A trade-off between high grain yield and high protein (or nitrogen, N) concentration is frequently observed for crop plants in agroecosystems and is difficult to resolve using conventional agricultural methods. Whether ecological strategies, such as exploring the interactions between plants and microbes, can be leveraged to tackle this problem remains unclear. Here, we used wheat as a model plant and focused on the interaction among plants, arbuscular mycorrhizal fungi (AMF) and hyphosphere bacteria. We conducted six independent but complementary experiments and demonstrated that AMF can enhance both wheat yield and grain N concentration, but only in specific varieties with high N conversion efficiency (grain yield per mean plant N at preanthesis). AMF can boost yield from increased grain weight via enhanced postanthesis photosynthetic carbon (C) assimilation through promoting plant phosphorus uptake, while elevating grain N concentration through stimulating postanthesis N uptake and assimilation. This dual effect arises from the enhanced postanthesis belowground C allocation, sustaining AMF hyphal network integrity and increasing soil nutrient availability via reshaping hyphosphere bacterial community structure. Our findings indicate that postanthesis plant-microbial interactions can potentially overcome an old dilemma between maximizing grain yield and N concentration in agricultural production.

Mineralization of soil organic carbon (SOC) is an important component of the soil carbon cycle. Studies have shown that rice–fish cocultures increased SOC; however, the question of whether raising aquatic animals with rice affects SOC mineralization remains unresolved. In this study, we conducted a field experiment to test SOC mineralization under three types of rice–aquatic animal cocultures (i.e., rice–fish coculture, RF; rice–crayfish coculture, RC; and rice–turtle coculture, RT) and rice monoculture (RM). SOC fractions, soil aggregate structure and SOC mineralization were determined in the experiment. Total SOC and microbial biomass carbon (MBC) under RT were significantly higher than under other treatments, and no significant differences in other SOC fractions were found among the treatments. For soil aggregates, there were significant differences in the proportions of large macroaggregates (LMA), microaggregates (MiA), and mean weight diameter (MWD) among the treatments. The LMA proportion significantly reduced while the MiA increased under the RT treatment compared to other treatments. SOC mineralization rates significantly differed among the treatments, where the RT and RC treatments had significantly higher mineralization ratios and daily average mineralization rates than the RF and RM treatments. RDA indicated that SOC fractions and soil aggregate structure influenced SOC mineralization. Our results demonstrate that aquatic animals exert differential effects on SOC mineralization, primarily through altering soil aggregate structure and SOC fractions. These findings highlight that the effects of aquatic animals on SOC dynamics should be considered in the assessment of coculture outcomes.

Soil heavy metal pollution poses a global environmental threat, demanding effective and sustainable remediation strategies. Arbuscular mycorrhizal fungi (AMF) play a multifaceted role in enhancing the remediation of heavy metal (HM)-contaminated soils through extensive hyphal networks that interact with plant roots and soil microbiota. AMF hyphae and their exudates, such as glomalin, directly immobilize metal ions and reduce bioavailability by modifying soil properties (e.g., pH). Furthermore, AMF reshape the rhizosphere microbiome by enriching metal-tolerant bacteria (e.g., Pseudomonas, Bacillus) and fostering synergistic microbial communities via cross-kingdom signaling. Within plants, AMF symbiosis-especially with hyperaccumulators-optimizes root architecture, enhances nutrient and water uptake, stimulates biomass production, and regulates key physiological and molecular responses. These include bolstering antioxidant defenses, maintaining photosynthetic efficiency, and upregulating genes involved in metal transport, compartmentalization, and stress signaling. Field studies confirm the potential of AMF-hyperaccumulator systems in metal extraction and stabilization. However, transitioning from controlled experiments to field applications remains challenging due to the complexity of multipartite interactions and a lack of predictive frameworks. This review critically integrates interdisciplinary insights into a forward-looking perspective, emphasizing the need to shift from empirical approaches to an intelligent, predictive design paradigm. We propose leveraging machine learning to decode interactions among AMF genotypes, plant phenotypes, microbial consortia, and soil properties, enabling the rational design of efficient remediation systems. Ultimately, overcoming barriers to field implementation requires integrating robust science with advanced engineering and supportive policy frameworks.

The phycosphere is an important ecological niche for bacteria and antibiotic resistance genes (ARGs). However, whether and how the interaction between microalgae and bacteria changed, and its further effect on the transmission of ARGs under pollutant stress remains enigmatic. Here, Auxenochlorella pyrenoidosa was co-cultured with bacteria screened from lake water to explore the algal–bacteria interaction and ARGs’ transmission in the presence of florfenicol (FF) and polylactic acid microplastics (PLA MPs). Our study demonstrated that the growth and metabolism of A. pyrenoidosa were promoted under FF treatment or co-treatment with PLA MPs, validated by phenotypic, transcriptome, and metabolome analyses. In contrast, the abundance of phycospheric bacteria was decreased as a result of niche competition. Nonetheless, the transmission of ARGs in the phycosphere was promoted due to the enrichment of antibiotic-resistant bacteria, especially Pseudomonas, rather than horizontal gene transfer. The algal-bacteria co-culture experiment further suggested that vitamin B6 secreted by Pseudomonas sp. likely contributes to underpinning A. pyrenoidosa’ survival under FF and PLA MPs stress. These findings underscore the dynamic interplay and co-evolution between algae and bacteria under pollutant exposure, and reveal a potential mechanism of vitamin B6-mediated mutualism. This study provides new insights into the assembly of phycospheric bacterial communities and the adaptive strategies of microalgae in contaminated aquatic environments.

Heavy metals are significant abiotic stresses that negatively affect plant growth and yield, thereby threatening food safety. However, in this study, we observed that low concentrations of Pb (lead) positively regulated plant growth in two model plants, Arabidopsis and tobacco, as demonstrated through controlled plate experiments. Pb treatment (e.g., 500 and 1000 & micro;M) increased biomass accumulation, promoted chlorophyll biosynthesis, and enhanced the growth of both adventitious and lateral roots whereas cadmium (150 & micro;M) exhibited significant toxicity to plant growth. Further biochemical analysis revealed that Pb treatment did not induce reactive oxygen species accumulation or activate antioxidant systems. To investigate the different responses of Arabidopsis seedlings to Pb and Cd, a comparative transcriptome analysis was performed on the roots and shoots of Arabidopsis seedlings. The transcriptomic analysis identified 400 and 589 differentially expressed genes (DEGs) in the Pb-treated leaves and roots, respectively, while Cd treatment resulted in 2718 and 3871 DEGs, respectively. Notably, KEGG analysis showed that the DEGs associated with the response to Cd were strongly associated with stress defense and detoxification processes, whereas the gene expression patterns induced by Pb were more diverse, suggesting that Pb functions as a plant growth modulator rather than a toxicant. Moreover, Pb enhanced lateral and adventitious root growth by increasing the endogenous indole-3-acetic acid content and activating its downstream signaling component, AIR1, whose overexpression promoted lateral root growth. In conclusion, this study demonstrates the promotive effect of low Pb levels on plant growth and biomass accumulation, revealing distinct biological effects of Pb and Cd on plant roots and leaves through comparative transcriptome analysis.

In both plant and animal innate immunity, rapid biosynthesis of cytokine-like peptides is essential for activating immune responses through plasma membrane receptor kinases. Peptide homeostasis is tightly controlled at multiple regulatory levels to avoid adverse effects caused by excessive phytocytokine production. However, the mechanisms underlying the rapid transition between transcriptional activation and repression of phytocytokine genes in response to immune stimuli remain largely unknown. Here we identify previously uncharacterized phytocytokine clusters in wheat, termed TaFIPs, which are rapidly induced by Fusarium infection. TaFIP genes are epigenetically regulated by H3K4me3 and H3K27me3 bivalent histone marks enabling rapid transcriptional shifts. Functionally, the leucine-rich repeat receptor kinase TaFIPR directly recognizes and binds TaFIPs to activate multiple immune responses, thereby enhancing wheat resistance to Fusarium infection. Our findings reveal an epigenetic mechanism that fine-tunes phytocytokine-mediated immunity in wheat.

Biodiversity-mediated trophic cascades are well established for plant diversity, but the role of biodiversity in the millennia-old Asian rice-fish agroecosystems has not been synthesized. We show in a meta-analysis of 113 studies worldwide that rice-fish coculture increases yields by 12.5%, while enhancing the abundance of invertebrate natural enemies (predators/parasitoids) by 99.3% and suppressing pest invertebrate herbivores (24.1%), disease (38.8%), and weeds (45.7%), compared with rice monoculture. These effects persist across organic and non-organic systems, as well as temperate and tropical zones. Biological pest control played a dominant role in enhancing crop production, with enemy-driven top-down effects suppressing herbivore populations. Four-year field experiments confirmed these patterns, demonstrating biological control and top-down effects. Behavioral assays further show fish preferentially target herbivores (e.g., planthoppers) while sparing predatory spiders, reinforcing trophic cascades. Our findings validate rice-fish coculture as a highly productive, sustainable agricultural system that enhances biodiversity, crop yields, and provides significant fish harvests for animal protein and additional farmer income. This approach aligns with the Food and Agriculture Organization (FAO) goals by harnessing biodiversity for ecological intensification and natural pest regulation, offering viable solutions for global food security and nutritional challenges.

Based on morphological and plastid data, Coptis wawushanensis (Ranunculaceae), a new species from Hongya, Sichuan, China, is described and illustrated. Phylogenetic analyses (Maximum likelihood and Bayesian inference) recover C. wawushanensis as sister to C. huanjiangensis with strong support, and place them in a well-supported clade including C. deltoidea and C. omeiensis. Morphologically, the new species most closely resembles C. omeiensis, but differs by an ovate leaf blade (vs. lanceolate to narrowly ovate), a central leaf segment 1.5–2.5× as long as the lateral segments (vs. 3–3.5×), shorter scapes (5–8 cm vs. 15–27 cm), and well-developed stolons (vs. absent). It is further distinguished from its sister species C. huanjiangensis by leaf blade shape (ovate vs. ovate-triangular), shorter scapes (5–8 cm vs. 20–32 cm), and the presence of stolons (vs. absent). An identification key to the new species and its closest relatives is provided, and its distribution and habitat are documented.

Functional traits have advanced our comprehension of crop-crop interactions and intercropping outcomes. Nonetheless, the role of intraspecific trait variation (ITV) in influencing intercropping productivity across various spatial arrangements has received little attention. This study examined three aspects of crop ITV (i.e., the plastic variation in trait means, trait range, and trait coordination) in a field experiment on maize (Zea mays)-pepper (Capsicum annuum) strip intercropping. We set up different spatial arrangements with maize to pepper row ratios of 2:2 (M2P2), 2:4 (M2P4), and 2:6 (M2P6). Results indicated that M2P4 was the only spatial arrangement to achieve overyielding (mean LER = 1.09, p < 0.05). Intercropped maize consistently exhibited competitive advantages, but pepper displayed significant variability in biomass under different spatial arrangements. Compared to monoculture, intercropping increased the mean values of plant height and leaf area in maize (by 5.83 % and 4.67 % on average, respectively, p < 0.05), but had minimal influence on trait range and trait coordination of maize. However, intercropping significantly increased the mean values of 6 out of the 11 traits (p < 0.05) with a significant decrease in root diameter (p < 0.01), magnified trait range (by 26.5 % - 58.8 %, p < 0.05), and diminished trait coordination (especially M2P2 and M2P6, p < 0.05). Structural equation model analyses showed that plastic variation in trait means benefited the biomass of maize, but an increased trait range and elevated trait coordination favored the biomass of pepper. All three aspects of ITV functioned as effective mediators of the effect of spatial arrangement on crop-crop competition and intercropping productivity. Our findings suggest that intraspecific trait variation has considerable implications for the design of species-diversified agroecosystems.

Red mud, an alkaline byproduct of aluminum smelting, can serve as a soil amendment to mitigate soil cadmium contamination. Rice uptakes cadmium mainly during the grain-filling stage after soils are drained. During the flooding-drainage process, substantial fluctuations in redox potential occur, and the effectiveness of red mud amendment under these conditions remains unresolved. The aim is to test the effects of red mud on soil cadmium mobility after soil drainage and subsequent rice cadmium accumulation. Soil cadmium fractions and release kinetics were assessed by sequential extraction and stirred-flow experiments followed by soil microcosm incubation with slightly cadmium-contaminated paddy soil (0.52 mg Cd kg−1), respectively. Rice cadmium accumulation was assessed in a potted rice experiment. Incorporating up to 2

Climate warming and nitrogen (N) deposition have already occurred and will continue to occur, profoundly affecting exotic plant invasion. Most studies on the effects of climate change focus on plant growth, biomass, and leaf traits, with limited reports on reproductive responses. We selected Solidago canadensis from North America and China as focal species and conducted a long-term common garden experiment simulating climate warming and N deposition to examine how climate warming, N addition, and plant origin influence its reproductive traits. Chinese Solidago canadensis exhibited significantly greater ramet height, more robust ramet diameters, longer and wider inflorescences, and higher seed mass compared to North American Solidago canadensis. Long-term warming and plant origin alone or in combination significantly influenced reproductive traits, while N addition did not influence these traits. The vegetative propagation of a native population was sensitive to warming and N addition, while the generative propagation of an invasive population was sensitive to their combined effects. These findings suggest that the reproductive strategies of Solidago canadensis varied with their origin, and plant origin might be important in mediating climate change effects on their reproduction under plant invasion.

Improved yields can occur in closely related cultivar mixtures. Despite increasing knowledge of the benefits of neighbour-relatedness in intraspecific interactions, little is known about chemically and microbially mediated kinship responses in cultivar mixtures. Using a series of field and controlled experiments that used two sets of rice cultivars of varying genetic relatedness, we demonstrated that increased yield in rice cultivar mixtures was mediated by a root signaling chemical and soil microbes in a relatedness-dependent manner. Focal rice cultivars could discriminate closely from distantly related cultivars responded by altering root behavior, biomass allocation, and flowering time, improving grain yield. Relatedness discrimination was accompanied by an alteration in root signaling (-)-loliolide and, subsequently, the soil microbial community. Furthermore, (-)-loliolide directly modified soil microbes that were related to flowering time and seed biomass. Therefore, neighbor relatedness shapes soil microbial communities, generating kinship effects in rice cultivar mixtures. In particular, root signaling (-)-loliolide levels and soil microbial responses generated improvement of grain yield in closely related rice cultivar mixtures. The findings not only yield critical insights into plant-neighbor and plant-soil interactions but also raise an intriguing possibility to increase crop production by manipulating kinship in cultivar mixtures.

Soil heavy metal (HM) pollution and biological invasions synergistically threaten ecosystem stability by impairing plant growth and reproduction. This study investigates the differential adaptability of the invasive Phytolacca americana and its congeneric relatives (P. icosandra and native P. acinosa) under cadmium (Cd) stress. Plants were cultivated in soils with Cd concentrations of 0, 2, 8, and 32 mg kg-1, and their growth, physiological traits, antioxidant responses, and Cd accumulation were analyzed. Results demonstrated that P. americana exhibited enhanced morphological traits (plant height, leaf area), photosynthetic efficiency, and reproductive output (fruit weight and biomass) under Cd stress, whereas P. icosandra and P. acinosa displayed significant declines. Antioxidant enzyme activities (superoxide dismutase, catalase) and proline content in P. americana increased markedly (e.g., 77.72 % proline elevation under high Cd), mitigating oxidative damage. Additionally, P. americana showed superior Cd bioaccumulation, with translocation factor (TF) 1.25- and 2.08-fold higher than P. icosandra and P. acinosa, respectively, alongside stable bioconcentration factors (BCF) under high Cd. In contrast, P. icosandra exhibited concentration-dependent Cd tolerance, while P. acinosa prioritized root Cd sequestration. Notably, P. americana maintained growth-reproduction equilibrium without trade-offs, a trait absent in its congeners. These findings highlight P. americana's robust Cd adaptability and hyperaccumulation potential, offering insights for ecological restoration of contaminated soils. However, molecular mechanisms and multi-metal interactions warrant further exploration.

The response of nitrous oxide (N2O) fluxes from croplands to warming is crucial in agricultural ecosystem-climate feedback. However, despite the area accounting for similar to 25 % of total cropland areas, the patterns and mechanisms controlling soil N2O fluxes in response to climate warming from abandoned croplands in the absence of further human interventions, remain poorly understood. Here, we examined the warming effect (+1.6 degrees C) on N2O fluxes from abandoned croplands in China through field warming experiments with different abandoned durations (5-9 years) and latitudes (22.33-46.58 degrees N). Moreover, we assessed the contribution of N2O emissions from abandoned croplands to all croplands by synthesizing global datasets on N2O fluxes and related parameters. We showed that warming led a significant increase (33.8 +/- 4.3 % per 1 degrees C increment in soil temperature) in N2O fluxes from abandoned croplands, which was primarily attributed to increased soil NH4+-N content and abundances of archaeal and bacterial amoA genes under warming, fostering nitrification and denitrification for N2O production. The impact of warming on N2O fluxes significantly declined over abandoned years due to the diminished warming effect on NH4+-N content with years of abandonment. Furthermore, the warming effect on N2O fluxes significantly decreased with increasing latitude, owing to reduced warming-induced increases in soil NH4+-N content and archaeal amoA gene abundance with latitude. The estimated N2O emissions from global abandoned croplands under control and warming conditions were lower than those from traditional croplands, accounting for only 10.0 % and 12.9 % of the total cropland N2O emissions, respectively. This minor contribution, given their areal proportion of global croplands, suggests that the abandonment of croplands could contribute to reducing N2O emissions. Our study underscores the importance of agricultural legacy and latitude in regulating the response of N2O fluxes from abandoned croplands to warming, thereby providing novel insights into mitigating cropland N2O emissions under a warming climate.

The Chinese soft-shelled turtle (Pelodiscus sinensis) is an aquatic reptile prized for its nutritional and health benefits. Given its adaptability to various culturing modes including the greenhouse, pond and rice culturing modes, we conducted a comparative analysis of the morphology, organ trait and nutritional composition of turtles cultured in three culturing modes. This study investigated the plasticity of morphology and physiology, as well as the variations in nutritional composition across varying culturing modes. The results demonstrated that after approximately 120 days of cultivation, significant changes were observed in the morphology, physiology and nutritional composition of turtles from each culturing mode. In terms of morphology, rice turtles exhibited an arched shell shape, broad plastron, elongated limbs, narrow interocular distance and slender head and neck. Pond turtles displayed similar morphological characteristics to rice turtles, with the additional features of a flattened body shape and narrower plastron. Greenhouse turtles presented a flattened shell shape, narrow plastron, shortened limbs, wider interocular distance and stocky head and neck. Regarding the organ characteristics, the specific weights of liver, viscera, internal fat lumps and condition factors were significantly higher in greenhouse turtles compared to rice turtles and pond turtles (p < 0.05). Conversely, the specific weights of the back carapace, calipash and edible part were significantly lower than those in rice turtles and pond turtles (p < 0.05). Nutritional analysis revealed that crude protein, total amino acid, essential amino acid, flavor amino acid, pharmacodynamic amino acid, collagen and EPA+DHA contents were significantly higher in rice turtles and pond turtles than greenhouse turtles (p < 0.05). However, crude fat and unsaturated fatty acid contents were significantly higher in greenhouse turtles than in rice turtles and pond turtles (p < 0.05). In summary, Chinese soft-shelled turtles exhibited significant morphological and organ plasticity in response to different culturing modes. While the rice and pond culturing modes could enhance the nutritional quality of turtles to some extent, the impact of commercial feed on fatty acid profiles must be carefully considered.

Although many effects of arbuscular mycorrhizal fungi (AMF) on host plants have been well documented, whether the effects of AMF on parental generations could affect offspring performance is not fully clear. We tested whether effects of AMF on current generation of host plants would transgenerationally impact on the offspring under different phosphorus (P) soil conditions by two experiments. The first experiment was continued for 4 consecutive years to determine whether AMF affect host plants adaptation to a low-P environment. The experiment had four treatments: low-P soil without AMF (NM-LP), low-P soil with AMF (M-LP), high-P soil without AMF (NM-HP), and high-P soil with AMF (M-HP). The second experiment was to determine the effects of AMF status of parental plants on offspring (seeds of third filial generation from the first experiment, F3 seeds) in four P levels (0, 9, 18, and 36 mg kg− 1) in agar without AMF. In the first experiment, M-LP host plants had earlier flowering time than NM-LP host plants in both parental plants and F3. Shoot biomass (P = 0.013), root biomass (P = 0.001), ratio of root biomass to shoot biomass (P < 0.001) and seed P concentration (P = 0.001) of M-LP host plants were higher than NM-LP host plants in F3. In second experiment, lateral root length and the ratio of lateral root length to main root length were highest for M-LP seedlings across all P levels for F3 seeds (P < 0.05). With P levels of 0 and 9 mg kg− 1, average root diameter was higher for M-HP seedlings than M-LP seedlings for F3 seeds (0 mg kg− 1: P = 0.007, 9 mg kg− 1: P = 0.027). Our results show that AMF not only influences the current generation of host plants, but also greatly affects their offspring especially when their parents have grown under low-P soil condition.

ABSTRACT The conservation of crop genetic diversity by farmers has been well studied, but little has been documented for farmed fish. Here, we show how indigenous farmers conserve the genetic diversity of a farmed fish species—the common carp (Cyprinus carpio), locally known as paddy field carp (PF‐carp)—within the paddy ecosystem. The PF‐carp have been cocultured with rice in paddy fields (i.e., rice‐fish coculture) by multiethnic farmers for thousands of years in southwestern China. Although converging to a similar morphological shape as an adaptation to the paddy ecosystem, PF‐carp have diverged into diverse phenotypes, displaying high genetic diversity and a distinct genetic structure pattern. Farmers from different ethnic groups showed distinct preferences for fish, resulting in phenotypic diversity and genetic variation. A large number of multiethnic farmers participated in fish propagation, thereby maintaining a high level of genetic diversity in PF‐carp. Our results highlight the critical role of indigenous farmers in preserving local genetic diversity and mitigating genetic degradation.

The practice of raising cyprinid fish alongside rice in paddy fields (i.e., the rice-fish coculture system) has a long history in China and has contributed to sustainable local food production. With the development of modern intensive agriculture, a key challenge is how to improve fish yields in traditional rice-fish coculture systems without compromising rice productivity and causing negative environmental impacts. In this study, we conducted regional-scale farm and field surveys, and a long-term field experiment to evaluate rice yields, fertilizer-nitrogen (N) use, soil organic carbon (C) content, and soil total N levels under rice-fish coculture systems with various fish yield levels. Using the delta N-15 stable isotope method, we designed a micro-plot field experiment to assess how fertilizer-N and fish feed-N are recycled and utilized by rice, fish, and associated organisms within the rice paddy ecosystem. The regional-scale farm survey revealed that rice yields in rice-fish coculture systems with three distinct fish yield levels (<0.5, 0.50-1.0, >1.0 t hm(-2)) showed no significant difference compared to the average rice yields from local monoculture rice farms. Paired comparisons of rice monoculture and rice-fish coculture systems demonstrated that rice-fish cocultures achieved an average fish yield of 0.99 +/- 0.07 t hm(-2), while maintaining rice yields comparable to those of corresponding rice monoculture systems. Rice-fish cocultures exhibited a significant reduction of fertilizer-N inputs while maintaining significantly higher soil organic C and total N contents compared to rice monoculture systems. The long-term field experiment demonstrated that rice-fish coculture systems achieving fish yields of 0.75 t hm(-2) and 1.5 t hm(-2) produced significantly higher rice yields compared to both rice monocultures and rice-fish cocultures with lower fish yields (about 0.3 t hm(-2)). Furthermore, in rice-fish cocultures with a target fish yield of 1.5 t hm(-2) and fish-feed supply of 2.54 t hm(-2), rice productivity and soil total N remained stable even when fertilizer-N application was reduced by 20%. The stable isotope delta N-15 tracer experiment showed that fish utilized 0.29% of the fertilizer-N-15, while rice utilized 10.54% of the feed-N-15. A diet analysis of the fish based on stable isotopes delta C-13 and delta N-15 further revealed that 46.68% of the fish's food sources originated from the paddy field, even though fish feed was supplied. The fish foraged on and transformed the nitrogen (N) from the supplied feed and natural food resources. A portion of the N from these food sources was released by the fish into the paddy fields, where it was utilized by rice plants and other organisms. Thus, N in the paddy ecosystem can be used complementary by rice and fish. The stable isotope delta N-15 tracer experiment also showed that 72.12% of feed-N-15 remained in the rice field at harvest, indicating potential risk of non-point source pollution arising from rice-fish coculture. Our results suggest that understanding how the rice-fish coculture system performs guide strategies to improve the sustainability of this system.

CONTEXT: Small farms account for most of the world's farms (approximately 84 % of the world's farms are <2 ha in size). Helping smallholder farms achieve sustainable production is one the Sustainable Development Goals (SDGs). Worldwide, traditional agriculture has contributed to food and livelihood security of smallholder farms for centuries. The values of traditional agriculture in supporting sustainable production and in conserving local resources, however, has often been overlooked in science and policy making. OBJECTIVE: Our objective is to examine whether and how traditional agriculture benefits sustainable production of smallholder farms and concomitantly conserving local resources. METHODS: We performed the study in sites of the Globally/China-Nationally Important Agricultural Heritage System (i.e., rice-fish system, RF), which has been practiced by smallholders in southwestern China. Six counties that have a long history of rice-fish farming were included. We used a stratified sampling protocol with three strata (county, town, and village) in the field and farmer surveys, and in the sample collections. Sixteen towns and twenty-eight villages were sampled. ArcGIS (10.3.1) was used to estimate the sizes of the paddy field and farms. Data of yields were collected from farmer harvest. Field surveys were conducted to measure the depth of water layer in paddy fields and to collect samples of rice and fish. Shannon- Wiener's diversity index (H) was used to indicate rice variety diversity. Microsatellite DNA was used to evaluate genetic diversity of rice and fish (common carp, Cypinus carpio). RESULTS AND CONCLUSION: Compared to rice monoculture (RM) smallholders, RF smallholders produced more stable rice yield but used fewer synthetic pesticides and fertilizers. RF smallholders obtained a certain quantity of fish yield from paddy fields, and had higher net income than RM smallholders. RF system in our study sites stored a large amount of rainwater during rainy season, and harbored diverse local rice varieties and indigenous common carp populations. Six morphotypes of indigenous common carp based on body coloration patterns and nomenclature assigned by local farmers were found in RF system. Shannon-Wiener's diversity index (H) of rice variety in RF system was higher than in RM system. Microsatellite DNA test further indicated that both local rice varieties and indigenous common carp exhibited high level of genetic diversity. SIGNIFICANCE: Our results highlight the importance of traditional agricultural systems (e.g., rice-fish system) in enhancing sustainable production of smallholder farms and conservation of local resources. Recognizing the value of these traditional agricultural systems would help to boost support policies.

Due to the extensive degree of the consumption of resources and energy by industrial agriculture, there is a growing awareness of sustainable agriculture development that should not only increase yield to meet people’s demands for food security, but should also improve product quality and promote the multi-functionality of the agricultural ecosystem [...]