Session 27

Anthurium


Contents

Introduction

30.1 Plant characteristics

30.2 Propagation

30.3 Breeding of Anthurium

30.4 Cultivation of Anthirium

30.6 Pests and Diseases

30.5 Harvesting Anthurium flowers

Summary

Objectives


Inroduction

Anthurium is one of the most popular of the tropical cut flowers which are being grown commercially for export as well as for the local market. The anthurium belongs to the complex family Araceae. Within the family Araceae, Anthurium is the largest genus, which comprises of some 900 varieties, including well-known cultivated varieties Anthuriurn andrenum and Anthurium scherzerianurn.

Anthurium varieties are common throughout South and Middle America. The northern boundary of distribution area lies near the Mexican town. Anthurium varieties are found in areas with widely different climatic conditions; from the dry regions of Mexico to the tropical rain forests of South America. The location altitude is species-related, varying from sea level to heights of 3000 meters.

Anthuriums are cultivated for its attractive long lasting ‘flower’ which is not really a flower but an inflorescence rising from the base of a bract. The morphological features of the plant are described in Botanical description of the plant


Anthuriums are propagated vegetatively, and this is dealt with under Propagation.

New varieties of Anthurium can be developed through hybridization and seedling production. This is the focus in Breeding of Anthurium.


Climatic requirements for the growth of Anthurium and the agronomic practices to be adopted in growing Anthurium are described in detail under Cultivation of Anthurium.

There is no serious damage in Anthurium due to pests, except for thrip and mite damage during a dry spell. It is affected by Anthurium bacterial blight and Anthurium root rot. Symptoms of theses diseases and their control are discussed in Pests and diseases.

Anthurium should be harvested at the correct stage and packed properly for transport. These are explained in Harvesting and packing.

27.1 Botanical description of the plant

A common feature of the Araceae is the typical, cup-shaped inflorescence. It consists of numerous flowers closely arranged in a spadix together with an outer colourful heart shaped sheath called spathe. Flowers are inconspicuous, hermoproditic with two carpelled ovary and four anthers (Fig.27.1 ). The sepals and petals are rudimentary, stigma appears as a rounded protuberance on the spadix when it is mature. Pollen matures week to ten days after stigma becomes receptive to prevent self pollination. The large variations in inflorescences are due to the variations in shape, color and the size of the spathe and spadix.



Figure 27.1 An inflorescence of Anthurium



27.2 Propagation

Anthuriums are propagated vegetatively by stem cuttings, axillary shoots or suckers and sexually by seeds. Propagation via seeds can be done when Anthuriums are cultivated as a hobby but not suitable for commercial cultivations, since it is a strict cross-breeder and the offspring are strongly heterogenous. On the other hand, vegetative propagation gives rise to plants that are similar to the parent and it is the best method for clonal propagation.

Stem cuttings are prepared by cutting the basal portion of plants into sections, each containing at least a single dormant bud. These sections are treated with a suitable fungicide and partially buried in a mixture of equal parts of coarse river sand and leaf mould in a bed or shallow box. The cuttings are kept in the shade under high humidity for a few weeks when dormant buds produce new shoots. Once they develop roots, they can be transferred into polythene bags or containers.

Suckers produced by mother plant are also good planting material but a plant produces only 2-3 suckers per year. Using these methods sufficient plant propagules cannot be produced for large scale commercial planting. In-vitro propagation is a reliable, fast method of obtaining a large number of clonal plants from a single mother plant.


Tissue culture of Anthurium


The micropropagation of Anthurium can be done with meristems and leaves as explants. However, both explants have their own culturing problems. It is very difficult to isolate meristems and establish them in sterile culture due to contaminants. The number of meristems per plant is also limited. However, a major advantage of propagation via meristem culture is that there are virtually no genetic deviations (mutations) in the offspring.


The plantlet development can be induced on pieces of leaves in culture. A large number of pieces can be cut from a single leaf and they can easily be made sterile. A disadvantage is that the induction of plants on leaf explants does not always go smoothly and varies with the variety. There is also a danger of mutations, since the plantlets are also produced from the callus that forms on the edges of leaves.



Activity 1

Complete the following table to compare the advantages and disadvantages of different methods available for propagation of Anthurium.

Method of propagation


Advantages

Disadvantages

Seedlings

Stem cuttings

Suckers

Meristem culture

Leaf explants













Refer section 27.2 to check whether your answer is correct.

27.3 Breeding of Anthurium

Though seedlings are not suitable for commercial cultivation of Anthurium, new varieties can be developed through hybridization and seedling production.

When parent plants are selected for hybridization, one should look for desirable characteristics in colour, shape, size and substance of the flower and also other characters like the length and size of the flower stalks and yielding capacity.

The stigma becomes receptive soon after unfurling of the spathe. The pollen is shed after 12-15 days after opening of the flower and production of powder like pollen can be observed on the spadix. Pollination does not occur within a single spadix and therefore for pollination, pollen is collected from the male parent and applied on the sticky receptive spadix of a mother plant with the help of a camel hair brush or with fingers.

Pollinated spadix is kept covered with a polythene cover for some time to avoid unknown crossings by insects and other means. If pollination and fertilization are successful, the spadix begins to thicken gradually and take on a warty appearance.

Seedling production

Anthurium fruits are berries, takes about 5-6 month to reach maturity. Mature berries are either yellow or orange in colour and protrude from the spadix. Each berry has one or two seeds embedded in a gelatinous sap. Ripe fruits are collected seed extracted by gently pressing the berries in water. They are washed in several changes of water and then in a disinfectant solution. A shallow pot or seed pan can be used to sow seeds. In preparing a pot or a pan for germination of seeds a layer of crocks is placed at the bottom of the pan followed by a layer of decaying leaves. Then the pan is filled with an Anthurium potting mixture. On the potting mixture is placed a layer of half inch tile pieces. Seeds are sown thinly on this layer and covered with a glass pad and the pan is kept in a shallow tray of water so that seed is kept moist through capillary action. Seeds start germinating immediately after sowing. When seedlings have developed about two leaves each, the pan may be removed from the tray of water, and seedlings watered in the normal way. 4-5 month after sowing, the seedlings are transferred to individual polythene pots.


27.4 Cultivation of Anthurium


Climatic requirements


Anthuriums thrive from sea level up to about 4000 feet elevation under mild and warm temperatures in the wet zone of Sri Lanka. The suitable areas for anthurium culture are found in the mid country where the temperatures are mild.


In the hot lowlands, leaf scorch and flower scorch may occur owing to high temperature and sunlight. When Anthuriums are grown in such areas, high light intensity should be controlled by effective shading. However, higher temperatures and higher relative humidity are favorable for growth and consequently more flowers are produced under such environmental conditions.


Anthurium is a tropical plant. It can be grown in a range of temperatures from 140 C to 350C. The optimum day temperature is 22-25°C and a night temperature is 18-20°C. The optimum light intensity is about 20,000 Lux.

Anthuriums are moisture loving plants but they cannot tolerate ‘wet feet’. They need good drainage and aeration at the roots. Anthuriums prefer a high atmospheric humidity for vigorous growth and a day time relative humidity of 70 percent has been found to be ideal.


Shade


Anthuriums do not produce good quality flowers when grown in the open. Shade must be provided for vigorous growth and flower production. For optimum performance, shade levels ranging from 70-75% are recommended. Such shade levels can be provided by growing the plants in lath houses, coir mesh enclosures and shade net houses.


Shade houses made out of nets are the most common among Anthurium growers at present. It is possible to provide the correct shade levels with these nets. Frameworks of net houses are made of L iron or galvanized pipes and the frames are covered with netting of required shade level. The netting of different shade levels is available in the market. The netting should be fixed at or below a height of 11 feet to get the correct shade level. The sides of the house also should be covered with net.

Anthurium can also be grown under the natural shade of trees. However this method is not recommended for commercial cultivation.


Cultivation systems and substrates

Different growing systems and substrates are used in Anthurium cultivation. The most common system among large scale growers at present is the use of cultivation beds.

Cultivation in beds

A cultivation bed consists of plastic foil (0.1mm thick), with a drainage tube for removing excess water located at the lowest point. The side of the bed can consist of a strong polystyrene sheet or other strong material such as wood. In general, the bed has a width of 1.2 to 1.4 meters. A cultivation bed as seen in a cross section is given in Fig.27.2 The bed is located on a small slope of about 0.03 percent (3cm per 100 meters).




Figure 27.2 A cultivation bed in cross section



Anthuriums are also cultivated in polystyrene gutters.

Gutter cultivation

Cultivation in polystyrene gutters is very new. There are two types of gutters, V shaped gutters and W shaped gutters. Two rows of plants are planted in a V-shaped gutter. In W-shaped gutters a row of plants is planted in each gutter. A plastic sheet is placed in the gutter, on top of which is placed a drainage hose and the substrate (Fig27.3)

Pot culture

Anthuriums can also be planted in pots. A dripper spike is inserted in each pot. Each dripper spike should provide the same amount of water. Dripper spikes can also be blocked when necessary.




Figure 27.3 V-shaped and W- shaped gutters in cross section



Substrates

In choosing a substrate to fill gutters, it is important to select a material with a stable structure. At the same time, the substrate must provide sufficient room for the roots to grow and to store oxygen. When Anthuriums are growing naturally in the forest, roots hang in the air or grow on stems covered with moss. They absorb water and oxygen from the moist air or from the surface of stems. Various substrates are used in cultivation of Anthurium at present and some of them are polyphenol foam, peat, and coir.


Polyphenol foam (Oasis)

Polyphenol is made from petroleum products. Due to the presence of minute pores, it retains much water. For Anthuriurm cultivation, Oasis is of granules, with much air between the granules. Oasis has no buffer capacity for nutrient elements therefore, it is necessary to have a good irrigation and a fertilizing system. Once Oasis dries out, it is poor in water absorption.


Rockwool

Rockwool has long fibers, and binders are added to improve water absorption when used in horticulture. It has no buffer capacity for fertilizers. Due to its sensitivity to skin, it is seldom used in the cultivation of pot plants.






Peat

Coarse, slightly decomposed peat is normally chosen as a substrate. It has a high percentage of air and is very stable.


Coir

The chemical and physical properties of coir are closer to peat moss than any other substrate component. Therefore, coir is used very often as a partial or total substitute for peat moss. Coir holds moderately less water than peat moss but is better aerated. A decided advantage of coir over peat moss is its superior rewetting capacity. When allowed to dry beyond a desired point, peat moss repels water, while coir continues to absorb it. Due to the higher salt content in coir, it must be treated before using it as a medium.

The coconut chips or a mixture of compost and coconut chips are also used locally, to cultivate Anthurium. In what ever form the coir is used, it should be replaced before it decomposes, otherwise, decomposed coir with low drainage and aeration promotes disease infection.

Royal Botanic Gardens, Peradeniya recommended the following growth medium for anthurium cultivation in 1977, which gives very good performances under local conditions.



Leaf mould 2 parts

Cattle manure 1 part

Sand 2 parts



Irrigation


There are number of ways of irrigating and fertilizing anthuriums.


Natural irrigation through rainfall


In this system, rain is the major source of irrigation. Manual watering is practiced during the dry period. Fertilization can be done with the use of slow-release fertilizers (such as Osmocote or N: P:K granule mixture ) or manually pouring the fertilizers on the bed.


Sprinklers above the crop


In this system, sprinklers are hung above the crop. Water from the sprinklers uniformly wet the beds and plants. Spraying water slowly dissolves the slow-release fertilizer that is added to the bed or the fertilizers can be manually poured on the bed.




One sprinkler line per bed for irrigation and fertilization


A single row of standing sprinklers is fixed 2-2.5 feet above ground level to wet the bed completely. The distance between two sprinklers is determined by the wetting diameter of the sprinkler head. Fertilizer is by the use of slow releasing granules.

Two sprinkler lines per bed for irrigation and fertilization


This method is also similar to the previous method. The only difference is the use of two sprinkler rows along the each border of the bed. Each sprinkler rotates and wets only half a circle of the bed.


Four internal drip lines per bed for irrigation and fertilization.


This is the most preferred method for bed culture. A drip line is installed along the plant row and there will be four lines per bed with four plant rows. Drippers of each line are placed at the base of a single plant and each plant is supplied with a dripper which would wet only the base of that particular plant. A recommended liquid fertilizer can be supplied with the irrigation water. The other advantage of drip irrigation over the sprinkler system is that, it does not wet the leaves minimizing the spread of disease.


A pot system with one dripper spike per pot for irrigation and fertilization


This method is used in pot culture of Anthurium. The dripper spikes are fixed to each pot to water the plant. The advantage of this system is that the dripper can be removed easily and transfered to another pot.

Sprinkler systems are often used in Anthurium cultivation, because they are easier and cheaper to install, and offer more advantages than drip systems. Sprinkler systems also help in increasing humidity.


A disadvantage in the use of a sprinkler system is that, it can damage leaves and flower buds as they get wet with water containing fertilizer. The symptoms of damage are similar to those caused by thrips. The damage can be minimized by lowering irrigation pressure, so that less feed water gets into the buds. As the plants grow, and the buds rise above the sprinkler heads, the growing points remain dry and the damage can be avoided.

Fertilization


The ideal pH for the Anthurium cultivation is around 5.7. For cultivation of Anthurium, the water should have sodium and chlorine percentages below 3 mmol/lite, and bicarbonate below 0.5mmol/liter. Sodium and chlorine raise the EC and since Anthurium is salt-sensitive, a high EC could result in lower production, smaller size flowers, with shorter stems.


A fertilizer mixture of N: P: K in the proportion of 6:14:7 has been recommended by the Royal Botanical Gardens for their leaf mould based medium.

It is better to supply Anthurium with fertilizer via irrigation water at the roots rather than as a foliar spray. Since Anthurium leaves are covered with a thick layer of wax, absorption through leaf is poor. Another advantage of fertilization via irrigation water at the roots is that, the leaves and flowers remain clean. Table 27.1…shows the amounts of macro elements and trace elements to be supplied with the irrigation water.


Table 27.1 Macro elements and trace elements to be supplied with the irrigation water.






Vegetative phase (0-11months

Generative phase>12month)

NO3

10.6mmol/L

8.0mmol/L

H2PO4

1.5

1.5

SO42

1.0

1.75

NH4

1.1

1.0

K

5.5

5.5

Ca2

3.0

2.5

Mg2

0.75

0.75

Fe

15(umol/L)

15(umol/L

Mn

5

5

Zn

3

3

B

10

10

Cu

0.5

0.5

Mo

0.5

0.5

EC

1.7

1.5

PH

5.8

5.8



27.5 Pests and Diseases

There is no serious damage in Anthurium due to pests, except for thrip and mite damage during a dry spell.


Anthurium thrip


Anthurium thrip is a common pest in anthurium. They suck the sap of young parts using their rasping and sucking mouth parts, which results in white colour patches on newly opened leaves and flowers. Proper sanitation and frequent mixing of growth medium are the best management methods. Spraying insecticides such as Imidocloprid, Carbosalfan and Dimethoate is effective in management, but spraying time should be decided using field observations of population levels.


Mite


Mite damage is very high during dry periods, which can be managed well by reducing the ambient temperature. Miticides can be sprayed during severe infestations.


Slugs and Snails


Slugs and snails become a common problem in compost and coconut husk based media. They eat succulent parts of the plants during night and hide in the medium during day time. Proper sanitation and hand picking can be practiced to minimize the damage and baits containing metaldehyde used as chemical control.


Diseases


Anthurium bacterial blight


This disease is a recent introduction into the country. It is caused by Xanthomonas campestrist pv. Diffenbachiae bacteria, and spread mainly through the watering equipment, and planting material. Prominent symptoms are yellowing of leaves followed by drying of yellowed areas and eventually, complete drying of plants. Recommended management practices are strict sanitation and uprooting and burning of infected plants.


Anthurium root rot


Several lower fungi can cause root rot of Anthurium. The disease incidence occurs mainly due to water logging and poor aeration in the growth medium. The infection can be minimized by providing good ventilation and drainage at the root zone. Captan, Thiram and Metalaxil are the common fungicides that can be used to prevent the spread of this disease.











Activity 2

Complete the following table

Disease


Causative organism

Symptoms

Control

Bacterial blight

Root rot






Refer section 27.5 to check whether your answer is correct

27.6 Harvesting and packing

Anthurium flowers should be harvested when they are fully mature. A flower is ready for harvesting about 8-12 days after the flower bud has completely unfurled. The female flower parts of the spadix are the first to mature in anthurium. When the flower is ready for harvest, the male flower parts are not yet mature. The spadix should have passed the sticky stage in part or full, and the pistils appear as points in opened flowers. When, flowers on about three-quartes of the spadix open, and pistils are seen as points, the flower can be harvested.

If flowers get dirty, they can be cleaned by treating them with a solution of 2g/l magnesium sulphate.


Packing

Since the flowers should be protected from damages and bruises until they reach their destination, packaging is very important in exporting of anthurium. Corrugated card board boxes are commonly used to pack anthurium flowers, but each flower has to be packed separately before packing them in the box.

Individual flowers are packed in many different methods, such as enclosing flowers in polyethylene bags, placing Styrofoam mats under the flowers, spreading moist paper around the flowers, placing foam inserts, and placing carton inserts between flowers etc.

Depending on the market requirements, there are standard categories of flowers and the size of the box used for packing varies with the flower size category. What ever packing material is used to pack flowers, a wet material such as wet cotton wool is fixed to the cut stem end of each flower and a tissue paper or polythene is placed between the spadix and the spathe to avoid damage. Flowers are arranged in layers in the box and in arranging layers of flowers, the flowers are placed in one direction in one layer and in the opposite direction in the next layer. Flower exporters use a packing material such as Styrofoam, or small pieces of paper between the layers. The packed boxes are cooled before transport. Flowers are stored at 18-20 C



Summary



Objectives

Now you should be able to



Review Question

Write and essay on Anthurium production in Sri Lanka.



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