Sustainable Water Management in Horticulture: Problems, Premises, and Promises

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I reviewed the manuscript entitled: Sustainable water management in horticulture: status and main challenges. They manuscript is very well written and summarized the important information with in the perspective of growing and water management in the horticulture crops. However, previously a lot of review articles are published based on water management in agriculture. As Horticulture is a subset of agriculture that deals specifically with cultivation of fruits, vegetables, flowers, and ornamental plants. Therefore, the information should be especially related to water management in flowers, and ornamental plants. As a lot of material is available on water management in fruits and vegetables. I gave you some of the examples here for your reference:

1.     Agricultural and Technology-Based Strategies to Improve Water-Use Efficiency in Arid and Semiarid Areas. Water 2024, 16, 1842.

2.     Horticultural Irrigation Systems and Aquacultural Water Usage: A Perspective for the Use of Aquaponics to Generate a Sustainable Water Footprint. Agriculture 2024, 14, 925.

3.     A Review of Precision Irrigation Water-Saving Technology under Changing Climate for Enhancing Water Use Efficiency, Crop Yield, and Environmental Footprints. Agriculture 2024, 14, 1141

4.     Water Resources Management under Climate Change: A Review. Sustainability 2024, 16, 3590.

5.     Application of Internet-of-Things Wireless Communication Technology in Agricultural Irrigation Management: A Review. Sustainability 2024, 16, 3575.

6.     Transformative Technologies in Digital Agriculture: Leveraging Internet of Things, Remote Sensing, and Artificial Intelligence for Smart Crop Management. J. Sens. Actuator Netw. 2024, 13, 39.

7.     An Overview of Smart Irrigation Management for Improving Water Productivity under Climate Change in Drylands. Agronomy 2023, 13, 2113.

Overall all manuscript is very well written but some of the suggestions are:

1.     Authors should clearly state the problems of the existing works.  How current study is different from above mentioned studies. The author should show us a deep analysis of the gaps in existing methods and why your research is essential. The study's novelty should be highlighted, and the topic should be focused on in-depth.

2.     There is a huge amount of information and a better summarization and classification would be appreciated. Your discussion should be particularly related to water management according to horticulture perspective. Some mentioned sections are general terms used for water management in agriculture and a lot of material is already published.

3.     Delete those keywords repeating with title.

4.     In introduction sections, I suggest adding one paragraph discussing about the whole body of the paper such as Section 2, discusses xyz and Section 3, which deals with xyz, and so on.

5.     It would be nice, adding one section about review methodology.

6.     Authors should add one more section discussing the future prospectus and major issues of water management for horticulture crops, which should be considered for future research.

Author Response

REVIWER 1

 

Comment: “They manuscript is very well written and summarized the important information with in the perspective of growing and water management in the horticulture crops.”

Response:

The authors would like to thank the Reviewer for the time spent with our manuscript, for the constructive comments provided, and the relevant suggestions that helped us to improve the quality of the manuscript. Details on how the comments were addressed in the manuscript are given in point order below. We hope our responses are clear and satisfactory.

 

Comment:

“However, previously a lot of review articles are published based on water management in agriculture. As Horticulture is a subset of agriculture that deals specifically with cultivation of fruits, vegetables, flowers, and ornamental plants. Therefore, the information should be especially related to water management in flowers, and ornamental plants. As a lot of material is available on water management in fruits and vegetables. I gave you some of the examples here for your reference:

1. Agricultural and Technology-Based Strategies to Improve Water-Use Efficiency in Arid and Semiarid Areas. Water 2024, 16, 1842.
2. Horticultural Irrigation Systems and Aquacultural Water Usage: A Perspective for the Use of Aquaponics to Generate a Sustainable Water Footprint. Agriculture2024, 14, 925.
3. A Review of Precision Irrigation Water-Saving Technology under Changing Climate for Enhancing Water Use Efficiency, Crop Yield, and Environmental Footprints. Agriculture2024, 14, 1141
4. Water Resources Management under Climate Change: A Review. Sustainability 2024, 16, 3590.
5. Application of Internet-of-Things Wireless Communication Technology in Agricultural Irrigation Management: A Review. Sustainability 2024, 16, 3575.
6. Transformative Technologies in Digital Agriculture: Leveraging Internet of Things, Remote Sensing, and Artificial Intelligence for Smart Crop Management. J. Sens. Actuator Netw.2024, 13, 39.
7. An Overview of Smart Irrigation Management for Improving Water Productivity under Climate Change in Drylands. Agronomy 2023, 13, 2113.”

Response:

As mentioned by the Reviewer and indicated in the manuscript (L49), Horticulture includes fruits, vegetables, ornamental, aromatic and medicinal plants. Since the aim of the manuscript is to provide a comprehensive overview in water management in horticultural crops (L119-120), we focus on all horticultural crops. Indeed, there is more information available for fruits and vegetables and less for the other crops. Nevertheless, we have tried to bring information for all horticulture crops, without a particular focus in flowers and ornamental plants, as suggested. In this revised version of the manuscript, we have included more information about the flowers and ornamental plants. We appreciate the very useful recent reference suggestions and have used all of them to enrich our literature review. Additional information and reference to the suggested paper were includes in different sections of the manuscript. Please, see the changes marked in the manuscript. Only a few examples of changes are included here:

“The use of nature-based solutions has been identified as innovative solutions to improve water resources management under climate change [Ciampittiello et al., 2024].” (section 3.1)

“Intercropping has been shown to increase the water use efficiency of horticulture crops (e.g. moth bean between paired rows of pearl millet and green gram between paired rows of pigeon pea) because of higher yields in intercropping systems [Alharbi et al., 2024].” (section 3.1)

“The reuse of water from aquaculture systems in horticulture has also received increasing attention due to the high content of nutrients [Abdelraouf, 2017]. Schoor et al. [2024] provides a literature review on the use of aquacultural water in horticultural irrigation systems.” (section 3.2)

“Although we do not know the exact numbers for the application of treated wastewater in horticulture, regions like the Mediterranean basin [Bahri, 2002], East Asia [Jiménez, 2006] and Middle East [Al-Jayyousi, 2003] have been reported on literature.” (section 3.2)

“Generally, drip irrigation has a water application efficiency of 65-95%, whereas sprinkler and furrow irrigation methos have an efficiency of 50-90% and 50-70%, respectively [Lakhiar et al., 2024].” (section 3.3.1)

“These irrigation strategies have a high potential to save water particularly in arid and semi-arid areas [Alharbi et al., 2024].” (section 3.3.1)

“It has been used to avoid waterlogging in horticulture crops like strawberries and tomatoes, and to prevent both waterlogging and drought stress in orchards [Strock et al., 2007]. Controlled drainage is mainly used in countries like the Netherlands and Denmark.” (section 3.3.1)

Other references were also included in the manuscript to support additional information included, following the suggestions of other reviewers.

 

Comment: “Overall all manuscript is very well written but some of the suggestions are:

1. Authors should clearly state the problems of the existing works.  How current study is different from above mentioned studies. The author should show us a deep analysis of the gaps in existing methods and why your research is essential. The study's novelty should be highlighted, and the topic should be focused on in-depth.”

Response: Following your suggestion, we have clarified the limitations of previous studies and better stressed the novelty of our manuscript:

“Previous studies have provided a literature review on water management strategies to enhance water savings in agriculture, but they tend to focus on specific strategies (e.g. agronomic practices [Bhinde and Shukla, 2019], drip irrigation [Yang et al., 2023], precision irrigation technology [Lakhiar et al., 2024], transformative technologies in digital agriculture [Penailillo et al., 2024], and IoT wireless communication [Tang et al., 2024]) or in specific regions (e.g. drylands [Ahmed et al., 2024], arid and semiarid areas [Alharbi et al., 2024]). A limited number of review manuscripts have focused on horticulture has a subset of agriculture, and they tend to concentrate on specific water management strategies (e.g. nanotechnology-based approaches [8] and adaptive microbial inoculants for alleviation of water stress [6]) rather than providing a broader overview of the topic.” (section 1)

“This study provides an up to date state of the art about different types of water management strategies in all types of horticultural crops, including flowers and ornamental crops not mentioned in previous review papers [Pan et al., 2024].” (section 1)

 

Comment:

“2.     There is a huge amount of information and a better summarization and classification would be appreciated. Your discussion should be particularly related to water management according to horticulture perspective. Some mentioned sections are general terms used for water management in agriculture and a lot of material is already published.”

Response:

We have revised the manuscript and did our best to better summarize the information. Indeed, there is some information which is more general for agriculture, but we have included it because we considered it relevant information for water management and we have not found literature with a focus on horticulture. We made this clearer in the manuscript. Since this is a literature review paper, we only used material that is already published. The changes performed over the manuscript are highlighted in track changes mode, but a few examples of changes are as follows:

 “Water stress … is one of the most destructive stresses for agricultural productivity [6], including horticulture.” (section 2.1)

“Specific water consumption for horticulture alone is difficult to point out due to varying methods of measurement and regional practices, and the significant differences in crop requirements (e.g. tomatoes, lettuce and citrus fruits are particularly water-intensive whereas ornamental plants require less but frequent watering) but is estimated to represent 20-30% of the agricultural water use [Molden, 2007].” (section 2.2)

“Nevertheless, in countries with high horticulture production, such as China and India, water consumption is high and may represent a relevant threat to the available water resources. In the Mediterranean region, the intensive fruit and vegetable production requires significant irrigation and represents a major threat to local water resources [Ferreira et al., in press]. In this region, as well as other arid and semi-arid areas, water demand for horticulture is expected to increase due to climate change and associated decreasing precipitation and increasing temperatures [33].” (section 2.2)

“Surface and subsurface runoff from horticulture croplands can transport many pollutants derived from the agrochemicals used. Previous studies have reported high loads of nutrients, such as phosphorus and nitrogen [38], heavy metals (e.g. cadmium and zinc) caused by using phosphate fertilizers and copper-based agrochemicals [10,40], and herbicide residues [41], posing a significant risk of contamination for water resources [14,39].” (section 2.2)

“Salinization caused by horticultural practices is a major problem in countries like Australia [Williams, 1999], Pakistan and India [Qureshi et al., 2008].” (section 2.2)

“Given the wide number of variables affecting soil water retention (e.g. soil type, rainfall patterns, evaporative demands), it is challenging to generalize about the efficiency of mulching in reducing water requirements in horticulture [Alharbi et al., 2024].” (section 3.1)

“Cover crops, planted between the growth cycles of main crops or during fallow periods, can improve water infiltration and retention by enhancing soil structure and increase organic matter content [95], although they are mainly used for soil erosion mitigation, weed control [2], and fixing atmospheric nitrogen thus reducing fertilization requirements [96]. Cover crops have been used e.g. in orchards and vineyards [97], ornamentals [98] and herbs [99], but knowledge on their contribution to reducing water-irrigation requirements is very limited.” (section 3.1)

“The above mentioned agriculture best management practices lead to improved soil structure and water holding capacity, relevant to decrease irrigation water demand [95], but also provides improvements on soil health (e.g. fertility), reduced nutrient losses [14] and soil erosion [36], relevant to mitigate the environmental impacts of horticulture on water resources quality. However, generalizations on their effectiveness in reducing horticultural water irrigation are difficult given the several factors affecting water availability and crop requirements in different regions. Future studies should focus on the effectiveness of different nature-based solutions in horticulture water savings to support water management.” (section 3.1)

“Tang et al. [2024] provide a literature review on the application of wireless communication technologies (e.g. 5G, WiFi and ZigBee) in agricultural irrigation management.” (section 3.3.2)

“Sensor technology has been used to optimize water savings and crop yields in e.g. tomato [Li et al., 2018], and lettuce and cabbage [Zhang et al., 2021].” (section 3.3.2)

“Ahmet et al. [2024] provides an overview of the use of AI, deep learning and predictive models in supporting water use efficiency in water-scarce agricultural regions, including a few examples of application in greenhouses. A recent literature review on precision irrigation water-saving technology has suggested that enhancements in irrigation efficiency alone can fulfil 50% of the anticipated rise in water demand, and that only by using IoT and AI tools it would be possible to achieve the long-term viability of global food production [Lakhiar et al., 2024]. Previous studies have shown that the use of new technologies and tools improved water savings of 19% in coffee [Zeng et al.], and 46% [Lakshmi et al., 2023] and 59% [Mason et al.] in tomato comparing to traditional irrigation methods. The potential of IoT and AI tools in agriculture, however, goes beyond decision-making to optimize irrigation, supporting improvement of several management practices (e.g. optimizing fertilization and pest control) [Penailillo et al., 2024].” (section 3.3.2)

“Phosphate-solubilizing bacteria and rhizobium inoculation also led to improving water use efficiency in crops such as chickpea [Alharbi et al., 2024].” (section 3.4.1)

Main changes were performed in section 3.3.2., as can be seen in the manuscript.

 

Comment:

“3.     Delete those keywords repeating with title.”

Response:

We appreciate the suggestion, but “Horticulture” is the only keyword repeating with title. Given the focus of the manuscript on horticulture, we consider relevant to keep it in the keywords.

 

Comment:

“4.     In introduction sections, I suggest adding one paragraph discussing about the whole body of the paper such as Section 2, discusses xyz and Section 3, which deals with xyz, and so on.”

Response:

Following your suggestion we have included the following sentences:

“The paper is structured in three main sections. Section 2 summarizes knowledge on horticulture crop water requirements, and discusses the impact of horticulture on water resources, including both quantity and quality. Section 3 presents measures and strategies to improve water management in horticulture, focusing on the use of nature-based solutions, unconventional water resources, emerging technologies (e.g. micro-irrigation, IoT and Artificial Intelligence), and other methods (i.e. drought tolerant cultivars and nanotechnology, and excess water management). Section 4 presents concluding

 

Comment:

“5.     It would be nice, adding one section about review methodology.”

Response:

We appreciate the suggestion. However, this paper aims to review and summarise the scientific literature with aim to advance essential knowledge of water management in horticulture. This is not a systematic review looking for evidence that, e.g., some specific method actually works, or to critically assess various study methods or scientific approaches. As so, we have not used a specific methodology to prepare this literature review paper. Similar literature review papers have been published in this journal and other highly prestigious journals. A few examples are:

Ahamed, Z., Gui, D., Murtaza, G., Yunfei, L., Ali, S. An Overview of Smart Irrigation Management for Improving Water Productivity under Climate Change in Drylands. Agronomy 2023, 13, 2113. https://doi.org/10.3390/agronomy13082113

Ferreira, C.S.S., Seifollahi-Aghmiuni, S., Destouni, G., Ghajarnia, N., Kalantari, Z., 2022. Soil degradation in the European Mediterranean region: Processes, status and consequences. Science of the Total Environment, 805, 150106. https://doi.org/10.1016/j.scitotenv.2021.150106.

 

Comment:

“6.     Authors should add one more section discussing the future prospectus and major issues of water management for horticulture crops, which should be considered for future research.”

Response:

Following your suggestion, we have adjusted the title of section 4 to “Concluding remarks and prospects”, and improved the text to clearly present the major issues of water management for horticulture crops. We have also clarified the main future perspectives for water management in this sector of the agriculture. 

 

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editor

I send my revision of the document with some comments in the attached file, it is necessary that the authors make some improvements in all sections of the document.

Regards

Comments for author File: Comments.pdf

Author Response

REVIWER 2

The authors would like to thank the Reviewer for the time spent with our manuscript, for the constructive comments provided, and the relevant suggestions that helped us to improve the quality of the manuscript. Details on how the comments were addressed in the manuscript are given in point order below. We hope our responses are clear and satisfactory.

 

Comment: “The article needs a thorough literature review, including detailed information on how the articles for the review were selected. This should encompass the years of publication covered in the search, the languages in which the search was conducted, and the specific search criteria used. Additionally, the selection process for thematic areas should be clearly outlined. Providing this information will ensure the study's replicability in other academic fields and topics, allowing for greater validation and comparison of results across different studies.” (L130)

Response:

We appreciate the suggestion. However, this paper aims to review and summarise the scientific literature with aim to advance essential knowledge of water management in horticulture. This is not a systematic review looking for evidence that, e.g., some specific method actually works, or to critically assess various study methods or scientific approaches. As so, we have not used a specific methodology to prepare this literature review paper. There were no specific search criteria or years. Similar literature review papers have been published in this journal and other highly prestigious journals. A few examples are:

Ahamed, Z., Gui, D., Murtaza, G., Yunfei, L., Ali, S. An Overview of Smart Irrigation Management for Improving Water Productivity under Climate Change in Drylands. Agronomy 2023, 13, 2113. https://doi.org/10.3390/agronomy13082113

Ferreira, C.S.S., Seifollahi-Aghmiuni, S., Destouni, G., Ghajarnia, N., Kalantari, Z., 2022. Soil degradation in the European Mediterranean region: Processes, status and consequences. Science of the Total Environment, 805, 150106. https://doi.org/10.1016/j.scitotenv.2021.150106.

 

Comment: “In this section it is necessary to include more data related to the exploration of water resources.” (section 2.2)

Response:

Following the suggestion, we have included more information as follows:

“Specific water consumption for horticulture alone is difficult to point out due to varying methods of measurement and regional practices, and the significant differences in crop requirements (e.g. tomatoes, lettuce and citrus fruits are particularly water-intensive whereas ornamental plants require less but frequent watering) but is estimated to represent 20-30% of the agricultural water use [Molden, 2007].”

“Nevertheless, in countries with high horticulture production, such as China and India, water consumption is high and may represent a relevant threat to the available water resources. In the Mediterranean region, the intensive fruit and vegetable production requires significant irrigation and represents a major threat to local water resources [Ferreira et al., in press]. In this region, as well as other arid and semi-arid areas, water demand for horticulture is expected to increase due to climate change and associated decreasing precipitation and increasing temperatures [33].”

“The overuse of fertilizers coupled with intensive irrigation practices and poor drainage in horticultural plantations can also lead to salinisation, i.e. the accumulation of soluble salts in the soil to levels that negatively impact water quality and agricultural productivity [37]. Salinization caused by horticultural practices is a major problem in countries like Australia [Williams, 1999], Pakistan and India [Qureshi et al., 2008].”

 

Comment: “More information is needed” (L281-285)

Response: We have included the following information:

“Horticulture plants, however, have been increasing grown on soilless media, with compost being used as a substitute of soil in greenhouse crops [84]. Soilless systems, i.e. cultivation on substrates such as peat moss, perlite, vermiculite, expanded clay pellets, provide a supportive environment for plant roots and have higher water use efficiency than soil cropping, given the better water retention properties of substrates compared to soil [56]. Soilless media are widely used in horticulture, particularly in controlled environments like greenhouses, vertical farms, and hydroponic systems. In hydroponic systems, water recirculation provides enhanced water use efficiency [Carotti et al., 2023]. Various types of horticultural crops are successfully grown in soilless media, such as lettuce, tomatoes, blueberries, roses and orchids. Savvas and Gruda [2018], provide a literature review on the application of soilless technologies in greenhouse industry.”

 

Comment: “Please include more detail, information on crop yields would be important to be presented in this paragraph.” (L354-367)

Response: We have included the following information

“Desalination for crop irrigation in horticulture has been used in countries like Spain (e.g. strawberries and lettuce), Israel (e.g. tomatoes, cucumbers, and peppers) and USA, namely in the states of Florida and California, and is under consideration in Chile, China and Australia [Martínez-Alvarez et al., 2016]. Water quality is a major concern for irrigation, since desalinated water is characterized by a chemical composition distinct from natural water sources, due to predominance of sodium and chloride ions, and very low concentration of other minerals such as calcium, magnesium and sulphate considering the nutritional requirements for horticultural crops [Martínez-Alvarez et al., 2016]. … There is also a lack of information on crop yields irrigated with desalinated water.”

 

Comment: “Please improve figure” (Figure 2)

Response: Figure 2 was improved.

 

Comment: “Here it is necessary to include more details, in terms of drought issues there is enough information that can be included and improve this section.” (L598-608)

Response: We have included some information about strategies to enhance crop resilience to drought:

“Physiological phenotyping is a tool to identify and select plant traits that enhance water-use efficiency and reduce water requirements in horticultural crops. This approach involves assessing various physiological parameters of plants, such as their ability to maintain growth under water-limited conditions, their water uptake and transport mechanisms, and their overall response to drought stress [Dalal et al., 2019]. By integrating these phenotypic traits into breeding programs, water scarcity resilient horticultural crops can be developed. Breeding programs have used physiological phenotyping to select for traits such as improved water use efficiency, leading to tomato, lettuce and grape varieties that require less water [Mir et al., 2019].

Nanotechnology offers innovative solutions for managing water stress in horticulture, such as hydrogel nanocomposites, materials that significantly enhance soil water retention and slowly release depending on plants need, silver nanoparticles to enhance plant growth under oxidative stress associated with drought, and silicon nanoparticles to improve drought tolerance by enhancing water uptake and reducing transpiration [Gupta et al., 2023]. Manzoor et al. [8] presents a literature review on nanotechnology-based approaches in horticulture, including for water stress tolerance. Hayat et al. [13] presents a literature review on the use and potential of nanoparticles for improving drought stress resistance of plants. As research progresses, these technologies are likely to become increasingly integrated into sustainable agricultural practices, helping to mitigate the effects of climate change and water scarcity on horticulture.

Adaptive microbial inoculants are increasingly recognized as effective tools for mitigating water stress in horticultural crops. These inoculants consist of beneficial microorganisms, such as bacteria, fungi, or a combination of both, that enhance plant resilience to drought. Examples of microbial inoculants include (i) arbuscular mycorrhizal fungi, widely used to enhance drought tolerance in tomatoes, peppers, and strawberries [Wahab et al., 2023]; (ii) plant growth promoting rhizobacteria for promoting root growth, enhancing nutrient uptake, and inducing systemic tolerance to drought in crops like lettuce, carrots, and cucumbers [1]; and (iii) phosphate-solubilizing bacteria and rhizobium inoculation to improving water use efficiency in crops such as chickpea [Alharbi et al., 2024]. … As research advances, the development and application of tailored microbial consortia could become a key strategy in sustainable horticulture, particularly in regions prone to drought. … Grafting involves joining the tissues of two plants so that they grow as one. This well-established technique often involves the use of rootstocks resilient to drought, and scions selected for specific fruit or vegetable production characteristics. Grafting has been used e.g. in Cucurbitaceae and Solanaceae families and grapevines [208, Yang et al., 2022]. The success of grafting in mitigating water stress lies in its ability to improve water uptake, regulate water loss, enhance root-to-shoot communication, and provide resilience against drought-induced oxidative stress. This approach is increasingly important in the context of climate change and water scarcity, making it a critical tool for sustainable horticulture [Coşkun et al., 2023].”

Detailed information on the topic can be seen in previous literature review papers, as indicated in the manuscript: “Manzoor et al. [8] presents a literature review on nanotechnology-based approaches in horticulture, including for water stress tolerance. … Kour et al. [6] provides a literature review on adaptive microbial inoculants for alleviation of water stress in horticultural crops. … Hayat et al. [13] presents a literature review on the use and potential of nanoparticles for improving drought stress resistance of plants, which comprise an interesting solution to improve.”

 

Comment: “This section should also be complemented with more information and references.” (section 3.4.2.)

Response: Information was included as follows:

“The impacts of flooding in horticultural crops can be mitigated using drainage systems, including both surface (e.g. drains, such as ditches or shallow trenches to quickly convey water from the field) and subsurface (tiles or pipes installed to remove excess water from the root zone, preventing prolonged waterlogging) systems [Wang and Xu, 2022]. Other agronomic practices include planting crops on raised beds to elevate the root zone above the saturated soil, reducing the risk of root hypoxia and improving aeration [Antolini et al., 2019]. In fields with gentle slopes, installing ridges can help channel excess water away from the plant roots. This technique is particularly effective for crops such as strawberries, tomatoes, and peppers [Antolini et al., 2019]. Selecting or breeding crop varieties that are more tolerant to waterlogging or temporary flooding can help mitigate losses. Some rootstocks or cultivars have better tolerance to low oxygen conditions [Ahmed et al., 2012].”

 

Comment: “To improve the conclusions of the article, it is recommended to ensure that they directly reflect the results and discussions presented, clearly highlighting the practical and theoretical implications of the findings. It is crucial to acknowledge the limitations of the study in a transparent manner and to propose clear directions for future research, showing how the current work can be extended or improved. Conclusions should be clear and concise, avoiding the introduction of new information not previously discussed in the article. In addition, it is suggested to focus on developing more cost-effective and user-friendly irrigation technologies, implementing educational programs for farmers on the benefits and efficiency of these technologies, and conducting long-term studies to evaluate the environmental and economic impact in different regions and crops.” (L670-686)

Response: Section 4 was renamed as “Concluding remarks and prospects” and improved following your suggestions:

“Horticulture is a crucial sector for food security and the global economy. Horticultural crops, including fruits, vegetables, aromatic herbs and ornamental plants, have noticed an increasing social demand over the last few decades. These types of crops require considerable amount of water, often necessitating irrigation, especially in arid and semi-arid regions. Increasing water scarcity due to climate change, population growth, and competing demands from other sectors (e.g., industry, urbanization) is a critical challenge for horticulture. Inefficient irrigation practices also represent a major for water management in horticulture. Traditional irrigation methos such as flood irrigation are often associated with over-irrigation, nutrient leaching and soil degradation (e.g. salinization).

The expansion of horticulture has raised environmental concerns due to impacts on water resources, such as over-extraction of groundwater and pollution driven by the intensive use of agrochemical, but the extent and magnitude of the impacts are not known. Further studies to assess the real impact of large-scale horticulture on both quantity and quality of the water resources are needed. This will require monitoring programs to assess the impacts on water resources availability, and chemical and biological status, at the basin scale. Particular attention should be provided to emerging contaminants (e.g. herbicides and microplastics).

To cope with water shortages and improve water use efficiency, a holistic approach combining sustainable agriculture practices and technological innovation to improve water management in horticulture is required. However, one of the primary challenges for water management in horticulture is the lack of knowledge among farmers regarding the water requirements of their crops. Farmers often rely on their perception of crop status and the availability of water, rather than actual crop water needs. Several horticulture crops have been well investigated regarding water needs in distinct growth stages (e.g. tomato and lettuce), but there is limited information about many crops, especially some perennial, ornamentals and aromatics. Additionally, studies on crop water demands are developed on specific environments, and information for varying regions is still lacking (e.g. the Mediterranean). A global database about crop water requirements in different environments, easily accessible to farmers would be useful.

The implementation of nature-based solutions based on best agricultural practices, such as mulching, organic amendments and cover crops, can enhance soil moisture by improving the water holding capacity and reducing losses by evaporation, and thus decrease water irrigation requirements. The use of hydrogels, for instance, can reduce evaporation losses up to 50%. However, there is a lack of comprehensive knowledge on the effectiveness of different measures in distinct horticulture crops and environments. For example, the impact of several mulches and application rates are highly variable. Other techniques to reduce irrigation requirements, such as nanotechnology-based approaches for water stress tolerance are promising, but studies at large scale application are still lacking. The development of drought resistant crop varieties can reduce the dependency on water and maintain productivity in challenging conditions. Breeding and genetically engineering crops that are more resistant to drought and can thrive in low-water conditions is a critical research area.

 The use of unconventional sources of water, comprising an important aspect of water management in horticulture, have been increasingly explored. Water sources such as treated wastewater and desalination provide sustainable alternative to freshwater resources, especially in water-scarce regions. However, these sources are more expensive than natural water resources, and inappropriate management can lead to the accumulation of salts, causing soil degradation and decreases in crop yields. This is a major issue for horticulture, especially in arid and semi-arid regions. The quality of treated wastewater is another major concern for horticulture, given the risk of food contamination and impact on public health. The extent of soil degradation and food safety problems have not been sufficiently investigated. Future research should focus on developing cost-effective technologies to improve water quality of alternative sources.     

Improved irrigation techniques are of utmost importance to enhance water use efficiency in horticulture. The adoption of more efficient technologies, such as drip irrigation, can optimize water use by delivering water directly to the root zone in appropriate amounts. Nevertheless, innovative technologies and tools are necessary to effectively optimize water management. Automation and remote sensing are emerging research fields to improve irrigation. The real-time integration of data from sensors (providing information about the water status of crops) and weather forecasts enable farmers to optimize irrigation. Precision irrigation and smart irrigation have high potential to improve water use efficiency by tailoring irrigation schedules and spatial variability, respectively, to the specific needs of crops. The use of IoT with 6G wireless systems has the potential to revolutionize horticulture, given the high capacity of 6G to support large-scale operations with numerous IoT devices. Other innovative tools such as data analytics, predictive modelling and Digital Twins provide remarkable improvements in decision support systems. The practical implementation of these technologies, however, has been limited. The high cost of the technology and the complexity of implementation are barriers to the widespread adoption of these water-efficient tools. Additionally, farmers are often resistant to change their established practices. Efforts to develop more cost-effective and user-friendly technologies and tools, and to educate and engage farmers will be crucial in driving the widespread adoption of water-efficient practices. Smart irrigation and the safeguard of water resources are essential to adapt to climate change, ensure food security, and achieve some of the sustainable development goals.”

 

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Author(s),

I read with great interest your review paper entitled “Sustainable Water Management in Horticulture: Status and Main Challenges,” which examines sustainable water management in horticulture.

This topic is intriguing, and the main themes have been covered in appropriate detail. I do not have any major reservations, only a few suggestions:

1.      The term “sustainable” is far from self-evident and requires some definition. While I am fully aware that the term encompasses many concepts, it is often misused. You may wish to address how water management in horticulture relates to sustainable development or sustainability.

2.      Although only remotely connected, the review does not address the dilemma of supply-driven versus demand-driven water management. This issue is unavoidable when discussing droughts, the climate crisis, and water scarcity.

Author Response

REVIWER 3

Comment: “I read with great interest your review paper entitled “Sustainable Water Management in Horticulture: Status and Main Challenges,” which examines sustainable water management in horticulture.

This topic is intriguing, and the main themes have been covered in appropriate detail. I do not have any major reservations, only a few suggestions:”

Response:

The authors would like to thank the Reviewer for the time spent with our manuscript, for the constructive comments and suggestions provided, that helped us to improve the quality of the manuscript. Details on how the comments were addressed in the manuscript are given in point order below. We hope our responses are clear and satisfactory.

 

Comment:

“1.      The term “sustainable” is far from self-evident and requires some definition. While I am fully aware that the term encompasses many concepts, it is often misused. You may wish to address how water management in horticulture relates to sustainable development or sustainability.”

Response: Thanks for the suggestion. We have included the following information on the Introduction section:

“Sustainable water management in horticulture involves using water efficiently to minimize wastage [Russo et al., 2014]. Ensuring the efficient use of water is important to prevent water scarcity, especially in arid and drought-prone regions, and avoid over-extraction and pollution of freshwater. This is essential for ensuring the long-term availability of water resources, protecting ecosystems and supporting human well-being. Its importance spans environmental, economic, and social dimensions both now and in the future.”

 

Comment:

“2.      Although only remotely connected, the review does not address the dilemma of supply-driven versus demand-driven water management. This issue is unavoidable when discussing droughts, the climate crisis, and water scarcity.”

Response: Indeed, the aim of the paper is not to focus on supply vs demand issue but this is a very important aspect. Following your suggestion, we have included the following information in section 4:

“Although this paper is focused on demand-driven water management by controlling and reducing the demand for water through more efficient use, conservation practices and drought tolerant crops to meet growing demands for horticulture crops, other demand-driven strategies are also available (e.g. water pricing policies). Effective water management in agriculture also involves supply-driven strategies and measures, such as the development of infrastructure like dams, reservoirs, and irrigation canals to store and deliver water to horticulture when it is needed. A holistic approach involving both supply-driven and demand-driven strategies are required to cope with increasing water scarcity, exacerbated by both growing societal demand and climate change, and ensure a sustainable water management required for food security.”

 

 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

N/A

Comments on the Quality of English Language

N/A

Reviewer 2 Report

Comments and Suggestions for Authors

Dear

Editor y Authors.

The new version of manuscript it ok.