Propagation of Ornamental Plants

Plants usually reproduce in two ways:

1. By seeds and
2. By vegetative parts of plant.

The letter method is very popular in the multiplication of fruit and ornamental plants.

Sexual propagation or propagation by seeds

This is the easiest method of propagation of plants. In this method the seeds are sown, covered with a layer of soil or leaf mould and watered. After germination the seedlings are allowed to grow up to 4-leaf stage and then they are transplanted in the beds or pots. In some cases the seeds are directly sown in the ground. These seeds originate by the union of male and female gamete. During pollination pollens of male reproductive organ female reproductive organ. When the ovules are fertilized by the pollens of the same flower the process is known as self-pollination. Cross-pollination occurs when the pollens come from a different source and usually the pollinating agents are wind or insects. Self-pollination occurs when the pollens come from a different source and usually the pollinating agents are wind or insects. Self-pollinated seeds are likely true to type or variety, but the cross-pollinated ones may not resemble the parents for all the character. After pollination, male gametes fertilize ovules resulting in the production of seed.

A sexual or vegetative propagation

The following are the reasons for propagating plants vegetatively:

1. Many plants do not produce seeds under local condition or have lost the ability of production of viable seed. It is found in several cases that plants which readily root from cuttings do not produce seeds e.g., Acalypha, Eranthemum.
2. Plants, which are cross-pollinated and have different varieties in cultivation, produce seeds of heterogeneous mixture. In such plants particular type can be maintained only by vegetative method or by careful crossbreeding with the same variety.
3. Double dahlias when grown from seeds show a wide range of colour and also a mixture single, and semi-double. Apple pear, peach, mango etc., do not grow true to type from seds.
4. Vegetative method of propagation results in earlier flowering and fruiting than those raised from seeds. Vegetative part of a fruiting plant is mature to bear, while a seedling take few years before the shoots ripen to produce flowers and fruits. Seedlings of Amherstia nobilis or Brownea ariza require 7-8 years to flower but a layer starts flowering in the second year.
5. Plants are also vegetatively propagated to increase their resistance or to develop immunity to particular disease or pest.
6. A well-rooted vegetative part of a plant can adapt more readily to new environment and has greater possibility to flower and fruit than a seedling.

Many parts of plant are capable of giving rise to new plants under natural condition.

Bulbs

Bulbs are underground-modified stem in which the central axis is much shortened and fleshy leaf scales are closely pressed. Amaryllis, Crinum, Hymenocallis, Hemerocallis and Haemanthus, are usually multiplied by bulbs which arise from the main bulb. Cooperanthes, Zephyranthes and tube rose are also manly grown from bulbs.

Corms

Gladiolus produces new corms and cormels on old ones, which are used for multiplication.

Rhizomes, tubers and fleshy roots. Rhizomes are defined as more or less cylindrical branches growing laterally or upward through the soil. Many ornamental plants such as Calathea, Anthurium, Alocasia, Alpinia, Hedychium, Heliconia, Gloriosa, Canna produce rhizomes or rhizomatours stem with buds on it which can be cut into pieces and each one will produce a new plant. Root tubers of dahlia are storage organs and shoots arise from stem attached to the tubers.

Runner

When a slender stem grows out of a crown and trails along the ground it is called a runner or stolon. Chlorophytum, Episcia send out stolons and produce young plants from the nodes. It is then detached and grown separately.

Offsets

Many ornamental plants are propagated by this method. Sanseviera and Agave americana send out branches terminating in rosette of leaves which ultimately grow as new plants. These can be separated from the mother plants. Chrysanthemums also produce offsets, which are detached for multiplication of plants. Gerbera also sends out suckers on offsets.

Root suckers

There are some plants, which produce suckers from roots and are detached from the mother plants for multiplication. Millingtonia hortensis, Clerodendron splendens, Quisqualis indica are few examples.

Trees

Most of the species of trees; grown in tropical conditions are raised from seeds. The seedlings with taproot grow tall and large and give necessary support against storm. Some species, however, often fail or produce seeds irregularly.

Seed

Species of Cassia and Poinciana regia, Thespesia populnea, Peltophorum ferrugineum, couroupita guinensis, Acacia auriculi formis, Pithecolobium saman, Saraca indica, Spathodia campanulata, Lagerstroemia flos-regineae and many other flowering trees produce seeds freely which germinate in seed compost consisting of garden soil and leafmould, one part each in bed or in seed pans. Seeds or mahogany have spongy seed coat and rot in excess moisture. Seeds of Polyalthia do not germinated if they become too dry. Seedlings of Eucalyptus and Jacaranda grow well in less humidity and temperature and should be sown in the spring.

Cutting

Plumerias root easily from stem cuttings. Cuttings are made in spring as excessive moisture in soil causes rotting. These are planted in sandy soil and light watering is done after callus formation. Plumerias produce large fruits containing many seeds but the seedlings do not flower before four years. Cutting from mature terminal shoot start flowering within few months. Gliricidia are also propagated from cuttings. In the case of Spathodia campanulata in addition to seed propagation, root suckers are also used.

Air layer and ground layer. Gustavia augusta, Brownea ariza and B. grandiceps though produce few fruits every year but the seedlings are very slow growing and are also propagated by air or ground layering. Ficus elastica and Ficus krishnae and F.benjamina are easily propagated from air layer.

Seeds

Few species of shrubs which produce seeds and the seedlings flower in one or two years without changing the character, are raised from seeds e.g., Galphimia gracilis, Cassia glauca, Cassia didymobotrya, Solanum macranthum, Tecoma stans, Sophora tomentosa, Brya ebenus, Callindra speciosa Bauhinia acuminata, B. tomentosa and Caesalpinia pulcherrima speciosa, Ochna wightiana, O.squarrosa, Carissa carundas, Jacquinia ruscifolia, Bauhinia galpinii, Portlandia grandiflora and Calliandra speciosa do not root easily from cutting and layering and so seed multiplication is commonly practised.

All species and varieties of Acalypha, Angelonia, Aralia, Asystasia, Buddleia, Cestrum, Daedalacanthus, Eranthemum, Graprophyllum, Justicia, Lagerstroemia indica, Malvaviscus, Pentas, Poinsettia, Russelia, Jasminum sambc, Brugmansia, Stachytarpheta and Thunbergia are very easily propagated from cuttings. In Aralia, Eranthemum, Pentas, Aphelandra and Daedalacanthus, tip cuttings produce quicker and better roots.

Green house plants

Greenhouse plants thrive in shade and grow well in high humidity especially during the hot months. These are mostly grown for beautiful foliage though flowering plants like Achimines and Pelargonium need suitable protection during dry and hot season.

Seeds

Plants can be raised from seeds of Coleus but to maintain a particular variety vegetative propagation has to be done.

Stem cutting

All the different species and varieties of Aglaonema, Philodendron, Anthurium, Scindapsus, Monstera and Dieffenbachia, have succulent stem which are cut into small pieces keeping one node in each and planted in ground or pot. The cuttings are planted horizontally about 1-2cm below the soil with the bud pointing upward. Several species of Dracaena e.g., Dracaena ugandense, D.victoria, D. deremensis "Bausii" D. reflexa "Variegata" are grown from top cuttings. The erect stem can also be cut into pieces with few nodes in each cutting and planted in soil. Top cuttings produce well-shaped plants after root formation, while shoots from lower cuttings have slower growth. Episcia, Syngonium, Gynura, Fittonia, Pellionia, Coleus, Zebrina Pendula, Setcrasea Purpurea, Perperomia, Pillea and Strobilanthes dyerianus are propagated from stem cuttings. It is safe to plant these soft cuttings in sand only. After root formation it can be transferred in pot or ground. Foliage begonias and African violets can be propagated from leaf cuttings but division is a safe method under our climatic conditions. Species of ferns, e.g., Nephrolepis, Pteris, Ptyrogramma, Polypodium and Davallia are divided with crown and rhizome. All palms produce seeds in suitable climate after attaining maturity. Pritchardia, Caryota, Livistonia and Oreodoxa often for seeds in Calcutta.

Ag.
Technologies
(Horticulture)