Off-season air layering in litchi needs special infrastructural facilities for successful propagation. The erection of net/poly house will enhance the viability of propagation period for 7-8 months and success percentage.
Hence, net house and poly house are required to be constructed. These structures with the facility of misting and exhaust (poly-house) to regulate the humidity and temperature in the microclimate will enhance the survival of detached layers. It should have enough ground space area to accommodate and maintain the propagated plants. The number, type, and size of such structures are need-based. To have an economically viable size proper lay out and planning of such structures are utmost important. Preparation of rooting media and containerization In the attempt of propagating litchi during the off-season, there exist some limitations. For good earth ball, loam or clay loam soil is required, and the earth ball carries some pathogens.
Preparation of rooting media and containerization
In the attempt of propagating litchi during the off-season, there exist some limitations. For good earth ball, loam or clay loam soil is required, and the earth ball carries some pathogens.
Solarization has been found effective and eco-friendly to reduce the pathogen load, which involves trapping of solar radiation through polyethene covering. This raises the temperature of media to the level, where it becomes lethal to temperature sensitive/ mesophilic soil microorganisms, in general litchi, air layers, require soil as rooting media, which may get infected with soil-borne fungi, nematodes, etc., requires special care and attention while used.
In the case of litchi propagation through air layering, white plastic cover as wrapping material is utilized. For p0tting in the nursery and easy for sale out the propagated plants, poly bags of appropriate size and strength are essentially utilized to avoid the tedious process of uprooting and re-potting in the nursery. It is quite cumbersome to sterilize the whole soil and hence the moss grass as rooting media are preferable, though it is expensive.
The trial on off-season propagation through air layering in the form of field experiments conducted on litchi plants cv. Shahi during 2007-08 & 2008-09 at NRC for Litchi, Muzaffarpur, with the integration of some imposed treatments along with a normal season traditional method of air layering practice. One hundred plants were kept in each treatment. The nine treatments comprised with the combination of polythene sheet cover over the entire tree, vegetative branches girdling and with or without IBA application as well as soil and moss grass wrapping as rooting media in the off-season and main season were imposed.
The modification in environmental condition (w.r.t temperature & humidity) enforced during the off-season
For three months, i.e., February to April each year by polythene sheet cover during night 12 hrs (7 PM to 6 AM) and making open ventilated during day time (7 AM to 6 PM). The used rooting hormone IBA had concentration @5000ppm. Air layering was done on current season growth of non-bearing ones (preferably of pencil thickness) by removing a bark ring of 2-3 cm from the base, applying the rooting media as prepared soil (100-125g) and sphagnum moss (25g) ), which was then wrapped around this exposed area and wrapped/sealed off with a polythene sheet binding.
Air layers were made at the start of the growing season, immediately after the fruit set period (last week of February) and that of the main season in July (last week). After about the recorded period, the roots can be seen through the plastic wrappings and air layers are ready for harvesting. The air layered litchi sticks were cut from the mother tree just at the base of the girdled area and as before transplanting (where roots are well developed) is shivered to half cut for 4-5 days and then detached finally from the original and the removed ones then planted into three situations (200 numbers in each situation) for the study of survivability (%).
The planted air layers are kept under 50% shade under shade-net nursery soil bed and in polythene bags as well as in open orchards and have regular irrigations which are essential. The new roots begin to adapt their environment and the young plants soon start to flourish after a few weeks.
These are gradually be hardened off after 1-2 months, the final survival was counted and are then ready for sale, and accordingly, the cost-benefit ratio was also calculated.
National Research Centre for Litchi