Haiqing Liu

Bolting height is a key genetic trait that affects the stress tolerance, environmental adaptation, and winter survival of Brassica napus winter rapeseed. It is particularly important for enhancing winter survival in the arid–frigid regions. This study aimed to elucidate the genetic relationship between bolting height and cold stress tolerance, thereby supporting breeding for enhanced cold tolerance. Ninety-five winter rapeseed accessions were used in this study. Through both spring and autumn sowing trials, the dynamic changes in bolting height under different environments were systematically analyzed, and the genetic stability of bolting height as well as its correlation with cold tolerance were clarified. Bolting height showed consistent variation trends between spring and autumn sowing trials, exhibiting high genetic stability. It displayed an extremely significant negative correlation with cold tolerance: genotypes with lower bolting height possessed stronger cold tolerance. The regulatory mechanism underlying low bolting and cold tolerance was revealed at cellular and molecular levels. Low bolting accessions exhibited flat and broad shoot apical meristems, with small and compact cells, a high nucleoplasmic ratio, and indistinct vacuoles. The gibberellin synthesis gene BnaA06g24070D was downregulated, while the key cold-tolerant gene BnCBF5 was upregulated. Exogenous hormone treatment preliminarily verified the causal regulatory effect of bolting height on cold tolerance. In both spring and autumn sowing trials, bolting height at the initial flowering stage showed an extremely significant positive correlation with vernalization index, with correlation coefficients of 0.80 and 0.78, respectively. Lower bolting height corresponded to a smaller vernalization index and stronger temperature sensitivity. Moreover, bolting height at the initial flowering stage showed an extremely significant negative correlation with comprehensive cold tolerance scores, with correlation coefficients of −0.77 and −0.80, respectively. Low-bolt materials had significantly higher overwintering rates and comprehensive cold tolerance scores, as well as a markedly lower semi-lethal temperature (LT₅₀), compared with high-bolt accessions. Low-bolt accessions presented significantly prolonged bolting stage, bud stage, initial flowering stage, and whole growth durations, and their agronomic trait stability across years was significantly superior to that of high-bolt accessions. This study confirmed that low bolting height is a crucial breeding trait for the cold tolerance of winter rapeseed, and thus an important selection indicator for the cold tolerance improvement of winter rapeseed in arid–frigid regions in northern China.

Polygonatum sibiricum Red, known as Huangjing in Chinese, is a perennial plant valued in traditional Chinese medicine and is a nutritional food ingredient. With increasing market demand outpacing wild resource availability, cultivation has become essential for sustainable production. However, the cultivation of P. sibiricum is challenged by the double dormancy characteristics of seeds, which include embryo and physiological dormancy. This affected the germination of seeds and the establishment of seedlings. This study investigates the role of plant hormones in breaking seed dormancy and regulating germination and emergence in P. sibiricum. We found that cold stratification at 4°C for over 70 d significantly alleviates seed dormancy, associated with changes in endogenous hormone levels. Auxin, gibberellin, abscisic acid, cytokinin, salicylic acid, jasmonic acid, and ethylene were identified as key players in these processes. Exogenous applications of GA3 and 2-coumarate (2-hydroxycinnamic acid) significantly enhanced seed germination, while 6-BA and GA3 promoted corm growth and development. In conclusion, our research provides insights into the hormonal regulation of seed dormancy and germination in P. sibiricum, offering valuable strategies for improving cultivation practices. Further studies are needed to explore the specific mechanisms of hormone interactions and to develop optimized germination and seedling establishment strategies for this medicinally important plant.

Abscisic acid (ABA) mediated stomatal closure is a highly effective mode of active stomatal regulation under drought stress. Previous studies on stomatal regulation have primarily focused on the leaves of vascular plants, while research on the stomatal behavior of bulbous plants remains unknown. In addition, ABA-induced stomatal regulation in bulbs has yet to be explored. Therefore, we aim to investigate the ABA-induced active regulation in the bulb of the Lanzhou lily (Lilium davidii var. unicolor). The morphological characteristics of epidermal strips were analyzed along with a stomatal aperture assay to investigate the bulb's stomatal response to ABA. Moreover, the mechanism of ABA signaling was explored using treatments with ABA signaling chemicals and corresponding scavengers. This study revealed that stomata are mainly distributed on the upper part and outer surface of the bulb. The guard cells of the lily bulb are inflated, and the stomata have a nearly circular shape with relatively low stomatal density. Exogenous ABA was found to induce varying degrees of stomatal closure in a dose-dependent manner, with significant stomatal aperture reduction observed after treatment with 10 µM ABA. Overall, the study indicated that both hydrogen peroxide (H₂O₂) and nitric oxide (NO) are involved in the ABA-induced stomatal closure process, with H₂O₂ functioning as an upstream component of NO.

The competition between species for soil water represents a significant constraint on the growth and productivity of species within agroforestry systems on the Loess Plateau. This study employed field experiments conducted in 2022 and 2023 to elucidate the impact of agronomic measures（straw mulching, film mulching, root barrier treatment and increasing the spacing between crops and trees）and supplemental irrigation（the lower limits of 55%, 70% and 85% of the field's water holding capacity at three key stages of Polygonatum sibiricum） on the growth, yield and water use efficiency of the components of the apple–Polygonatum sibiricum intercropping system. The findings indicated that all agronomic measures resulted in an increase in soil water content within the intercropping system, with film mulching emerging as the most effective approach. Moreover, the application of film mulching markedly enhanced the growth and yield of the components of the intercropping system, thereby establishing it as an optimal agronomic measure for the apple–Polygonatum sibiricum intercropping system. With the exception of water use efficiency, the growth and yield of the components of the intercropping system increased with the greater quantity of supplemental irrigation. In the Loess Plateau region, where precipitation resources are scarce, film mulching was employed in the apple–Polygonatum sibiricum intercropping system. Meanwhile, the lower supplemental irrigation limits for the Polygonatum sibiricum at the flowering–fruiting stage, fruiting–mature stage and seedling–flowering stage were set at 55%, 85% and 70% of the field water holding capacity, respectively. These measures can assist in alleviating interspecies soil water competition in the apple–Polygonatum sibiricum intercropping system, thereby enhancing the growth, yield and water use efficiency of the intercropping system.