In the process of vegetation restoration for karst desertification management, the lack of scientific and rational intercropping technology and the blind application of large amounts of nitrogen fertilizer have made the soil the main source of atmospheric N₂O in this region. How soil N₂O emissions vary under different intercropping modes is a scientific question worthy of study. This study took a three-year-old loquat (Eribotrya japonica L.) artificial forest in the karst plateau canyon as the experimental site and designed loquat intercropping with peanut, corn, and sweet potato (Ipomoeabatatas (L.) Lam.) as well as non-intercropping to analyze the differences in soil physicochemical properties and greenhouse gas emissions under different intercropping patterns. The results showed that intercropping with peanut significantly increased loquat yield, soil moisture, temperature, SOC, MBC, TN, and MBN content. The emissions of N₂O and CO₂were mainly positively correlated with soil moisture and temperature, while CH₄ showed a negative correlation with soil moisture and soil temperature. The soil absorbed CH₄ in the control of karst desertification. Karst area soils exhibited higher N₂O emissions. Intercropping patterns significantly influenced soil N₂O emissions, with N₂O-N cumulative emissions ranging from 5.28 to 8.13 kg·hm⁻² under different intercropping conditions. The lowest N₂O-N cumulative emissions were observed for peanut intercropped under the forest. The peak N₂O emission occurred in April 2022, which may be attributed to the higher rainfall and soil moisture during that month. Intercropping peanut with loquat significantly reduced the global warming potential. Therefore, intercropping peanut in young forests can improve soil water and fertilizer conditions, reduce soil N₂O emissions and global warming potential, and serve as a nitrogen fixation and emission reduction technique suitable for karst desertification areas.

Background/Objectives: Peanut landraces (Arachis hypogaea L.) from Guizhou, a karst region of southwestern China, represent an underexploited breeding resource whose phenotypic architecture and marker associations remain insufficiently characterized. Methods: We evaluated 300 local accessions for 30 morphological, agronomic, and quality traits using three-year mean values and analyzed the data using phenotypic diversity statistics, Pearson correlation, stepwise regression, principal component analysis (PCA), hierarchical clustering, and genome-wide association study (GWAS). Results: The collection exhibited substantial phenotypic variation, with Shannon-Wiener indices ranging from 0.54 for leaf color to 2.09 for the equivalent yield per hectare (fresh weight). The Shannon-Wiener index for seedling uniformity was 0.69 in both Liupanshui and Tongren, indicating comparable phenotypic diversity for this trait rather than a direct measure of seedling uniformity. Guiyang accessions had the highest Shannon-Wiener index for sucrose content (1.99). Among 465 trait pairs, 113 showed significant positive correlations and 76 showed significant negative correlations. Stepwise regression retained 100-kernel weight, leaf color, leaf shape, 100-pod weight, main stem height, length of the first branches, and pod number per plant as the main statistical predictors of quality traits. PCA retained eight principal components with eigenvalues above one, which together explained 75.77% of the total variance. A total of 137 accessions had composite scores ≥ 0, and the top ten, including G23212 and G23172, were selected as candidate elite materials. Cluster analysis divided the accessions into four groups and identified 23 representative types. At a suggestive threshold of −log10(P) > 3, the GWAS detected 33 protein- and 27 sucrose-associated SNPs; these loci should be regarded as candidate associations pending validation. Conclusions: Collectively, these results indicate that Guizhou peanut landraces harbor substantial, geographically differentiated phenotypic variation and provide candidate materials and loci for further germplasm evaluation and marker validation.