Plantlets and seed procurement

Seed orchards are a common method of mass-multiplication for transferring genetically improved material from breeding populations to production populations (forests) and in this sense are often referred to as “multiplication” populations. A seed orchard is often composed of grafts (vegetative copies) of selected genotypes, but seedling seed orchards also occur mainly to combine orchard with progeny testing. Seed orchards are the strong link between breeding programs and plantation establishment. They are designed and managed to produce seeds of superior genetic quality compared to those obtained from seed production areas, seed stands, or unimproved stands.

In first generation seed orchards, the parents usually are phenotypically-selected trees. In advanced generation seed orchards, the seed orchards are harvesting the benefits generated by tree breeding and the parents may be selected among the tested clones or families. It is efficient to synchronize the productive live cycle of the seed orchards with the cycle time of the breeding population. In the seed orchard, the trees can be arranged in a design to keep the related individuals or cloned copies apart from each other. Seed orchards are the delivery vehicle for genetic improvement programs where the trade-off between genetic gain and diversity is the most important concern. The genetic gain of seed orchard crops depends primarily on the genetic superiority of the orchard parents, the gametic contribution to the resultant seed crops, and pollen contamination from outside seed orchards

In addition to our seed orchids we contract farms for Seed Procurement to ensure quality input for maintaining a sound system for effective distribution of quality seed. The greater emphasis has to be placed on procurement ensuring compliance with the set best industry practices for production and multiplication of seed.

Plantations International created a means by engaging growers with large scale cultivatable area to multiply and produce certified seed, engage growers after survey of their properties by virtue of a legal binding agreement. These growers after registration with the Plantations International are provided with basic seed of major crops for multiplication and production of certified seed. The quality and purity of the seed is tested ad monitored at various stages by the continuous involvement of Plantations International. The certified seed produced by the grower is purchased by Plantations International at the rate agreed in the agreement for future supply.

The achievement of high crop yields is indirectly dependent upon the stringent controls exercised over the purchased quantities to ensure that they are free of inert matter and waste. The procurement department of Plantations International is vested with the responsibility to purchase high quality seed with the lowest percentage of inert matter. The variety wise procurement target is on the basis of demand and supply position of the relevant crop and approved by the committee.

Tissue Culture

Tissue culture, an important area of biotechnology can be use to improve the productivity of planting material through enhanced availability of identified planting stock with desired traits.

Micro propagation is one of the important contribution of Plant Tissue Culture to commercial plant propagation and has vast significance. The name micro propagation derives Item the miniature shoots/plantlets initially produced horn this method of plant propagation. Micro propagation is the true to type propagation of selected genotype using in vitro culture technique. This technique provides a rapid reliable system for a production of large number of genetically uniform disease free plantlets.

Nursery Multiplication System

Plantlets of the 3-5 leaf stage are moved from the Ziploc plastic bags to polybags or to nursery beds.  If they are planted in polybags (24x18cm size), each is filled with a 2-kilo mixture of sieved soil, sand and manure in a 1:1:1 ratio.  NPK can be applied by time-release fertilizer, NPK at 5:20:5 ratios at the rate of 55/220/55 lbs. per acre is applied.  This is about two tablespoons per bag of 5:10:5 fertilizers.  Another method would be to apply urea (N=46.4%) = 0.05gm/polybags @ 25 kg N/ha; super phosphate (P2O5=16%)=0.59gm/polybags @ 100 kg P2O5/ha; and murate of potash (K2O = 56-60 %) = 0.04gm/polybags @ 25 kg K2O /ha; this is mixed in 30 ml of water / polybag.  This mixture as time release fertilizer is put in the planting hole just before inserting the plantlet at the time of planting.  The plantlets are then fertilized at monthly intervals with urea (N=46.4%) = 0.05gm/polybags @ 25 kg N/ha; super phosphate (P2O5=16%) = 0.59gm/polybags @ 100 kg P2O5/ha; and murate of potash (K2O = 56-60 %) = 0.12 gm/polybags @ 75 kg K2O/ha; this is mixed in 30 ml of water/polybag is applied as a top dressing.

The plantlets with all the additional tillers, the rhizome and roots are carefully removed from the nursery bed or polybags.  Each tiller along with a part of the rhizome and roots, are separated by cutting the rhizome with sharp pruners or heavy-duty scissors.  These are the new propagules and they must be kept in high humidity or water until planted in another polybag.  During this whole operation the plantlets must not dry out.  The expected multiplication is over five new polybags for every old polybag divided.  Out of this group, the smallest propagules are planted back in nursery beds or the selected polybags are kept to propagate more plantlets (500,000 bags).  The remainder (2,000,000 bags) is grown for field planting.  By end of July, 3-10 tillers have formed in these polybags and the process is ready to be repeated.

The multiplied tillers of (100,000) propagules are retained for the nursery, and the other (400,000+) plantlets are grown out for field planting next year.

This cycle can be repeated for several years but eventually new stock plantlets must be supplied from the laboratory or nursery.  The bamboo stock plants derived from this system remain relatively small, which conserves nursery space, and is an advantage in transport to the planting site, as well as, in handling in the nursery.

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Techniques

Preparation of plant tissue for tissue culture is performed under aseptic conditions under HEPA filtered air provided by a laminar flow cabinet. Thereafter, the tissue is grown in sterile containers such as petri dishes or flasks in a growth room with controlled temperature and light intensity. Living plant materials from the environment are naturally contaminated on their surfaces (and sometimes interiors) with microorganisms, so their surfaces are sterilized in chemical solutions (usually alcohol and sodium or calcium hypochlorite before suitable samples (known as explants) are taken. The sterile explants are then usually placed on the surface of a sterile solid culture medium, but are sometimes placed directly into a sterile liquid medium, particularly when cell suspension cultures are desired. Solid and liquid media are generally composed of inorganic salts plus a few organic nutrients, vitamins and plant hormones. Solid media are prepared from liquid media with the addition of a gelling agent, usually purified agar.

As cultures grow, pieces are typically sliced off and subcultured onto new media to allow for growth or to alter the morphology of the culture. The skill and experience of the tissue culturist are important in judging which pieces to culture and which to discard.

As shoots emerge from a culture, they may be sliced off and rooted with auxin to produce plantlets which, when mature, can be transferred to potting soil for further growth in the greenhouse as normal plants.

Mass Production of Bamboo for Plantation Development

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