Chitosan is playing very vital role in post-harvest technology by increasing shelf life of fruits and vegetables and extending vase life of flowers. It is applied to soil in case of nutrient deficiency and to cope with seed and soil borne diseases. It was declared first time as bio-pesticide when space shuttle of NASA grown plants in space and there they applied it and so, activity of beta,1-2 glucanas enzyme was enhanced resulted in increase of biomass and resistance to pathogens. Its fertilizers are applied in organic farming.
It has ability to boosts nutrients uptake of plants, stimulates flower process. It makes plant able to cope with environmental stress, seed vitality and plant vigor. Its salt solution increases resistant to freezing injury.
Chitosan is used to cure different diseases in plants. Its bio-control ability protects plants from harmful pathogens, microorganisms and insects. Normally low molecular weight chitosan is used in horticulture. Here is another interesting example; people spray chitosan on “Christmas Tree” to maintain it in good condition for long time. It is also used in bio-printing.
Response of fruit crops to chitosan
It did not change the taste, appearance and smell of fruits when applied. Chitosan was spread on strawberry fruits for 20 days. It reduces 99% anti-microbial agents.
In post-harvest by edible coating on fruits it decreases respiration rate in apple and retarded browning in apple. Increase total phenolic contents and antioxidant activity.
After harvesting and making edible coating around fruits, it increases total phenolic contents and antioxidants activity in apricot.
During post-harvest handling of fruits dipping with by hands, it results delay in ripening of fruits, change in peel color, firmness and soluble solids and decrease diseased severity in banana.
By using post-harvest technology fruit dipping with chitosan, improves vitamin c synthesis, increase total phenolic and anthocyanin contents in cherry.
In post-harvest fruit dipping with chitosan results in protect from fruit decay in citrus. It also improves firmness, titratable acidity and water contents in citrus fruits.
Coffee enhances leaf chlorophyll in leaf and net photosynthesis by foliar application of chitosan on seedling.
With the help of post-harvest technology, fruit dipping of dragon fruit with chitosan maintained post-harvest quality (weight loss, increased fruit firmness and titratable acidity. It increases total phenolic contents, flavonoids, lycopene and antioxidants. And it delays increase of respiration rate.
Addition of chitosan as filler in wounded fruits, increases fruit firmness, titratable acidity and vitamin C in peach. Dipping of bruised fruits in chitosan solution extended shelf life of yali pears.
Spraying on clusters of grapes possibly decreased weight loss, super oxide dismutase activity and decay index. After dipping of root cuttings before planting, improved rooting of cuttings as well as increased leaf chlorophyll contents under normal and drought conditions.
Reduced weight loss, improve yield, inhibit vitamin C synthesis, reduced anthocyanin and total phenolic contents in strawberries.
On kiwi fruits its spray on field grown plants every 2-4 weeks increased fruit fresh weight after 3 years of application.
During post-harvest operation fruit dipping in litchi maintained anthocyanin and oxidative enzymes composition. Fruit coating inhibited decay during storage. It reduced PPO and POX activity so retained membrane integrity, prevented decline in pericarp color during storage. It retarded weight loss and sensory quality decline.
Application of chitosan in the form of fruit coating on papaya decreased respiration, increased glucanase enzyme activity.
Response of vegetable crops to chitosan
Enhanced seed germination in artichoke was seen, when chitosan was applied as seed coating after harvest.
It is also proved more effective when applied in the form of fruit coating in post-harvest application and increase shelf life of bell pepper fruit,
In chilies it increases height, canopy diameter, leaf number, leaf width and length after the soil application of chitosan.
Increases leaf number, height, branches and fresh weight in indian-spinach, when plant sprayed during growing season.
Foliar application of chitosan increases plant height, leaf number relative growth and yield of okra.
But plant spraying two weeks on oregano crop before anticipated flowering time increased plant height and growth.
It reduces plant transpiration in pepper, net photosynthetic rate in okra and decreases seedling death in watermelon.
It increases photosynthesis, plant growth, sprouting and germination after seed treatment in sugar beet and potato.
Response of flowering plants to chitosan
Seedling pretreatment and soil application of chitosan promoted seedling growth and induced earlier flowering in chrysanthemum.
After corms dipping of gladiolus in chitosan solution before planting leads to increase emergence/germination, number of flowers, increases the vase-life and increases number of cormlets.
Increase in relative chlorophyll contents, increases corm weight, plant height, induced early flowering and increase in number of inflorescence was observed in freesia.
After comprehensive examination on tulip flowers it was proved that vase life of tulip was increased by application of chitosan.
Seedling pretreatment and soil application promoted seedling growth and induced early flowering after application of chitosan on monkey flower. Persian violet flowering plants also showed same results as was observed by monkey flowers.
Promoted seedling growth and induced earlier flowering was found after its application of wishbone flower seedling plants.
1Mujahid Ali, 2Dr. C.M. Ayyub, 2Dr. Iftikhar Ahmad, 2Mohsin Bashir,
1NCSU (US), 2IHS (UAF)