All treatments led to 100 % germination of seeds showing that nano-ZnO did not adversely affect rice
seed germination. The toxicity of nano-ZnO to rice roots is apparent from root length (Table. 2) and number
of roots (Table. 3); concentration is greatly involved with the toxicity, and soaking period also affects (df = 8,
134; F = 3.39; p = 0.002), higher concentration show reduction effect on root length started from 100 mgL-1
and greatly inhibited at concentrations 500 and 1000 mgL-1, with longer soaking time inducing inhibition of
root growth. For number of roots, no interaction (day * concentration) was found (df = 8, 134; F = 0.729; p =
0.67), but it was affected by nano-ZnO concentration similar to root length (df = 4, 134; F = 46.6; p = 0.00)
(Figure 4). Effect by soaking time (day) has no significant (df = 2, 134; F = 2.08; p = 0.129).