Abstract:

This study aimed to investigate the physiological mechanisms by which seed coating agent alleviate low temperature sowing obstacles in spring peanut of Northern China, thereby ensuring normal germination and seedling establishment. Using the peanut cultivar 'Jihua 25' as the material, three temperature treatments were composed: 25℃ (control), 10℃ (mild stress), and 8℃ (moderate stress). Seeds were treated with either seed coating agent or distilled water (soaking). Observations were conducted at both germination and seedling stages to systematically compare the effects on seed germination, seedling growth, root morphology, photosynthetic fluorescence, membrane stability and antioxidant enzyme activity. The results showed that seed coating agent increased the germination potential by 98.92% at 8℃ and the germination rate by 11.26% at 10℃. At 8℃, seed coating agent increased the total root length, root surface area, plant height, and dry weight of the seedlings by 14.78%, 23.23%, 32.59%, and 12.91%, respectively; at 10℃, the total root length and dry weight of the seedlings were increased by 11.13% and 16.10%, respectively. Under low temperature stress, seed coating agent significantly increased the Fv/Fm (8℃: +2.50%; 10℃: +1.23%) and ΦPSII (8℃: +15.38%; 10℃: +5.16%), reduced NPQ (8℃: -24.12%; 10℃: -21.32%), and dramatically enhanced the net photosynthetic rate, stomatal conductance, and transpiration rate while decreased the intercellular CO₂ concentration of functional leaves. Moreover, seed coating agent reduced the malondialdehyde content and relative electrical conductivity while increased the relative water content and activities of antioxidant enzymes (POD, SOD, CAT) of functional leaves. In summary, seed coating agent effectively alleviated peanut low temperature stress by promoting seed germination and improving root morphology. Additionally, seed coating agent also increased photosynthetic rate, enhanced antioxidant capacity, and maintained plasma membrane integrity of functional leaves. Particularly, the promotion effect of seed coating agent on seed germination was more pronounced at 8℃ whereas its stimulatory effect on biomass accumulation was more pronounced at 10℃. This study provides theoretical and technical support for low-temperature-resistant and stable-yield cultivation of spring peanut in Northern China.

Key words: peanut, low temperature stress, seed coating agent, seed germination, seedling growth, physiological mechanism, photosynthetic characteristics, antioxidant characteristics