title: Timing and rate of nitrogen application influence grain quality and yield in maize planted at high and low densities.
abstract: BACKGROUND
  Efficient use of nitrogen (N) is considered one of the most important inputs needed for increasing grain quality and crop productivity. Hypothesis was that grain quality and yield of maize (Zeamays L.) in north-west Pakistan are enhanced by increasing the rate of N, and that response to applied N is greater with an increase in the number of N split applications at high plant density compared to low density.
  
  
  RESULTS
  Field experiments were carried out on maize (cv. Azam) in summer 2002 and 2003 consisting of two planting densities and three N rates as main plots, and six split N applications as sub-plots. Year 1 had higher shelling percentage and stover yield (SY). Harvest index (HI) decreased but SY increased with increase in plant density. Increase in N rate and number of split N applications increased grain weight and protein content, HI and SY.
  
  
  CONCLUSIONS
  The highest N rate in four to five split applications increased maize grain quality and yield at both densities. Maize response to the interactive effect of year x plant density, year x N rate, and year x N timing suggests zonal specific effective N management practices for sustainable maize production in different agro-ecological zones.
authors.affiliation: Department of Agronomy, NWFP Agricultural University, Peshawar, Pakistan. draman_agronomist@yahoo.com
authors.lastname: Amanullah
authors.forename: Paigham
authors.initials: P
authors.lastname: Shah
mesh_terms: D000383:Agriculture / Q000379:methods*; D018533:Biomass; D002523:Edible Grain / Q000737:chemistry / Q000254:growth & development / Q000592:standards; D005308:Fertilizers; D009584:Nitrogen / Q000494:pharmacology*; D010154:Pakistan; D010940:Plant Proteins / Q000032:analysis*; D013997:Time Factors; D003313:Zea mays / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development
chemical_list: D005308:Fertilizers; D010940:Plant Proteins; D009584:Nitrogen