Yield and nitrogen use efficiency of wheat increased with root length and biomass due to nitrogen, phosphorus, and potassium interactions

• Published in: Journal of plant nutrition and soil science 2018-06, Vol.181 (3), p.364-373
• Main Authors: Duncan, Elliott G., O'Sullivan, Cathryn A., Roper, Margaret M., Palta, Jairo, Whisson, Kelley, Peoples, Mark B.
• Format: Article
• Language: English
• Subjects: Biomass; crop nutrition; Crop yield; Efficiency; Fertilizers; Grain; grain yield; Nitrogen; nutrient availability; Nutrition; Phosphorus; Plant growth; Plants (botany); Potassium; rhizoboxes; Rooting; Shoots; specific root length; Wheat
• ISSN: 1436-8730; 1522-2624
• DOI: 10.1002/jpln.201700376

Balanced applications of nitrogen (N), phosphorus (P), and potassium (K) are known to increase grain yield of wheat but the impact of the interactions among N, P, and K on root growth and nitrogen use efficiency (NUE) have not been proven. The aim of this study was to investigate the effect of balanced applications of N, P, and K on the rooting patterns and NUE of wheat. Two glasshouse experiments were conducted. A rhizobox study was used to assess the impact of interactions among N, P, and K fertilisers on total root length, biomass, specific root length, root length density, N use efficiency (NUE), and N uptake efficiency of the shoots (NUpEshoot) and N nutrition index. In a separate pot study, plants were grown to maturity to confirm the effect of the observed changes in root growth on NUE, NUpEgrain, and grain/biomass yield. In the rhizobox experiment when plants were supplied with N+P+K, total root biomass increased approximately six‐fold relative to plants grown with N alone or with no fertiliser. Plants exposed to N+P+K had NUpEshoot and NUE values that were five and ten times higher, respectively, than plants that received just fertiliser N. Plants supplied with N+P or N+P+K had N nutrition indices close to one (N‐adequate), while plants that only received N had an index of 0.62 (N‐deficient). The pot study confirmed that the changes in root length and biomass in plants exposed to N+P+K resulted in significant increases in NUE, NUpEgrain, shoot biomass, and grain yield at maturity. Interactions among fertiliser N, P, and K played a critical role in influencing root biomass and length, which was associated with increases in NUE, NUpEshoot and NUpEgrain.