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Background and aims: The growth of green plants depends not only on photosynthesis, but also on the successful remobilization and translocation of seed phosphorus (P) reserves to the vegetative parts of the developing seedling during early growth. Remobilization and photosynthesis are therefore two parallel and co-coinciding processes involved in better seedling establishment and early growth. Methods: A study was conducted to evaluate the priority of developing maize seedlings to translocate the remobilized seed P reserves and external P uptake to seedling root and shoot sinks during 4 weeks of early growth. Two fluxes of P in growing seedlings, one from seed remobilized P reserves and one from external P uptake, were distinguished by labelling external nutrient solution P with P. Results: The seedling phytomass was equally distributed between seedling roots and shoots for 530 cumulated degree days after sowing. Seedlings partitioned up to 71 % of P from seed reserves and up to 68 % of P acquired from the nutrient solution, to the shoots, depending on the seed P content and P concentration in the nutrient solution. It appears that accumulation of P slows down in seedling roots corresponds to the translocative functions of root P towards shoots for start of photosynthesis. Conclusions: Our results suggest that the major part of seed P reserves and external P uptake were used in early development of the seedling and the preferred sink was seedling shoots. [ABSTRACT FROM AUTHOR]

Rose breeders need reliable and efficient germination protocols to exploit all viable embryos in their breeding programs. In this study, different treatment combinations were assessed to overcome the mechanical resistance of the pericarp and enhance germination of rose seeds obtained from hybridisation among hybrids roses. In the 3 treatments, 30 days of a warm temperature followed by 60 days of cold stratification and 30% sulphuric acid treatment for 10 min proved more effective in getting higher seed germination (18.54%) and seed vigour index (261.18) of the progenies. This led to lower germination (18.20 days) and imbibition (23.64) periods with respect to the other 3 treatments including the control. This treatment also helped increase the total length of progeny (14.1 cm) and number of leaves per progeny (6.44), whereas the response of other growth parameters of progeny was variable to this treatment. Correlation (r) between pericarp thickness and seed germination percentage, germination period, and imbibition period proved highly significant (r = 0.347, P < 0.05). [ABSTRACT FROM AUTHOR]

Background and aims: Phosphorus (P) nutrition is very important during early maize seedling growth. Remobilization of endogenous seed P and uptake of exogenous P are therefore of prime importance during this period. Our objectives were to study the effect of the availability of endogenous and exogenous P on i) remobilization of endogenous seed P, ii) the beginning of exogenous P uptake and its intensity, iii) their interaction and effect on seedling development. Methods: Seeds with high and low reserves of endogenous seed P were cultivated at three rates of availability of exogenous P (0, 100, 1,000 μM) over a growth period of 530 cumulated degree days after sowing. Exogenous P was labeled with radioactive P (P) to distinguish the two fluxes of P in seedlings, one due to remobilization of seed P and the other to uptake of exogenous P. Results: Initially, 86% of endogenous seed P was localized in the scutellum, mainly in the form of phytate, regardless of initial endogenous seed P. At 89 cumulated degree days after sowing (base temperature: 10°C), 98% of seed phytate was hydrolyzed in all treatments. In treatments with available exogenous P, significant uptake of exogenous P started at 71 cumulated degree days after sowing. Efficient uptake of exogenous P depended on its availability, but was independent of phytate hydrolysis and seedling P status. Significant loss of P from germinating seeds due to efflux was observed and was also independent of the availability of exogenous P. Conclusions: Our results show that hydrolysis of seed P was not influenced by the availability of exogenous P, and conversely, that uptake of exogenous P was not influenced by endogenous P in the seed. This suggests that remobilization of endogenous seed P and uptake of exogenous P by seedling roots are controlled independently. [ABSTRACT FROM AUTHOR]

Adequate phosphorus (P) nutrition during early stages is critical for maize growth. Our objective was to evaluate the relative contribution of seed P reserves and exogenous P to maize nutrition during early growth stages. Seedlings were grown with labeled nutrient solution (P). Seedlings were harvested periodically over the course of the three-week study. Initially, 87% and 77% of the total C and N in seeds were located in the endosperm, whereas 86% of seed P was located in the scutellum as phytate. Up to the 7th day after sowing, 96% of phytate was hydrolyzed. Hydrolyzed forms of P were temporarily stored in the seed before being translocated to growing organs, suggesting that the hydrolysis of phytate was not a limiting step for P supply to seedlings. Significant P uptake by roots was observed from the 5th day after sowing on. Both sources of P supplied roots and leaves, with a slightly higher proportion of P from seed reserves going to leaves rather than to roots. Of total seed P, 60% and 92% was exported towards newly growing seedlings till 7th and 17th days after sowing and ceased to be a significant source of P for growth thereafter. We conclude that although both P supply processes overlap in time, seed P was the main P source during early growth stages. [ABSTRACT FROM AUTHOR]

Information regarding the germination and seedling growth behavior of a potential weed species is an important tool to manage weeds without the use of agricultural chemicals that cause harmful effects on human health and the environment. A series of experiments were directed to investigate the influence of different environmental factors (temperature, pH, NaCl, moisture stress, and seed burial depth) on germination and seedling emergence of perennial ryegrass (Lolium perenne L.) under controlled conditions. Results suggested that 25 °C is the optimum temperature for maximum germination (95%) and seedling growth of perennial ryegrass, however, a quick decline was observed at 35 °C. Seed germination was unaffected by pH levels ranging from 5 to 10. The 92% seed germination was recorded where no salt stress was applied and germination was reduced by 87% at 250 mMNaCl concentration. Seed germination was unaffected by osmotic potential ranges from 0 to − 0.4 MPa thereafter declined and completely inhibited at − 0.8 or − 1.0 MPa. No seed emerged at the soil surface or a soil depth of 6 or 7 cm and 90% emergence occurred at 1 cmsoil depth. The germination and seedlings parameters like time to initial germination, mean germination time, time taken to 50% germination and germination index, root and shoot length, and fresh and dry weight of root and shoot are significantly affected with the environmental factors. The information obtained in this study will be helpful to develop better management strategies for germination and the emergence of perennial ryegrass in areas where it has the ability to rapidly colonize. [ABSTRACT FROM AUTHOR]

Indian squash (Praecitrullus fistulosus) crop faces heat and drought during its growth that is considered the most important abiotic stress in semi-arid areas. Seed priming with growth regulators enhances stress tolerance; hence, mitigates the adverse effects of unpredictable stresses due to adverse weather conditions. This two-year (2019 and 2020) study was conducted to infer the role of seed priming in improving heat tolerance of Indian squash (cultivar Sahavi) through improvement in physiological and antioxidant defense systems. Six treatments that included no priming (control), hydropriming, priming with indole acetic acid (IAA) at 100 mg L-1, salicylic acid (SA) at 50 mg L-1, ascorbic acid (AA) at 100 mg L-1 and thiourea at 500 mg L-1 each for 06 hours) were included in the study. Results revealed that priming with AA and SA significantly (P ≤ 0.05) enhanced germination (39 and 47%), germination index (57 and 58%), plant height (23 and 22%), vine length (15 and 14%), number of fruits per plant (62%), fruit weight per plant (66 and 67%), economic yield (32%), photosynthesis rate (18 and 17%), protein content (10%), proline (23%), glycine betaine (3%), malondialdehyde content (11 and 10%) and catalase activity (24%) compared to control treatment. Furthermore, seed priming with AA and SA significantly (P ≤ 0.05) shortened the mean germination time (25 and 28%) compared to the control. The results indicated that AA and SA had significant potential to mitigate adverse effects of heat stress in Indian squash. Findings from this study showed that seed priming with AA and SA promoted heat-stress tolerance and enhanced growth and productivity of Indian squash. [ABSTRACT FROM AUTHOR]

Dormancy of weed seeds is a significant feature contributing to their survival rate since it helps the weeds to avoid herbicides and other weeding practices along with unfavorable environmental conditions. We investigated the effects of different dormancy breaking treatments on the germination of Rhynchosia capitata, a common summer annual weed, which is emerging as a weed threat in Pakistan. Seeds were soaked in thiourea, KNO3, HCl, HNO3, and H2SO4, and they were also mechanically scarified (sandpaper). Results indicated that R. capitata seeds show signs of physical dormancy that is mainly due to the impermeability of their coat. Mechanical scarification and acid scarification (soaking of seeds in H2SO4 for 60 and 80 min and in HCl for 12 and 15 h) were very efficient in breaking dormancy and promoting germination. Seed soaking in HNO3 for 1 to 5 d showed little effect whereas various concentrations of thiourea and KNO3 were ineffective in breaking R. capitata seed dormancy. [ABSTRACT FROM AUTHOR]

Developing high yielding safflower cultivars with good adaptation to diverse environmental conditions can improve production in terms of seed yield and reduce the deficiency in edible oil. The genetic variability that exists among and within populations for desirable agronomic traits can be used to develop elite cultivars. A total of 94 safflower accessions from 26 different countries were used in this study to evaluate morphoagronomic performance, determine the pattern of similarity centers, and identify the best performing accessions by conducting 2 field experiments in Pakistan and Turkey using augmented design. Genetic diversity for important yield and yield traits was described including capitulum diameter (17.30 to 28.30 mm), branches per plant (5.10 to 17.30), capitula per plant (8.70 to 80.40), and seed yield per plant (4.86 to 51.02 g). These analyses showed a good level of variation in the current study. Using principal component analysis, it was observed that days to flower initiation, days to 50% flowering, days to flower completion, seed yield per plant, capitula per plant, branches per plant, seeds per capitulum, and capitulum diameter were the major contributors to the observed genetic variability in the evaluated safflower panel. Seed yield per plant reflected a significant and positive correlation with capitula per plant, branches per plant, and capitulum diameter, and these traits can be suggested as a selection criterion in safflower breeding programs. The hierarchical clustering was in agreement with the patterns of 7 similarity centers based on seed yield per plant, capitula per plant, capitulum diameter, and branches per plant. During this study, a few promising safflower accessions were selected for future breeding programs. [ABSTRACT FROM AUTHOR]

Application of the nanopriming technique to alleviate seed dormancy has shown promising results in various agricultural crop species. However, there is a dearth of knowledge regarding its potential use in native peatland boreal forest species to alleviate seed dormancy and improve their propagation or vigor for forest reclamation activities. Herein, we demonstrate the use of nanopriming with carbon nanotubes (CNT) to alleviate seed dormancy, improved seed germination, and seedling vigor in two boreal peatland species. Bog birch (Betula pumila L.) and Labrador tea (Rhododendron groenlandicum L.) seeds with embryo or seed coat dormancy were nanoprimed with either 20 or 40 µg/mL CNT, cold stratified at 2–4 °C for 15 days, and allowed to germinate at room temperature. The emerged seedlings' lipidome was assessed to decipher the role of lipid metabolism in alleviating seed dormancy. We observed significant (p < 0.05) improvement in seedling germination and seedling vigor in seeds primed with multiwalled carbon nanotubes functionalized with carboxylic acids. Phosphatidylcholine (PC 18:1/18:3), phosphatidylglycerol (PG 16:1/18:3), and lysophosphatidylcholine (LPC 18:3) molecular species (C18:3 enriched) were observed to be highly correlated with the increased seed germination percentages and the enhanced seedling vigor. Mechanistically, it appears that carbon nanoprimed seeds following stratification are effective in mediating seed dormancy by remodeling the seed membrane lipids (C18:3 enriched PC, PG, and LPC) in both peatland boreal forest species. The study results demonstrate that nanopriming may provide a solution to resolve seed dormancy issues by enhancing seed germination, propagation, and seedling vigor in non-resource boreal forest species ideally suited for forest reclamation following anthropogenic disturbances. [ABSTRACT FROM AUTHOR]

Nanopriming has been shown to significantly improve seed germination and seedling vigor in several agricultural crops. However, this approach has not been applied to native upland boreal forest species with complex seed dormancy to improve propagation. Herein, we demonstrate the effectiveness of carbon nanoparticles functionalized with carboxylic acids in resolving seed dormancy and improved the propagation of two native upland boreal forest species. Seed priming with carbon nanoparticles functionalized with carboxylic acids followed by stratification were observed to be the most effective in improving germination to 90% in green alder (Alnus viridis L.) compared to 60% in the control. Conversely, a combination of carbon nanoparticles (CNPs), especially multiwall carbon nanoparticles functionalized with carboxylic acid (MWCNT–COOH), cold stratification, mechanical scarification and hormonal priming (gibberellic acid) was effective for buffaloberry seeds (Shepherdia canadensis L.). Both concentrations (20 µg and 40 µg) of MWCNT–COOH had a higher percent germination (90%) compared to all other treatments. Furthermore, we observed the improvement in germination, seedling vigor and resolution of both embryo and seed coat dormancy in upland boreal forest species appears to be associated with the remodeling of C18:3 enriched fatty acids in the following seed membrane lipid molecular species: PC18:1/18:3, PG16:1/18:3, PE18:3/18:2, and digalactosyldiacylglycerol (DGDG18:3/18:3). These findings suggest that nanopriming may be a useful approach to resolve seed dormancy issues and improve the seed germination in non-resource upland boreal forest species ideally suited for forest reclamation following resource mining. [ABSTRACT FROM AUTHOR]