Zinc-oxide-nanoparticles-to-mitigate-salinity-in-tomato.

Tomato (Solanum esculentum) is an annual vegetable crop and is widely distributed. It belongs to Solanaceae family. It can be taken as raw or cooked or may be used after processing like canning, used in juices, paste, pulp, or as a variety of sauces.

By Filza Ishfaq, M. Mujahid Ismail, Farhat Naseem, Hira Razzaq,Safura Bibi, Maria Naqve, Anjum Zia, Athar Mahmood

As tomato is a moderately sensitive crop (grow in little salty soil) but when it faces salt in higher amount then its growth and development is disturbed. Young plants cannot tolerate this environment and die at their early developement stage. To overcome this problem, advanced nano-technology is introduced. Nanotechnology is broad and versatile field. Zinc oxides (ZnO) nanoparticles are used to reduce salt stress in tomato and the growth of plants gets normal.

Nanotechnology

The “Nano-Era” that comes in 1990s is a new field of science and technology for researchers. The size of nano-particles is in between 1 to 100 nm. Nanotechnology (NT) improves the ability of plants to absorb minerals and also enhances the properties of soil.

Nanoparticles

It is defined as the small object that acts as a whole unit in term of transport and properties. They are very smaller in size and can easily mix with the soil. There are many methods through which nanoparticles can be synthesized i.e., physical, chemical or biological. According to FAO reports, there is a major challenge among scientific community to increase 70% food crop production towards world agriculture for an additional 2.3 billion people by 2050 worldwide. NPs can be engrossed by foliage and transferred to all plant tissues via above ground organs and cellular structures

Effects of Salinity on Tomato

Germination

Germination of tomato seeds is disturbed due to presence of salts. The effect of salinity on germinating seeds in tomato is not only on lowering the percentage of germination, but also on lengthening the time needed to complete germination.

Growth

Salinity decreases the root and shoot length, root fresh and dry weight, shoot fresh and dry weight but with the application of calcium we can reduce these negative effects occurred by salinity. Due to salinity leaf area decrease which affects the rate of photosynthesis. When plant faces salt stress then roots will be affected first. Growth, structure and functioning of roots changes and roots cannot absorb nutrients and water more. As a result, whole plant is then affected when roots are growing in salty medium.

Hormones

Plant hormones are molecules produced in low concentration to regulate the cellular processes in tomato plant like abscisic acid (ABA) stimulate seedling (baby plant) growth and gibberellic acid (GA) is on the weakening mechanical restraint of the endosperm. ABA and GA contents in the seeds depend on the genotype and on the environmental conditions in which seeds are developed. But these hormones are disturbed due to higher concentration of salt.

Fruit Quality

It is believed earlier that fruits of tomato plants grow under saline condition possess higher quality. Fruit quality is also disturbed by salt in higher concentration and it affect the size of tomato (size of tomato is decreased or small).



Zinc-oxide as Nanoparticles Disease in tomato fruit under salt stress

Salinity produces blossom end rot which makes fruits unacceptable for both the fresh market and the processing industry.

(ZnO-NPs) Induce Salt Tolerance

In recent research, tomato plants were subjected to salt 150 mM NaCl at the time of transplantation. Foliar application (applying fertilizer directly to plant’s leaves) zinc oxide significantly increased shoot length, root length, leaf area and chlorophyll content in the presence of salts. When tomato plants are treated with zinc oxide nanoparticles different ratios 0, 2, 4, 8 or 16 ppm for 15, 30 and 45 min and after application (45 days)  this treatment increases photosynthetic efficiency together with antioxidant system. These both are disturbed due to higher concentration of salt in the soil. Nutritional arrangement of tomato depends on the quantity and type of the nutrients taken from the growing medium such as foliar application. For that purpose, enough amount of micro-nutrient Zn in the form of ZnO-NPs is important for tomato fruit production.

Foliar application (the spray of nanoparticles on leaves) gave the most influential results in term of healthy growth of root, shoots, seed germination, and efficiency of photosynthetic rate. It makes the defensive of plants strong against diseases. More attention is given to increase the quantity and quality of tomato production.

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Importance of Zn Nutrients on Tomato Plants

  • Zinc is an essential micro-nutrient that increases the enzymatic reaction and also improves photosynthesis and antioxidant potential of tomato plants.
  • Controlling the generation and detoxification of free oxygen radicals, which affects the lipids of membrane.
  • Zinc in combination with boron, regulate synthesis of auxin and growth of cell walls.

Limitations of Nanoparticles

  • Some negative effects of nanoparticles on biological systems and the environment like chemical hazards on edible plants after the treatment with high concentration of nanoparticle. As size of nanoparticles is very small so they can easily enter into the biological system which is not possible for the larger particles. These can be inhaled easily by the workers of farm while spraying and this can reach the blood and may reach the target sites such as brain, liver or heart.
  • Nanotechnology should be carefully evaluated before increasing the use of nanoparticles as it generate free radicles in living tissues leading in DNA damage