Seed osmopriming with polyethylene glycol (PEG) enhances seed germination and seedling physiological traits of Coronilla varia L. under water stress.

Water stress can adversely affect seed germination and plant growth. Seed osmopriming is a pre-sowing treatment in which seeds are soaked in osmotic solutions to undergo the first stage of germination prior to radicle protrusion. Seed osmopriming enhances germination performance under stressful environmental conditions, making it an effective method to improve plant resistance and yield. This study analyzed the effect of seed osmopriming with polyethylene glycol (PEG) on seed germination and physiological parameters of Coronilla varia L. Priming treatments using 10% to 30% PEG enhanced germination percentage, germination vigor, germination index, vitality index, and seedling mass and reduced the time to reach 50% germination (T50). The PEG concentration that led to better results was 10%. The content of soluble proteins (SP), proline (Pro), soluble sugars (SS), and malondialdehyde (MDA) in Coronilla varia L. seedlings increased with the severity of water stress. In addition, under water stress, electrolyte leakage rose, and peroxidase (POD) and superoxide dismutase (SOD) activities intensified, while catalase (CAT) activity increased at mild-to-moderate water stress but declined with more severe deficiency. The 10% PEG priming significantly improved germination percentage, germination vigor, germination index, vitality index, and time to 50% germination (T50) under water stress. Across the water stress gradient here tested (8 to 12% PEG), seed priming enhanced SP content, Pro content, and SOD activity in Coronilla varia L. seedlings compared to the unprimed treatments. Under 10% PEG-induced water stress, primed seedlings displayed a significantly lower MDA content and electrolyte leakage than their unprimed counterparts and exhibited significantly higher CAT and POD activities. However, under 12% PEG-induced water stress, differences in electrolyte leakage, CAT activity, and POD activity between primed and unprimed treatments were not significant. These findings suggest that PEG priming enhances the osmotic regulation and antioxidant capacity of Coronilla varia seedlings, facilitating seed germination and seedling growth and alleviating drought stress damage, albeit with reduced efficacy under severe water deficiency.

Thiamethoxam Application Improves Yield and Drought Resistance of Potatoes (Solanum tuberosum L.).

(1) Background: Potato is the most important tuber crop in the world that can contribute to food security. However, the crop has been shown to be sensitive to drought and its yields decline significantly during successive periods of stress. Drought triggers a number of responses in potato, ranging from physiological changes to fluctuations in growth rates and yields. In light of global climate change, it is important to understand the effects of thiamethoxam on potato growth and yield under drought conditions. (2) Methods: The objective was to evaluate the impact of thiamethoxam on improving drought resistance and yield of potato under drought conditions. The drought-tolerant and sensitive-genotypes Qingshu No. 9 and Atlantic were used for a two-year pot experiment. Potato seeds were coated with 70% thiamethoxam before sowing (treatment group (T)), with a control group without treatment (NT). Two experimental treatments were applied: normal irrigation (ND) and drought stress (D). (3) Results: The results showed that root length, plant yield, chlorophyll content and superoxide dismutase (SOD) activity significantly increased under both genotypes, while malondialdehyde (MDA) and proline (Pro) content were reduced under thiamethoxam under drought stress. The best indicators were obtained in the comprehensive evaluation for the T-D treatment, suggesting that the application of thiamethoxam under drought stress was more effective than normal irrigation. (4) Conclusions: Our results suggest that the application of thiamethoxam improves potato growth, thereby increasing drought tolerance and potato yield. However, thiamethoxam is a neonicotinoid pesticide, and the limitation of this study is that it did not explore the ecological effects of thiamethoxam, which need to be systematically studied in the future. Moreover, considering the potential risks of thiamethoxam to the environment, specific agronomic measures to effectively degrade thiamethoxam residue should be taken when it is applied in agricultural production.

Photosynthetic Physiological Basis of No Tillage with Wheat Straw Returning to Improve Maize Yield with Plastic Film Mulching in Arid Irrigated Areas.

Surface mulch is an efficient plant production technique widely used in arid and water-scarce areas. In this study, a field experiment was conducted to determine whether plastic film combined with wheat straw returning could boost grain yield of maize via optimizing photosynthetic physiological characteristics and coordinating yield components. The results showed that no tillage with wheat straw mulching and straw standing treatments had better regulation on photosynthetic physiological characteristics and had a greater impact on the increase in grain yield than conventional tillage with wheat straw incorporation and without wheat straw returning (the control treatment) in plastic film-mulched maize. Meanwhile, no tillage with wheat straw mulching had a relatively higher yield than no tillage with wheat straw standing through better regulation of photosynthetic physiological characteristics. No tillage with wheat straw mulching decreased the leaf area index (LAI) and leaf area duration (LAD) of maize before the VT stage and maintained higher LAI and LAD after the VT stage, which effectively regulated the growth and development of maize at early and late stages of development. From VT to R4 stage of maize, no tillage with wheat straw mulching had greater chlorophyll relative content, net photosynthetic rate, and transpiration rate by 7.9-17.5%, 7.7-19.2%, and 5.5-12.1% than the control, respectively. In addition, leaf water use efficiency was increased by 6.2-6.7% from the R2 to R4 stage of no tillage with wheat straw mulching in comparison to the control treatment. Thus, no tillage with wheat straw mulching had a greater grain yield of maize by 15.6% than the control, and the high yield was attributed to the synchronous increase and cooperative development of ear number, grain number per ear, and 100-grain weight. Collectively, no tillage with wheat straw mulching had a positive effect on regulating the photosynthetic physiological traits and can be recommended to enhance the grain yield of maize in arid conditions.