Do plants have preference for the form of nitrogen as nutrient?
Quoting verbatim from this site. The reference is not really a scientific article but you can check the references it cites. Some were not in English so I did not check. However these points are fairly logical


  Nitrates are the preferred nitrogen source:  
  
  
  Non-volatile: unlike ammonium, nitrate is non-volatile, so there is    no need to incorporate it in the soil when applied by top- or side dressing, which makes it a convenient source for application.
  Mobile in the soil - direct uptake by the plant, highest efficiency.
  Nitrates synergistically promote the uptake of cations, such as K, Ca    and Mg, while ammonium competes for the uptake with these cations.
  Nitrates can be readily absorbed by the plant and do not need to    undergo any further conversion, as is the case with urea and ammonium, before plant uptake.
  No acidification of the soil if all the nitrogen is applied as    nitrate-nitrogen.
  Nitrates limit the uptake of harmful elements, such as chloride, into    large quantities.
  The conversion of nitrates to amino acids occurs in the leaf. This    process is fuelled by solar energy, which makes it an energy-efficient process. Ammonium has to be converted into organic N compounds in the roots. This process is fuelled by carbohydrates, which are at the expense of other plant life processes, such as plant 
  growth and fruit fill.
  


Many plants can carry out nitrification but this is not universal. From this article:


  Nitrification is sometimes considered so universal and rapid that
  applications of NH4-N are considered equivalent to
  NO3-N. This is not true in many forest, orchard, and
  grassland soils.


However, nitrate being more soluble is susceptible to leaching and wash off, care has to be taken when using nitrate based fertilizers. From the previously mentioned paper:


  Unlike the positively charged ammonium ion, which is relatively
  stationary because of its adsorption to organic matter or clay
  particles, the negatively charged nitrate ion is freely mobile in the
  soil solution (166). Thus, leaching and denitrification primarily
  involve a loss of NO3-N (171). Inhibition or retardation of
  nitrification of applied NH4-N can reduce nitrogen losses,
  increase efficiency of applied N, and establish a predominantly
  ammoniacal form of nitrogen available for plant uptake (105, 171,222,
  232).