Linking seed germination and plant height: a case study of a wetland community on the eastern Tibet Plateau

Trends in Seed Priming Research in the Past 30 Years Based on Bibliometric Analysis

Seed priming (SP) treatments are widely used in agriculture and restoration to improve seed germination and seedling vigor. Although there exists a considerable amount of scientific literature on SP, it has seldom undergone visual and quantitative analyses. To gain insights into the patterns observed in SP research over the last three decades, we conducted a bibliometric analysis using the Science Citation Index-Expanded (SCI-E) database, aiming to minimize the similarity score in plagiarism detection. This analysis offers a thorough examination of yearly publications, temporal patterns in keyword usage, the top-performing journals, authors, institutions, and countries within the field of SP. Our research findings suggest a steady annual increase of 10.59% in the volume of SP publications, accompanied by a significant upward trajectory in the average citations received per paper annually. According to the analysis of keywords, it was found that "priming" and "germination" emerged as the most frequently used terms in the field of SP research. Seed Science and Technology ranked first among the top journals, and Plant Physiology had greater influence in the field of SP in terms of number of citations. The majority of the top 10 productive institutions were situated in developing countries. In addition, these nations exhibited the highest volume of published works and citations. Our analysis revealed a shift in research focus within the field of SP over the past three decades, transitioning from agricultural science to encompass plant science and environmental science. With the growing recognition of SP's research across different disciplines, there exist abundant prospects for international and interdisciplinary partnerships, collaborative organizations, and progress in this field.

Affordable phosphor-converted LEDs with specific light quality facilitate the tobacco seedling growth with low energy consumption in Industrial Seedling Raising

Industrial Seedling Raising (ISR) is increasingly becoming an important part of Modern Agriculture because of its efficient utilization of land, water, and fertilizer as well as its advantages of being not easily affected by the weather. However, the high cost and high energy consumption of light sources for plant growth is limiting the popularization of ISR technology. Phosphor-converted light-emitting diodes (pc-LEDs) make use of relatively affordable red phosphor and blue light chips, providing an adjustable spectrum to optimize plant growth. To identify the energy-saving light quality of pc-LEDs, we investigated the effects of a variety of light qualities on the growth of tobacco seedlings. Y₃Al₅O₁₂:Ce³⁺, CaAlSiN₃:Eu²⁺, KAl₁₁O₁₇:Eu²⁺ phosphors were combined with the blue light chip according to different proportions to produce the following light sources: CK (white light), T1 (blue light), T2 (red light), T3 (red: blue light ratio = 1:4), T4 (red: blue light ratio = 4:1). The tobacco variety Xiangyan7 grown continuously under T1, T2, T3, and T4 significantly increased the leaf area, stem length, biomass, root area and main root length compared with those grown under white light. Among the five kinds of light qualities tested, T4 treatment exerted the best effect on leaf development and biomass increase, while T2 exerted the best effect on stem elongation. The cytological analysis demonstrated that the promotion of the cell size and cell number of leaf epidermal cells by T1-T4 might contribute to the leaf expansion. Further analysis at the molecular level suggested that the light quality affected the RNA levels of the genes involved in cell division and expansion. When tobacco seedlings reached the same biomass, T1-T4 light sources saved 71%, 86%, 80% and 89% of electric energy respectively compared with white light. Therefore, the application of specific pc-LEDs not only reduces the cost of light source production, but also saves energy consumption, offering great potential for ISR technology to cut costs and increase efficiency.

Seed Traits Research Is on the Rise: A Bibliometric Analysis from 1991–2020

Seed traits (ST) influence seedling establishment, population dynamics, community composition and ecosystem function and reflect the adaptability of plants and the environmental conditions they experienced. There has been a historical and global accumulation of studies on ST, but with few pertaining to visual and quantitative analyses. To understand the trends in the field of ST research in the past 30 years, we conducted a bibliometric analysis based on the Science Citation Index-Expanded (SCI-E) database. The analysis provided annual publications, time trends for keywords, the most productive journals, authors, institutions and countries, and a comprehensive overview of the ST field. Our results showed that in the past 30 years, the number of publications in ST research has increased at an average annual growth rate of 9.1%, while the average number of citations per paper per year showed a rapid increase–slow increase–decrease trend. Keyword analysis showed that “germination” was the most popular research section. Crop Science ranked first among the top journals and Theoretical and Applied Genetics had greater influence in this area and more citations than other journals. The 10 most productive institutions were mostly located in the United States, China and Australia. Furthermore, the three countries also had the largest number of publications and citations. Our analysis showed that the research interests in ST have evolved from genetics and agricultural science to ecological research over the last thirty years; as more fields embrace ST research, there are opportunities for international and interdisciplinary collaborations, cooperative institutions and new advances in the field.

Germination Characteristics Is More Associated With Phylogeny-Related Traits of Species in a Salinized Grassland of Northeastern China

Knowing the determinants of seed germination helps us understand plant adaptive strategies to the environment and predict population and community regeneration under climate change. However, multiple factors, including plant and seed traits that influence germination and their relative importance, have received little attention. Here, seed germination experiments were conducted on newly collected seeds for 89 herbaceous species from salinized Songnen grassland. We tested the effects of multiple phylogeny-related plant traits and seed morphological and physiological traits on germination percentage and initial germination time and their relative contribution to shaping germination variation. We found that biennials had higher germination percentages and rates than annuals and perennials. Species with brown seeds had higher germination percentages than those with yellow and black seeds. Eudicots germinated faster than monocots, and seeds with morphophysiological dormancy required more time to initiate germination than those with other kinds of dormancy. Phylogeny-related factors explained more of the variation in germination than seed traits. Seed mass and volume of the large-seeded, but not small-seeded group species were positively correlated with germination percentage. Our findings provide important information for understanding germination variation across species and local adaptation for species in the salinized Songnen grassland.

Effect of Nitrogen Addition on Selection of Germination Trait in an Alpine Meadow on the Tibet Plateau

Seed germination requirements may determine the kinds of habitat in which plants can survive. We tested the hypothesis that nitrogen (N) addition can change seed germination trait-environmental filter interactions and ultimately redistribute seed germination traits in alpine meadows. We determined the role of N addition on germination trait selection in an alpine meadow after N addition by combining a 3-year N addition experiment in an alpine meadow and laboratory germination experiments. At the species level, germination percentage, germination rate (speed) and breadth of temperature niche for germination (BTN) were positively related to survival of a species in the fertilized community. In addition, community-weighted means of germination percentage, germination rate, germination response to alternating temperature and BTN increased. However, germination response to wet-cold storage (cold stratification) and functional richness of germination traits was lower in alpine meadows with high-nitrogen addition than in those with no, low and medium N addition. Thus, N addition had a significant influence on environmental filter-germination trait interactions and generated a different set of germination traits in the alpine meadow. Further, the effect of N addition on germination trait selection by environmental filters was amount-dependent. Low and medium levels of N addition had less effect on redistribution of germination traits than the high level.

Seed germination responses to seasonal temperature and drought stress are species-specific but not related to seed size in a desert steppe: Implications for effect of climate change on community structure

Investigating how seed germination of multiple species in an ecosystem responds to environmental conditions is crucial for understanding the mechanisms for community structure and biodiversity maintenance. However, knowledge of seed germination response of species to environmental conditions is still scarce at the community level. We hypothesized that responses of seed germination to environmental conditions differ among species at the community level, and that germination response is not correlated with seed size. To test this hypothesis, we determined the response of seed germination of 20 common species in the Siziwang Desert Steppe, China, to seasonal temperature regimes (representing April, May, June, and July) and drought stress (0, -0.003, -0.027, -0.155, and -0.87 MPa). Seed germination percentage increased with increasing temperature regime, but Allium ramosum, Allium tenuissimum, Artemisia annua, Artemisia mongolica, Artemisia scoparia, Artemisia sieversiana, Bassia dasyphylla, Kochia prastrata, and Neopallasia pectinata germinated to >60% in the lowest temperature regime (April). Germination decreased with increasing water stress, but Allium ramosum, Artemisia annua, Artemisia scoparia, Bassia dasyphylla, Heteropappus altaicus, Kochia prastrata, Neopallasia pectinata, and Potentilla tanacetifolia germinated to near 60% at -0.87 MPa. Among these eight species, germination of six was tolerant to both temperature and water stress. Mean germination percentage in the four temperature regimes and the five water potentials was not significantly correlated with seed mass or seed area, which were highly correlated. Our results suggest that the species-specific germination responses to environmental conditions are important in structuring the desert steppe community and have implications for predicting community structure under climate change. Thus, the predicted warmer and dryer climate will favor germination of drought-tolerant species, resulting in altered proportions of germinants of different species and subsequently change in community composition of the desert steppe.