Effect of nitrogen application timing on dry matter and nitrogen assimilation and partitioning in six wheat cultivars under rain-fed conditions of Jordan

Abstract

The current study was implemented to assess the effect of nitrogen (N) timing application and cultivars and their interaction on grain yield, and the amount of pre-anthesis dry matter (DM) and N accumulation as well as the remobilization of the assimilates to sink (i.e. grain) under rain-fed conditions of West Asia and North Africa (WANA) region. The treatments comprised of six wheat cultivars and two methods of N application timing (single and split N application). Nitrogen was applied at a rate of 40 kg N ha−1 (the recommended rate in Jordan) as diamonumphosphate (DAP) just before planting (i.e. single N application) or 20 kg ha−1 before planting as DAP plus 20 kg ha−1 top dressed at early boot stage as urea (i.e. split N application). The results suggest that single N application was relatively better than split N application in improving DM accumulation in vegetative parts at anthesis and maturity stages, grain and biological yield and N translocation efficiency (NTE). Cultivar NTE ranged from 73–80%, and the contribution of pre-anthesis assimilates to grain from 26–63%, indicating the importance of pre-anthesis accumulated assimilates for attaining high yield under semi-arid rain-fed-conditions of WANA region.