The characteristics of the stomatal movement of winter Brassica napus with different cold resistance in northern China in a low-temperature environment were analyzed, and the relationship between cold resistance and stomatal movement was clarified, which provided a basis for analyzing the cold resistance mechanism of winter Brassica napus and cultivating strong cold resistance varieties.

The physiological indexes of 14 winter Brassica napus varieties under semi-lethal temperature and low temperature were determined to judge the difference in cold resistance. At the same time, 12 stomatal indexes of the lower epidermis of the leaves of the plants treated at 24℃ for 12 h, 0℃ for 1 h, and 0℃ for 12 h were determined. Stomatal evaluation indexes significantly related to cold resistance evaluation indexes were screened by correlation analysis.

(1) According to the results of semi-lethal temperature determination, the cold resistance of the tested varieties was identified as gau-1 (-8.06)>gau-24 (-7.83)>gau-30 (-7.58)>gau-39 (-7.44)>ts309 (-7.28)>ts312 (-7.08)>nts158 (-6.81)>npz269 (-6.62)>Tianyou 14 (-5.98)>16-2444 (-5.4)>17-2251 (-5.13)>Tianyou 2266 (-4.8)>Tianyou 2238 (-4.6)>Tianyou 2288 ( -4.38 ). According to the comprehensive evaluation value of physiological indexes, the results of cold resistance were gau-1 (0.990)>gau-24 (0.876)>gau-30 (0.693)>gau-39 (0.644)>ts309 (0.534)>ts312 ( 0.463)>nts158 (0.439)>npz269 (0.388)>Tianyou 14 (0.352)>16-2444 (0.307)>17-2251 (0.282)>Tianyou 2266 (0.236)>Tianyou 2238 (0.126)>Tianyou 2288 ( 0.000). The cold resistance measured by semi-lethal temperature was consistent with the comprehensive evaluation results of physiological indexes. (2) 12 stomatal movement-related indicators changed significantly after low-temperature treatment. The correlation analysis showed that there was no significant correlation between the 12 stomatal indexes and the semi-lethal temperature at room temperature and 0℃ after 1 h treatment. After 12 h treatment at 0℃, the stomatal pore length, area of stomatal pore, circumference of stomatal pore, stomatal apparatus length, area of stomatal apparatus, Circumference of stomatal apparatus, and stomatal closure rate were significantly correlated with cold resistance. The semi-lethal temperature was significantly correlated with the comprehensive evaluation value (Z) of stomata, and the correlation coefficient was-0.572.

Low-temperature treatment can significantly affect the stomatal movement of winter Brassica napus, and the characteristics of stomatal closure tend to be more obvious with the extension of low-temperature treatment time. At the same time, the relative changes of stomata of different temperature-sensitive varieties were different, and the varieties with strong cold resistance had stronger ability to keep stomata open after low-temperature treatment.

Brassica rapa L. originated from China, whose qualify analysis and evaluation was highly important for its development and utilization.

In this study, rapeseed was used as the research object. After grinding extraction and ion exchange column treatment, the glucosinolate extract was obtained. The high performance liquid chromatography (HPLC) was utilized to determine and analyze the content and components of glucosinolates in 323 B. rapa L. accessions.

The total content of glucosinolates in 323 B. rapa L. samples ranged from 26.19 to 238.21 µmol∙g^-1, with an average of 137.22 µmol∙g^-1. A total of 9 glucosinolate components were identified, consisting of five aliphatic glucosinolates (progoitrin, glucoraphanin, gluconapoleiferin, gluconapin and glucobrassicanapin), three indole glucosinolates (4-hydroxyglucobrassicin, glucobrassicin, and 4-methoxyglucobrassicin), and one aromatic glucosinolate (gluconasturtiin). The predominant glucosinolate in B. rapa L. was gluconapin, which belonged to the aliphatic glucosinolate group. It had an average concentration of 122.68 µmol∙g^-1, making up 93.71% of the aliphatic glucosinolate content and 89.40% of the overall glucosinolate content. The comparison of the total glucosinolate content in accessions originated from various ecological zones indicated that the Yangtze River basin had the highest glucosinolate content, followed by the Huanghuai region, Xizang, and Gansu accessions. Among accessions, the content of 4-hydroxyglucobrassicin and glucobrassicin in Gansu accessions was more than that in accessions originated from the other three ecological zones. The content of gluconapin in Gansu accessions was the lowest compared to other accessions. The content of indole glucosinolates exhibited significant variations based on their sensitivity to temperature, with the highest levels observed in harsh winter types (11.50 µmol∙g^-1), followed by winter types (7.60 µmol∙g^-1), semi-winter types (6.77 µmol∙g^-1), and spring types (3.87 µmol∙g^-1). The findings demonstrated that, the content of progoitrin and indole glucosinolates differed significantly among the germplasm collection used in this study. Six accessions with high-indolyl glucoside content (ranging from 5.86 to 13.81 µmol∙g^-1) and three accessions with progoitrin content (ranging from 50.14 to 68.38 µmol∙g^-1) were selected by screening.

Aliphatic glucosinolates were the primary components of glucosinolates in B. rapa L., with gluconapin being the predominant component. The glucosinolate components exhibited significant variations depending on the genotype of the accessions. Different genotypes were selected based on their concentration of ultra-high glucosinolate, high indole glucosinolate, and high progoitrin.