Nitric oxide as a way to mitigate copper (Cu) toxicity in the emergence and initial growth of maize seedling (Zea mays L.)

Abstract

The aim of this study is to assess the effect of sodium nitroprusside-NPS (nitric oxide donor) on the emergence and initial growth of maize seedlings (Zea mays L.) subjected to different copper concentrations. The study followed a completely randomized design at 4 x 3 factorial arrangement, with 12 treatments and 8 repetitions, totally 96 trays with 25 seedlings per repetition. Seedlings were soaked in sodium nitroprusside (SNP) solution (0.75 and 150 µM - donor), sodium ferrocyanide (SF) (0.75 and 150 µM - compensator) and deionized water (control) on Germitest paper for 48 hours. Next, they were placed on sand saturated with CuSO4.5H2O at concentrations of 0, 100 and 200 µM. The results showed that SNP doses were not capable of mitigating copper toxicity in seedling emergence, influencing emergence speed coefficient and prolonging the mean emergence time of plants subjected to copper concentrations of 100 µM and 200 µM. Copper concentrations rose the number of abnormal seedlings and had negative influence on plant biometrics and biomass. Copper concentration of 200 µM increased proline content in the roots. NPS and sodium ferrocyanide application had effect on emergence speed index, shoot and root dry mass and on proline content in the shoot and roots. This outcome highlights that such effects were caused by treatments related to release of cyanide found in sodium nitroprusside (SNP), rather than to nitric oxide (NO)