Leaf nitrogen and phosphorus resorption improves wheat grain yield in rotation with legume crops in south-eastern Australia

Abstract Nutrient resorption from senescing leaves to grain at physiological mature stage is critical to recover nutrients and improve grain production in semi-arid environment in south-eastern Australia. The aim of this study is to examine nitrogen (N) and phosphorus (P) resorption patterns and their effects on grain yield and quality of wheat in rotation with legume crops. A range of legume crops were grown in the field followed by one and two wheat crops in contrast with continuous wheat and canola crops with N fertiliser over 3 years. The soil N and P availability, flag leaf N and P nutrient status and resorption were measured in the first and second wheat crops after legume crops. Including legume crops in crop rotation increased soil available N concentration. Green leaf N concentration, and senesced leaf N and P concentrations increased as soil available N increased. However, N resorption efficiency (NRE) and P resorption efficiency (PRE) decreased as soil available N concentration increased. The NRE and PRE were positive correlated to grain yield and 1000-grain weight, but negative correlated to grain protein. The soil N benefit from legume crops can last more than one growing season. Under moisture stress conditions increased grain yield was associated with improved nutrient resorption efficiency via increased grain size regardless soil nutrient availability.