Application of Chronobiology in Plant Agriculture

Abstract

Plants grow, develop, and reproduce within a rhythmic environment. Environmental cues—such as light, temperature, nutrition, water—initiate, sustain, or terminate basic physiological processes within the plant, such as photosynthesis, respiration, nutrient uptake, water management, transpiration, growth, and hormone regulation. Simultaneously, inside the plant, internal “living clocks” are ticking and helping plants to synchronize internal processes with environmental cues and defend themselves against stressful conditions. These clock-regulated processes underlie a variety of plant traits, such as germination capability, growth and development rate, time of flowering, fruiting and yielding, development of plant shape, and size and biomass production. Most of these physiological traits are important attributes of crop plants. In recent years, the growing understanding of environmental rhythms as environmental cues and the mechanisms underlying plant internal clocks has begun to play an increasingly important role in agricultural practices. This is an emerging area of research that integrates insights from chronobiology with practices in plant agriculture. In this review, this new research area is studied and mapped using Scopus, Web of Science, Google Scholar, Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA protocol), and VOSviewer1.6.20 software. The analyses were carried out on 18 July–27 August 2025. For the VOSviewer author keywords co-occurrence analysis, all 1022 documents covering the time range of the last 7.5–2.5 years (2018–July 2025) were included and three maps were generated. Additionally, 59 review documents covering the last 27 years (1988–July 2025) were extracted by relevance using Google Scholar. In this review, recent advances and topics in plant chronobiology were examined. The issue of how these advances respond to key challenges in plant agriculture was explored. The bidirectional influence between chronobiology and practices in plant agriculture were also considered.

1. Introduction

The fundamental physiological processes in plants involve photosynthesis, respiration, nutrient uptake, water management, transpiration, growth, and hormone regulation. The properties of these processes underlie the agriculturally important characteristics of plants. Agricultural traits of plants determine their agricultural and cropping suitability. These traits include yield potential, length of the growing season, resistance to diseases, pests and abiotic stresses (e.g., drought or frost), and suitability for mechanical harvesting. Quality and nutritional traits (e.g., protein or starch content), storability, and adaptation to different soil and climatic conditions are also important. These traits of plants play an important role in plant variety selection, crop production, and cropping programs.

The circadian clock links environmental cues with numerous physiological and developmental processes in plants. It enables plants to anticipate daily environmental changes, such as fluctuations in light and temperature, thereby enhancing their overall fitness and survival [1]. In the past, the existence of an internal clock was predicted and called a “living clock” [2,3].

Chronobiology, the science of biological timekeeping, encompasses circadian, ultradian, and seasonal rhythms that shape plant physiology, development, and ecological interactions [1,2,3,4,5]. In plants, endogenous circadian clocks integrate environmental cues—light, temperature, and photoperiod—to optimize such processes as photosynthesis, water transport, flowering, stress responses, and defense [6,7,8,9,10,11,12,13,14,15,16,17,18,19]. These rhythms are tightly linked to plant–pollinator synchrony [20], pest dynamics [10,21], and plant–microbe interactions [22].

At the molecular level, clock genes and regulatory networks govern agricultural traits and adaptive capacity [7,18,23] shaped through domestication and diversification [24]. Chronobiology also encompasses biochemical frequency control [25], bioinformatics approaches [26], and circadian computing models [27,28]. Phytomelatonin and related molecules emerge as multifunctional regulators of growth, stress tolerance, and development [29,30,31,32,33,34,35,36,37,38,39].

The applied field of chronoculture integrates time biology into crop production, storage, and controlled-environment agriculture to enhance yield, quality, and sustainability [40,41,42,43]. Seasonal and phenological studies highlight the role of annual rhythms in adapting to environmental change [44,45,46,47,48]. By uniting ecological, molecular, and technological perspectives, chronobiology offers a framework for sustainable agriculture in the context of climate variability and environmental stress [49]. This review systematically examines the literature to map current knowledge, applications, and future directions for integrating biological time into plant agriculture.

The aim of this work is to contribute to the scientific discussion on the need for information exchange between chronobiologists and agronomists in order to promote interdisciplinary collaboration moving towards improved crop yield and health [11]. It proposes a systematic review and conceptual solutions that do not require funding or technical tools, rather taking into account rhythms in a broad sense in the approaches of chronobiologist and agronomists, drawing attention to current socio-economic challenges.

2. Materials and Methods

This review addresses an emerging interdisciplinary field at the interface of chronobiology and plant agricultural practices [11]. To systematically identify and analyze relevant literature, a structured methodology was employed, incorporating searches in the Scopus and Web of Science databases. The review protocol was guided by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework [50] (Table S1, Figure 1), and bibliometric mapping was conducted using VOSviewer 1.6.20 software https://www.vosviewer.com/ (accessed on 18 July 2025) [51]. For the VOSviewer author keywords co-occurrence analysis, all 1022 documents covering the past 7.5 to 2.5 years (2018–July 2025) were included, and three maps were generated. The analyses were conducted between 18 July and 29 and on 27 August 2025. Additionally, 59 review documents spanning the past 27 years (1988–July 2025) were retrieved from Google Scholar based on relevance. The selected literature was examined to elucidate recent developments in plant chronobiology and to assess how these advances address critical challenges in plant agriculture. Additionally, the reciprocal interactions between biological rhythms and agricultural practices were investigated.

2.1. Potential Sources of Bias

Despite the systematic approach employed in this review, several potential sources of bias should be acknowledged. First, the search was limited to three major bibliographic databases (Scopus, Web of Science, and Google Scholar), which may have excluded relevant studies indexed elsewhere or in non-English-language journals. Second, the selection of publications was constrained to those available in the last 7.5 years up to July 2025 and to a sample of 1022 articles and 59 review documents spanning the past 27 years (1988–July 2025), which were retrieved from Google Scholar. These documents may not fully capture the whole research landscape in plant chronobiology and plant agriculture. Third, the reliance on bibliometric tools such as VOSviewer [51], while useful for visualizing trends and networks, may introduce interpretative bias depending on author keywords. Finally, although the PRISMA protocol was followed [50] (Table S1, Figure 1), subjective judgment during study the screening and data extraction stages may have influenced inclusion decisions. Information on the share of open-access publications, the geographical distribution, and the language of the analyzed documents was not taken into account. Although the author-provided keywords may reflect the subjective perspective of researchers, they remain the most commonly applied standard in bibliometric studies and ensure comparability of results with other analyses. The co-occurrence network analysis [51] allows identification of the main thematic fields and conceptual linkages but does not capture the full complexity. The results provide a generalized representation of the thematic structure.

2.2. Detailed Method of Searching of Literature Databases

The exact search strings, queried fields, filters, languages, time windows, and execution dates for each database are provided in Figure 1 (PRISMA flow diagram).

• Scopus: All Field, filters were not applied.
• Web of Science: Core Collection, filters were not applied.
• Google Scholar: by relevance. Google Scholar ranks documents based on the full text, publication venue, authorship, and citation metrics, with emphasis on citation frequency and recency.
  (https://scholar.google.com/intl/en/scholar/about.html, access date: 18–29 July and 23 and 27 August 2025)

2.3. PRISMA Protocol

The PRISMA framework [50] was introduced into this work by using the PRISMA 2020 flow diagram (Figure 1). This flow diagram illustrates the entire workflow during the research on the impact of chronobiology on plant agriculture by examining existing scientific papers. The author keywords co-occurrence analysis (1022 documents) and the topic analysis (59 documents) were carried out.

3. General Bibliometric Analysis

3.1. Keywords

The systematic presentation of the topic “chronobiology applications in plant agriculture” began with the identification of the main keywords and providing the number of documents (and years) found in the Scopus and Web of Science databases.

Table 1. Number of documents (and years of publication) in the Scopus and Web of Science databases related to chronobiology and plant agriculture. Scopus, all fields, Web of Science Core Collection, all fields. Access date: 18–29 July 2025, * https://en.wikipedia.org/wiki/Scopus (Access date: 18 July 2025) ** https://en.wikipedia.org/wiki/Web of Science (Access date: 18 July 2025). Maps 1–3 were made based on the data from the Scopus database and are presented later in the article. Figures 3–5.

Keywords	Number of Documents
	Scopus	Web of Science
all documents	82,400,000 (1788–present) *	79,000,000 (1900–present) **
chronobiology	79,075 (1958–2025)	7580 (1970–2025)
agriculture	3,416,701 (1848–2026)	2,644,651 (1899–2027)
plant(s) AND agriculture	1,801,725 (1875–2026)	594,441 (1900–2026)
chronobiology AND plant(s) AND agriculture	760 (1979–2025) 491 documents (2018–2025) for Map 1	30 (1990–2025)
rhythms	890,317 (1855–2026)	192,366 (1924–2026)
rhythms AND plant(s)	73,378 (1892–2026)	6011 (1947–2025)
rhythm(s) AND plant(s) AND agriculture	14,147 (1964–2026)	1661 (1973–2025)
agronomy	736,612 (1907–2026)	63,928 (1940–2025)
chronobiology AND agronomy	188 (1976–2025)	2 (2018–2021)
rhythms AND agronomy	4785 (1970–2025)	41 (1977–2025)
seasonality AND agronomy	11,352 (1977–2025) 424 review documents (2023–2025) for Map 2	89 (1963–2025)
chronoculture	107 (2021–2025) for Map 3	4 (2021–2024)
agro chronobiology	191 (1998–2025)	3 (2019–2025)

compares the number of documents found in the Scopus and Web of Science for the following keywords and their combinations: “chronobiology”, “plant”, “agriculture”, “rhythms”, “agronomy”, “seasonality”, “chronoculture”, and “agro chronobiology”. The database search was carried out from 18 to 29 July 2025.

3.2. Number of Documents and Time Span in Scopus and Web of Science

Overall, Scopus contains a larger number of documents than Web of Science across nearly all categories, as well as a longer historical coverage (dating back to 1788 for all documents in Scopus, compared to 1900 for Web of Science) (Table 1).

For the main keywords “chronobiology” and “agriculture”, Scopus consistently returns higher counts (e.g., 79,075 vs. 7580 for “chronobiology” and 3,416,701 vs. 2,644,651 for “agriculture”). While “agriculture” represents a vast and long-standing field of study, with over 3.4 million documents in Scopus (1848–2026) and 2.6 million in Web of Science (1899–2027), the field of “chronobiology” is considerably more recent and specialized. Publications in chronobiology began appearing in 1958 in Scopus and in 1970 in Web of Science. This indicates that chronobiology is a niche discipline compared to the extensive body of agricultural research (Table 1).

Similarly, for more specific combinations, such as “chronobiology and plant (s) and agriculture”, Scopus indexes 760 records, compared to only 30 in Web of Science. The same trend is observed for keywords related to “rhythms” and “agronomy” and their combinations with “chronobiology”, “plants”, and “agriculture”.

The disparity is particularly pronounced for the keyword “chronobiology”, where Scopus contains over ten times more records than Web of Science. In contrast, for “agronomy”, Web of Science provides overall fewer records (63,928 vs. 736,612) but with comparable temporal coverage.

Therefore, researchers focusing on chronobiology in agricultural contexts may find Scopus more comprehensive for literature retrieval.

3.3. “Chronobiology and Plants and Agriculture”—A Very Small Fraction of All Indexed Documents

The combination “chronobiology AND plant (s) AND agriculture” represents a very small fraction of all indexed documents (Table 1). In Scopus, 760 records correspond to less than 0.001% of the 82.4 million total documents, while in Web of Science, 30 records account for an even smaller proportion of the 79 million documents. This highlights the rarity of studies specifically linking chronobiology with plant agriculture compared to the overall scientific output. A notable annotation for the Scopus results (Table 1) indicates that 491 of these 760 documents were published between 2018 and 2025, highlighting a dramatic and very recent surge in the research interest in this specific domain (Figure 2). The keywords “chronobiology AND plant (s) AND agriculture” were mapped using VOSviewer and are shown in Figure 3.

Number of Documents by Year and by Country/Territory

The above data were also analyzed using statistics provided by the Scopus database (“Analyze results”). Figure 2 presents the number of documents published each year between 1979 and 2025 and the number of documents published by individual countries during this period (Top 20). A noticeable increase in publications began around the year 2000 (from fewer than 10 per year to approximately 20 per year after 2011). This number doubled around 2017 (to about 40 per year) and doubled again from approximately 2021 onwards (to nearly 80 per year) (Figure 2a). The largest number of publications originated from the United States (approx. 180) and China (approx. 120) (Figure 2b). The United Kingdom, Japan, India, Germany, Spain, Australia, and Canada followed, each contributing approximately 60–90 publications. In other countries, the number of publications was generally below 30. These results indicate that the main research centers focusing on chronobiology and plant cultivation are widely distributed across the world.

3.4. Chronobiology and Agronomy

The combination of “chronobiology AND agronomy” yields even fewer results, with 188 documents in Scopus (1976–2025) and only 2 in Web of Science (2018–2021), underscoring the novelty of this specific research intersection (Table 1).

3.5. Seasonality and Agronomy

“Seasonality AND agronomy” were chosen to describe the phenomenon of seasonal change and its impact on crop production. This research area is represented by 11,352 and 89 papers in Scopus and Web of Science, respectively, over the last half-century (1977–2025, Scopus; 1963–2025, Web of Science) (Table 1). This dynamic area of research was mapped in VOSviewer based on 424 review documents (Table S3) published in just the past 2.5 years (2023–2025) and is shown in Figure 4.

3.6. “Chronobiology” vs. “Rhythms”

The comparison of the two keywords “chronobiology” vs. “rhythms” shows that research on rhythms (890,317 records in Scopus and 192,366 in Web of Science) is much more prevalent than research on chronobiology (79,075 and 7580, respectively, Table 1). This indicates that the overlap of these two topics is likely limited, as chronobiology forms only a small subset of rhythm-related studies.

In Scopus, the time span is 1958–2025 for chronobiology and 1855–2026 for rhythms, indicating that rhythm-related research has a much longer historical record. In Web of Science, chronobiology covers 1970–2025, while rhythms spans 1924–2026, again showing that studies on rhythms have been published for almost half a century longer.

This suggests that rhythm-related research has a deeper historical background, while chronobiology emerged as a distinct field only in the second half of the 20th century.

3.7. “Chronoculture” vs. “Agro Chronobiology”

Both of the concepts “chronoculture” vs. “agro chronobiology”, are very recent and rare. Scopus indexes 107 documents on chronoculture (2021–2025) and 191 on agro chronobiology (1998–2025) (Table 1). Web of Science contains only four records for chronoculture and three for agro chronobiology. This demonstrates that both fields are still emerging, with chronoculture being overall slightly less represented but more concentrated in the most recent years. The keyword “chronoculture” was mapped using VOSviewer and is shown in Figure 5.

The co-occurrence of keywords for the “agro chronobiology” topic was mapped using VOSviewer (source file from Scopus—Table S6) and is shown in Table S5. Map parameters are the same as for Map 3 (for chronoculture) shown in Table 2.

In summary, the data shown in Table 1 clearly demonstrate that the foundational concepts of agriculture and rhythms have been studied for over a century. The specialized fields exploring their direct intersections, particularly under terms like “chronoculture” and “agro chronobiology”, are emergent areas of research with a publication history that is largely confined to the last few decades and to the last few years in the “chronoculture” cases. The number of documents in these specialized areas is several orders of magnitude smaller than the literature available for the broader foundational topics.

4. VOSviewer Maps

4.1. How the VOSviewer Maps Were Created

The subject of this paper is illustrated using three main VOSviewer maps [51] (Figure 3, Figure 4 and Figure 5) based on the data retrieved from Scopus (Tables S2–S4) and presented in Table 1:

• Map 1: “chronobiology AND plant (s) AND agriculture”, derived from a database of 491 documents published over the past 7.5 years (2018–July 2025), Figure 3, Table S2: Scopus source for Map1 (.csv).
• Map 2: “seasonality AND agronomy”, based on a database of 425 review documents published in the past 2.5 years (2023–July 2025), Figure 4, Table S3: Scopus source for Map2 (.csv).
• Map 3: “chronoculture”, based on a database of all 107 documents published in the past 4.5 years (2021–July 2025), Figure 5, Table S4: Scopus source for Map3 (.csv).

4.2. VOSviewer Maps—General Description—Visualization

The VOSviewer [51] maps presented in this review are a co-occurrence network visualization of author keywords (Figure 3, Figure 4 and Figure 5). Each node represents a keyword, and the size of the node indicates the frequency of occurrence (frequency of their appearance in the literature). The distance between the nodes indicates the strength of their relationship—closer nodes are more frequently studied together [51]. The color of the nodes reflects the cluster to which a keyword belongs based on co-occurrence relationships. These clusters are the major sub-domains of research that are revealed, highlighting the interdisciplinary nature of the studied fields [51].

4.3. Map 1 “Chronobiology and Plants and Agriculture”

The map, created on the basis of a combination of keywords “chronobiology AND plant (s) AND agriculture” from literature from the last 7.5 years, is centered around circadian biology (Figure 3). In the 491 documents found, three main keywords: “circadian clock”, “circadian rhythm”, and “melatonin” are used most frequently (Table 2 and Table S5). These words form the foundational pillars of this research landscape. Their central position and large size signify their overarching importance and high frequency in the analyzed literature. In addition, the network demonstrates a clear hierarchy: the “circadian clock” (green color) represents the endogenous molecular time-keeping mechanism. This internal clock drives the “circadian rhythm” (light blue color), which encompasses the physiological and behavioral outputs lasting about 24 h. “Melatonin” (yellow color) is a key hormonal regulator signaling darkness and synchronizing various rhythms in the body. Melatonin occurs mainly in animals, but its role in regulating processes in plants is considered [36,37,38,39].

4.4. Map 2 “Seasonality and Agronomy”

“Seasonality AND agronomy” is a keyword combination that extracted 11,352 (1977–2025) documents from the Scopus database. From this pool, 424 recent review documents covering the past 2.5 years (2023–2025) were taken for further analysis of the author keywords co-occurrence (Table 1, Figure 4). “Climate change” is the central driver directly connected with “food security”, “global warming”, and “remote sensing” (Figure 4a, Table 2 and Table S5). Food security is a primary concern directly related to climate change, global warming, abiotic stress, sustainability, and remote sensing. The scientific community is not only documenting the impacts of climate change (“global warming”) on food security but is actively seeking integrated (“sustainability”) and technologically advanced solutions (“remote sensing”, “machine learning”).

In the midst of these main important topics, there is a blue cluster containing the keyword “seasonality” (Figure 4b). It is directly adjacent to and connected to the word “phenology”. These nodes are not large, but they occur close to the nodes pointing to important agricultural and societal issues (water, soil moisture, drought, heat stress, food security). “Phenology” ranks 10th in the frequency (eight occurrences), while “seasonality” ranks 35th (two occurrences) in Map 2 (Table S5). This suggests the potential for future research on seasonality and phenology to address these issues [23,44,45,46,47,48]. Future phenological research using new technologies, such as remote sensing and machine learning, may be particularly interesting and important.

4.5. Map 3: Chronoculture—This Is What We Are Looking for

Map 3, shown in Figure 5, illustrates the keyword co-occurrence of the term “chronoculture”. It is dominated by a large central node labeled “circadian clock”, confirming its role as the core concept connecting all associated research areas (Table 2 and Table S5). The main thematic areas include studies of the circadian oscillator, plant biology (particularly photosynthesis and flowering), environmental adaptation, and agriculture (Figure 5a).

Fundamental research into the molecular machinery of the circadian clock is reflected in such keywords as “circadian oscillator” and “evening complex”, which represent essential components of genetic feedback loops that constitute the clock (yellow cluster). Photosynthesis serves as the basis for plant growth and development and biomass production in crop management. The clock’s relationship with “photosynthesis” is evident either directly or through studies on photoperiodism (purple cluster). This core circadian oscillator also plays a key role in plant reproduction by regulating flowering. The regulation of “flowering” and “flowering time” is a prominent research topic, extensively studied in the model plant Arabidopsis thaliana and in major crops, such as Oryza sativa (rice) and wheat (blue cluster). The “drought stress”, “cold stress”, and “salt stress” keywords appear tightly grouped and strongly connected to the circadian clock (red cluster). This highlights the critical role of the clock in mediating stress tolerance and environmental adaptation—key factors influencing agronomic traits (Figure 5a, Table 2 and Table S5).

The green/light blue cluster bridges (Figure 5b) fundamental research and practical applications. It links “circadian rhythms” with broader concepts, such as “environmental fitness”, “crops”, “yield”, “agriculture”, and “chronotherapy”. The keyword “chronoculture” appears within the context of these themes. Chronoculture constitutes an emerging integrative framework that aims to align circadian biology with agronomic innovation, thereby guiding future research in chronobiology and time-based optimization of crop systems [40]. Moreover, the term is also associated with new socio-economic phenomena related to sustainability.

4.6. Map Metrics

The thematic maps presented in visual form (Figure 3, Figure 4 and Figure 5) were additionally summarized quantitatively. During data analysis in VOSviewer software, the numerical data characterizing the occurrence and co-occurrence of author keywords and describing clusters and network parameters (corresponding to Maps 1–3) were exported to an csv file, which is collectively provided in Table S5. Based on these data, the consolidated Table 2 was prepared. The numerical parameters presented in Table 2 are coherent with the visual analysis presented above.

Interestingly, the keywords “ultradian” and “infradian” rhythms did not appear in any of the interdisciplinary maps and require separate literature investigations (Table S5).

Table 2. VOSviewer map metrics. TLS (total link strength). The source data are shown in Table S5.

Map Development Phase	Map Parameter		Map 1	Map 2	Map 3
Initiation in Scopus database	keywords for searching		“chronobiology AND plant(s) AND agriculture”	“seasonality AND agronomy”	“chronoculture”
Export data from Scopus database	number of documents		491	424	107
	time span		7.5 years (2018–July 2025)	2.5 years (2023–July 2025)	4.5 years (2021–July 2025)
VOSviewer protocol	minimum number of occurrences of a keyword (threshold)		3	3	2
	total number of author keywords		2027	1897	359
	number of author keywords meeting the threshold (items)		(86) 80	(87) 84	45
Node analysis (author keywords)	top 10 nodes by size (keywords and their occurrences)		melatonin 31 circadian clock 23 circadian rhythm 21 nutrition 14 chronobiology 13 antioxidant 11 diet 9 oxidative stress 9 circadian rhythms 9 obesity 8	climate change 42 food security 19 sustainability 16 agriculture 11 remote sensing 11 drought 10 global warming 9 soil organic carbon 9 biodiversity 8 phenology 8	circadian clock 28 circadian 7 circadian rhythms 7 photosynthesis 7 chronobiology 5 circadian rhythm 5 rna-seq 5 arabidopsis thaliana 4 flowering 4 photoperiod 4
Cluster analysis	clustering		resolution 1.00 min. cluster size 1	resolution 1.00 min. cluster size 1	resolution 1.00 min. cluster size 1
	cluster number		11	13	8
	average cluster size		7.3	6.5	5.6
Network analysis	total links		231	239	120
	TLS		276	276	135
	robustness evaluation	varying threshold	3, 7, 10	3, 7, 10	2, 7
		normalizations	association strength	association strength	association strength

Table 2. VOSviewer map metrics. TLS (total link strength). The source data are shown in Table S5.

Map Development Phase	Map Parameter		Map 1	Map 2	Map 3
Initiation in Scopus database	keywords for searching		“chronobiology AND plant(s) AND agriculture”	“seasonality AND agronomy”	“chronoculture”
Export data from Scopus database	number of documents		491	424	107
	time span		7.5 years (2018–July 2025)	2.5 years (2023–July 2025)	4.5 years (2021–July 2025)
VOSviewer protocol	minimum number of occurrences of a keyword (threshold)		3	3	2
	total number of author keywords		2027	1897	359
	number of author keywords meeting the threshold (items)		(86) 80	(87) 84	45
Node analysis (author keywords)	top 10 nodes by size (keywords and their occurrences)		melatonin 31 circadian clock 23 circadian rhythm 21 nutrition 14 chronobiology 13 antioxidant 11 diet 9 oxidative stress 9 circadian rhythms 9 obesity 8	climate change 42 food security 19 sustainability 16 agriculture 11 remote sensing 11 drought 10 global warming 9 soil organic carbon 9 biodiversity 8 phenology 8	circadian clock 28 circadian 7 circadian rhythms 7 photosynthesis 7 chronobiology 5 circadian rhythm 5 rna-seq 5 arabidopsis thaliana 4 flowering 4 photoperiod 4
Cluster analysis	clustering		resolution 1.00 min. cluster size 1	resolution 1.00 min. cluster size 1	resolution 1.00 min. cluster size 1
	cluster number		11	13	8
	average cluster size		7.3	6.5	5.6
Network analysis	total links		231	239	120
	TLS		276	276	135
	robustness evaluation	varying threshold	3, 7, 10	3, 7, 10	2, 7
		normalizations	association strength	association strength	association strength

5. Integration of Chronobiology into Modern Agriculture

Plant chronobiology, i.e., the study of endogenous biological rhythms in plants, offers profound insights into optimizing agricultural practices for enhanced productivity and crop health [11,41]. By adapting agricultural strategies to the internal timing mechanisms of crops, it is potentially able to address some short-term and long-term challenges and problems in plant cultivation. This analysis, based on an interdisciplinary framework, explores the role of plant chronobiology across genetics, physiology, environmental sciences, informatics, and sustainability, as shown in

Table 3. Key findings of plant chronobiology in relation to the most important problems of modern plant agriculture—an interdisciplinary perspective. CAB (chlorophyll a/b-binding protein), ccg (circadian clock genes).

References	Plant Chronobiology Findings	Plant Agriculture Problems	Field
[7,14,24,57]	ccg universal control key agricultural traits of plants (Figure 3 and Figure 5)	selection of plant species and variants for cultivation, domestication properties of genetic material selection of chronotypes so-called early and late varieties	GENETICS
[5,13,16,40,58,59,60]	biological clocks regulate fundamental plant physiological processes ultradian, diurnal, circadian infradian, seasons, annual rhythms	control of plant life cycle germination, growth, development and reproduction increase in yields	PHYSIOLOGY
[29,30,31,32,33,34,35,36,37,38,39]	melatonin (Figure 3)	oxidative stress stress protection
[18]	photosynthesis circadian rhythm of CAB expression	photosynthetic efficiency crop yield
[4]	circumnutation ultradian and circadian rhythms of growth and organ movements, “sun tracking”	crop climbing plants (Vitis vinifera, Phaseolus, Pisum, Humulus) plant lodging pollination (e.g., sunflower, buckwheat) mechanical harvesting of plants
[15,41,61]	monitoring of natural seasonal and daily light rhythms, light-regulated circadian clock and its receptors, photoperiodism	use of appropriate intensity quality of light and photoperiod various light sources, oxygen stress	ENVIRONMENTAL SCIENCES
[17]	observation of periodic water availability rhythms of water uptake	water management and storage droughts, osmotic stress
[9,18]	monitoring of natural seasonal and daily temperature rhythms, entrainment of circadian clock by temperature	plant temperature resistance heat stress
[18]	nitrogen cycle, circadian-regulated nitrogen metabolism, crop rotation cycles	soil depletion, salt stress nitrogen fertilization
[8,10,20,21,22,41]	seasons and daily rhythm of resistance to infection and pest and pathogen activity pest phototactic rhythm plant–animal interrelation	plant disease and pest control weed control flowering-pollination Apis mellifera
[6,12]	rhythms of microbiomes of plants and soil	introduction of plant and soil microbiome to crop production
[42,43]	daily rhythm of secondary metabolite synthesis	cultivation of herbs, medicinal plants
[23,44,45,46,47,48]	phenology	seasonality of field work early or late spring autumn frosts sudden weather changes
[25,26,27]	chrono-agro-informatics analyzing data from the environment and the plant and detecting cycles in the environment (e.g., precipitation or drought) and the plant growth rhythm algorithms for time series analysis	remote sensing and machine learning necessity for continuous monitoring of field and greenhouse crops using a variety of electronic sensors, monitoring of environmental factors, plant growth and health parameters using the internet of things, big data analysis, prediction of weather changes, frost, drought, rainfall	INFORMATICS
[2,3,18,40,49,57]	theoretical analyses of rhythmic fluctuations of the environment and the operation of the biological clock (detection of rhythms entrainment, oscillator models)	sustainable agriculture (Figure 5)	SUSTAINABILITY

.

5.1. Genetics

Genetics—Core Clock

At the core of plant chronobiology is the circadian clock, an internal oscillator that regulates a vast array of biological processes. Research has universally established that ccg are fundamental in controlling key agricultural traits [7,19,24] (Table 3, Figure 3 green cluster). This genetic control has significant implications for the selection and domestication of plant species, as manipulating these genes can improve the inherent properties of the genetic material [7,19,24].

5.2. Physiology

5.2.1. Physiological Foundations of Crop Traits—Rhythms

The influence of the circadian clock extends throughout the plant’s life, as these biological timekeepers regulate fundamental physiological processes [40]. Plants exhibit a wide range of rhythms—from ultradian to infradian and annual—that govern their life cycle, including germination, growth, development, and reproduction [40]. By harnessing this knowledge, there is a significant opportunity to increase crop yields in the future (Table 3).

A crucial physiological process under circadian control is photosynthesis, with the expression of CAB following a distinct circadian rhythm [18]. Optimization of this rhythm is directly linked to improving photosynthetic efficiency and, consequently, crop yield and biomass production [18]. Furthermore, ultradian and circadian rhythms are responsible for rhythmic growth and organ movements like circumnutation—the helical motion of plant organ tips. Circumnutations are typical for climbing crops, such as Vitis vinifera (grape), Phaseolus (bean), Pisum (pea), and Humulus (hop), and for ordinary plants in the growing phase [4,52,53,54,58]. The diurnal “sun tracking” is vital for the pollination of species like Helianthus annuus (sunflowers).

The circadian movements of flowers, including daily sun-tracking (heliotropism), are of considerable importance for reproductive success, particularly in relation to pollination. The timing of flower opening and closing is often synchronized with the periods of activity of pollinators, such as bees. This coordination ensures that floral rewards, i.e., nectar and pollen, are available when pollinators are most active, thereby maximizing the chances of successful pollination. Disruptions to these circadian rhythms, for example by delaying the time of flowering, have been shown to reduce pollinator visits.

5.2.2. Crop Yield—Circumnutation and Wind

In plant agriculture, in the context of mechanical harvesting, the physical characteristics of the plant stem, such as height and stiffness, are of paramount importance, especially in cereal crops [55] (Table 3). Adequate stem length and rigidity are critical for preventing lodging, a condition where the stem bends or breaks, leading to significant yield losses. Research into the dynamics of plant growth, particularly the contribution of ultradian rhythmic movements known as circumnutations [52,53,54] https://circumnutation.umcs.lublin.pl/ (accessed on 9 August 2025), is essential for elucidating the development of these mechanical properties. Circumnutation, i.e., the helical movement of a growing plant organ, is thought to play a role in how plants explore their environment and respond to stimuli [52,53,54]. Investigations of these common movements through time-lapse video imaging can provide insights into the biomechanics of stem development and resistance to mechanical stress.

Wind is a significant, yet often underestimated, environmental factor in plant cultivation [55]. Its effects on crops are multifaceted, ranging from mechanical stress to physiological responses. The use of time-lapse photography, for instance in studies on wheat [55], can help visualize and quantify the dynamic responses of plants to wind stress over time.

5.3. Environmental Sciences

5.3.1. Environmental Synchronization

The study of synchronization and entrainment of plant biological rhythms with external environmental cues is fundamental to understanding plant development and productivity [28]. The successful interaction between plants, insects, and rhizobial bacteria necessitates a high degree of temporal synchronization of their biological rhythms (Table 3). For instance, the release of volatile compounds by plants to attract beneficial insects or deter herbivores often follows a distinct diurnal or nocturnal pattern. Similarly, the establishment of nitrogen-fixing symbioses with rhizobia is a complex process that is likely influenced by the plant’s internal clock.

5.3.2. Environmental Stress Management

Similarly, the observation of periodic water availability and the corresponding rhythms of water uptake by plants could be useful for effective water management and storage, particularly in the face of increasing drought and osmotic stress [17]. Temperature is another powerful environmental cue; the circadian clock is entrained by natural daily and seasonal temperature rhythms, which influences the plant’s temperature resistance and its ability to cope with heat stress [9,18] (Table 3). The influence of chronobiology also extends to nutrient management. The nitrogen cycle and the circadian-regulated metabolism of nitrogen are critical considerations for plant cultivation [18]. Understanding these relationships could help address problems of soil depletion, salt stress, and the optimization of nitrogen fertilization and support of crop rotation cycles [18].

5.3.3. Rhythmic Interactions, Phenology, and Crop Protection

Chronobiology also governs the interactions between plants and other organisms. There are distinct seasonal and daily rhythms in plants’ resistance to infection and the activity of pests, as well as the phototactic rhythms of the pests themselves [21,41] (Table 3). This knowledge could be useful for effective plant disease, pest, and weed control. The timing of flowering must synchronize with the activity of pollinators like Apis mellifera (honey bees) to ensure successful reproduction [21,41]. Furthermore, the rhythms of plant and soil microbiomes are an emerging area of interest, suggesting that introducing beneficial microbiomes at the right time could enhance crop production [6,12]. The daily rhythm of secondary metabolite synthesis is of particular importance for the cultivation of herbs and medicinal plants, as it determines the optimal harvest time for maximizing their potency [42,43].

Phenology, i.e., the study of the timing of seasonal biological events, is intrinsically linked to chronobiology and is a cornerstone of agricultural planning [23,44,46,47,48]. The seasonality of fieldwork is dictated by these natural rhythms, but such challenges as early or late springs, autumn frosts, and sudden weather changes disrupt these cycles, impacting crop success [23,44,46,47,48]. The underestimated role and interest in phenology is visible as the small node “phenology” alongside “seasonality” in Figure 4, Table 2, and mainly in Table S5.

5.4. Informatics and Sustainability

Informatics for a Sustainable Future

The convergence of chronobiology and modern technology (remote sensing, machine learning) has given rise to chrono-agro-informatics, a field with the potential to support agriculture [25,26,27] (Table 3). This discipline focuses on analyzing continuous multiday data from the environment and the plant to detect cycles in factors like precipitation and drought as well as in the plant growth and development rhythms [53]. By employing algorithms for time series analysis, it may be possible to leverage remote sensing and machine learning for enhanced crop management (Figure 4, Table S5). This necessitates the continuous monitoring of field and greenhouse crops with a variety of electronic sensors and the Internet of Things (IoT) to track environmental conditions and plant health parameters [53]. The resulting big data can be used to predict weather changes, frost, drought, and rainfall, allowing proactive interventions.

Theoretical analyses of the rhythmic fluctuations of the environment and the functioning of the biological clock—including rhythm detection, entrainment, and oscillator models—provide a robust framework for these technologies (Figure 4, Table S5). Ultimately, integrating these multifaceted chronobiological principles into agriculture is fundamental for achieving sustainability and ensuring future food security [2,3,19,40,49,57]. The broadly understood sustainability topic could also include the concept of the circular bioeconomy [56].

6. Reciprocal Relations Between Chronobiology and Plant Agriculture

The present literature analysis revealed the existence of interrelationships between chronobiology and plant agriculture (Table 2, Table 3 and Table S5). The three maps presented above (Figure 3, Figure 4 and Figure 5) showed that issues related to broadly defined biological rhythms constitute small nodes scattered among the dominant nodes of the main contemporary issues: climate change, sustainability, and food security. The dominant common themes were circadian biology and melatonin (Figure 3, Table 2 and Table S5). The topics of both domains were also compared and summarized in Table 2, and source data are shown in Table S5. The need for information exchange between these two fields, which is best addressed by the topic of chronoculture, is schematically presented in Figure 6. Figure 7 also schematically presents the differences in the number of documents in the Scopus database and the time range of research conducted within plant agriculture, chronobiology, and chronoculture (also presented in Table 1).

7. Discussion

7.1. Methodological Issues

• The present systematic review reveals both the emerging significance and current limitations in the application of chronobiology to plant agriculture. Although the keywords identified in Table 1 are well-represented in the literature quantitatively, their relatively minor presence as nodes in the VOSviewer maps (Figure 3, Figure 4 and Figure 5, Table 2 and Table S5) indicates a fragmented and underdeveloped research landscape. Despite the large number of documents retrieved (491, 424, and 107 respectively) based on author keywords, the field remains dispersed and thematically narrow, highlighting the need for more integrative and systematic investigations.
• While this review relied on keyword-based data extraction, the significant number of relevant documents analyzed justifies the methodological approach. Moreover, the combined application of the Scopus-based PRISMA methodology and VOSviewer bibliometric mapping proves to be a valuable strategy not only for structuring the current literature but also for uncovering hidden thematic connections. These tools also facilitate the exploration of older and often-overlooked literature that may serve as a conceptual reservoir for future innovations [2,3]. For instance, early studies on photoperiodism or diurnal cycles could inform modern approaches to precision agriculture studies.
• The presented work and the applied methodology are an attempt to address the problem of the increasing volume of publications and analysis methods (Table 1). The combination of using databases, keywords analysis, specialized software, and text analysis accounts for the diversity of approaches (Figure 3, Figure 4 and Figure 5, Table 2 and Table 3). Simultaneously, it expresses the rigor, repeatability, and standardization of the method (Tables S1–S6).

7.2. Thematic Issues

• Our analysis confirms that current research is primarily focused on the circadian clock and circadian rhythms and their relevance to photosynthesis, nutrition, climate change, flowering, and photoperiodic responses (Table 2, Table 3 and Table S5). However, other rhythmic processes, such as infradian, ultradian, and seasonal rhythms, as well as phenological patterns, are underrepresented, even though their central positioning in bibliometric networks suggests untapped potential for future studies. These non-circadian rhythmic processes could enhance our understanding of plant stress adaptation, flowering time, resource use efficiency, and seasonal crop scheduling.
• The presence of keywords linked to melatonin—not just in the context of flowering but also in stress adaptation—suggests a broader role for this molecule, potentially analogous to glutamate, in mediating cross-kingdom metabolic communication (Figure 3, Table 3). The role of melatonin in plant stress responses, especially under environmental stresses, mirrors the findings in animal systems and may exemplify a shared biochemical strategy across kingdoms.
• Another thematic cluster that has emerged involves the intersection of chronobiology with digital technologies, such as remote sensing and machine learning (Figure 4, Table 3 and Table S5). These innovations tend to develop “biological clock/calendar-based agriculture” where plant cultivation will be regulated by environmental cycles and by intervention at a precisely defined time. This points toward the necessity of time-based optimization of cropping systems—an approach that aligns biological rhythms with farming operations to enhance efficiency and crop health.
• There is a growing need to shift the focus of chronobiological research from the model plant Arabidopsis thaliana toward economically important crop species (wheat, rice, legume plants) (Figure 5, Table S5). Understanding circadian but also ultradian, infradian, and seasonal regulation in agricultural crops may expand the knowledge about their growth and development and especially flowering and fruiting.
• Interestingly, on the basis of the extracted literature, the integration of chronobiology findings into broader agricultural and socio-economic themes is observable. The emerging framework of chronoculture, which aims to align agricultural practices with biological rhythms, is a promising direction, but it needs to be expanded to include seasonality and ultradian rhythmicity (Figure 5, Table S5). This broader conceptualization may better reflect the multifaceted temporal regulation in plant systems and its relevance to food security, soil health, and environmental stress resilience.

7.3. Conceptual Framework of Chronoculture

7.3.1. Chronoculture—Operational Definition

The conceptual framework of chronoculture was elaborated on the basis of Figure 5, Table 2, Table 3 and Table S5 and is presented in

Table 4. Conceptual framework of chronoculture on the basis of Figure 5, Table 2, Table 3 and Table S5.

Basic science investigation		Temporal Scale	Examples of Cultivation Operations	Expected Outcomes
		ultradian (hours)	irrigation scheduling (sub-daily cycles) greenhouse light/pH/temperature adjustments, fertigation pulses	improved resource-use efficiency reduced stress, optimized micro-environment
		circadian (day–night)	sowing at optimal times of day diurnal pest control applications synchronization of pollination practices	higher crop vigor reduced pesticide use improved quality
		infradian (weeks–months) seasonal/annual phenological phenomena	timing of sowing and harvesting crop rotation, seasonal irrigation regimes, application of growth regulators	optimized yield, resilience to climate variability sustainability of production

. This framework is merely a preliminary outline and requires further development. More detailed studies may prove highly valuable and could lead to the establishment of a list of concrete practices. However, further progress necessitates a detailed and methodologically rigorous analysis of the existing literature on ultradian, circadian, seasonal, and phenological time scales.

7.3.2. Agro Chronobiology—Operational Definition

Based on the analysis of the “agro-chronobiology” map (Tables S5 and S6), it was found that it encompasses research on the circadian clock, circadian rhythms, melatonin, and metabolism and is distinctly directed toward topics related to animal physiology. It brings together basic chronobiological studies and may be directed toward agriculture in a broad sense, rather than being focused on plant agriculture. The “Chronoculture” map is more clearly directed towards plant agriculture, as follows from Figure 5, Table 2, Table 3 and Table S5.

7.3.3. Chronoculture vs. Agro Chronobiology—Operational Definitions

The operational definition of “chronoculture” introduced is understood as the practical implementation of knowledge concerning biological and environmental rhythms (ultradian, circadian, and seasonal) in the planning and execution of agronomic operations (sowing, irrigation, crop protection, harvesting). The term “agro chronobiology” is employed to designate the fundamental research discipline focused on the analysis and description of the circadian clock, rhythms, and metabolism in agriculture, broadly encompassing animal physiology as well.

Within this framework, chronoculture constitutes the applied dimension of agro-chronobiology directed toward crop cultivation practice.

7.4. Challenges and Limitations in Applying Chronobiology to Plant Agriculture

Although plant chronobiology holds significant potential for addressing agricultural problems (Table 3), its application remains constrained by several key limitations. The complexity of rhythmic processes in different species and the complexity of environmental rhythms (seasonality, phenological phenomena) and weather phenomena complicate the direct translation of laboratory findings to field conditions. Furthermore, the integration of multiscale rhythms is insufficient; current research predominantly focuses on circadian regulation, while ultradian, infradian, and phenological rhythms remain underexplored. Technological and analytical barriers also pose a considerable challenge. Addressing these limitations will require significant methodological advances in literature analysis and interdisciplinary collaboration for transition of plant chronobiology from a conceptual promise to a practical agricultural application.

8. Conclusions

• Literature mapping revealed that the most widely researched topics are those related to the circadian clock, circadian rhythms, and melatonin. Genetic, molecular-level, and hormonal insights into circadian regulation can be translated into plant cultivation practice.
• Issues directly related to seasonality and phenology as well as ultradian and infradian rhythms are poorly represented in the context of chronobiology, and their development may provide new solutions.
• Development of chronobiological research that will shift focusing from Arabidopsis to key crops is necessary.
• Based on chronobiological research analysis, it is possible to develop better (resource-saving) time-aware irrigation, lighting, fertilization, disease, and pest control protocols.
• Focus on analyzing continuous multiday data from the environment and plants by developing integrative remote sensing and machine learning is also important.

In conclusion, although this review serves as an initial framework rather than an exhaustive analysis, it reveals many limitations but also the significant potential of applying chronobiological principles in agriculture. A more detailed synthesis of both contemporary and historical studies is needed to fully harness this potential. Future research should prioritize interdisciplinary integration, methodological innovation, and the expansion of chronobiological inquiry beyond the circadian focus to build holistic time-informed plant agriculture.

Understanding the mechanisms of the plant’s internal biological clock—a precise system that governs plant internal temporal regulation—offers a promising foundation for the development of future precision agriculture. Deciphering how this endogenous timekeeping system operates may facilitate the synchronization of agricultural practices with plant’s innate rhythms, leading to more efficient resource use, improved crop yield, resilience, and optimized plant growth conditions.

Possibly, just as modern society benefits from the precision of an atomic clock, future precision agriculture will benefit from the use of a “living clock”.