Guava (Psidium guajava), is one of the important and major fruit of the Pakistan. It is also considered as the apple of tropics. In Pakistan, area under Guava cultivation is approximately 66.6 thousand ha and yield production is 49.52 thousand tons.
It is enriched with water 82%, protein, minerals, vitamins and soluble fibers which makes it vital for the digestive system, immune system and reducing cholesterol level. Mostly due to attractive flavor and sweetness, it is eaten directly freshly plucked from tree.
However, international market for fresh guavas is small. Its byproducts are Juices and nectars, Jam and Jellies, fruit paste, canned whole and halves in syrup. Its commonly commercial varieties in Pakistan are Safeda, Allahabad, Karela, Seed less, Red fleshed and Apple colour.
Although this fruit tree has a great potential for production all over the Pakistan, but unfortunately insect and fungal attack during rainy season causes the severe damage to the plant.
Phytophthora parasitica, Fusarium solani and Macrophomina phaseoli are the major causing organism of fungal diseases which is responsible for gradual decline in production and death of under nourished, 1-5 years old guava trees. So there is a keen need to improve the potential of Guava plant and to develop disease resistant varieties.
For this purpose tissue culture is a best technique to develop resistant variety. Because it make the exact copy of plants whose cell or tissues were used to grow the plant. It creates plants in short period of time. Plants without seed can be grown through tissue culture. The whole plants can be grown by a single cell of genetically modified plant.
The formation of plants in sterile conditions reduced the chances of transmitting diseases, bugs, and pathogens. It is helpful because through seed chances of germination of a plant are very low.
Plant tissue culture relies upon the manner in which that many plant cells can produce a whole plant. Single cells, plant cells without cell wall, leaves, stems or roots can frequently be used to create another plant on culture media given the required supplements and plant hormones.
These are the methods which are used to grow disease resistant Guava plants.
- In Vitro or in Lab conditions
In vitro culture, Tissue culture is the best way for the growing different plants with in short time period. Tissue culture is technique used to grow plant cells, tissues or organs under sterile and controlled conditions on a supplement called as growing media. By Tissue culture best verities of guava are being produced all through the Punjab. Plant tissue culture is used to produce clones of a plant.
- Take energetic branches and make their pieces having size of (1-2 cm).
- Make sure these branches must contain two or three eyes on it.
- Clean these little pieces with bleach and wash with refined water.
- Place them into test tubes containing growing media and put these test tubes into growth room with perfect light and temperature (25-27 C°).
- Sprouting begins from these little branches with in one and half or two months.
- Segregate these little branches and set them into roots formation media.
When the most ideal roots develops then remove the little plants from the test tubes and set them into pots for the strategy of acclimatization in which plant set itself up to fight the outside environmental conditions.
After this move the plants into packs containing purified soil and put these packs into green house where these plants complete their improvement works out.
In Vivo or Field Conditions
Vivo mean the creating of seed typically in open field conditions. As the seed layer of guava is so hard so it retards the improvement of plant. So for best plant growth make a solution of 10% Sulphuric Acid carefully and rinsed each one of the seeds of guava in it for 10-12 hours and stirrer continuously.
This strategy will increase the growing rate at 80% extent and will also save the seed from other damages. For more care of seed rinse the seed in commercial bleach for 20-30 minutes and then grow them into the field. For better improvement of seed used sand.
Do not grow nursery direct into the field condition because many disease creating germs may be present in the soil. So first sterilize the soil and fill it into the plastic bags then grow nursery in it.
How to sterile the Soil?
Use the sun rays and decontaminate the soil by heat. This is an easy way and free of all the chemicals but can be used only in summer months. Use formalin to kill all the germs present in the soil. Make the 30% solution of formalin and mix it with soil after hoeing deeply then cover the soil for 3-4 days with plastic sheet it will increase the temperature and all the germs in the soil will be killed.
For certain cleaning the soil use the steam. This steam is passed through the soil at a perfect temperature for the specific time. This will helpful to make soil free from soil-born pathogens. After this transplant these plants created in the sand within the green house to the open field.
By the use of modern techniques we can improve our important fruit trees which will be helpful for the farmer to increase their farm income and export of fruits.
Authors: Ahmad Zia Khan, Mudassar Khan, Haroon Zaman Khan, Muhammad Atif Shabir, Amir Maqbool, Syed Ali Zafar, Ahmad Mukhtar and Muhammad Abrar.
University of Agriculture Faisalabad.
Nigde Omer Helisdemir University, Turkey.
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