EFFECTS OF NANOFERTILIZERS ON PLANT GROWTH AND DEVELOPMENT, AND THEIR INTERRELATIONSHIP WITH THE ENVIRONMENT - Fertilizers: Components, Uses in Agriculture and Environmental Impacts - page 215

Autónoma Agraria Antonio Narro ', Coahuila, Mexico, while the common bean seeds were
donated by ‗ INIFAP-Celaya ', Mexico. The seeds were all kept in the dark at 4 ﾰC until use.
Germination in Pure Culture
For each individual treatment, 200 seeds of each species were soaked for 1 h in 5 mL of
either i) 0.0, 0.3, 0.5, 1.0, 1.6, and 3.0 g nano-Fe 3 O 4 L -1 ; ii) 1.0, 1.6, and 3.0 g nano-Fe 2 O 3 L -1 ,
or iii) deionized water as a control without surface disinfection. Once the seeds were placed in
the treatment solution, each jar received a five-second shake three times over the course of the
hour to ensure that all the seeds were thoroughly and evenly coated with the solutions. One
piece of filter paper was placed in each 100 × 15 mm Petri dish, and 10 mL of the appropriate
treatment test solution was added. The seeds were then transferred onto the filter paper, with
25 seeds per dish. The Petri dishes were covered and sealed with tape before being placed
together randomly in a stove set to 33 °C for 38 days. Three replicates of each treatment were
prepared, for a total of 30 Petri dishes per each plant species.
We measured the seed germination rate, shoot length, and root length for all replicates
after 38 days of incubation, with the exception of lettuce, common bean, maize, and
sunflower, which were measured on the 16th, 6th, 6th, and 6th days, respectively, due to their
quick germination and growth rates. The seed germination was defined as the moment when
the radicle or plumule emerged from the seed coat; the seed germination rate (GR) was
calculated as the proportion of the total seeds that germinated. The shoot length (SL) and root
length (RL) were measured by a slide caliper. From these data we calculated three ratios.
(a) Treatment effects on germination:
where GR TRT is the germination rate of the treatment sample and GR CONTROL is the
germination rate of the control.
(b) Treatment effects on leaf length:
where LL TRT is the leaf length of the treatment sample and LL CONTROL is the leaf length of the
control.
(c) Treatment effects on root length:
where RL TRT is the root length of the treatment sample and RL CONTROL is the root length of
the control.