CONTRIBUTION OF SORGHUM TO GRAIN REQUIREMENTS OF KENYA

The Kenya government outlines the challenges facing the agricultural sector in its Vision 2030 blue print and reckons that the sector can play an increasing role in economic development of the country. For example sorghum is said to contribute up to 1 % of food grain crops. It has been noted that over one million hectares of land in semi arid regions is lying idle. This huge acreage is suited to various varieties of sorghum and other dry-land crops. Sorghum can play a leading role in food security if this land is reclaimed and put under proper use.

According to Opole et al, in his research titled, Improving Ratoon Management of Sorghum for Increasing Yields in Western Kenya, There has been on steady decline of the area under sorghum. By the year 1994; 175,000 hectares were covered by sorghum which yielded 108,000 metric tons. This reduced to 123,184 ha in 1999 which yielded 90,000 metric tons. The reduction was attributed to production constraints including competition from maize, reduced farm holdings and pests and diseases. By the year 2006, after amplified promotion of the crop as a solution to beat harsh environmental conditions, the acreage increased to 123,000 hectares.

CLIMATE CONDITIONS, SOIL AND WATER MANAGEMENT FOR SORGHUM

Sorghum is adapted to a wide range of environmental conditions and will produce significant yields under conditions that are unfavorable for most other cereals. Sorghum is particularly adapted to drought. Sorghum also tolerates water logging and can be grown in areas of high rainfall. It is, however, primarily a plant of hot, semi-arid tropical environments with rainfall from 250 mm that are too dry for maize but performs best with more than 900 mm annually.

It is also grown widely in temperate regions and at altitudes of up to 2500 m in the tropics. Sorghum tolerates a wide range of temperatures. Sterility can occur when night temperatures fall below 12-15°C during the flowering period. Sorghum is killed by frost.

Sorghum can be grown successfully on a wide range of soil types. It is well suited to heavy clay soils (vertisols) found commonly in the tropics, where its tolerance of water logging is often required, but is equally suited to light sandy soils. It tolerates a range of soil pH from 5.0-8.5 and is more tolerant of salinity than maize. It is adapted to poor soils and can produce grain on soils where many other crops would fail.

HUSBANDRY OF SORGHUM

Sorghum is a rain fed crop, sown after the onset of the long rain season. Where the seed bed is not fine it is paramount to increase the seeding rate to compensate for poor seed-bed or to allow for unfavorable moisture conditions. A fine seed bed is compulsory for better seedling establishment.

The planting field should be prepared well in advance of sowing. Seed rate is 7-10 kg/ ha or 3-4 kg/acre. Dry planting is highly recommended.  When dry planted, planting depth should be 5 cm but when planting in a moist soil use planting depth of 2.5-4 cm.  Row spacing is 75 cm and distance between plants about 20 cm. For semi arid areas, row spacing should be 90 cm and the spacing between plants is 15 cm. 

Sorghum requires about 20 kg N/ha and 20 kg P/ha at planting time, which can be supplied by alternate cropping with legumes and application of compost or manure. Also intercropping with legumes is recommended with grain legumes such as beans, cowpeas, pigeon peas and green gram. Manure and compost improve organic matter content of the soil, soil moisture retention ability and soil structure.

Manure can be broad cast in the field or applied in planting furrows and mixed with soil before seeds are planted. The standard farm wheelbarrow when full holds approximately 25 kg of dry manure/compost. At a low rate, two wheel barrows are enough for a 10m by 10m area. This translates into 200 wheelbarrows or 5 tons/ha. When aiming for high seed rate, apply 400 wheelbarrows or 10 tons of manure per hectare.

PROPAGATION AND PLANTING OF SORGHUM

Sorghum is normally grown from seed. A fine seed-bed is preferable but is often not achieved. The seed is usually sown directly into a furrow following a plough, but can also be broadcast and harrowed into the soil. Optimum plant spacing depends on soil type and availability of moisture. For favorable conditions, row spacing of 45-60 cm and plant-to-plant spacing of 12-20 cm, giving populations of about 120 000 plants per ha, are normal. For drier or less fertile conditions, wider spacing and lower plant populations are usually optimal. The seed rate varies from 3 kg/ha in very dry areas to 10-15 kg/ha under irrigation. Occasionally, seedlings are grown in a nursery and transplanted into the field early in the dry season, e.g. on the floodplains round Lake Chad in Africa

SORGHUM RATOONING

Ratooning is where a farmer gets more than one harvest from a single sowing. This is achieved by cutting the sorghum stalks to the ground level without removing the rooting system. When the roots from the previous season’s crop are in contact with some moisture, they produce tillers; which grow into full size plants.

A ratoon crop compared to a newly sown crop has an established root system which will utilize the available water in the root zone for crop growth early in the season, reduce plowing and planting labor and avoid migratory quelea birds in August by maturing early. To make best use of sorghum, this practice is preferred where environmental factors prohibit continuous cropping throughout the year.

Ratooning is important because starter water is reduced i.e. very little rainfall is required for the commencement of seed germination, crop growth and development hence the crop matures earlier. Yields per unit are reduced but not significantly when compared to yield from direct sowed seeds.

HARVESTING AND USES OF SORGHUM

HARVESTING OF SORGHUM

Sorghum is usually harvested by hand when it has reached physiological maturity - which means the grain is hard and does not produce milk when crushed. Cut the heads with sickles or a sharp knife from plants in the field or cut the whole plant and remove the heads later. Sun-dry the harvested panicles to moisture levels of 12-13 % and thresh and store the grain.

USES OF SORGHUM

Sorghum is a versatile crop. Some types are boiled like rice, some milled to flour for porridge, some "malted" like barley for beer, some baked like wheat into flatbreads, and some popped like popcorn for snacks. A few types have sugary grains and are boiled in the green stage like sweet corn. The whole plant is often used as forage, hay, or silage.

The stems of other types yield sugar, syrup, and even liquid fuels for powering vehicles or cooking meals. The living plants are used for windbreaks, for cover crops, and for staking yams and other heavy climbers. The seeds are fed to poultry, cattle, and swine

Mzee Matheka who lives in a village in Kitui district of Kenya says “The high cost of Kerosene has made us to use dried stems of sorghum for cooking. I don’t know where i could have got money to buy kerosene considering the hard economic times,” such stories abound in many parts of the world and the importance of sorghum is apparent.

Sorghum plays an important role as a food security crop especially in semi arid lands of Kenya. This is because of its adaptation where it rolls up its leaves and thus decreasing transpiration. Sorghum, changing fortunes Sorghum has been viewed as a crop for the poor and marginalized communities in the drought-prone arid and semi-arid regions of Kenya.

FACTORS AFFECTING THE POST HARVEST QUALITY OF CUT FLOWERS

The most important factors affecting the life of cut flowers in addition to maturity stage include;

  1. FOOD SUPPLY

This refers to respiratory metabolites. In a cut flower, all the metabolites are channeled towards flower development. Starch sugar stored in the stem, leaves and petals provide much food needed for flower opening. Simple nourishing food for flowers is sugar but sugar is also a suitable substrate/ food for bacteria hence you need a good preservative

Vase life can be improved by supplying food (sugar) after harvest. e.g. in tuberose and gladiolus in which flowers open further up the spike, flowers are bigger and have a longer vase life when ‘pulsed’ with a preservative solution containing 20% sucrose prior to shipping.

In those flowers where foliage is part of flower quality, e.g. Alstroemeria, if supply of carbohydrates is inadequate, leaves ‘blacken’. Tuberose flowers pulsed with 20% sucrose showed an increase of florets opening from 34% to 57% and an increase of vase life from 5-11 days.

2. TEMPERATURE

This is the most important factor because it influences the factors. Flowers are living and respiring. Respiration increase exponentially with temperature; Temperature also affects the rate of water loss, growth and development, production and response to ethylene, growth of microbes.

To reduce water loss temperature must be kept low. Flowers held at 30⁰ will respire 45 times faster than flowers held at 2⁰ C. Rapid removal of field heat and optimum storage temperature for cut flowers is 0-2⁰ C for tropical flowers, e.g. anthuriums, strelitzia and orchids, storage temperature of between 10-15⁰ C.

3. WATER SUPPLY

Plants are about 80-90% water. Cut flowers have a high surface area to volume ratio, and frequently have many leaves; hence are prone to loosing water much more rapidly compared to most perishable commodities. By detaching the flower, its source of water supply is cut off. Cut flowers should be stored under high relative humidity 95% to minimize water loss; particularly during long term storage. Loss of water causes loss of quality, accelerated aging, ethylene production, flowers can be rehydrated provided there is no obstruction to water flow. Movement of water in the stems of cut flowers can be obstructed in a number of ways:

4. AIR EMBOLISMS

The water column in the xylem vessels is under tension due to transpiration. When the stem is cut, this tension is released and a small bubble of air enters each conducting tube.

The air bubbles do not move up the stem, and may restrict water flow when the stem is placed in a vase. Removal of embolism is re-cutting the stem about 2.5 cm under water. Rehydration is improved by acidifying the vase solution ph 3.5 or by heating the vase solution to 40⁰ C

5. WATER QUALITY

Alkaline water does not readily flow through the cut flowers stems. Use or hard water can therefore substantially reduce flower vase life. This problem can be overcome by acidifying to a PH of 3.5-4.0 citric acid is commonly used. HQC (Hydroxy quinine citrate) at a concentration of 250ppm is also effective.

6. BACTERIAL PLUGGING

Sugar solution enhances vase life; but it is also an excellent substrate for the growth of bacteria and fungi. Bacterial and fungal growth is further enhanced by materials that leak out of the cut stem ends. Substrates produced by the bacteria, and the bacteria and the bacteria themselves may rapidly clog the fine tubes of the water conducting system. Buckets should therefore be regularly cleaned to prevent growth of bacteria (biocides like HQC)

7. PHYSIOLOGICAL PLUGGING

When a plant is cut, wounding occurs. To protect the wound, the plant produces latex (phenolics and tannins). The exudates leak into the vase solution and are later absorbed with the water. Being gummy, they block the vascular system of the cut flower; thereby hindering free flow of the vase solution. To restore free flow, re cut the stem to remove the cemented end of the flower.

8. ETHYLENE

Certain flowers especially those of caryophyllaceace family (carnations and gypsophilla) senesce rapidly if exposed to minute concentrations of ethylene. The higher the available ethylene concentration, the sooner the flower will bloom and wilt. In general, that ethylene can induce different damage symptoms including

a) Short longevity/vase life

b) Insufficient opening of the flower bud

c) Early wilting

d) Drop of buds and petals

e) Drop of buds and petals

f ) Discoloration of the flowers

Ethylene can occur at concentrations of 1-5ppm is already detrimental to cut flowers. Flowers should be handled in areas with the least ethylene contamination. Effects of ethylene can be minimized by holding produce at low temperatures and by using ethylene inhibitors e.g. silver thiosulfate and 1MCP

DISTINCTIVE CHARACTERISTICS SHARED BY ALL CUT FLOWERS

Characteristics shared by all cut flowers

1. Generally a very high rate of respiration- when exposed to high temperatures, they easily wilt because of rapid loss of water. Remember, flowers are used to convey emotions of love, care, to someone. It is thus presenting a wilting flower to someone is undesirable and unkind.

2. Very high surface to volume ratio- this makes them susceptible to rapid water loss and wilt is not stored at temperatures that reduce the rate of respiration.

3. Substantial growth and development after harvest. Most flowers are harvested at the tight bud stage therefore they should be handled with care so that this biological process continues unabated in the vase of the customer. The quality of flowers is measured by their ability to continue in the aforementioned process.

4. High sensitivity to mechanical damage, pests and disease- pests like thrips bore pin holes on petals leading to their eventual fall. Diseases like botrytis attack the blooms causing water soaked lesions on them.

FACTORS THAT AFFECT THE VASE LIFE OF CUT FLOWERS

1.Exposure to ethylene is the precursor to senescence of flowers. A flower that is exposed to, or is producing high levels of ethylene will age faster, thus reducing the enjoyment of its beauty by the customer.

Exposure to ethylene occurs during storage. Never store different flowers or other agricultural produce in the same store; they produce varying levels of ethylene and their sensitivity also varies.

2. Yellowing of leaves- This condition is typically observed in Alstroemeria. Yellowed leaves reduce the appeal of cut flowers. Yellowing can be delayed by applying plant growth hormones like Florissant 100 or 200 that contain silver thiosulfate to facilitate the inhibition of ethylene production; consequently increasing vase life.

3. Insufficient nutrients

4. Insufficient uptake of water- water is responsible for the turgidity of the cells, therefore when a flower does not take sufficient water; its petals will be droopy. A flower that uptakes sufficient water appears fresh healthy and beautiful

5. Growth/ infection by micro-organisms

The end of vase life of a cut flower is marked by one of a number of factors including

1. Wilting of the flower

2. Wilting of the foliage

3. Shattering i.e. loss of flowers/florets

4. Ethylene related senescence

5. Non ethylene senescence

6. Leaf yellowing

DIFFERENCES BETWEEN CUT FLOWERS AND OTHER AGRICULTURAL PRODUCTS

A flower is composed of many morphological units; including sepals, petals, androecium, gynoecium, stem; and often leaves. Each of these structures is complex in their own right and differ both morphologically and physiologically. Flowers, stems and leaves interact- e.g. endogenous and applied sugars move from leaves to the flower. These interactions between these organs of flowers make flowers more susceptible to post harvest loss of quality compared to fruits, vegetables and seeds. 

1) Most cut flowers have two distinct stages physiologically, on the other hand once fruits and vegetables are harvested, the subsequent stage is senescence.

a) Flower bud growth and its development to full opening- A flower may be harvested at the tight bud stage; with its remaining life cycle concluded in a vase, when it fully opens. A flower must therefore be harvested at the correct maturity stage. For example Alstroemerias are harvested when the first flower is just about to open, (tight stage) if it is meant for export; or when it is fully open for direct sales.

When handling cut flowers, care should be taken to ensure that when they reach the customer, this paramount biological process continues. These are some of the quality requirements of flowers; without which a flower is rejected by the market.

b) Maturation, senescence and wilting

Though vase life depends on the type of flower, variety and growth conditions, it can be greatly influenced by post harvest treatment. Cut flowers have to face all kinds of aberrant environment like, lengthy and waterless storage in boxes, bumpy transport, violent handling and fluctuating temperature changes as they are moved from the farm to the consumer; who is often thousands of miles away. Only flowers treated with great care can survive these conditions and give the consumer the beauty and pleasure he paid for.

FACTORS AFFECTING THE POST HARVEST QUALITY OF CUT FLOWERS

The most important factors affecting the life of cut flowers in addition to maturity stage include;

  1. FOOD SUPPLY

This refers to respiratory metabolites. In a cut flower, all the metabolites are channeled towards flower development. Starch sugar stored in the stem, leaves and petals provide much food needed for flower opening. Simple nourishing food for flowers is sugar but sugar is also a suitable substrate/ food for bacteria hence you need a good preservative

Vase life can be improved by supplying food (sugar) after harvest. e.g. in tuberose and gladiolus in which flowers open further up the spike, flowers are bigger and have a longer vase life when ‘pulsed’ with a preservative solution containing 20% sucrose prior to shipping.

In those flowers where foliage is part of flower quality, e.g. Alstroemeria, if supply of carbohydrates is inadequate, leaves ‘blacken’. Tuberose flowers pulsed with 20% sucrose showed an increase of florets opening from 34% to 57% and an increase of vase life from 5-11 days.

2. TEMPERATURE

This is the most important factor because it influences the factors. Flowers are living and respiring. Respiration increase exponentially with temperature; Temperature also affects the rate of water loss, growth and development, production and response to ethylene, growth of microbes.

To reduce water loss temperature must be kept low. Flowers held at 30⁰ will respire 45 times faster than flowers held at 2⁰ C. Rapid removal of field heat and optimum storage temperature for cut flowers is 0-2⁰ C for tropical flowers, e.g. anthuriums, strelitzia and orchids, storage temperature of between 10-15⁰ C.

3. WATER SUPPLY

Plants are about 80-90% water. Cut flowers have a high surface area to volume ratio, and frequently have many leaves; hence are prone to loosing water much more rapidly compared to most perishable commodities. By detaching the flower, its source of water supply is cut off. Cut flowers should be stored under high relative humidity 95% to minimize water loss; particularly during long term storage. Loss of water causes loss of quality, accelerated aging, ethylene production, flowers can be rehydrated provided there is no obstruction to water flow. Movement of water in the stems of cut flowers can be obstructed in a number of ways:

4. AIR EMBOLISMS

The water column in the xylem vessels is under tension due to transpiration. When the stem is cut, this tension is released and a small bubble of air enters each conducting tube.

The air bubbles do not move up the stem, and may restrict water flow when the stem is placed in a vase. Removal of embolism is re-cutting the stem about 2.5 cm under water. Rehydration is improved by acidifying the vase solution ph 3.5 or by heating the vase solution to 40⁰ C

5. WATER QUALITY

Alkaline water does not readily flow through the cut flowers stems. Use or hard water can therefore substantially reduce flower vase life. This problem can be overcome by acidifying to a PH of 3.5-4.0 citric acid is commonly used. HQC (Hydroxy quinine citrate) at a concentration of 250ppm is also effective.

6. BACTERIAL PLUGGING

Sugar solution enhances vase life; but it is also an excellent substrate for the growth of bacteria and fungi. Bacterial and fungal growth is further enhanced by materials that leak out of the cut stem ends. Substrates produced by the bacteria, and the bacteria and the bacteria themselves may rapidly clog the fine tubes of the water conducting system. Buckets should therefore be regularly cleaned to prevent growth of bacteria (biocides like HQC)

7. PHYSIOLOGICAL PLUGGING

When a plant is cut, wounding occurs. To protect the wound, the plant produces latex (phenolics and tannins). The exudates leak into the vase solution and are later absorbed with the water. Being gummy, they block the vascular system of the cut flower; thereby hindering free flow of the vase solution. To restore free flow, re cut the stem to remove the cemented end of the flower.

8. ETHYLENE

Certain flowers especially those of caryophyllaceace family (carnations and gypsophilla) senesce rapidly if exposed to minute concentrations of ethylene. The higher the available ethylene concentration, the sooner the flower will bloom and wilt. In general, that ethylene can induce different damage symptoms including

a) Short longevity/vase life

b) Insufficient opening of the flower bud

c) Early wilting

d) Drop of buds and petals

e) Drop of buds and petals

f ) Discoloration of the flowers

Ethylene can occur at concentrations of 1-5ppm is already detrimental to cut flowers. Flowers should be handled in areas with the least ethylene contamination. Effects of ethylene can be minimized by holding produce at low temperatures and by using ethylene inhibitors e.g. silver thiosulfate and 1MCP

POST HARVEST HANDLING AND CARE OF CUT FLOWERS IN KENYA

Floriculture is a very rewarding occupation worldwide. It contributes about 40-50% of the revenue earned in horticultural sector, despite the fact that the acreage of floriculture is the smallest in horticulture sector; it is the largest in earnings. It covers about 25% of the volume of horticultural exports. It can be concluded that this industry largely depends on cut flowers for revenue; with quality of cut flowers being of greatest importance.

The floriculture sector is dominated by a myriad of large industry players who have an advanced production and post harvest technologies. Small scale farmers are now venturing into floriculture thanks to poverty reduction efforts by nongovernmental organizations.

The small scale farmers face numerous challenges; on handling cut flowers, the correct stage of harvesting, use of agro-chemicals and market quality requirements. This article seeks to explain the concepts behind post harvest management of flowers so that these farmers may be able at least to cut down post harvest losses by 50%.

It is a known fact that flowers are more delicate than other agricultural commodities. This is based on the premise that; a cut flower is a more complex organ than a seed, a fruit and a vegetable, which are single morphological units this calls for specialized care of the cut flowers as discussed in the below popular topics.

  

 

 

 

 

 

 

 

 

 

 

 

 

GROWING OF FLOWER BULBS, RHIZOMES, TUBERS AND CORMS

Cut flowers produced from bulbs include a wide range of ever admired varieties like lilies, gladioli, arabicum, tulips, irises, calla lilies, tuberose, and liatris.

Strictly speaking lilies are bulbs, Alstroemerias are rhizomes, calla lilies are tubers, gladioli are corms, but they have many qualities in common.

LIFTING OF FLOWER BULBS

Lifting involves the removal of the underground reproductive organs from the soil.

Once they are lifted they need to be separated, washed, sterilized, and stored in the approved manner until replanting in the next time of year.

Why flower bulbs are lifted

To obtain the finest grades of cut flowers, lilies, gladioli and tulips should be lifted after every growing season.

Others like tuberose and Alstroemeria only need to be lifted after a few years.

The quality of reproductive organs determines the quality of flowers. Lifting of underground flower organs allows the grower to select the best seed for subsequent planting.

Larger bulbs or corms typically produce larger flowers or flowering stems; once bulbs are lifted, separate them into various sizes. They are as well planted in blocks of according to their varying sizes.

When the bulbs flower, a more standardized production of flowers per block is achieved; this facilitates to great extent actions like grading.

DRAINAGE REQUIREMENTS FOR RHIZOMES, TUBERS AND CORMS

All these types of flowers have a preference for well drained soils. They don’t like waterlogged conditions, on the other hand, they don’t like the soil to dry out completely.

The soil should be moist and cool, but not drenched or soaking.

Mulching encourages luxurious growth; thus high quality flowers are achieved.

This is because mulch is wonderful in maintaining dampness in the soil and reducing the soil temperature around the root and bulb region.

Bulbs grow best in sandy soil because drainage is better in such soils than in clayey soil. The process of bulb expansion is favored in sandy soils or very loose soil.

Plants like Alstroemeria, Gladioli and Calla lilies can handle heavier soils than lilies and tulips, but thrive in loose, well manured soil with lots of organic matter.

DISEASES OF FLOWER BULBS, RHIZOMES, TUBERS AND CORMS

All bulbs are relatively susceptible to soil borne diseases especially when the drainage is not good and when regularly exposed for extended periods in wet and soggy soils.

CLEANLINESS OF THE FIELD BEFORE PLANTING FLOWER BULBS, RHIZOMES, TUBERS AND CORMS

Ensure the soil is devoid of diseases; inoculate soil with ‘good micro-organisms’ after sterilizing the soil.

Planting material of all these bulb and rhizomes is very expensive because of the many farm operations conducted to raise them.

Bulbs take 2-3 years before they flower, during this time the grower must lift, clean and replant them; all this trouble contributes to the cost of planting material.

When buying planting material, make sure you have correct bulb size so as to produce the quality you desire.

CARE OF FLOWER BULBS, RHIZOMES, TUBERS AND CORMS DURING FLOWERING

With the exception of rhizomes, all bulbs and corms produce only one flower per season.

It is very easy to damage the emerged growing point during planting. You only get one flowering stem per bulb per season; meaning, once the bulb is damaged, you have lost the flower for that season.

Handle the flowers with care after harvesting to minimize post harvest loses and improve their vase life.

PRODUCTION REQUIREMENTS OF FLOWER BULBS, RHIZOMES, TUBERS AND CORM

I. LILIES

Grow best under 40% shade cloth during summer. Plant 48-64 bulbs per M2 depending on the bulb size and time of the year. When the bulb size is small plant more of them.

II. GLADIOLI

Grow well during summer months in the open field. When temperatures get too hot, they suffer from leaf burn.

They do well under a shade cloth that helps to break the worst heat. Plant 40-70 per M2 depending on corm size and the time of the year.

III. TULIPS AND IRISES

They don’t like heat at all; they need to be grown in the cool areas of the country, 150-250 bulbs per M2

IV. CALLA LILIES

They don’t like excessive heat and do best under shade. Plant around 15-30 tubers per M2 depending on size.

VI. TUBEROSE

Planting densities can vary from 50-120/ M2 depending on variety.

ALSTROEMERIA

Temperature is very vital for the flowering of Alstroemeria; therefore, it has been established that altitudes of 1800 m to 3000 m above sea level are ideal for its growing in the tropics.

The absolute temperature requirement for flower induction of 10 to 16⁰ C is only achievable in the aforesaid altitudes; temperatures above 25⁰ C hinder flower initiation, and lead to the production of non flowering shoots.

This utter temperature requirement restricts the area where Alstroemeria can be grown profitably. Alstroemeria plants thrive best in areas with temperature ranges of 10 to 20⁰C.

After the plants have been induced to flower, the environmental temperature and light conditions control the rate of shoot and flower development.

A return to the vegetative stage can occur if the temperatures get high. The plants need to be protected from wind, which leads to lodging of tall plants.

SUITABLE SOILS

Soils should be rich, well drained and contain high organic matter. The ideal soil PH is 6.5. Plants can acclimatize to a wide variety of soils provided the soils are deep and well drained.

In areas where of soils are high in aluminum and manganese, it may be necessary to apply agricultural lime at the rate of 5 tons /Ha to prevent chlorosis and leaf tip burn. It is important to analyze the soil regularly.

High soil temperatures can be reduced by using overhead irrigation, mulching or a good plant cover.

Suitable areas for growing Alstroemeria in Kenya include Limuru, Kericho, Kaptagat, Wundanyi, Timboroa, Molo and Meru but it can be grown in much warmer area but under shade netting.

SUITABLE CULTURAL PRACTICES FOR ALSTROEMERIA

Planting should be done in April/ May to produce export flowers by September or October. The land should be well prepared and should include 20 to 30 tons of manure. Make raised beds of 1 meter and incorporate 500 kg/ha of TSP.

PROPAGATION OF ALSTROEMERIA

Most of the present day Alstroemeria varieties are sterile hybrids hence propagation through vegetative means however the plant can be propagated through seeds by plant breeders.

The most common method of propagation is by division of underground rhizomes that have attached roots (splits).

The propagation rhizomes are obtained from 2-3 year old plants, meristem cuttings are used in developed countries.

Before planting, it is necessary to dip the rhizome in a fungicide solution to prevent its rotting. Thereafter, plant the rhizome at a depth of 10-15 cm.

The soil can also be drenched with a fungicide if the rhizomes were hot treated before planting.

SPACING IN ALSTROEMERIA

Alstroemeria is grown on a one meter wide bed with 50 cm paths. Each bed contains 2 rows of plants with 35 to 40 cm between rows and 40 to 50 cm between plants.

FERTILIZER APPLICATION IN ALSTROEMERIA

Alstroemeria is a heavy feeder that requires a lot of nitrogen and potassium. Plants grown in soils with low levels of nitrogen produce flowers with poor keeping quality.

Nitrate forms of fertilizers have the nitrogen more available to the plant than ammonium forms for the cooler areas where Alstroemeria is grown.

Plants with low potassium content tend to have fragile and tender stems. After six months of plant growth, apply potassium as a top dressing.

For a new plantation, apply nitrogen, phosphorus, potassium 20-10-10 or 17-17-17 and calcium ammonium nitrate in the ratio of 1:1 at the rate of 2 kg /100 meter of the bed length every two weeks.

Applying Nitrogen at the time of planting helps to increase the level if cytokinins in the plant which promotes chlorophyll development.

This helps to delay leaf yellowing which is a common problem with Alstroemeria flowers.

THINNING OF ALSTROEMERIA

It is performed to reduce the competition of water, nutrients and to open the plants up. Weak and non flowering shoots are pulled out the shoots.

Pulling is a healthier practice as it reduces crowding in the bed, although care should be taken not to uproot the rhizome.

MALE SHOOTS IN ALSTROEMERIA

The male shoots tend to lean on the female shoots. The male shoots can be distinguished in that they have an opened head tip while that of the female is cone shaped at the point where the flower bud emerges.

The male shoots have large leaves and shorter stalks (stems) compared to the female shoots. Too much thinning of the male flowers should be avoided as they act as a shade for the female shoots; also excess thinning tends to induce early flower opening.

Male shoots have an advantage in that they help to store carbohydrates in the rhizomes for use by the female shoot.

SUPPORT FOR ALSTROEMERIA

For high quality plants, Alstroemeria stems need a good support system. This is achieved by using either a net support system or a simple wire or twine system.

When using a net support system, it is necessary to place the net in position when planting. Two or four layers of support are necessary depending on the variety grown.

The first one should have a height of 25cm; the others should have a height of 60, 90, and 125 cm. The squares should be approximately 12.5x12.5 cm for all the other layers.

IRRIGATION PROGRAM FOR ALSTROEMERIA

It requires a lot of water because of their nature of roots and its bushy growth. Overhead irrigation can be used till flowering commences to prevent damage to flower.

Irrigation can be done in the evening to prevent high water loss due to evaporation during the day.

Overwatering normally results in yellowing of the leaves. Continuous overhead irrigation can lead to the incidence of leaf spot diseases.

WEED CONTROL IN ALSTROEMERIA

In the field should be kept weed free. Shallow cultivation is encouraged so as not to disturb the root system.

MATURITY, HARVESTING AND POST HARVEST HANDLING OF ALSTROEMERIA

Harvesting starts 4 to 6 months from planting. Good yields are achieved in the fifth and sixth months.

The best quality cut flowers are those with long and straight stems. The cut stages will depend on the market and cultivar.

Flowers are cut when the first flower is just about to open or the beginning of the tight stage for export, but for direct sales or local market can be harvested by pulling them at the base.

The whitish part of the stem is then cut off and the flower is dipped in the bucket with water to prevent drying and then carefully transported to the pack house.

YIELD OF ALSTROEMERIA

Expected yields can be 180-300 stems per M² per season.

GRADING OF ALSTROEMERIA

The flowers are sorted and graded immediately after harvest. Grading parameters to be observed after harvest are wholesomeness, stem length, stem strength, straightness uniformity, and symmetrical flower head with 7 to 10 florets.

Depending on the cultivar and bright green leaves. Grading by stem length

Grade I 80 cm

Grade II 70 cm

Grade III 60 cm

The graded cut flowers are then bunched into tens or twenty’s depending on the market, wrapped with either paper or plastic.

CHEMICAL TREATMENTS OF ALSTROEMERIA AFTER HARVESTING

Leaf yellowing in Alstroemeria can be delayed by use of chemical preservatives with plant growth hormones such as Florissant 100 or 200 and crystal.

Florissant 100 contains silver thiosufate which inhibits ethylene production by the flower, thus increasing vase life, whereas Florissant 200 contains plant hormones which prevent yellowing.

PACKING OF ALSTROEMERIA

The sleeved bunches are packed in ventilated carton boxes. The number of stems is determined by the length of the stems and the market requirements.

Flower heads are placed on both ends of box for better use of space. The heads of the flowers should be placed 7-12 cm from the end of the box to avoid the petals from being bruised.

The flowers should be packed firmly in boxes in such a way that transport damage is minimized.

PRE COOLING OF ALSTROEMERIA

Forced air cooling is used to bring down the temperature of the flowers to 2 to 4⁰C and to remove the field heat.

Cool air is blown through the boxes and the warm air is sucked out through the ventilation holes.

STORAGE OF ALSTROEMERIA

The packed flowers can then be kept in a cold room at the same temperature of 2-4⁰ C and a relative humidity of 90 to 95% prior to being transported to the airport.

DISEASES AND PESTS OF ALSTROEMERIA

There are two diseases that affect Alstroemeria in Kenya

Root rot- this disease is caused by Rhizoctonia sp which affects the stem first, then the roots. The fungus clogs the stem which eventually dies due to reduced nutrient uptake.

Control is through the use certified planting material and dipping the rhizomes in fungicides solutions before planting.

Damping off-Caused by pythium sp

This disease affects juvenile or succulent tissues. The roots of the plants turn waxy and rot. This is the most common diseases affecting the seedlings of a very wide host range.

Stems become very weak and have lesions at the soil level and leaves start rotting. Control sterilization of soil media and spraying benomyl or thiophanate methyl at 0.2%

Botrytis grey mold-Symptoms appear on the flower and buds spots turn brown and fungal growth forms on the leaves. Control use of Ravral or Bavistin; or Fumigate with chlorothamomil

PESTS

The common pests affecting Alstroemeria are aphids, caterpillars, mites and fussy flies, nematodes.

Control

For caterpillars and fussy flower spray Rogor E. Pyrethroids and miticides are effective against aphids and mites. Use nemacure every 3 months as control against nematodes.

CONTROLLING THRIPS

There are many species of thrips that cause severe loss of flowers, vegetables fruit and other crops. First, others are acknowledged to be virus vectors spreading viral diseases. Secondly, they also exact superficial damage on fruits making them appear uneatable; or, and spoiling the appearance of foliage and flowers.

MORPHOLOGY OF THRIPS

Thrips differ in size from 1-2mm in length depending on whether they are adult or they or immature. The immature, are wingless and yellow, becoming darker as they mature. Adults differ from orange, to dark brown or black.

LIFE CYCLE OF THRIPS

A female lays eggs that are 0.2 mm long, within leaves, fruits or flowers. Growth cycle consists of the egg hatching in a larva, then another lava stage commences.

After the second larva stage, a pupa emerges that gives rise to an adult. The growth cycle is completed in two weeks during favorable weather. Thrips cause spotted scars to flower petals as a result of their feeding habits.

ORGANIC METHODS OF CONTROLING THRIPS

To control thrips, formulate a spray that contains garlic, canola oil and natural pyrethrum a concoction that, despite controlling thrips, it is lethal to virus vectors like; aphids, whiteflies and jassids/leaf hoppers. It’s perfect for application on edible crops like; tomatoes, green beans, cucumbers as well as in roses, ornamentals flowers and various salad crops.

Secondly, removing infected leaves and flowers can assist in reduction of population significantly. Thirdly using yellow or blue sticky traps placed around plants can also trap a small proportion of trips moving from one plant to another. The traps are very useful to enable you to be aware of thrip activity at a very early stage and take remedial measures.

THRIPS ON AUBERGINE/EGG PLANT

Thrips attack the leaves and the fruit of egg plants causing considerable reduction of growth and surface deformities on fruit respectively. Both nymphs and adults leave scars and deformities on the plants. The extent of damage on plants and fruit depends on the stage the plant was attacked. Heavy invasion results to the death of the plant especially during its early growth. They also transmit tomato spotted wilt virus that leads to 100% loss of plant produce.

The plant is susceptible throughout it growth cycle making it the most dangerous pest for aubergine. The optimal condition for thrips is sizzling temperatures followed by a short period of rain. The most optimal temperature for the reproduction, growth and development of thrips is 20⁰C. Thrips are serious pests on eggplant in Zambia especially during the months of September to November. No data is obtainable showing the impact of the pest in Kenya.

THRIPS ON AVOCADO

Thrips start feeding near the calyx, producing a scar; that gradually covers the fruit wholly. Economic injury occurs on the fruit when it measures to 2 cm in length, 2-3 weeks after fruit set.

The pesticides approved in Kenya for the application on thrips on avocado are; Azadirachtin, Deltamethoate and Dimethoate

THRIPS ON MANGO

As thrips seek shelter on mango trees, they attack the young tender shoots. This makes the young leaves to develop to a creased form. It has been observed that the pest population increase exponentially during hot dry weather; making the hot seasons the most favorable for the pest. Thrips on mangoes are difficult to control using chemicals though Spinosad has proven to be effective. Other chemicals that can be effectively used are Chlorpyriphos-Ethyl, Deltamethrin, Malathaion

THRIPS ON CUCURBITS

There is significant reduction of growth when, thrips attack young leaves of cucurbits. This is because terminal buds are destroyed, thus stunting the crop. The most serious damage is due to the egg laying lesions on the fruit. Feeding cause’s damage not by the fact of punctures, but by deformations due to saliva injected. The tissues on which the trips feeds become sullen in appearance and spotted, they are particularly tarnished especially the petals. Thrips are a serious pest in Senegal on cucurbits especially during the months of July to October.

Thrips move by means of wind thus the establishment of windbreaks minimizes the thrip population. It is important to ensure host plants like tomato, cotton and tobacco are not near cucurbits. Plowing and harrowing before planting buries their eggs deep in the soil thus reducing their population. Solarization can kill eggs in the soil from previously infested crop. Plant crops that are natural repellants to thrips like, citronella and pyrethrum.