Seed pre-treatments help improve maize performance under sorghum allelopathic stress.

摘要

Besides affecting basic processes in receiver plants, allelopathy can also provoke cross-stress response. The prime mechanism behind allelopathic stress is induced oxidative damage. This study was conducted to evaluate the role of pre-sowing seed treatments, viz., hydro-priming and osmo-hardening (CaCl₂), in mitigating allelopathic stress of sorghum [Sorghum bicolor (L.) Moench] on hybrid maize (Zea mays L.). Aqueous extract of sorghum was prepared in distilled water (1:10 w/v ratio) and five concentrations (0, 25%, 50%, 75%, and 100%) were used. Non-treated maize seeds and distilled water-treated seeds were maintained as control and positive control, respectively. Aqueous sorghum extracts exhibited phytotoxicity to maize by inhibiting and delaying maize emergence and suppressing seedling growth, although the magnitude of suppression was far less in the case of hydro-primed and osmo-hardened seeds. Pre-sowing seed treatments activated the antioxidant enzymes and helped ameliorate the allelopathic stress evoked by exposure to sorghum extract. Although the effect of both the pretreatments was found to be stimulatory, osmo-hardening with CaCl₂ was more effective in improving most of the studied attributes at all extract concentrations. The study suggests that pre-sowing seed treatments can be exploited to alleviate allelopathic stress on maize via the induction of enzymatic antioxidants.