Agriculture Reference
In-Depth Information
loading of nutrients on the nanoparticles is usually done by (a) absorption on
nanoparticles, (b) attachment on nanoparticles mediated by ligands,
(c) encapsulation in nanoparticulate polymeric shell, (d) entrapment of polymeric
nanoparticles, and (e) synthesis of nanoparticles composed of the nutrient itself.
Corradini et al. (
2010
) evaluated the interaction and stability of chitosan
nanoparticles suspensions containing N, P, and K fertilizers which can be useful
for agricultural applications. Similarly, Kottegoda et al. (
2011
) synthesized urea-
modified hydroxyapatite (HA) nanoparticles for gradual release of nitrogen with the
crop growth. These nano-fertilizers showed initially burst and subsequently slow
release of nitrogen up to 60 days of plant growth compared to commercial fertilizer
which shows release only up to 30 days. The large surface area of HA facilitates the
large amount of urea attachment on the HA surface. Strong interaction between HA
nanoparticles and urea contributes to the slow and controlled release of urea.
Similarly, polymer-based mesoporous nanoparticles can also provide efficient
carrier system to agrochemical compounds which improves the efficiency and
economical utilization. Mesoporous silica nanoparticles (150 nm) have been
reported to entrap urea. It has been observed that 15.5 % of urea was loaded inside
the nanoparticles pores and demonstrated a controlled urea release profile in soil
and water. The study revealed at least fivefold improvement in release period
(Wanyika et al.
2012
). Zinc solubility and dissolution kinetics of ZnO nanoparticles
and bulk ZnO particles coated on macronutrient fertilizers (urea and
monoammonium phosphate) have been compared by Milani et al. (
2012
). They
reported that coated monoammonium phosphate granules show faster dissolution
rate. The mode of fertilizer application influences their efficiency and impact on
plant systems. The following methods can be used for nano-fertilizer delivery to
plants:
4.5.1
In Vitro Methods
4.5.1.1 Aeroponics
This technique was first reported by Weathers and Zobel (
1992
). In this technique,
roots of the plant are suspended in air and the nutrient solution is sprayed contin-
uously. Through this method, the gaseous environment around the roots can be
controlled. However, it requires a high level of nutrients to sustain rapid plant
growth, so the use of aeroponics is not widespread.
4.5.1.2 Hydroponics
This method was first introduced by Gericke (
1937
) for dissolved inorganic salts.
The method is also commonly known as “solution culture” as the plants are grown
with their roots immersed in a liquid nutrient solution (without soil). Volumes of
