Influence of nitrogen and phosphorus fertilization on quality and germination potential of smooth bromegrass seed

Abstract

A field experiment was conducted to evaluate the effects of two nitrogen levels (N: 0,100 kg ha-1) and four phosphorus levels (P: 0, 60, 90, 120 kg P2O5 ha-1) on smooth bromegrass (Bromus inermis Leyss.) seed quality by measuring germination, mean germination time (MGT), protein and phosphorus contents, acid phosphoesterase (APT) and antioxidant enzymes activities, hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents and electrical conductivity. Nitrogen application improved seed protein content and reduced P content at different P application levels, while there was a contradicted effect for P application on increasing seed P content and decreasing protein content. Mean germination time of seeds harvested from 100 kg N ha-1 treatment was significantly (P < 0.05) prolonged, indicating that N application could delay seed germination rate. Phosphorus deficiency or excessive P application level would also delay the initiation of germination. Seed-aging assays showed that N application could decrease relative loss of germination (RLG) through improving CAT and APT activities and reducing the content of H2O2 and MDA at the lower P application. From the findings of the present study, optimum application ratio of N and P improved germinability and longevity of smooth bromegrass seed.