Effects of Inorganic Salt Solutions on Vigour, Viability, Oxidative Metabolism and Germination Enzymes in Aged Cabbage and Lettuce Seeds

Regulation effect of seed priming on sowing rate of direct seeding of rice under salt stress

Direct seeding of rice (DSR) is a widely used method for its labor- and cost-saving advantages. However, the global intensification of soil salinization presents a significant challenge to food security. Increasing sowing rates is a common practice to enhance germination under salt stress, although it leads to higher seed costs. Recently, seed priming has emerged as an effective technique to improve seedling emergence under abiotic stress, but the regulation of seed priming treatment on the sowing rate of DSR under saline soil conditions has rarely been reported. Therefore, field experiments were conducted at two salinity levels of 1.5‰ (1.5 g kg-1) (T2) and 3.0‰ (3 g kg-1) (T3) and under one non-saline condition (0‰) (T1). The control (P1) consisted of non-primed seeds, while priming treatments included 160 mg L-¹ ascorbic acid (P2), γ-aminobutyric acid (P3), and 200 mg L-¹ zinc oxide nanoparticles (P4); three sowing rates were applied: 90 (S1), 150 (S2), and 240 seeds m-2 (S3). Our results demonstrated that under T1-T3, the germination rate, α-amylase activity, and soluble sugar and protein contents were significantly increased after priming treatments. The contents of reactive oxygen species (i.e., O2 - and H2O2) and malondialdehyde (MDA) were decreased, while the activities of enzymatic antioxidants (i.e., superoxide dismutase, peroxidase, and catalase) and the K+/Na+ ratio of rice were significantly increased after the above seed priming treatments. Under T1-T3, the grain yield increased by 13.39%-36.94% after priming treatments, primarily due to enhanced seed germination, which boosted panicle number per unit area. Among P2-P4 treatments, P4 treatment consistently resulted in the highest yield increase (26.96%-36.94%) compared to P1, outperforming P2 and P3 under T1-T3. Furthermore, under T1-T3, the grain yield with priming treatment at 90 seeds m-2 was equivalent to that obtained without priming treatment at 240 seeds m-2. The potential mechanisms by which priming treatments enhance rice salt tolerance include increased levels of osmoregulatory substances and elevated activities of antioxidant enzymes, which collectively support improved seed germination. Therefore, to optimize the economic benefits of DSR when the salt concentration is below 3‰, the sowing rate could be reduced to 90 seeds m-2 using ZnO-nanoparticle priming treatment.

Effect of different salinity on seed germination, growth parameters and biochemical contents of pumpkin (Cucurbita pepo L.) seeds cultivars

Soil and water salinity is an important limiting factor affecting yield and production levels in arid and semi-arid areas. Salt tolerance during germination is an important parameter that also affects the other plant development stages. In this respect, this study was designed to determine the responses of pumpkin seed varieties (Develi, Ürgüp, Hybrid) to different NaCl salinities. The study was carried out in 2022 in the laboratory of Biosystems Engineering Department of Erciyes University in randomized plots design with 3 replications. Experiments were conducted with 5 different water salinity. Germination percentage (GP), germination index (GI), mean germination time (MGT), seedling vigor index (SVI), ion leakage (Il), radicula length (RL) and plumule length (PL), root and shoot fresh and dry weights and some mineral composition (Na, K, Ca) were examined. Proline, antioxidant capacity, total phenolic and DPPH content were significantly affected by salinity. In scatter plot correlation analysis SVI a positive correlation was observed between GP (r2 = 0.774), GI (r2 = 0.745), RL (r2 = 0.929), FRW (r2 = 0.837), FSW (r2 = 0.836), DRW (r2 = 0.894), AC (r2 = 0.747), TP (r2 = 0.640) and DPPH (r2 = 0.635). It was determined that there were negative correlations between SVI and MGT (r2 = - 0.902), II (r2 = - 0.588), DSW (r2 = - 0.682) and PR (r2 = - 0.344). Present findings revealed that investigated parameters were significantly affected by increasing salinity levels. While Hybrid cultivar was the most affected by salinity, Develi cultivar was found to be resistant to saline conditions.

Effect of Seed Priming with Chitosan Hydrolysate on Lettuce (Lactuca sativa) Growth Parameters

Seed priming increases germination, yield, and resistance to abiotic factors and phytopathogens. Chitosan is considered an ecofriendly growth stimulant and crop protection agent. Chitosan hydrolysate (CH) is an unfractionated product of hydrolysis of high-molecular-weight crab shell chitosan with a molecular weight of 1040 kDa and a degree of deacetylation of 85% with nitric acid. The average molecular weight of the main fraction in CH was 39 kDa. Lettuce seeds were soaked in 0.01-1 mg/mL CH for 6 h before sowing. The effects of CH on seed germination, plant morphology, and biochemical indicators at different growth stages were evaluated. Under the 0.1 mg/mL CH treatment, earlier seed germination was detected compared to the control. Increased root branching was observed, along with 100% and 67% increases in fresh weight (FW) at the 24th and 38th days after sowing (DAS), respectively. An increase in the shoot FW was found in CH-treated plants (33% and 4% at the 24th and 38th DAS, respectively). Significant increases in chlorophyll and carotenoid content compared to the control were observed at the 10th DAS. There were no significant differences in the activity of phenylalanine ammonia-lyase, polyphenol oxidase, β-1,3-glucanase, and chitinase at the 24th and 38th DAS. Seed priming with CH could increase the yield and uniformity of plants within the group. This effect is important for commercial vegetable production.

Research Progression of the Genus Merremia: A Comprehensive Review on the Nutritional Value, Ethnomedicinal Uses, Phytochemistry, Pharmacology, and Toxicity

The genus Merremia Dennst. ex Endl. (Convolvulaceae) is a rich source of structurally diverse phytochemicals with therapeutic relevance. This review presents the first comprehensive, up-to-date information and research progression on the nutritional value, ethnomedicinal uses, phytochemistry, pharmacological activities, and toxicity of the genus Merremia. Using the key search term “Merremia”, relevant documents and information were retrieved from electronic databases. Relevant documents were uploaded in RStudio with installed bibliometric software packages and used for data retrieval, tabulation, and network visualization. Bibliometric analysis revealed that ca. 55% of the studies related to Merremia were published in the last decade, which can be grouped into four thematic areas: (i) drug formulation, (ii) taxonomy, (iii) chemical analysis, and (iv) treatment of diseases. Ethnomedicinal uses, phytochemistry, and biological activities studies showed that species in the genus are promising medicinal plants with various pharmaceutical potentials. However, clinical studies to validate the efficacy of the reported bioactivities and the mechanisms underlying the various activities are lacking and should constitute a future research focus. Additionally, reports on the nutritional and antinutritional constituents of Merremia species revealed that the species meet high nutritional quality criteria for animals and are therefore suitable for inclusion in livestock diets. The few available investigations on toxicity indicated that most Merremia species are safe for human and animal use but not with prolonged chronic administration.

Exogenous Antioxidants Enhance Seedling Growth and Yield of Artificially Aged Cabbage and Lettuce Seeds

Aged seeds exhibit compromised vigour in terms of germination, seedling emergence and growth, but this can to some extent be alleviated by invigoration treatments before sowing. This study aimed to investigate ageing rates and patterns in cabbage (Brassica oleraceae) and lettuce (Lactuca sativa) seeds and whether the beneficial effects of invigorating aged seeds with exogenous antioxidants translate to enhanced seedling performance. Seeds were artificially aged to 25% viability before soaking in 0.4 mM glycerol, 0.6 mM GSH and 0.2 mM trolox for cabbage, and 0.6 mM glycerol, GSH and trolox for lettuce; deionised water served as a control. After 14 days of sowing, seedling emergence percentage, mean emergence time, mean daily emergence, and time taken to 25% emergence were computed. Seedling vigour index, root and shoot dry weight, root:shoot ratio, leaf area, leaf area ratio, and leaf chlorophyll content were assessed 6 weeks after sowing. Furthermore, the photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), and chlorophyll fluorescence were measured 6 weeks after sowing. Notably, ageing resulted in the loss of seed vigour and viability at higher rates in lettuce than cabbage. Seed pretreatment with glycerol promoted seedling growth in both species and shoot dry weight in lettuce, while glycerol and GSH enhanced Pn, Gs and E in lettuce. Trolox also enhanced Pn and E in lettuce. The beneficial effects of the antioxidant treatments are thought to be associated with the protection of photosystems from oxidative stress and/or stimulation of enzymes involved in photosynthesis, possibly through an enhanced antioxidant defence system during the early development stages when seedlings are particularly vulnerable to stress.

Vegetation coverage change and erosion types impacts on the water chemistry in western China

Exploring the characteristics of water chemistry under different vegetation coverage and erosion types is important for water resource utilization and ecological environmental protection. After investigating the water chemistry of the surface water and groundwater in Xinjiang and Tibet in western China, this study revealed the response of hydrochemistry to vegetation coverage and erosion types. The results showed that different ions have different responses to the NDVI (normalized difference vegetation index). Sodium (Na⁺) in the surface water and groundwater was negatively correlated with the NDVI, while magnesium (Mg²⁺) and bicarbonate (HCO₃^-) experienced no significant changes with vegetation. Moreover, potassium (K⁺) in the surface water was positively correlated with vegetation, while that in the groundwater was negatively correlated with vegetation. Furthermore, calcium (Ca²⁺) and nitrate (NO₃^-) in the surface water were negatively correlated with the NDVI, but the groundwater experienced no evident change. In addition, chlorine (Cl^-) and sulfate (SO₄^2-) in the groundwater were negatively correlated with the NDVI, but these indexes in the surface water had no evident variation trend. In addition, different erosion types have different effects on hydrochemistry. Assuming the same amount of erosion occurs, wind erosion has the greatest effect on hydrochemistry, followed by hydraulic erosion, and freeze-thaw erosion has the least effect. The results of this study can help improve our knowledge of water evolution and the relationship between hydrochemistry and vegetation coverage and erosion types, promote effective management of water resources and provide a new direction for water research.