Correlation of the corn compensatory growth mechanism after post-drought rewatering with cytokinin induced by root nitrate absorption

The mechanism of compensatory growth in corn after post-drought rewatering at the seedling stage was explored by investigating the levels and effects of several plant hormones. This study consisted of two treatment conditions: nitrate (NO3−) addition to the roots and cytokinin addition to the leaves. Results showed that drought stress reduced the biomass of aboveground parts and the whole plant, but increased root soluble carbohydrate concentration and root activity. Post-drought rewatering under the addition of NO3− to the roots increased corn growth. Biomass values of the aboveground parts and the whole plant were similar between the rewatering and wetness at 10 days after rewatering conditions. Upon addition of NO3− to roots, post- drought rewatering increased the cytokinin contents of leaves and its delivery rate from roots to leaves. Addition of cytokinin to leaves without the addition of NO3− to roots increased the growth rate of corn seedlings upon post-drought rewatering and simultaneously caused high leaf cytokinin concentration. Thus, increase in concentration of root-derived cytokinin concentration in leaves was closely related to compensatory growth in corn upon post-drought rewatering at the seedling stage.