Exogenous Application of Oxidized Glutathione During the Seedling Stage Promotes Root Growth After Transplantation and Potentially Increases Panicles in Rice

Abstract

Various stresses, such as transplanting damage, inhibit the initial growth of rice (Oryza sativa) seedlings to varying extents. Oxidized glutathione (GSSG) is involved in stress responses and metabolic activation in plants. In this study, we performed three experiments that investigated whether GSSG application affects root development in seedlings following transplanting and the number of panicles at maturity. In Experiment 1, “Koshihikari” seedlings were cultivated in a nursery bed and received 4 mM GSSG, ammonium sulfate, or amino acids, or left untreated 1 week before transplanting. In Experiment 2, “Koshihikari” and “Akitakomachi” seedlings received either 4 or 12 mM GSSG. Finally, in Experiment 3, “Haenuki” seedlings received 4 mM GSSG. In Experiment 1, the number of emerging roots and total root surface area in the 4 mM GSSG group were higher than those in the ammonium sulfate group, whereas the aboveground plant growth did not differ between treatments. In Experiment 2, the number of panicles of “Koshihikari” treated with GSSG increased by 10% compared to the control. Similar results were obtained for “Akitakomachi,” with a 4%–26% increase in panicle number. In Experiment 3, the number of emerging roots and tillers in the 4 mM GSSG group were higher than those in the control group. GSSG application had no negative effects on plant performance, indicating that GSSG application at the seedling stage can promote the emergence of crown roots after transplanting, which contributes to an increase in panicle number.