The morphological, physiological, and biochemical characteristics of leaves result from the long-term adaptation of plants to their environment and are closely related to plant growth and development. In this study, 37 prickly ash germplasm resources from 18 production areas were utilized as the subjects of research. Logistic equations, principal component analysis, and cluster analysis were employed to comprehensively evaluate the leaf traits of prickly ash germplasm resources, with an analysis of their correlation with ecological and geographical factors in the production areas. The results showed that the leaf traits of prickly ash germplasms of different origins are substantially different and diverse. The coefficient of variation for the 14 leaf traits was greater than 10%. The coefficient of variation of the compound leaflet number was the highest among all the considered leaf traits, and the coefficient of variation of leaf thickness was the lowest, at 49.86% and 11.37%, respectively. The leaf traits of the prickly ash germplasm originating from Chongqing in Yongchuan, Chongqing in Rongchang, and Yunnan in Honghe ranked highest, whereas the leaf traits of the prickly ash germplasm from Henan in Jiaozuo, Gansu in Tianshui, and Shanxi in Yuncheng ranked lowest. The results of the correlation analysis showed that among the ecological and geographical factors of the origins, latitude had the strongest correlation with the leaf traits of the prickly ash germplasm. As latitude increased, the leaves of prickly ash gradually decreased in size, weight, and leaf shape index. The factor with the second strongest correlation was temperature. The leaves of the prickly ash germplasm originating from warmer climate areas were larger and heavier than those from areas with colder climates. Altitude and longitude did not significantly affect the leaf traits of the prickly ash germplasm, but at similar latitudes, the leaves of the prickly ash germplasm in high-altitude areas were smaller, and the leaves of the prickly ash germplasm in low-altitude areas were larger. These findings can provide valuable references for breeding and the sustainable utilization of new varieties of prickly ash resources.

In this study, we investigated the physiological response to low-temperature stress and comprehensively evaluated the cold resistance of green prickly ash germplasms. One-year-old branches of 23 green prickly ash varieties were used as experimental materials, three branches were selected from each variety, and three replicates of single branches were established. Subsequently, the physiological responses of the 23 green prickly ash germplasm resources to low-temperature stress were analyzed based on the relative conductivity (REC), osmotic adjustment substances, and antioxidant enzyme activities. We found that as the temperature decreased, the REC of each germplasm increased. The most rapid REC increase occurred from 0 to −10 °C and continued to gradually gently increase from −10 to −30 °C. The lethal dose-50 temperature (LT₅₀) of the germplasms was between 3.16 and −12.37 °C. The top three cold-resistant varieties were TJ, SCHJ, and CJ, and the last three cold-resistant varieties were EWJ, DYSJ, and HYXJ. The results of a correlation analysis revealed a significant correlation between superoxide dismutase (SOD) activity and REC, between REC and free protein, and between SOD activity and catalase. The results of the PCA revealed that the first category includes 5 pepper varieties of CJ, LFJ, and XYTJ with higher cold-resistance score indexes; the second category includes 13 pepper varieties of YQ2 H, WCFZ, and TZJ with appropriate scores; and the third category includes 5 pepper varieties of HYXJ, HNJ, and DYSJ with lower scores. Cluster analysis was performed to classify the cold-resistance physiological indices, and four groups were obtained. The most cold-resistant groups included CJ and LFHJ, whereas the most cold-sensitive groups included HYXJ, DYSJ, and HNJ. Finality, the subordinate function method was used to determine the cold resistance from strong to weak. The varieties with the strongest cold resistance were LFJ, EWJ, and CJ, and the weakest varieties were DYSJ, YQ1H, and HYXJ. The strongest cold-resistant varieties were LFHJ and CJ, followed by DYSJ, YQ1H, and HYXJ. Based on multiple lines of evidence, the most cold-resistant varieties were CJ and LFJ, while the most cold-sensitive varieties were DYSJ and HYXJ. In conclusion, in this study, we elucidated the low-temperature tolerance of different varieties of green prickly ash, and varieties with high cold resistance were selected. These findings provide theoretical guidance and technical support for the screening of cold-resistant green prickly ash germplasms, which will facilitate their introduction to northern China.

To explore the differences in dry matter accumulation and yield of maize varieties having different nitrogen‐use efficiencies in Southwest China, a field experiment was conducted in Yongchuan, Chongqing, and Deyang, Sichuan, from 2019 to 2020. Two varieties, the nitrogen‐efficient Zhenghong 311 (ZH 311) and the nitrogen‐inefficient Xianyu 508 (XY 508), were tested across four nitrogen levels (0–360 kg ha⁻¹). The results showed that compared to XY 508, ZH 311 exhibited a significantly higher accumulation of dry matter at various stages and periods, particularly in the roots during the R6 stage, and in the stem sheaths and leaves throughout all stages. Furthermore, the number of kernel rows, number of kernels per row, number of kernels per ear, and grain yield were significantly higher for ZH 311 than XY 508, whereas the 100‐grain weight was significantly lower for ZH 311 than XY 508. The yield difference between the two varieties was the largest when the nitrogen application rate was 240 kg ha⁻¹. The yield performance of ZH 311 was always better than that of XY 508, and less nitrogen was needed to obtain the best yield. The accumulation of maize dry matter had a highly significant effect on the number of kernel rows, kernels per row, and kernels per ear, and grain yield. The direct effect of the number of kernels per ear on grain yield was very low. However, it affected grain yield through the number of kernel rows and kernels per row. The dry matter accumulation of V6−V12 and R3−R6 contributed the most to grain yield, while in vegetative organs, the effect of leaf dry matter accumulation and yield was the greatest. This investigation will provide insights into factors affecting variations in maize yield under low nitrogen conditions and offer guidance for N‐fertilizer management strategies.

Low temperatures are a key factor affecting the growth, development, and geographical distribution of prickly ash. This study investigated the impact of ecological and geographical factors on the freezing tolerance of prickly ash germplasm. Thirty-seven germplasm samples from 18 different origins were collected, and their freezing tolerance was comprehensively evaluated. The correlation between freezing tolerance and the ecological and geographical factors of their origins was also analyzed. Significant differences in freezing tolerance were observed among germplasm from different origins. The semi-lethal temperature of the germplasm ranged from − 12.37 to 1.08 °C. As temperatures decreased, the relative conductivity (REC) and catalase (CAT) activity of the germplasm gradually increased, while soluble sugar (SS), soluble protein (SP), free proline (Pro), and Peroxidase (POD) activities decreased and then increased. Superoxide dismutase (SOD) activity initially increased and then decreased. A comprehensive evaluation of freezing tolerance was conducted using a logistic equation, membership function, and cluster analysis. Germplasm from Tongchuan and Hancheng (Shaanxi Province, China), Asakura (Japan), and Yuncheng (Shanxi Province, China) exhibited the highest freezing tolerance, whereas those from Rongchang (Chongqing Municipality, China), Qujing (Yunnan Province, China), and Honghe (Yunnan Province, China) had the lowest. The correlation analysis revealed a significant positive correlation between freezing tolerance and latitude, and a significant negative correlation with the temperature of origin. Germplasm from higher latitudes showed higher SS content, SOD and CAT activities, stronger antioxidant enzyme activity, and better freezing tolerance compared to those from lower latitudes. REC was lower in germplasm originating from low-temperature areas than in those from high-temperature areas. Additionally, SP, Pro content, SOD, and POD activities were higher, indicating effective scavenging of active oxygen free radicals. No significant correlation was found between altitude and longitude of origin and freezing tolerance. However, at similar latitudes, prickly ash from higher altitudes displayed higher antioxidant enzyme activity and stronger freezing tolerance compared to those from lower altitudes. These findings provide a scientific basis for breeding prickly ash cultivars suited to different ecological regions.

This study aimed to reveal the diversity and variation in panicle traits of the Chinese prickly ash and clarify their influence on the its systematic classification to provide a theoretical basis and technical support for the efficient utilization of Chinese prickly ash germplasm resources and breeding. Sixteen panicle traits were identified from 35 Chinese prickly ash germplasm resources from 2021 to 2022. The diversity of these panicle traits and their role in the plant’s systematic classification were studied using variance, correlation, cluster, and principal component analyses. Cluster analysis showed that the 35 Chinese prickly ash germplasm resources could be divided into two groups with Euclidean distances of 25. Further analysis showed that yield traits such as panicle length, panicle width, primary branching, grain number per panicle, and grain weight per panicle were significantly positively correlated with grain chlorophyll content, while grain anthocyanin content was negatively correlated with both panicle (panicle length, panicle width, panicle length to width ratio, primary branching, grain number per panicle, and grain weight per panicle) and grain characteristics (single grain weight, thousand-grain weight, grain length, grain width and fruit shape index). In conclusion, Chinese prickly ash germplasms have diverse panicle traits. Z. armatum has dark green grains, long and wide panicles, a long conical shape, many primary branches, high grain weight, and high grain number per panicle. In contrast, Z. bungeanum has bright red seeds, a panicle width larger than its length, short and conical panicles, a small number of primary branches, and low grain weight per panicle and number of grains per panicle. Overall, Z. armatum had a significant yield advantage over Z. bungeanum.