Gibberellic acid and urease inhibitor optimize nitrogen uptake and yield of maize at varying nitrogen levels under changing climate

Worldwide, nitrogen (N) deficiency is the main yield limiting factor owing to its losses via leaching and volatilization. Urease inhibitors slow down urea hydrolysis in soil by inhibiting urease enzyme activities whereas gibberellic acid is growth regulator. That is why, we evaluated the role of urease inhibitor [N-(n-butyl)thiophosphorictriamide (NBPT)] and gibberellic acid (GA₃) in improving nitrogen uptake and yield of maize under different N levels (120 and 150 kg ha^-1) along with control. Both N levels alone and in combination with GA₃ and NBPT significantly increased yield and yield components of maize over control. In addition, 150 kg N ha^-1 + NBPT + GA₃ produced highest biological, grain, and stover yields, 1000 grain weight, plant height, and N uptake exhibiting 33.15%, 56.46%, 27.56%, 19.56%, 23.24%, and 78% increase over 150 kg N ha^-1, respectively. The sole use of gibberellic acid or NBPT with each level of N also improved the yield and yield components of maize compared to sole N application and control. Furthermore, application of 120 kg N ha^-1 along with NBPT and GA₃ performed at par to 150 kg N ha^-1 + NBPT + GA₃ but it was superior than sole applied 150 kg N ha^-1 for all the studied traits. These results imply that application of GA₃ and/or NBPT can reduce dependence on urea and improve the yield and N uptake in maize by slowing urea hydrolysis in calcareous soils and shall be practiced.