Amalgamation of Nanotechnology with Plant Sciences

This review paper deals with the basic aspects and advancement of Nanotechnology and its varied applications in every possible field starting from biotechnology, pharmaceuticals, drug science energy related sectors and so on. They show some explicit properties like strength, electrical, optical and chemical properties. Nanoparticles show increment in plant productivity by showing direct interactions with plants or indirectly with soil. Nanoparticles can easily be synthesized utilizing microbes and plants so they are organically protected, savvy, and climate amicable. Nanoparticles are termed as “magic bullets” because of their extraordinary properties, and for this reason they are employed in production of nano herbicides, nano pesticides. Nanotechnology does the job of addressing distinctive natural and medical problems which occurs to happen with the unreasonable utilization of pesticides and fertilizers in horticultural practices. When used in an appropriate amount and concentration they cause positive effects on the respective plants. Some of these include increment in crop production, better quality, increased photosynthetic activity, biomass, chlorophyll content and the list go on. With every positive effect comes the detrimental ones also. Inhibition of root and shoot length, reduced seed germination, inefficiency in photosynthetic activity.


INTRODUCTION
Nanotechnology is one of the rising and captivating field of science, that grants progressed research in numerous fields and revelations in this field has the potential to unfold many biotechnological applications, life sciences, medicine and farming [1]. Nanoparticles (NPs) generally possess size around 100 nm and huge surface region facilitating binding with functional ligands [2][3]. They show some explicit properties like strength, electrical, optical and chemical properties [4][5]. Because of their wide applications in Agri business, they are rightly called as "magic bullets" [6]. NPs can be derived either from normal resources or from humancentered ones, for example, designed or undesirable NPs [2]. Nanofertilzers exhibit properties that are successful to crops, such as controlled release of compounds regulating plant growth and development, release of nutrients on demand with upgraded target activity and providing phytopathogen resistance to plants [1,5]. It is sensible to contend that the possibility and the advantages of the utilization of NPs in plant sciences and agribusiness are yet not completely utilized, because of certain hindrances, which can be momentarily summed up as follows: (i)the methods of extraction of NPs and their uptake are still under study(ii) the manufacturing of NPs that are sustainable and do not meddle adversely with plant development and improvement [7].
Nanotechnology is certifiably not a solitary innovation yet it is a combination of a few innovative discoveries, which works at the nanolevel. In the field of horticulture, nanotechnology has varied applications, for example, recording data related to ecological stress by usage of nano sensors. resilience against biotic as well as abiotic factors resulting in improved crop quality [8]. Nanomaterials can be utilized as promising source to transport the genes or the synthetic substances to the objective site needed for plant working with high precision in a controlled way [9]. NPs show increment in plant productivity by interacting directly(plants) or indirectly (with soil).By chelation of salts existing in soil,NPs improve soil health by regulating soil pH and interacting with soil microbes [5]. They have high proficiency and thus lessen the bothersome natural impacts that outcome from the gigantic use of ordinary fertilizers. Effects of various nano-fertilizers like nano-calcium carbonate, nano-phosphorus manure, iron, magnesium, molybdenum oxides,zinc,manganese were studied on plants and positive outcomes were recorded in accordance with their respective dosage [10].

SYNTHESIS
NPs' synthesis can be achieved by mainly three ways: chemical, biological and physical. Ordinarily, physical and chemical methods are popularly used [6]. Physical and chemical techniques employ usage of hazardous substances like organic solvents, reducing agents etc., that can prove to be toxic [11].Nanoparticle production utilize various bacteria, algae and plants waste from agricultural activities [6]. Nanoparticles can easily be synthesized utilizing microbes and plants so they are organically protected, savvy, and climate amicable commonly known as Green Synthesis. Plants and microorganisms have inbuilt mechanisms to eat up and collect inorganic metal particles from their adjoining niche [11]. Agrarian waste like corn cob, mango peels, rice husk, sugarcane bagasse and extract from plants like Citrus sinensis , Glycine max, , Azadirachta indica, Mangifera indica and algae like Chlorella, Euglena, , Chlamydomonas spp . are employed for synthesis of various nanoparticles [6].

CLASSIFICATION
On the basis of chemical nature, Nanoparticles can be classified into four categories like carbon, polymeric compounds, metal and ceramic (metal oxides). Ceramic based nanomaterials contain inorganic solids made of metal oxides (ZnO, FeO 2 , and TiO2). On the other hand, Carbonbased nanomaterials consist of graphene, fullerenes and carbon nanotubes. Metal based nanomaterials include Cu, Ni, Au, and Ag which lead to plant growth and development [4].

Zinc Oxide Nanoparticles
According to research by various scientists, Zinc oxide(ZnO) NPs were beneficial in increasing plant growth in many crops like wheat, soybean, peanut etc [1]. ZnO NPs have been broadly utilized, as zinc is a fundamental micronutrient essential for various physiological reactions. According to few researchers, ZnO NPs are less harmful for crops in comparison to other nanoparticles like ZnO bulk particles or Zn 2+ [5]. These NPs when supplemented with MS media lead to advancement in plantlets regeneration, shooting, somatic embryogenesis, and furthermore promoted synthesis of proline, action of dismutase, superoxide, catalase and peroxidase consequently developing resistance to any sort of biotic stress [1]. Nano manure like Nano-Ag Answer R , Nano-GroTM, TAG NANO (NPK, Zinc, PhoS etc) are quite in demand [5].

Silicon Dioxide Nanoparticles
Many researchers studied the effect of nano Silicon dioxide (SiO 2) on variety of crop plants like maize, tomato, soybean and many more [1]. Lately, silicon has given a great deal of consideration by the agrarian researchers It had been accounted that Si might assume a basic part in expanding plant's resistance against biotic stresses in cucumber [12]. Improvement in seed germination was observed on treating tomato with low dosage of nano SiO 2 . Likewise, the same was observed in maize which was aided by better availability of nutrients to the seeds. Exogenous utilization of nano-SiO 2 on seedlings of Changbai larch developed root collar diameter, mean height, fundamental root length, seedlings the induction of chlorophyll synthesis [16]. Subsequently, silicon influences plant development under conditions of stress by influencing an assortment of cycles which covers plant water relations, upregulation of phyto defence, changes in ultra-construction of leaf organelles. The leaf spray of SiO2 on cucumber plant led to increment in number of fruits per plant, fruit diameter, plant height, number of leaves, etc [16].

Carbon Based Nanoparticles
Carbon is one of the few components which has the tendency to polymerize at the nuclear level, and therefore framing extremely long carbon chains. It is tetravalent in nature and nonmetallic, therefore it forms covalent bonds [17]. Carbon based nanoparticles include Carbon graphene [4], fullerenes and nanotubes.
Lately, Carbon Nanotubes (CNTs) have been the subject of broad examination due to their exceptional properties (chemical, mechanical, thermal) and wide scope of biotechnological applications [18]. Because of their extraordinary properties, they can infiltrate the cell wall and the plasma membrane and furthermore give an appropriate transport arrangement of chemicals to cells [1]. Because of these properties, they are widely used for pollution control, crop management, nutrient carriers, detection of pesticides and as nanofertilizers [18]. Multiwalled carbon nanotubes (MWCNTs) act as plant growth regulators which increases fresh weight of tomato plant [18]. The single-walled-CNTs (SWCNTs) help conveyance of various dyes and DNA into plants cells [1].
Fullerenes comprise of 20 hexagonal and 12 pentagonal rings forming a close caged structure [17]. The fullerene, C 60 and CNTs have been displayed to build the water holding capacity, fruit yield and biomass in plants up to ~118% which is a wonderful accomplishment of nanotechnology lately. When treated with the fullerene, the bitter tasting melon seeds showed increment in the phytomedicine constituents for example lycopene (82%), cucurbitacin-B (74%),insulin (91%), and charantin (20%). The fullerenes also act as antioxidants, antiviral and anti-cancerous agents [19].
Graphene is a 2D allotrope of carbon which is made of single layer of carbon atoms having sp 2 hybridized C atom [17]. Graphene is the most acknowledged nanoparticle for manufacture of biomedical sensors for bio imaging and bio sensing. It is curative because of its invigorating characteristics like exceptional surface properties, fluid processability and cell development capacity [20].

Titanium Dioxide Nanoparticles
Titanium dioxide (TiO 2 ) is considered as one of the useful components for plant development which finds its usage in agribusiness, consumer goods, and energy areas [8]. According to various studies, TiO 2 NPs led to advancement in radical and plumule development on Canola seedlings [1]

Silver and Gold Nanoparticles
Silver and gold nanoparticles (AgNPs and AuNPs, respectively), have been utilized progressively due to their potential benefits, like high stacking capacity and stability [3]. Gold and silver nanoparticles find their utilization in biomedicine as enhancers, immunomarkers and converters of the optical signal [22].
AgNPs when administered on Bacopa monnieri led to protein and carbohydrate synthesis in the plant. Also, an increase in leaf area, shoot length, root length along with biochemical properties (antioxidant enzymes, protein and carbohydrate contents, chlorophyll) was observed in Brassica juncea [1].
The effects of AuNPs were studied on Gloriosa superb that advanced seed germination. Overall, these increased chlorophyll content, surface area of leaves, height of the plant resulting in high yield of crops [1]. Viability of tissue infiltration of AuNPs depends on surface charge, particle size and plant species. AuNPs containing positive charge are taken up exclusively by plant roots through absorption. On the contrary, those contain negative charge move towards stems and leaves via roots [22].

NANOPARTICLES-A BOON TO PLANTS
Nanotechnology does the job of addressing distinctive natural and medical problems which occurs to happen with the unreasonable utilization of pesticides and fertilizers in horticultural practices. When used in an appropriate amount and concentration NPs like titanium oxide, sulfur, gold, zinc, carbon nanotubes, iron, copper, silver, chitosan NPK NPs show further developed plant development and an increment in crop harvest [9].

Plant Growth and Development
Lately, various examinations have been directed to investigate and portray the impact of NPs on crops [23]. Plants on interaction with NPs causing numerous physiological and morphological alterations which are entirely contingent upon the properties of nanoparticles. Adequacy of NPs is controlled by their size and shape, reactivity, surface area , charge and in particular the dosage at which they are operative and effective. Concentrations of NPs determine its efficacy which differs from plant to plant [1]. On treating soybean (Glycine max) with nano-TiO 2 and nano-SiO 2 , nitrate reductase activity was hastened thereby amplifying water absorption and utilization by the crop plant [24]. Water-stressed plants treated with SiO 2 NPs gave higher yield than those without the SiO 2 NPs application [25]. Graphene Oxide can be utilized to accelerate growth of the plant (root elongation, increases surface area of leaves), increase sugar content of and its ripening process [26]. The use of certain NPs can advance the movement of proteins like amylase, Carbonic anhydrase, phosphatase ,nitrate reductase, and phytase which are associated with digestion and supplement procurement [27].

In Photosynthesis
Photosynthesis is a vital process that converts light energy into chemical energy [1]. Ongoing advancements in science have started to exhibit that nanoparticles (NPs) can be manufactured and linked with photosynthesis resulting in increased crop yields [28].
When treated with nano anatase, higher activity of Rubisco was observed in spinach plants which was an outcome of increased rates of photophoryaltion, electron transport and evolution of O 2 [9]. TiO 2 and ZnO NPs can invigorate biogenesis of chlorophyll and photosynthetic activity [27]. TiO 2 NPs have proved to be beneficial in improving absorbance of light , in stimulation of CO 2 consolidation and acts as shield to inhibit ageing of chloroplasts from long brightening hours [1,29]. Titanium dioxide nanoparticles are useful in transfer of energy away from PSII, which enhances the proficiency in conversion of energy for PSII, in this way permitting more light to get absorbed [28]. Nanoparticles such as SWCNTs increased the photosynthetic activity by three times by upgrading mechanism of electron transport which assisted in detecting NO -a signaling molecule [1]. Single-walled carbon nanotubes (SWCNTs) when conveyed into the chloroplast lipid bilayers enhanced photosynthesis and electron transport [26]. Analysts have recognized transportation of electron out from the photosystems that can be useful in accelerating ATP synthesis and thereby photosynthetic activity. Studies suggest that QDs (quantum dots) behave as artificial light harvesting antennae distributing energy to LHCs [28].

In Agri Industry
In the farming sector nanoscience acts as a contributing factor in the fields of research and discussion in the present century. Due to extraordinary properties of Nanoparticles (NPs) these are termed as "magic bullets" in this sector [6]. Metal, metal oxide, composite and polymeric nanoparticles are applied to plants through different modes to enhance the crop yield and shield from pathogenic assault [12]. NPs can be utilized to shield plants from natural effects, for example, in salty or dry conditions, these refrain from settling of hazardous metals [27]. Utilization of NPs as nano pesticides, nano herbicides nanofertilizers, prove to be helpful in controlling over usage of synthetic manure, manage plant growth and development, their biological activity resulting in better crops efficiency, and furthermore increase survivability against biotic pressure [6]. NPs have come out as an excellent source of micronutrients. For example (Fe,Mn based NPs, ZnO), consequently expands wellness and assists plants to adapt to pressure conditions. TiO2 and iron-based NPs can defer senescence and accelerate cell division by means of changes in phytohormonal levels [27]. NPs might affect the plant development on the basis of species and the dosage used. What may be beneficial for one, might be harmful for another species [6].
The effects of AuNPs were studied on Gloriosa superb that advanced seed germination. Overall, these increased chlorophyll content, surface area of leaves, height of the plant resulting in high yield of crops [1].
Application of Nano-fertilizers boost the crop harvest by enhancing fatty acids, amino acids, reducing sugar content in a plant [23]. There are three different ways in which plant nutrients get distributed to their destination utilizing nano fertilizers.
Emulsions of nanoscale measurements [12]. ZnO NPs enhances plant growth and helps to curb the zinc deficiency [4].
Nano-herbicides are used to kill weeds and stop their spread further [6]. Encapsulated Polymeric NPs are extensively used .Chitosan NPs proved to be beneficial and less hazardous when utilized in encapsulation of paraquat [4]. Various nano pesticides like nano silica, are commonly used to control the spread of diseases in crops [6].

CONCLUSION
In Agri business, nanotechnology has been utilized to elevate the annual harvest with quality improvement by working on cultivation techniques [31]. Nanotechnology in farming is a clear-cut resolution for a high food supply demand due to ever increasing human population [12]. The rise of designed nanomaterials and their operation inside the boundaries of sustainable farming have reformed world agribusiness significantly by quick development to meet the ever-increasing food demand around the globe [31]. Agriculture waste can be utilized to synthesize NPs thereby, acts as promising substitute for waste management [12]. NPs can be orchestrated through green innovation by utilizing extracts from plants, algae, and agrarian waste. It would be a financially savvy, ecofriendly and simple to deal with in comparison to chemical and physical techniques [6]. The capability of nanomaterials empowers sustainable agricultural practices minimizing the environmental and health hazards. Despite all the advancements, there are a few pit holes in our insight regarding the take-up limit, acceptable dosage admissible and the toxicity of various nanoparticles. Further exploration regarding the same is required to resolve the advanced nano typified agricultural inputs and the way they interact with environment [31].