Proline osmopriming improves the root architecture, nitrogen content and growth of rice seedlings

Abstract

Osmopriming is a pre-sowing technique that allows improving the emergence and establishment of seedlings in environments with or without adverse conditions. This work aimed to evaluate the proline osmopriming in favoring the emergence, growth and total nitrogen content in rice seedlings. The treatments included hydropriming and proline osmopriming at 5, 10 and 20 mM (−0.012, −0.025, −0.049 MPa, respectively), for 16 h at 25 °C. The experimental design adopted was completely randomized, with seven replications. Untreated seeds were used as comparison treatment (control). Rice seedling primed with water and proline improved the seedling emergence rate. Osmopriming with 10 mM proline favored growth (up to 29%), dry matter (up to 20%) and nitrogen content of seedlings (up to 20%) at 11 days after emergence (DAE). Besides, in the same period, the root system branching increased which favored the number of crossings, forks and tips. There was also an increase in volume, surface area and total root length. Osmoconditioning with 10 mM proline also increased, at 11 DAE, the activity of glutamine synthetase in the shoot seedlings. Pre-sowing treatment based on proline, mainly at a concentration of 10 mM, was an efficient technique for improving the growth and nitrogen content of the rice seedlings, as well as the root system architecture. • This is the first report on the use of proline as a priming agent in rice seeds. • Proline osmopriming favored initial growth and dry matter accumulation in rice seedlings. • The application of proline at a concentration of 10 mM provided an increase of up to 20% in the shoot and root N content. • Proline improved the root architecture, evidenced by the increase in forks, crossings, tips, volume, area, and root length.