This work was carried out with the objective of testing the comparative efficiency of
different tests in the physiological quality of onion seeds (Allium cepa L.), looking for information that
may indicate options to better utilization of this quality control test, as well as to verify the relations with
the field emergency. In order to do that, seeds of five lots were valued, by the germination test, first
count germination, electrical conductivity, accelerated aging, cold without soil, field emergency, and
seedling length under hydric stress at 0,0; -0.2; -0.4 and -0.6 matric potentials.The trials were carried out
at the Seed Lab and experimental field of Embrapa Semi-Árido, Petrolina - PE, in the period from January
to June 1996, in a completely randomized way with four replications. The results indicated that the
electrical conductivity test and cold without soil and seedling length under stress at -0.4MPa were the
most effective ones to detect differences of physiological quality among lots of onion seeds, and at the
same time they showed the biggest levels of correlation with the emergency.