Development of acid-resistant seed pelletization formula and its effects on improving rapeseed growth in acidic soil.

Background and aims: Soil acidification impedes crop growth. Seed pelletization was used to improve crop resistance to various stress environments but not acidic soil. This study aimed to develop rapeseed seed pelletization and to assess the promotional effects of pelletization on rapeseed growth under acidic conditions. Methods: Two main acid-resistant functional agents (Ca(OH)2, and biochar) and a basic formula including sodium carboxymethyl cellulose, H3BO3, nano-silica, brassinolide, sodium naphthalene acetate, indoleacetic acid, and yeast metabolite were used to evaluate the effects on rapeseed growth by seed pelletization. Then, the mechanism of alleviating acidic stress by seed pelletization was investigated. Results: A basic formula were developed by soil test. Three acid-resistant seed pelletization cases (① 0.5% Ca(OH)2 + a basic formula; ② 10% biochar + a basic formula; ③ 0.25% Ca(OH)2 + 5% biochar + a basic formula) were confirmed to have significant plant growth promotion. Compared to the unpelletized treatment, seed pelletization significantly increased root length and dry weight of rapeseed seedling by 67.32%-78.34% and 46.47%-74.12%, respectively. It also increased nutrient uptake and reduced the accumulation of toxic Al by 11.72%-16.23% in rapeseed roots. Moreover, seed pelletization modulated the local soil environment at the sowing site, increased soil pH by 0.88–1.11 in the microzone, thereby reducing the adverse effects of acidic stress. Conclusion: Seed pelletization in rapeseed can enhance its tolerance to acidic stress and promote plant growth. Additionally, our results provide new insights into the strategies to alleviate the inhibitory effects of acidic soil. [ABSTRACT FROM AUTHOR]