Sunday, June 27, 2010

Chitosan for tropical plants

Quick experiments here showing that Chitosan ( Poly-D-glucosamine )applied to plants reduces stress from foliar evapotranspiration. Preparing tropical plants for export and travels of several days bare roots put plants under the stress of foliar evaporation ( water loss from the leaves ).

aleyagarden CHITOSAN with Synsepalum seedlings_test_1

Fragile Synsepalum dulcificum seedlings will make our first test.

Seedlings of
SYNSEPALUM DULCIFICUM have grown only 4 weeks in a light soil mixed with coco fiber; their stems are still very thin leaves are young so these plantlets are prone to stress.

After washing out the roots with water ( a gently dip suffices, no soil particles are firmly attached ), 5 plantlets are dipped in our CHITOSAN solution and 5 are not. The two groups are wrapped separately using two dry papers during 3 days, our temperature being 25 - 33 Celsius with a high humidity of the air : such conditions of heat coupled with lack of water soil put much stress on the bare rooted plantlets. On day 2, by applying the hands on the paper we clearly feel that much less evaporation has occurred from the plants treated with CHITOSAN .
After day 3 the two groups are separately grown under plastic sheet in a a pot ( below ). Until day 4 it looks like all plantlets will survive. But on day 5, one of the non treated plantlets die. On day 6 the results are shown below :

Plants are divided in two groups : treated, non treated.

The group of the 5 untreated plantlets on the right side ( a piece of bark separates the 2 sides ) have not dried out yet but they are obviously on the verge of dying. On the left side with the 5 CHITOSAN treated plantlets, 2 are in a bad shape and 3 seem to have recovered definitely.

On day 7 the result are as follows : the 5 non treated plantlets have died while in the 5 CHITOSAN treated plantlets ( with a yellow point below ), 3 have recovered.
Non treated plantlets with Chitosan have died
Non treated plantlets with Chitosan have died
Now the idea is to test 20 Synsepalum sprayed with CHITOSAN a week before packing and see how they react to different packing conditions. The plants are 40 cm high and about 2 years old. Rooting soil is washed out :

Synsepalum dulcificum roots are washed : dipping in clear water is not efficient if the plants must pass through a strict phytosanitary control : many bits of soil and dirt are still attached to the roots; using hands to withdraw them would stress the roots and take time; whereas at this stage speed is the key to a good survival rate.
Hence we use a fine mist of water under pressure to remove fast all the attached soil particles.
The 20 Synsepalum are dipped in pesticides and fungicide, then divided into 4 groups to test the effects of using CHITOSAN dipping and PLASTIC BAG for a 3 days stay in cartons.

Four sorts of Chitosan use




Plant gel keeps roots from drying out Plant gel and moist paper will prevent the roots from drying out during 3 days in the carton. On day 4 the 4 groups are unpacked and potted in a well drained soil mixed with coco bits , rice husk and charcoal.

Synsepalum before repotting Fom day 4 to day 10 the 20 plants are put with their pots under close plastic bags. ( a single big bag for several plants ).

Synsepalum dulcificum restarting in closed plastic bags

Synsepalum dulcificum are restatring in closed plastic bags without watering.

Our temperature ( we are in the rainy season ) is from 25 Celsius at night to 33 daytime. It rains long hours almost every day outside the bags.

On day 11 the plastic bags are open. We don't have the contrasted results of our test # 1 above with the plantlets lacking moisture during 3 days in cartons; in this test # 2 the plants without CHITOSAN dipping look slightly more stressed, but all of the 20 plants are in a very good shape, whatever be their group. Based on the results of our test # 1 we link this good shape to the spraying of CHITOSAN several days before packing.

Synsepalum dulcificum unpacked
Synsepalum dulcificum unpacked

In horticulture solutions of Chitosan are multifunctional : natural substance extracted from shrimp skin, it is an efficient reducer of foliar transpiration and a fertilizer. It is also a growth stimulator in tissue culture and an active ingredient of bactericides and fungicides for crops, ornamental plants and turf.
Owing to its transpiration reducing properties it is particularly recommended when tropical plants face environments with lower than standard humidity levels of the air. Many phyto-caring products intended to increase resistance of plants to pathogenic agents and environment include Chitosan as the main ingredient of their formulation. These products also include vitamins and hormones. ( Besides, Chitosan is a bio-material known in Medicine for its valuable applications in surgery. )

0.2 to 1 gr diluted in salicylic acid or any other non phyto-toxic acid will add to water to make 1 liter of solution.

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