developmental differences between the two species under controlled cultivation conditions.

Emphasize the practical implications of understanding morphological traits, such as how variations in leaf area, stem structure, and growth patterns can influence cultivation techniques. For instance, you could discuss how these traits inform decisions related to planting density, irrigation schedules, or harvesting strategies, directly connecting the research findings to potential agricultural applications.

Response 3: The suggestion was accepted and corrected. "Açaí smoothies are an important food for indigenous peoples and traditional populations of the Amazon. In recent decades, they have reached national and international markets. Extractive production has failed to meet the growing market demand, which highly rewards the product, and the areas of cultivated açaí palm have been continuously expanding, predominantly with the species E. oleracea."

To address the second observation, the article presents the information that for E. oleracea, production systems already exist, whereas for E. precatoria, no recommendations are available. However, we emphasize in the article that:
"There are significant knowledge gaps regarding the morphological and developmental differences between E. oleracea and E. precatoria under controlled cultivation conditions. Specifically, while E. oleracea already has developed cultivation technologies and is widely studied, such as cultivars and production systems, E. precatoria lacks such advancements. There are no recommended cultivars or production systems for E. precatoria, and knowledge about the behavior of this species under local cultivation conditions is quite limited, based on empirical experiences of farmers. This highlights the need for more research to explore the growth, productivity, and morphological responses of E. precatoria under agricultural management, with the aim of optimizing production and reducing the non-productive phase of this species, promoting its economic viability."

Understanding morphological characteristics, such as leaf area, stem structure, and growth patterns, is essential to optimize cultivation techniques. These characteristics influence decisions such as plant spacing, irrigation management, and harvesting strategies. For example, plants with larger leaf areas, like E. oleracea, may require wider spacing and more water, while their faster growth and earlier onset of the productive phase favor quicker harvesting. Thus, this information is fundamental for improving productivity and efficiency in managing açaí plantations.

Comments 4 (Materials and Methods): While the current structure is detailed, organizing the section into more concise subheadings with clear descriptions will help readers follow the experimental setup easily. For example, use subheadings like "Study Site and Climate Conditions," "Soil Preparation and Planting Procedures," and "Nutrient Management and Pruning Practices" to guide readers through each stage of the methodology.

Briefly explain the rationale behind specific experimental choices, such as why the BRS Pará and Chumbinho cultivars were selected, the significance of using aged laying hen manure, and the choice of measurement tools like the CI-203 Portable Laser Area Meter. Providing these justifications will help readers understand the scientific basis behind each method.

Ensure all procedural details are sufficiently precise for replication. For instance, specify the exact protocols for phenotypic assessments, including the criteria for identifying nutritional deficiencies and the standards used for recording growth metrics. Explicitly mention any calibration steps or quality control measures taken for the measuring instruments, as these details are critical for other researchers attempting to replicate the study.

Response 4: The suggestion was accepted and corrected. We have addressed the suggestion to subdivide the item as requested.

The cultivars BRS Pará and Chumbinho were used to represent the species E. oleracea as they were the only ones available with commercial seed production at the time of the experiment's establishment. These cultivars were primarily selected to increase productivity and early reproductive maturity, characteristics that make them more suitable for intensive cultivation systems. The use of aged laying hen manure is due to local availability, the cultivation methods used by regional farmers, and because it is a rich source of essential nutrients, such as nitrogen, phosphorus, and potassium, which improve soil fertility, promote root development, and increase water retention capacity, contributing to plant development.

The CI-203 Portable Laser Area Meter allows for precise and non-destructive measurements of leaf area, which is essential for assessing the photosynthetic capacity of plants. In the study, this tool was used to create allometric models based on simple leaf dimensions, such as leaflet length and width, facilitating rapid and accurate assessment of plant growth.

Criteria for Identifying Nutritional Deficiencies: The assessment of nutritional deficiencies was conducted on 227 E. precatoria plants and 179 E. oleracea plants at 48 months after planting. Visual symptoms were directly observed on the plants and classified into: a) potassium deficiency, b) combined deficiency of potassium and boron. The methodology for identifying these deficiencies involved observing typical symptoms on leaves, such as marginal chlorosis for potassium and growth deformations in young leaves for boron. Additionally, the incidence of plants in the reproductive stage was recorded, counting those that displayed inflorescences or fruit clusters, regardless of whether abortion occurred before or after the assessment.

The area meter allows for precise and non-destructive measurements of leaf area, which is essential for assessing the photosynthetic capacity of plants. In the study, this tool was used to create allometric models based on simple leaf dimensions, such as leaflet length and width, facilitating rapid and accurate assessment of plant growth.

For leaf area measurement, the CI-203 Portable Laser Area Meter®️ was used, properly calibrated according to the manufacturer's instructions before each use, to ensure data accuracy. Leaves were harvested destructively, and all leaflets were measured in-dividually. The CI-203 was calibrated at regular intervals to maintain accuracy, and the leaves were carefully handled to avoid any alteration in shape during measurement. To ensure consistency and avoid bias, measurements were carried out by the same trained technician, and any anomalous values or those outside the expected standards were investigated and, if necessary, excluded from the final analysis.

The measurement of leaf morphology followed a completely randomized experi-mental design with three treatments (BRS Pará and Chumbinho cultivars of E. oleracea and E. precatoria plants) and three repetitions, with three plants per treatment. Leaf 3 from each plant was used, considering leaf 1 as the most recently expanded leaf of the plant. In addition to individual leaf area, the following measurements were taken for all leaves: a) petiole length (cm); b) petiole height (cm); c) petiole width (cm); d) rachis length (cm); e) leaf width (cm); f) number of leaflets; g) leaflet length (cm); h) leaflet width (cm); and i) distance between leaflets (cm).

A random selection of 44 E. oleracea plants (27 from the BRS Pará cultivar and 17 from the Chumbinho cultivar) and 121 E. precatoria plants were chosen to assess stem growth and leaf number. Plants from the outer rows and edges were excluded, as were those showing visible symptoms of nutritional deficiencies, pest attacks, or abnormal charac-teristics. The measured parameters were for stem: a) stem height (m), measured from the base to the bifurcation between the first expanded leaf and the young leaf, using a graduated ruler; b) internode distance (cm), calculated from the average of five internodes below 1.50 m in height; and c) stem diameter (cm), measured at the base with a tape measure; d) number of leaves per plant, including the main stem and up to three lateral shoots; the measurements for rachis width (cm); and rachis height (cm) were taken using a graduated ruler, with the width measured adjacent to the insertion of the first leaflet and the height measured in the same region. The presence of a yellow stripe on the rachis was visually assessed, noting whether this distinctive trait was present or absent. The shape of the rachis was determined by visual inspection and described based on its geometric characteristics, such as trapezoidal or triangular.

Leaf area was measured using the CI-203 Portable Laser Area Meter®, which pro-vided accurate values by scanning individual leaves. The total plant leaf area (m²) was calculated by summing the leaf area of all green, active leaves on each plant..

Quality Control in Statistical Analyses: Statistical analyses were conducted using IBM SPSS®️ software, and data normality was verified graphically, as well as the homoscedasticity of standardized residuals in the allometric models developed to estimate leaf area. Outlier values were identified when standardized residuals exceeded ±2, and were then excluded from subsequent analyses.

Comments 5 (Results and Discussion): Expand on the implications of the observed nutritional deficiencies in E. precatoria, particularly in the context of its lower reproductive performance and slower growth compared to E. oleracea. Discuss how the increased sensitivity to boron and potassium deficiencies might affect long-term productivity and what targeted interventions could mitigate these impacts, such as tailored fertilization schedules or soil amendments specifically designed for E. precatoria.

While the section provides valuable insights into the growth metrics of both species, emphasize how these morphological differences translate into practical agricultural benefits. For instance, discuss how the superior stem and leaf growth of E. oleracea can enhance its suitability for intensive cultivation, contrasting this with the potential challenges of managing E. precatoria in similar settings. Highlight how these traits could guide species selection for specific environments or cultivation goals.

Integrate a discussion on how leaf area directly influences photosynthetic capacity, light interception, and overall plant vigor. Explain the practical significance of the allometric models developed for estimating leaf area, such as their potential use in optimizing planting density, predicting growth responses to environmental stress, or assessing the impacts of different cultivation practices. This will help bridge the gap between physiological measurements and their practical application in improving açaí cultivation.

Response 5: The suggestion was accepted and corrected. For most evaluated characteristics, the effect of treatments was significant (Table 1). According to the classification proposed by Pimentel-Gomes [33], among the nine morphological characteristics evaluated on leaves, the coefficient of variation (CV) was low for rachis length (CV = 9%), high for petiole height (CV = 22%), and very high for petiole length (CV = 47%).

The nutritional deficiencies observed in Euterpe precatoria, particularly increased sensitivity to boron and potassium shortages, have significant implications for its reproductive performance and slow growth compared to Euterpe oleracea. In the study, E. precatoria exhibited a 13.9% incidence of plants with boron deficiency and 2.4% with potassium deficiency, while E. oleracea showed no visual symptoms of these deficiencies.

Boron deficiency affects the formation of young cells and tissues, directly impacting leaf growth and the formation of reproductive organs, while potassium deficiency interferes with water regulation and photosynthesis, impacting the overall health of the plant and its long-term productive capacity. The low productivity and delayed onset of the reproductive phase, due to these deficiencies, may result in slower economic returns for farmers who choose to cultivate E. precatoria.

To mitigate these impacts and enhance long-term productivity, specific interventions may be necessary. One strategy could be the development of fertilization programs tailored to the specific needs of E. precatoria, including the application of fertilizers with higher concentrations of boron and potassium at critical growth stages. Additionally, the use of soil amendments and management techniques that enhance the availability of these nutrients over time, such as the use of slow-release fertilizers or organic compounds rich in micronutrients, can help reduce this species' sensitivity to nutritional deficiencies. Field trials to test different doses and sources of fertilizers would also be useful to adjust fertilization recommendations and maximize the economic return of this species by optimizing its management similarly to what has been done with E. oleracea. The results of the study clearly indicate that the two species have distinct nutritional requirements, with E. precatoria showing greater sensitivity to boron and potassium deficiencies. This sensitivity may be linked to its lower reproductive performance and slower development compared to Euterpe oleracea. Thus, the need for specific studies on nutritional management for E. precatoria is evident. Further research is essential to develop fertilization strategies that better meet the nutritional demands of this species, thereby increasing its productivity and long-term economic viability. The proposal for tailored fertilization programs and the need for field trials to test different nutrient combinations and dosages align with the knowledge gaps identified in the study.

{In response to the reviewer, it is important to clarify that, as described in the methodology, plants that exhibited visual nutritional deficiencies were properly excluded from phenotypic assessments, ensuring that these deficiencies did not directly influence the results related to slower or reduced growth observed in Euterpe precatoria.}

The morphological differences between E. oleracea and E. precatoria translate into practical benefits for agriculture. The superior stem and leaf growth of E. oleracea demonstrate its greater suitability for intensive cultivation, where its rapid development and larger leaf area result in higher photosynthetic capacity and productivity in less time, making it ideal for environments where space optimization and maximizing quick economic returns are priorities. In contrast, E. precatoria shows slower growth, smaller leaf area, and greater sensitivity to nutritional deficiencies, such as those of boron and potassium, which can pose challenges in intensive cultivation scenarios. However, E. precatoria may be more suitable for low-density environments or agroforestry systems, where less intensive management is feasible, and the pressure for high yields in the short term is lower. These morphological differences should, therefore, guide species selection according to the environment and cultivation objectives, with E. oleracea being more suitable for intensive cultivation systems with efficient management, while E. precatoria may be better utilized in conditions that favor its slower growth cycle and specific nutritional needs.

Leaf area is a determining factor that directly influences photosynthetic capacity, light interception, and the overall vigor of plants, playing a central role in the productive capacity of açaí species. Plants with larger leaf areas, like E. oleracea, have a greater ability to capture sunlight, converting it into energy through photosynthesis, which results in greater vegetative and reproductive growth. Conversely, the smaller leaf area observed in E. precatoria may limit this capacity, reflecting in lower vigor and slower growth. In this context, the allometric models developed to estimate leaf area are valuable practical tools for agricultural management. These models allow for the rapid and accurate estimation of leaf area based on simple measurements, such as the length and width of leaflets, which can be used to optimize planting density, adjusting plant spacing to maximize light interception and minimize competition. Additionally, these models are useful for predicting plant responses to environmental stresses, such as variations in light, water, or nutrient availability, allowing for management adjustments, such as changing irrigation regimes or modifying fertilization to better meet the specific needs of the plants. They can also be used to assess the impact of different cultivation practices, such as thinning, on the growth and productivity of plants. The application of allometric models in agricultural practice not only improves the efficiency of açaí cultivation management but also maximizes the productive potential of plants, ensuring better adaptation to environmental conditions and management practices.

Comments 6 (Conclusions): Write one logical paragraph for conclusion.

Expand the conclusions to connect the findings to broader implications, such as how the results can influence regional agricultural practices or impact local economies. Highlight the potential for E. oleracea to drive economic growth in Amazonian communities due to its faster growth and earlier reproductive phase, which can attract investment in açaí cultivation.

Based on the observed differences between the two species, provide specific recommendations for cultivation adjustments. For example, suggest exploring increased planting densities or tailored nutrient management protocols for E. precatoria to mitigate its slower growth and smaller leaf area, enhancing its productivity.

Clearly state the need for future research, such as developing cultivars of E. precatoria with improved growth traits or testing allometric models across different environmental conditions. Highlight how these research efforts could bridge the identified gaps, optimize cultivation, and improve the commercial viability of both species.

Response 6: The suggestion was accepted and corrected.  While the early maturity of the Euterpe oleracea species is an initial advantage, it should not be the only aspect considered when choosing a species for planting. Productivity data for fruit yield and pulp output of Euterpe precatoria still need to be obtained for an economic analysis of the species considering the lifespan of the plantations. Moreover, the species have distinct harvest periods, which is important for market price stability, considering that price variation is very high due to product scarcity, especially during the off-season of E. oleracea.

Among future research efforts to promote the sustainable development of the E. precatoria production chain, the development of cultivars with homogeneity in growth, early maturity, and high fruit and pulp productivity is highlighted. The superiority of E. oleracea in terms of rapid growth and early onset of the reproductive phase underscores its potential to boost economic growth in the Amazon, making it ideal for intensive, high-productivity cultivations. Its ability to enter production earlier offers quick financial returns, which can attract investments for the expansion of açaí cultivation, essential for the local economy. With the use of appropriate management techniques and allometric models, producers can optimize inputs and space, increasing the efficiency and sustainability of the plantations.

The differences in nutritional requirements between E. oleracea and E. precatoria reinforce the need for specific management practices for each species, with E. oleracea being more suitable for intensive systems and E. precatoria for agroforestry systems in more sensitive ecosystems. This understanding can diversify agricultural practices and promote environmental preservation. The economic impact can be significant, given the international interest in the açaí market, generating more jobs and income in rural communities, promoting sustainable development, and enhancing the global competitiveness of the region.

To improve the productivity of E. precatoria, it is recommended to increase planting density due to its slower growth and smaller leaf area, optimizing the use of space. Additionally, specific nutritional protocols, focusing on nutrients such as boron and potassium, can mitigate deficiencies and stimulate growth. Controlled-release fertilizers and adjusted irrigation practices can accelerate its development, making its cultivation more competitive and productive.

Once again we thank you for your willingness to consult our work and also for your valuable criticism.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses an interesting topic on the morphology and allometry of juvenile Acai palms under cultivation conditions. However, a bit of confusion arises when the comparison of different species of Acai palms is added. From the information provided in the introduction, it is known in advance that the species analyzed - Euterpe oleracea and Euterpe precatoria - are different, not only in their natural development but also in the process of genetic improvement of each of them. This situation is even more complicated when, for one of the species, E. oleracea includes two cultivars. In fact, the genetic purpose for generating these cultivars is not specified. Although the methodology in general seems well structured, some doubts increase when considering different numbers of plants in the analysis of stem growth and number and area of ​​leaves. It seems important to me that these points must be clarified in the document to give clarity, solidity and foundation to the work and therefore, to the results.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The quality of English looks ok

Author Response

Dear Reviewer #2,

We appreciate your constructive criticisms certainly contributed to the improvement of the document. We attended most of the points raised by the reviewers, modified others and addressed detailed answers. Other changes were inserted directly into the text and are highlighted with the track changes tool.

Comments 1: The manuscript addresses an interesting topic on the morphology and allometry of juvenile Acai palms under cultivation conditions. However, a bit of confusion arises when the comparison of different species of Acai palms is added. From the information provided in the introduction, it is known in advance that the species analyzed - Euterpe oleracea and Euterpe precatoria - are different, not only in their natural development but also in the process of genetic improvement of each of them. This situation is even more complicated when, for one of the species, E. oleracea includes two cultivars. In fact, the genetic purpose for generating these cultivars is not specified. Although the methodology in general seems well structured, some doubts increase when considering different numbers of plants in the analysis of stem growth and number and area of ​​leaves. It seems important to me that these points must be clarified in the document to give clarity, solidity and foundation to the work and therefore, to the results.

Response 1: We are grateful for your valuable suggestions and studies presented related with our work.

We appreciate the questions and relevant observations. Indeed, the comparison between Euterpe oleracea and Euterpe precatoria was conducted with full awareness of their natural differences and levels of genetic improvement. We recognize that E. oleracea has undergone a domestication process and the development of cultivars, such as BRS Pará and Chumbinho, while E. precatoria still largely relies on the empirical knowledge of farmers. However, the intention of the comparison was precisely to highlight how these differences affect their performance under controlled cultivation conditions, offering insights that may guide future management and improvement strategies for both species. We acknowledge that the genetic objective for the generation of E. oleracea cultivars was not detailed clearly in the manuscript, as it is not the focus of the research. These cultivars were developed with the intention of increasing productivity and early reproductive maturity, which makes E. oleracea more suitable for intensive cultivation, while E. precatoria still has gaps in terms of technical recommendations for maximizing its productivity. All this has been clarified in the article. Regarding the number of plants used in the analysis of stem growth and number and area of leaves, we understand the concern about variability in the samples. The difference in the number of plants analyzed between the species is due to the availability of plants in development within the experiment and the exclusion criteria established in the methodology, such as excluding plants with visible symptoms of nutritional deficiencies or growth anomalies. This procedure was adopted to ensure the homogeneity of the plants analyzed and to prevent external factors from affecting the study results. These points have been clarified in the document, reinforcing the methodological robustness and the foundations that underpin the results, and better contextualizing the differences between the species.

Comments 2: if the two palm species already develop distinct characteristics, why authors want to compare the morphological characteristics?

Response 2: The suggestion was accepted and corrected. Comparing the morphological characteristics between Euterpe oleracea and Euterpe precatoria is important to assess how their differences manifest under controlled cultivation conditions, allowing for a better understanding of their responses to agricultural management. This helps identify the advantages and limitations of each species, such as the rapid growth and early reproductive maturity of E. oleracea compared to E. precatoria. The analysis of these differences provides valuable information for selecting species or cultivars that are more suited to different cultivation goals. Information on the morphology and growth of E. precatoria under controlled conditions can guide studies to increase the species’ production in cultivation, taking as a reference the practices already adopted for E. oleracea cultivars.

Comments 3: The question arises as to why the study was conducted under controlled conditions, without clarifying which factors were controlled to resemble or prove a condition.

Response 3: The suggestion was accepted and corrected. The study was conducted using management practices recommended for Euterpe oleracea, including planting spacing, pit preparation, and fertilization. The study was conducted under controlled conditions to minimize the interference of external environmental variables, allowing for an accurate assessment of the morphological and growth characteristics of the açaí species, Euterpe oleracea and Euterpe precatoria. Factors such as soil management, plant spacing, pest control, and fertilization regime were standardized to ensure that the differences observed were primarily attributed to the intrinsic characteristics of the species, rather than environmental variations. The purpose of these conditions was to simulate an intensive cultivation environment, eliminating external factors that could distort the results, such as light and nutrient availability, enabling a fair comparison between the species. This approach provides a solid foundation for understanding the performance of each species under modern agricultural management, aiding in the formulation of more effective and tailored cultivation strategies. These points have been clarified in the manuscript.

Comments 4:  Explain whay you use diffent number of plants per type.

Response 4: The suggestion was accepted and corrected. As there are no cultivars for Euterpe precatoria, to represent the genetic variability of the species, seedlings obtained from open-pollinated seeds from different clusters and collection origins were used. Therefore, to obtain more accurate estimates of the evaluated characteristics, the number of E. precatoria plants assessed was higher than that of the E. oleracea cultivars, which have undergone selection processes and exhibit lower genetic variability.

Comments 5: In total, 34 leaves from E. oleracea and 33 from E. 189 precatoria were evaluated.

Response 5: The suggestion was accepted and corrected. We appreciate the reviewer's observation regarding the difference in the number of leaves analyzed between the two species. However, we would like to clarify that the sampling was carried out based on the number of plants, using 3 plants from each species, and all leaves were analyzed, considering, in the case of Euterpe oleracea, the leaves from the main stipe. Although the total number of leaves was different between the species, we believe that removing a leaf from E. oleracea to equalize the number of leaves of E. precatoria would not be an appropriate solution. This would require the definition of an arbitrary criterion for exclusion, which could introduce a more significant bias in the results than analyzing an additional leaf. We chose to maintain the integrity of the collected data to ensure that the conclusions accurately reflect the characteristics of each species, without the introduction of artificial variables that could compromise the comparative analysis.

Comments 6: It will be important to point out in the methodology the characteristics by which these cultivars were genetically generated. Maybe from there comes the difference with E. precatoria.

Response 6: The suggestion was accepted and corrected. We appreciate the suggestion and agree that including more details about the genetic characteristics for which the Euterpe oleracea cultivars were developed will be important to clarify the differences observed in comparison with Euterpe precatoria. We have added a more detailed explanation in the methodology section about the objectives of the genetic improvement of the BRS Pará and Chumbinho cultivars, which were selected primarily to increase productivity and early reproductive maturity, characteristics that make them more suitable for intensive cultivation systems. This genetic distinction may indeed be one of the main factors explaining the growth and morphological differences between the two species. By providing this context, we hope to clarify the impact of the breeding process on E. oleracea, differentiating it from E. precatoria, which still relies on seeds from natural populations without genetic interventions.

Comments 7: For all (all? most of) evaluated traits, the effect of treatments was significant (Table 1).

Response 7: The suggestion was accepted and corrected. We appreciate the observation. Indeed, the phrase "for all evaluated traits" could lead to incorrect interpretation, as not all traits exhibited the same level of variation. The phrase was revised to better reflect the observed data. The correct formulation would be: "For most of the evaluated characteristics, the effect of the treatments was significant (Table 1). According to the classification proposed by Pimentel-Gomes [33], among the nine morphological characteristics evaluated in the leaves, the coefficient of variation (CV) was low for the rachis length (CV = 9%), high for the petiole height (CV = 22%) and very high for the petiole length (CV = 47%)". This provides a more accurate representation of the results and eliminates incorrect generalization.

Comments 8: Unlike what was observed in E. precatoria, in E. oleracea the correlation value between height and stem diameter was negligible (r = 0.29, p>0.05), indicating no correlation. This result may be due to the morphological differences between the species, notably that in E. oleracea, measurements were only taken on the main stem, and the species has a clumping habit with up to three offshoots maintained per plant, whereas E.  precatoria has a solitary stem

This morphological difference should have been pointed out and considered. Otherwise, the differences between species are obvious, which raises doubts about the importance of the comparisons made.

Response 8: The suggestion was accepted and corrected. We appreciate the comment and would like to clarify that the morphological difference between the species was not disregarded. On the contrary, in the article we highlighted that the correlation between height and diameter observed in Euterpe precatoria, but not in Euterpe oleracea, "may" be attributed to the characteristic tillering of E. oleracea. This tillering results in several stems of different heights, with the main stem being the one that most reflects the plant's vertical growth, which justifies our choice to measure the height only on this main stem. Measuring the other stems of E. oleracea, which are shorter, would not provide an accurate comparison with E. precatoria, which presents a solitary stem. Therefore, the option to focus on the main stem of E. oleracea was the most appropriate way to ensure a fair comparative analysis between the two species, respecting their distinct morphological characteristics. Thus, the approach adopted allows for a more faithful evaluation of the development of these plants under controlled conditions. We reaffirm that the morphological differences were considered and discussed in order to clarify how these peculiarities influence the results and interpretations of the study.

Once again we thank you for your willingness to consult our work and also for your valuable criticism.

 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

 Accept in present form

Comments on the Quality of English Language

 Accept in present form

Reviewer 2 Report

Comments and Suggestions for Authors

The authors responded and adequately addressed the comments made during the review process. Therefore, I have no additional comments on the work.

Comments on the Quality of English Language

The quality of English looks good