1 Introduction

Edamame (vegetable soybean) is a specialty type of soybean harvested at the R6-R7 stages, when pods are fully filled, bright green, and rich in protein, oil, sugars, vitamins and dietary fibre, making it an increasingly important functional vegetable in global markets (Moseley et al., 2021). China is both the centre of vegetable soybean production and a major supplier to international markets, while domestic consumption has also expanded rapidly with growing demand for nutritious, plant-based foods. Edamame is generally considered a low-input, short-cycle, and soil-improving crop, which fits well into diversified vegetable systems and offers attractive economic returns to farmers, especially where market access and post-harvest handling are well developed. For coastal provinces such as Zhejiang, with mild monsoon climates, high population density and strong fresh-produce demand, optimizing local edamame production systems is therefore of both agronomic and economic significance.

The performance of edamame is tightly linked to environmental conditions, especially temperature, rainfall and light, which are largely determined by sowing or planting season (Zeipiņa et al., 2022). The duration of the vegetative period, thermal time accumulation and hydrothermal conditions jointly regulate plant development, pod setting and the attainment of marketable quality, including pod size and colour. Studies on soybean and other field crops in China indicate that inappropriate sowing dates can expose crops either to early-season cold and moisture stress or to late-season heat and water deficits, shortening grain filling or increasing stress damage and thereby reducing yield and quality (Xu et al., 2024). In Zhejiang, which is characterized by distinct spring, summer and autumn climatic patterns and frequent extreme weather events, clarifying how different planting seasons affect edamame growth, yield and quality is thus essential for stabilizing production, extending the supply window and improving land-use efficiency.

Internationally, research on edamame and vegetable soybean has focused on cultivar selection, sowing date, planting density and season-extension technologies to secure yield and maintain pod quality across diverse environments. In the United States and Europe, early and staggered planting of different maturity groups, combined with protected culture or high tunnels, has been used to extend the harvest period from a few weeks to several months and to better match market demand for fresh pods (Moseley et al., 2021). At the same time, multi-environment trials have revealed strong genotype × environment × planting-date interactions, showing that cultivar adaptation and stability differ markedly among sites and sowing windows, and that edamame often requires specific management distinct from grain-type soybean (Van Der Merwe et al., 2024). Although vegetable soybean has been widely promoted along China’s east coast, systematic studies integrating planting season, local climate characteristics and edamame performance in Zhejiang remain limited, resulting in empirical planting schedules and uncertain production risks.

Against this background, the present study is designed to evaluate the performance of edamame under different planting seasons in Zhejiang, with the aim of providing a scientific basis for optimizing cropping calendars and agronomic management. Building on previous work on edamame yield and quality drivers, including the roles of planting date, thermal units and harvest timing, the study examines how key growth and yield traits, pod appearance and harvest window respond to changes in sowing season under Zhejiang’s subtropical monsoon conditions (Zheng et al., 2024). The main objectives are: (i) to quantify the effects of contrasting planting seasons on edamame phenology, growth and fresh pod yield; (ii) to assess associated changes in pod quality indicators relevant to fresh markets; and (iii) to identify suitable planting seasons and cultivar-season combinations for stable, high-quality production in Zhejiang. The results are expected to provide technical support for local farmers and extension services, contribute to regional edamame branding, and offer a reference for adapting vegetable soybean production to changing climatic conditions in similar agro-ecological zones (Zeipiņa et al., 2022).

2 Effects of Different Sowing Seasons on Edamame Growth and Development

2.1 Emergence rate and seedling growth performance

Sowing season in Zhejiang modifies soil temperature and moisture at planting, which are critical for edamame emergence. Laboratory-field simulations showed that edamame has an optimal emergence temperature of 25 °C-32 °C and requires more thermal time than grain-type soybean, implying that earlier sowing into still-warm soils favors rapid and uniform stands. Under favorable field conditions with adequate temperature and moisture, emergence of multiple edamame genotypes exceeded 70%, comparable to grain-type soybean, indicating that poor stands often reflect suboptimal sowing environments rather than inherent genetic limitations (Li et al., 2024).

Seedling growth is also affected by sowing-related temperature conditions and seed traits. Edamame seeds are 65-100% larger than grain-type seeds, leading to slower imbibition and delayed emergence, but this delay is mitigated in warm, moist soil typical of well-chosen early or main-season sowing windows. When emergence occurs near the optimal thermal range, larger seed surface area may even enhance water uptake, supporting vigorous hypocotyl elongation and robust early growth, whereas cooler late-sown conditions can prolong emergence time and increase the risk of stand gaps (Li and Zhang, 2022).

2.2 Growth dynamics during the vegetative stage

Planting season shifts the length and thermal environment of the vegetative phase, influencing canopy development and adaptation. In high-latitude trials, early sowing was essential to secure a vegetation period of at least 123-127 days with ≥650 growing degree days, which supported normal vegetative growth and marketable yields of 3-10 t/ha; delayed sowing shortened the vegetative window and constrained biomass accumulation (Zeipiņa et al., 2022). A broader review similarly reports typical edamame vegetation periods of 75-100 days, with breeders prioritizing early maturity to match local growing seasons and reduce risk under shorter or cooler conditions.

Within a given season, growth responses also depend on genotype-environment interactions. North European trials showed that under suitable hydrothermal conditions, edamame attained plant densities of 20-25 plants/m² with satisfactory height and canopy structure, indicating that adequate moisture and temperature during early to mid-vegetative stages are more decisive than latitude per se (Zeipiņa et al., 2022). Comparative evaluations highlight wide genotypic variation in plant height and architecture, suggesting that in Zhejiang different sowing seasons should be matched with cultivars of appropriate maturity and growth habit to ensure sufficient vegetative development before flowering.

2.3 Developmental characteristics during the reproductive stage

Sowing date determines the thermal and photoperiodic environment during reproductive stages, thereby affecting flowering time, pod set, and marketable pod quality. In Egyptian experiments, sowing on 1 April, 1 May, or 1 June significantly altered plant architecture and yield components: early sowing enhanced 100-green-seed weight and pod quality ratio, while mid-season sowing (1 May) maximized pod number per plant and total green pod yield, reflecting a favorable balance between vegetative duration and reproductive conditions (Nabila, 2021). Later June sowing promoted taller plants with more leaves and branches but did not necessarily translate into superior pod yield or quality, indicating that excessive delay can misalign peak reproductive growth with optimal temperature and radiation regimes.

For edamame, harvested at R6-R7, reproductive timing is closely linked to pod size and color. A multi-environment study found that delayed planting generally improved pod green color and weight, but harvest quality showed a quadratic decline when harvest was delayed too long, with an 18-27 day window of near-maximum quality around the peak (Moseley et al., 2021). The number of days from first bloom (R1) to harvest consistently emerged as a key driver of quality, underscoring that in Zhejiang, different sowing seasons must be paired with precise monitoring of phenology to time harvest when pods are both fully filled and intensely green.

3 Effects of Different Sowing Seasons on Yield and Its Constituent Factors

3.1 Single-plant yield and population yield performance

Edamame yield at both single-plant and population scales is closely linked to sowing season because temperature and radiation patterns determine vegetative growth duration and biomass accumulation. Multi-year evaluations in Tennessee showed that spring sowings (May-June) produced significantly higher fresh pod yield than July sowing, with mean plot yield declining from 3118 g in May to 2131 g in July, indicating that late sowing shortens the effective growth period and limits canopy development. Similarly, in Egypt, intermediate sowing (1 May) gave the highest total green pod yield per unit area, while earlier or later dates favored vegetative traits or pod size but not overall yield, underscoring the need to synchronize crop growth with the local optimal hydrothermal regime (Nabila, 2021).

At the plant level, sowing season interacts with genotype to shape single-plant productivity. Under Egyptian conditions, the second sowing date (1 May) combined with a high-yielding cultivar significantly increased pod number per plant and fresh pod weight, which translated directly into greater population yield. In broader edamame trials, large differences in fresh pod yield among genotypes and years have been reported, with coefficients of variation for yield traits larger than for plant height or 100-seed weight, suggesting that seasonal climatic variability and planting time exert stronger control on yield than on basic morphology, and that optimal sowing windows can partly buffer these environmental effects.

3.2 Variations in pod number, seed number, and 100-seed weight

Yield components respond differentially to sowing season, with pod and seed number typically more sensitive than seed weight. In central Europe, changing soybean sowing date markedly affected seed yield through variation in plant height, nodulation, and seed set, whereas 1000-seed weight remained relatively stable across dates, indicating that compensatory changes in pod and seed numbers are the main drivers of seasonal yield differences (Borowska and Prusinski, 2021). In edamame, Tennessee trials found that earlier sowing (May) not only increased fresh pod weight per plot but also resulted in higher 100-seed weight (49 g) compared with June (45 g) and July (42 g), showing that late planting can simultaneously reduce both reproductive sink size and individual seed filling.

Sowing time also influences pod set efficiency and the distribution of 1-, 2-, and 3-seeded pods. In Florida, the number of pods per plant and 100-green seed weight showed significant positive correlations with fresh pod yield, identifying these components as key selection indices under variable environments (Guo et al., 2020). Egyptian experiments demonstrated that the May sowing promoted more green pods per plant and a higher proportion of marketable pods, while the April sowing maximized 100-green-seed weight, suggesting a trade-off between pod number and seed size under different thermal conditions and highlighting that edamame sowing season should be chosen according to whether yield or pod size is the primary production goal (Nabila, 2021).

3.3 Analysis of yield formation mechanisms

The mechanisms by which sowing season affects edamame yield are largely mediated through its impact on phenology, canopy structure, and source-sink balance. Studies on edamame lines in Virginia showed that year effects, reflecting weather and planting time, were significant for plant biomass and pod yield, whereas genotype-by-year interactions were limited, implying that environmental conditions during critical periods such as flowering and pod filling dominate yield formation. Likewise, soybean sowing-date experiments in central Europe found that early sowing aligned reproductive stages with more favorable June-July precipitation, resulting in higher seed yield; in contrast, delayed sowing increased exposure to late-season moisture deficits, elevating flower and pod abortion and reducing final pod and seed numbers (Borowska and Prusinski, 2021).

At the physiological level, sowing season determines the length of the period between first flowering and harvest and the thermal time available for green pod filling. Work on planting date and harvest window in Arkansas revealed that delayed planting improved edamame pod quality indicators but narrowed the interval during which pods remained at optimal size and color, suggesting that late sowing may constrain cumulative assimilate supply even as cooler late-season temperatures help maintain visual quality (Moseley et al., 2021). Integrative reviews further emphasize that environmental conditions associated with different growing seasons alter canopy development, photosynthetic capacity, and partitioning to pods and seeds, so that yield is ultimately expressed through the interaction of genotype, planting season, and management in a given production region such as Zhejiang.

4 Analysis of Interaction Effects Between Environmental Factors and Sowing Seasons

4.1 Effects of temperature on growth and yield

Temperature regimes associated with different sowing seasons strongly influence edamame growth duration and yield formation. In high-latitude trials, successful edamame production required a vegetation period of at least 123-127 days with growing degree days ≥650 and a hydrothermal coefficient above 1, conditions more reliably achieved with earlier sowing that positions critical growth stages in a favourable thermal window. When these requirements were met, marketable yields of 3-10 t ha⁻¹ were obtained, indicating that aligning sowing date with adequate seasonal heat accumulation is essential to realize the crop’s yield potential (Zeipiņa et al., 2022).

Temperature also interacts with sowing season to affect pod quality near harvest. Multi-environment work on edamame showed that pod weight and green colour respond to planting date and harvest timing, with delayed planting generally improving quality but only within a thermal and phenological window where excessive heat or late-season cooling do not hasten senescence or colour loss (Moseley et al., 2021). Climate-metabolome analyses further revealed correlations between average temperature before harvest and the levels of specific metabolites, implying that interannual and intra-seasonal temperature variation around maturity can alter flavour and nutritional profiles even under the same calendar sowing date (Oikawa et al., 2023).

4.2 Effects of light intensity and photoperiod

Light intensity and spectrum, which vary with season and canopy development, modulate vegetative growth and space-use efficiency. In controlled plant-factory systems, increasing photosynthetic photon flux density (PPFD) from 300 to 700 μmol m^-2 s^-1 substantially enhanced edamame fresh and dry biomass, stem length, and reduced specific leaf area, demonstrating that higher light intensities within a suitable range promote more compact, productive canopies. Light quality also mattered: a higher blue:red photon ratio increased plant height but decreased projected leaf area, showing that seasonal or artificial light environments can shape morphology and thus influence how different sowing windows translate into canopy structure and yield potential (Liu et al., 2024).

Photoperiod interacts with sowing season to regulate flowering time and, consequently, the balance between vegetative and reproductive growth. Molecular studies in soybean demonstrate that flowering is tightly controlled by photoperiod-sensing pathways, where key loci integrate daylength signals to adjust floral transition and thereby determine regional adaptation and yield (Lin et al., 2020). When edamame is sown at different times in regions with marked seasonal changes in daylength, plants encounter contrasting photoperiod environments during early development and flowering, which can either accelerate or delay reproductive onset; this in turn modifies the effective growth period available for pod filling and the calendar of harvestable green pods (Zeipiņa et al., 2022).

4.3 Effects of precipitation and soil moisture conditions

Precipitation patterns and soil moisture status, both season-dependent, interact with sowing date to shape water availability during sensitive stages. In temperate soybean systems, irrigation experiments under wet, semi-dry, and dry years showed that seasonal precipitation below about 300 mm necessitated supplemental water to achieve high yields, whereas in wet years, rainfed yields approximated fully irrigated ones due to favourable rainfall distribution. Water deficits during pod development and filling were particularly detrimental to yield, indicating that for edamame, sowing seasons that place these stages in typically drier periods will require careful water management to maintain both pod number and size (Zeleke and Nendel, 2024) (Figure 1)

Figure 1 Sowing season strongly conditions edamame growth and yield by aligning criticalgrowth stages with optimal temperature, light, and moisture

Around harvest, short-term rainfall and soil moisture fluctuations also affect edamame quality. A six-year study linking meteorological data to edamame metabolomes found relationships between accumulated rainfall before harvest and the concentrations of several low-molecular-weight compounds, suggesting that wetter or drier pre-harvest periods can shift metabolic profiles and potentially sensory attributes (Oikawa et al., 2023). For regions like Zhejiang with monsoon-driven rainfall, choosing sowing dates that avoid excessive precipitation near harvest may help reduce quality variability, while in drier sowing windows, maintaining adequate soil moisture is critical for stable pod filling and consistent metabolite accumulation.

5 Evaluation of Economic Benefits and Production Adaptability

5.1 Input-output analysis for different sowing seasons

Economic returns from edamame are highly sensitive to sowing season because planting date determines yield level and, in some systems, production costs per unit output. Large-scale simulations for Brazilian soybean-maize succession showed that shifting sowing dates within the recommended window altered net revenue substantially, with the highest profits obtained when soybean was sown near the start of the optimal climatic window, while delays reduced revenue through lower yields and, in some regions, higher climatic risk for the following crop. Similar analyses on US soybean cultivar trials demonstrated that advancing sowing by about 12 days relative to farmers’ practice could increase national yield by 10%, corresponding to an estimated additional US$9 billion over a decade, underscoring the strong leverage of sowing date on aggregate economic outcomes (Oikawa et al., 2023).

For vegetable soybean, input-output relationships also depend on how planting season interacts with quality traits and the harvest window. Review work on edamame emphasizes that, as a high-value fresh vegetable, profitability hinges on achieving both high fresh-pod yield and premium pod appearance, with labor and post-harvest handling dominating variable costs. Season-extension and staggered planting systems using different maturity groups in the United States increased the fresh harvest period from roughly two weeks to several months without compromising seed composition, thereby spreading fixed costs and improving overall land and capital use efficiency, a strategy that is directly relevant to maximizing returns from multiple sowing seasons in regions like Zhejiang.

5.2 Risk assessment and stability analysis

Sowing season strongly influences production risk by modifying exposure to temperature and water stress, which in turn affects yield variability and economic stability. In southern Brazil, crop-model simulations across 30 years and 187 locations showed that optimizing planting dates and maturity groups reduced crop failure risk (yield below break-even) by 15%, particularly by avoiding combinations of late planting and high water stress during critical phases, thus stabilizing profits over time (Hintz et al., 2025). ENSO-based regional analyses in Brazil similarly found that sowing within climate-tailored windows reduced the area under high agroclimatic risk, especially in dry scenarios, illustrating how season-specific sowing windows can buffer climatic variability and support more reliable returns (Figure 2) (Reis et al., 2020).

Figure 2 A comprehensive evaluation framework for the economic benefits and adaptability of edamame production under different sowing dates

At farm level, yield and lodging risks associated with conventional early sowing under warming climates also require reassessment. In Korea’s southern coastal region, earlier sowing under recent climate conditions prolonged vegetative growth and increased lodging risk, while also reducing pod number due to altered flowering photoperiod, leading to recommendations to postpone sowing to late June to improve yield stability and feasibility of double-cropping (Chae et al., 2025). In North-Eastern Poland, analyses of three sowing dates showed that seed yield and length of growing season were closely correlated, and that an “optimal” mid-May sowing balanced frost risk, season length, and yield stability, highlighting that risk-minimizing sowing windows may not always coincide with the earliest possible planting date (Fosrdoński et al., 2023).

5.3 Comprehensive evaluation of the optimal sowing season

Determining the optimal sowing season for edamame in Zhejiang requires integrating yield, quality, risk, and profitability into a comprehensive evaluation framework. Work on defining optimal soybean sowing dates in the US used machine learning to relate yield responses to in-season weather, then quantified yield and monetary gains from earlier sowing, demonstrating that region-specific recommendations can be built from combined agronomic and economic indicators rather than yield alone. National-scale modeling of soybean-maize succession systems in Brazil similarly identified sowing periods that maximized net revenue rather than just biological yield, showing that optimal windows varied among regions depending on climate patterns and production costs, a principle equally applicable to diverse microclimates within Zhejiang .

For edamame, quality and market timing add further dimensions to “optimality.” Studies on edamame planting date and cultivar maturity in Arkansas found that later planting improved pod color and weight, and that harvest quality remained near maximum for 18-27 days around a cultivar- and season-specific peak, implying that appropriate sowing dates can be chosen to align premium-quality harvest with peak consumer demand or processing capacity (Moseley et al., 2021). Evaluations of off-season and protected-culture edamame systems showed that combining early and main-season sowings across maturity groups extended the fresh harvest window from two weeks to several months, while maintaining acceptable protein and sucrose contents, suggesting that in Zhejiang, a mosaic of sowing seasons—rather than a single date—may best optimize economic returns and production adaptability across years and market segments.

6 Case Study: Optimization Practices for Edamame Sowing Seasons in a Typical Region

6.1 Overview of the case region and planting patterns

A typical edamame production region in the Yangtze River Delta, adjacent to Zhejiang, is characterized by a humid subtropical monsoon climate with long frost-free periods and high demand for fresh maize and fresh soybean products. Field experiments in Nantong, Jiangsu, show that fresh soybean is commonly integrated into intensive annual systems, such as wheat-fresh soybean or wheat-fresh maize-fresh soybean relay intercropping, to better utilize light, temperature, and precipitation resources (Fogelberg and Mårtensson, 2021). Under these conditions, vegetable soybean benefits from relatively high accumulated temperature and sufficient rainfall during its 75-100-day growing period, which is suitable for achieving marketable yields and stable quality (Li et al., 2024).

Planting patterns in this region increasingly emphasize multiple cropping and relay intercropping to raise annual land productivity. Compared with conventional wheat-fresh soybean double cropping, introducing fresh maize and fresh soybean in a triple-cropping pattern significantly increased annual yield, biomass, and economic return, while also improving radiation and temperature use efficiency (Fogelberg and Mårtensson, 2021). From a broader perspective, vegetable soybean is recognized as a short-cycle, high-value crop with strong adaptability to diverse rotations, and its high nutritional and functional value has driven rapid market expansion and interest in optimizing planting arrangements within intensive vegetable and grain-vegetable systems (Figure 3) (Nolen et al., 2016).

6.2 Results of comparative trials on different sowing dates

Comparative studies on planting dates and season-extension techniques provide guidance for optimizing sowing windows in such regions. In Arkansas, staggered planting of different maturity-group edamame cultivars, combined with high tunnels and plastic-covered fields, extended the harvest period from about two weeks to several months while maintaining comparable seed protein and sucrose content across systems. Early and mid-spring sowings under protected cultivation allowed harvests beginning in early July, whereas conventional late-spring sowings supported mid-summer to early-autumn harvests, showing that well-planned sowing calendars can greatly improve market supply continuity.

Trials manipulating planting date and cultivar maturity further reveal how sowing season affects pod quality. Work in the U.S. Mid-South demonstrated that delayed planting generally improved pod green color and weight, with an “Edamame Harvest Quality Index” peaking over an 18-27-day period around optimum harvest. Pod quality depended strongly on the interaction among cultivar, planting date, and harvest timing, and the number of days from first flowering to harvest consistently emerged as a key predictor of quality, highlighting that regional sowing-date trials must jointly consider phenology and post-harvest quality requirements (Figure 4) (Zeipiņa et al., 2022).

Figure 4 Effects of different sowing dates and cultivation methods on the extension of the edamame harvesting period and pod quality formation

6.3 Production recommendations and extension value

Evidence from intensive fresh soybean and edamame systems suggests several practical recommendations for Zhejiang-like regions. First, sowing dates should be arranged to ensure adequate growing degree days and favorable hydrothermal conditions, often requiring relatively early sowing within the local warm season and, where needed, the use of plastic tunnels or other microclimate-moderating measures (Moseley et al., 2021). Second, integrating fresh soybean into multi-crop annual systems, such as wheat-fresh maize-fresh soybean relay patterns, can markedly raise annual yield, climate-resource use efficiency, and economic returns compared with simpler double-cropping, providing a template for high-value edamame integration in Zhejiang (Fogelberg and Mårtensson, 2021).

From an extension perspective, region-specific sowing-date and cultivar recommendations can help stabilize supply and enhance profitability. Review work on vegetable soybean emphasizes that cultivar choice, planting date, and fertilization are central levers for improving establishment, yield, and seed quality, and that adapting these practices to local climate and market niches is essential for successful commercialization. At the same time, case-region results show that optimized multi-cropping patterns with fresh soybean are suitable for broader promotion across the Yangtze River basin, suggesting that similar sowing-season optimization and cropping-system designs could be disseminated to edamame producers in Zhejiang to improve resource use and support regional branding of fresh vegetable soybean (Li et al., 2024).

7 Conclusions and Outlook

This study showed that sowing season in Zhejiang substantially regulates edamame growth duration, reproductive allocation, and final yield, mainly through shifts in temperature and hydrothermal conditions across the crop cycle. Evidence from soybean systems in eastern and northern China confirms that phenology and the balance between vegetative and reproductive phases are highly sensitive to mean temperature, accumulated temperature ≥10 °C, precipitation, and sunshine hours, with sowing date and cultivar choice acting as major management levers. Within a suitable climatic window, adjusting planting time allows better matching of critical stages such as flowering and pod filling with favourable temperature and moisture, thereby stabilizing yield and pod quality under a warming and more variable climate.

The results also highlighted that appropriate sowing seasons can enhance resource-use efficiency and economic returns when integrated into local cropping systems. Studies in the Yangtze River Basin and Northeast China indicate that optimized arrangements of fresh soybean within wheat-maize-soybean sequences or other intensive systems increase annual yield, radiation and temperature use efficiency, and farm income, provided that sowing dates are aligned with regional climate resources. At the national scale, modelling work further shows that optimizing sowing windows and related management practices can close a substantial share of the yield gap attributed to agronomic factors, underscoring the broader significance of fine-tuning sowing season for soybean-based systems such as edamame in Zhejiang.

Despite these advances, important limitations remain in understanding edamame-specific responses to sowing season under Zhejiang’s diverse microclimates. Many long-term datasets and crop-model applications focus on grain soybean across broad regions, so their phenological and yield responses may not fully represent vegetable soybean harvested at R6-R7 and evaluated for fresh-pod traits such as colour and size. Moreover, phenology observations and climate records are often from agro-meteorological stations with limited spatial resolution, which may not capture local variations in coastal, hilly, and peri-urban production zones typical of Zhejiang.

Methodologically, most adaptation assessments emphasize temperature and precipitation, with relatively fewer scenarios explicitly combining sowing season, cultivar thermal requirements, and detailed management packages tailored to fresh soybean. Case studies in Northeast China and Fujin City stress that single-site or short-term experiments constrain the robustness of conclusions, and that more management options and multiple models are needed to reduce uncertainty about future yield responses. In addition, many simulations consider only one or a few cultivars, limiting insight into genotype × sowing-season × climate interactions that are central to designing resilient edamame systems under continued warming.

Future work on edamame in Zhejiang should integrate long-term phenology and yield observations with process-based models to quantify how alternative sowing windows perform under projected climate scenarios. Studies on soybean and maize show that combining optimized sowing dates with cultivar shifts of longer growth duration can partly offset climate-induced shortening of key growth periods and potential yield losses, especially under 1.5°C-2 °C warming. Applying similar frameworks to edamame would enable identification of sowing-cultivar combinations that maintain adequate vegetative growth, robust reproductive development, and high fresh-pod quality despite changes in temperature, rainfall, and sunshine.

From an application perspective, regional-scale suitability mapping and system design offer promising pathways for scaling optimized planting seasons. National assessments using MaxEnt and related approaches have delineated current and future high-suitability zones for soybean and identified provinces with large but underused potential, including Jiangsu and neighbouring regions in the Yangtze River Basin. Coupling such spatial analyses with evidence from intensive soybean/maize intercropping and wheat-fresh maize-fresh soybean relay systems suggests that, in Zhejiang, carefully scheduled edamame sowing within diversified rotations could enhance land-use efficiency, climate-resource utilization, and economic benefits, while providing a more stable fresh edamame supply to meet growing market demand.

Acknowledgments

I would like to thank the anonymous reviewers for their detailed review of the draft. Their specific feedback helped us correct the logical loopholes in our arguments.

Conflict of Interest Disclosure

The author affirms that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

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