Cassava (Manihot esculenta): It is a staple food crop in many parts of the tropics and it is capable of producing high yield under condition of poor soil fertility and rainfall. It is also known as tapioca. It is also an important component of traditional cropping system.
Cassava originated in part of Central America it was introduce to West Africa by the Portugus in 16th Centenary.
This is an I.T Report on Agriculture
BOTANY OF CASSAVA:
It is a short – lived dicotyledonous shrub which grows to a height of 1 – 5m with later in all parts, the root comprise tuber which develops as a swollen on advantageous root, a short distance from the stem by a process of secondary tuckering once a tuber becomes tuberous, it no longer participate actively in the absorption of water and mineral salt. Starch accumulation in the tuberous cassava root commence near it point of attachment to the stem and progresses towards the distance portion of fastest near it point of attachment to the stem and tapper gradually toward the distance portion.
The tuber is attached to the stem by a stout wood neck. The number, shape, size angle at which they penetrate the ground, colour of outer cock and internal tissue varies greatly among different cultures.
Cassava tubers vary between 5 – 10 per plant and they are either cylindrical or tapping. 15 – 100cm long and 3 – 25cm across, the tuber consist of outer (peridem) the ring or Core and core (pith).
In addition to the tuber, fibrous adventitious root develop horizontally and vertically which are active in the absorption of water and mineral salt. The stem varies greatly in height and branching habit. Branching near the base in some cultures, high up in other; the angle of branching with the main stem determines whether plants are erect or branching.
Cassava plant is a common root crop that matures between 8 – 9 month depending on the variety or species planted. Cassava is like any other plant, it has leaves, stem and the root.
There are three parts of cassava that are very useful to humans.
1. The leaf is a very good source of vegetable
2. Stem is sold to other farmers for planting
3. Root is processed to various finished products for human consumption.
The leave are spirally arranged the petiole 5 - 30cm long, usually deeply palmate divided with 3 – 9 lobes usually 5 – 7 and numbers may vary on the same plant, lower leaves term to have more than upper leaves. Some cultures have reddish colour petioles and varies which in orders they are green. The flowers are unisexual with male and female flowers in the same inflorescence the cater near the base. Female flowers are usually bigger than male flowers; male flower opens 7 -8 days after the female (protogynous) and so if is cross pollinated. Many of the varieties now in cultivation rarely flower.
The cassava fruit is a spherical capsule about 1.5cm long, glabrous with narrow longitude wing – like structure in the outside, three seeded, wooden endocarp.
Splitting explosively on ripening 3 – 5 months after pollinating and ejecting seeds the seeds are about 12mm long, gray mottled with Clark blotches.
Many varieties of cassava are cultivated in Nigeria; most of the currently recommended varieties grown in Nigeria were released by IITA
Ibadan and NRCRI Umudike Umuhia, There are TMS or NR series respectively. Many varieties can be differentiated by morphological characteristics such as leaf size, colour and shape, branching habit, plant height, colour time of maturity and yield.
Land can be acquired by purchase to own it, or for a year, two or the number of years you intend to use it. The site for cassava cultivation should be selected to be a well drained fertile soil that is accessible.
WHEN TO PLANT CASSAVA
Cassava planting has no rigid time of plant, it is advisable to plant when the rainy season is about to end or the dry season is about setting in. This depends on the weather or season in your area.
Land preparation can be treated under two ways:
i. Mechanized way of land preparation
ii. Traditional or local way of land preparation.
MECHANIZED WAY OF LAND PREPARATION
This involves the use of heavy equipment such as bulldozer, tractors etc. The mode of operation, the bulldozer is used to remove the big trees i.e. open up the lands, and pack the entre stomp and the wood to side of the farm and allow to fallow for about two months. Thereafter, tractor is used to plough and harrow the land before ploughing and harrowing per – land preparation weed control are used at rate of 4 – 5 liter/h.
TRADITIONAL OR LOCAL WAY OF LAND PREPARATION
In this method, do it the way it is done in your place. For example, in Imo state, land preparation for cassava is very easy. The select farm area is brushed by casual laborer; it is all owed to stay for about two weeks to allow the cut down plants to try properly. At the end of the 14th day, between the periods of 3.30 – 4.30pm they will go the end set fire and ensure the farm is thoroughly burnt.
CASSAVA CAN BE GROUPED INTO TWO LARGE SPECIES
ii. Sweet varieties
This classification is according to HCN level (hydrocyanic acid)
Better cassavas have higher HCN content and the HCN are usually destructed throughout the tuber.
· Sweet cassava with low HCN conforms to the outer skin (periden) cassavas are also classified according to HCN content. In terms of HCN content per 100g fresh weight to give three groups as follow:
1. Cassava with low HCN content: less than 5mg/100g fresh weight of ten concentrations in the peal e.g. TMS 4(2)1425 and TMS 30555
2. Cassava with intermediate level of HCN in which the level range between 5 -10mg/100g fresh weight e.g. TMS 30572, TMS 30555.
3. Cassava with HCN content: 10mg/100g fresh weight or more. E.g. Tms 50395.
CLASSIFICATION OF CASSAVA ACCORDING TO MATURITY DATE
1. Short season varieties (early maturing) which mature as early as 6months after and can be left in the ground longer than 9 – 11 months without serious discoloration, these cassavas sweet.
2. Long season varieties (late maturing) takes cutlass a year or more and can be left in the ground for 3 – 4 years without serious.
CLIMATIC AND SOIL REQUIREMENT:
The crop is widely cultivated from the mangrove swarm in Nigeria dealt to the savannahs; it can operate a long period of draught when it shell it leaves and come up quickly when there is rain. It is extremely prone to excessive flooding, it requires warm temperature, high rainfall that most exceed 750ml, it can be grown in almost all soil types provided they are not water logged to shallow, stony or heavy (clay soil) it grow best in sandy or sandy – loamy soil of reasonable fertility. It can also tolerate poor soil and will give economically adequate yields on soil that are too poor for other crops such as maize, yam, plantain and leafy vegetable.
1. PRODUCTION SYSTEM: Cassava can be planted on mound ridges on the flat after ploughing in most traditional cropping system (production system) cassava is inter planted with cereals such as maize and rice or legumes such as soya beans millet in the first 3 months after planting.
2. METHOD OF PROPAGATION: The main method of propagation in by stem cutting propagation by seeds in confired to breeding work cultivars readily take off and produce fibrous adventitious root system which becomes very extremely developed both laterally and vertically. Cutting should at least be 25cm long and planted in a starting position or buried at a spacing of 1m by 1m. Sweet cassava may be planted closely at 0.75m to 1.00m. The cuttings must be treated with Adres 40 of termites are present.
3. TIME OF PROPAGATION: Cassava should be planted as soon as rainfall established around April in South and June in the North.
There are numerous cassava varieties exist in each zone where the crops grown. There are about 2,200 different varieties of cassava in (NRCRI). Examples of cassava varieties NR 8082, NR 8086, TMS 05051, TMS 419, TMS 2205, TMS 84292, TMS, 8410, TMS 84104, TMS 1080, TMS 98/058/, TMS 97/2205
QUALITY OF CASSAVA STEM FOR PLANTING
The ideal cassava stem for planting should have the following qualities:
i. The cassava stem should be allowed to stay for at least one week before use for planting after cutting.
ii. The planting length should be in between 25 – 50cm long a very long stem and short stem is not good for planting.
iii. Use cutlass to cut the cassava stem for planting and it should produce a whitish liquid substance, to indicate that the cassava stems viable for planting.
METHOD OF PLANTING CASSAVA
The planting distance is (1 x 1)m it could be planted in a role zigzag form, depending on your planting choice. The cutting of 2.0 – 3.0 diameter should not be laid horizontally or vertically, but be tinted or slanted at an angle or 10 – 20. The older part of the stem should be the part that is deeper in the soil than the younger part. The stem should be completely covered with soil or small part or the top open.
1. WEED CONTROL:
A. Manually: two – three manual weeding within the first 3 months is very important for good field establishment.
B. Chemical: uses of perimeter at the rate of 3gai applied/emergence. If weeds are already present after planting perimeter can be mixed with round up (city phosphate)
C. Culturally: Dense plant population and the use of low branching varieties promote early closing a canopy and checking of weed growth.
2. FERTILIZER APPLICATION:
I participated in applying NPK 20:10:10 to the cassava by the recommended side band application method. Although cassava tolerates poor soils, increased tuber yields are obtained with fertilizer application, particularly where cassava is cropped continuously. As a heavy feeder, on per crop basis, cassava extracts more nutrients from the soil than most tropical crops. It extracts more K than other crops. It also extracts large amounts of N while the extraction of P and mg is relative low.
According to Prevott (1958), cassava has the highest K/N extraction ration. This underscores the need to have high levels of K and N in the fertilizer formulation for cassava production.
Excessive nitrogen leads to vegetative growth at the expense of root-tuber production. Therefore, a proper balance of N should be the goal. It is therefore recommended that soil analysis be carried out to determine the nutrient status of the field before sourcing for fertilizers. The inclusion of adequate amount of micro nutrient is also important, since absence of some micronutrient in cassava nutrient causes about 30% reduction in cassava yield (Mortvedt, 1985).
Additionally, plant tissue analysis may also serve as an indicator of the nutritional status of the plant.
Highlights of Good Fertilizer Policy
A good fertilizer policy for minimum cassava production should be arrived at after due consideration of the following:
· Data from soil analysis
· Effects of soil type and texture
· The previous cropping and residues
· The rainfall regime
· Land tenure systems
· The purpose for which the crop is grown
· The amounts required
· Choice of type of fertilizer to be used
· The method of application, manual or mechanical
· Time of application
· The cost of the fertilizer vis-à-vis economic returns
Recommended Fertilizer Types/Rates (Kg/Ha)
· NPK: 20:10:10:2S:1Zn at the rate of 400 – 600kg/ha
· NPK: 12:12:17:2Mg at the rate of 400 – 600kg/ha
The rate of application depends on:
· Nature of soil
· Previous cropping history
· Plant density
· The cultivar in use
The method of application was by band placement or ring application and the time of application depends on crop performance but preferably any time from 8weeks. At this period, tuber initiation has taken place and the carbohydrate reserve in the stem cutting would have been exhausted. In other words, sink source relationships are quite in place.
In some plots where poultry manure were made readily available, 200kg NPK plus 2000-4000kg poultry manure was applied per hectare. For ease of application, that poultry manure was incorporated into the soil at the time of land preparation followed by the application of NPK at 8weeks after crop establishment. Where the pH value is less than 4.0, lime was applied at the rate of 1000-1,500kg/ha.
Identified pest at the cassava farm
1. Grasshoppers – Zonocerus variegates
2. Mites – Tetranychus spp. (Red mite)
- Monoychelius spp. (cassava green mite)
3. Cassava mealy Bug – Phenacocus Manihoti
4. Termites – coptolermes spp.
PEST AND DISEASE CONTROL ON CASSAVA TUBER
a. Use of clean planting material
b. Use of resistant varieties
c. Plant at the right time
d. Avoidance of infested site
e. Insecticidal spray such as vector 85 sketching applied at 2kg effectively control meanly bug, spider mites and grass hoppers.
SYMPTOMS OF DISEASES ON CASSAVA
· Yellow green mosaic
· Various degree of deformation/distortion
· Stunted growth usually between 6 – 14 weeks
Diseases that attack the cassava
CONTROL OF PESTS AND DISEASES OF CASSAVA
Field inspection should be conducted during the rainy season on plant that is 6 – 14 weeks old. Cutting for planting should be inspected before use.
HARVESTING OF CASSAVA
Cassava is harvested at 9 month for early maturing varieties and 1 – 1 quarter years for late varieties. Harvesting is done manually by and pulling of tubers from the soil, digging may be necessary for easy of pulling.
Harvested tuber should be process immediately or buried in the ground temporary as fermentation is rapid.
YIELD OF CASSAVA
In some crop, yield may vary between 10 – 40 tones per hectare. Under more intensive management and proper fertility. A yield of 70 tones per hectare could be obtained.
STORAGE OF CASSAVA TUBERS
First tubers do not keep well beyond 24 hours restricted harvesting is recommended to the quantity that can be processed or sold out.
Tubers can be processed into Flour, Garri, Cassavita, Akpu, Starch, Chips.
USES OF CASSAVA
Cassava starch is used in laundry and manufacturing many product such as beer and other alcoholic drinks. Cassava flour can be used to replace wheat in baking powder for bread, biscuit and cake making.
Cassava root being the major source of raw materials to several products, as explained in the diagram below can be processed in several ways for different uses.
MATERIALS USED FOR POLLINATION AT THE INSTITUTE
Sieved bags that measured 20cm x 25cm were used to protect flowers from undesired pollen. Small sieve bags that measured 10cm x 18cm were used to collect the matured seeds. The bags were made of cotton material of 60 to 80 meshes and had a string attached to close its mouth on the plant. tags of 3cm x 4cm were used to label pollinated flowers (necessary for data collection). Bottles of 3 to 5cm in diameter and 5 to 8cm high were used to carry male flowers during pollination.
CASSAVA POLLINATION PROCEDURE
· The method used at Umudike is called hybridization (cross breeding)
· Mature male and female flowers were identified prior to pollination.
· The mature female flowers (gynoecium) were covered with the sieved bags in the morning to enhance the opening of their petals before noon and also prevent other pollinating agents like bees from pollination the flowers.
· The desired male flowers (androecia) were collected and carried in bags.
· The above 2 steps were done in the morning, between 7:00am and 9:00am before the sun started to rise.
· The pollination was done in the noon between 1:00pm and 5:00pm before sunset (to pollinate, the bag used to cover flower, the androecia was burst open and its pollen rubbed properly on the stigma of the gynaecium).
· Having completed pollination, the gynaeciums so pollinated were covered with the bags.
· Each flower branch on which the pollination was made, was made, was labeled with a lay indicating the cross combination, date of pollination and number of gyaecium pollinated.
3. DATA COLLECTION: Data collection is a very critical and important aspect of cassava breeding as lack of such at any stage of the research may adversely affect the research or even nullify the authenticity of labourers and potted bags per day (for calculation of man days, cost of production etc); date of planting sowing, number of seeds sown per day date of germination, date of transplanting to the field.
SOIL SCIENCE LABORATORY ACTIVITIES
The activities performed in the soil science laboratory of the National Root Crops Research Institute Umudike.
Characteristics of soils which includes:
1. Organic matter/carbon
2. Available phosphorous
3. Total Nitrogen
4. Total exchangeable bases (TEB) (Cu, Mg, K, Na)
5. Exchangeable acidity (Al+ + H+)
6. Effective cation exchange capacity.
Analysis of fertilizer and plant samples
1. Nitrogen (N)
2. Phosphorous (P)
3. Potassium (K)
APPARATUS/EQUIPMENTS IN THE LABORATORY AND THEIR USES
1. FUME CUPBOARD: This is used for heating poisonous chemical/samples and for digesting some samples to avoid the dangerous odour from the samples from polluting the environment.
2. MILLING MACHINE: This is used in milling plant/food materials like leaves, roots, grains etc. This is to ensure homogeneity, intimate chemical reaction and mutual chemical interaction.
3. WATER BATH: this is used for mixing soil samples for particle size distribution.
4. PH METER: This is used for taking the reading of PH of samples. The most essential part of this machine is the electrode.
5. SPECTROPHOTOMETER: This is used in advanced chemical analysis for detecting the presence of solution e.g. determination of available phosphorous and heavy metals.
6. SENSITIVE ANALYTICAL BALANCE: This is used for taking the weight of samples.
7. MUFFLE FURNACE: It is used for heating plant materials e.g. root, leaves etc up to 800oc.
8. MECHANICAL SHAKERS: This is used to shake samples to a required hour for nutrient or minerals extraction from the soil, plant, water or food samples.
9. DRY OVER: This is used in drying glass wares, leave samples, grains and some reagents. It has an inbuilt thermostat.
Volumetric flasks, standard flasks, conical flasks, beakers, forcepts plastic rubber turbine, (bottles) automatic burette crucibles, pipette, measuring cylinder, soil hydrometer, plungers, dissicastor, spatulas etc.
PARTICLES SIZE DISTRIBUTION (MECHANICAL ANALYSIS)
· Sedimentation cylinder
· Motor stirrer and cup
· Bouycous hydrometer
· Special stirring peddle
· Stop watch
· Funnel 10 – 12cm diameter
· Wash bottler (Plastic)
· Balance accurate to 10mg
· Percolation basing
i. Sodium hexametaphosphate (Na2PO3)b and Sodium Carbonate Na2 Co3. These two reagents are called Calgon solution or dispersing solution.
The calgon solution is prepared by dissolving 35.7g dry powdered sodium hexametaphospate and 7.94g anhydrous sodium carbonate to 1 liter.
Dissolve the (Na2PO3)6 first by adding the dry powder slowly to about 750ml water which is well stored during the addition. Then add the sodium carbonate and make up to one (1) liter, this solution contains 0.35N (Na2 Po3)6 and 0.5N (Na2Co3) = 0.5N Na+10N.
ii. Hydrogen Peroxide 30% 100 volume.
The Bouycous hydrometer method for particles size distribution follows the procedures:
· Weigh out 50g of the prepared soil sample and transfer to a cup of mechanical stirrer.
· Add 50ml of calgon solution and allow it to stay for 24 hours for complete separation.
· Stir very well using plunger for 2 – 10 minutes depending on soil and then wash down the stirring blades as they are removed from suspension.
· Read the temperature using thermometers. The temperature should be between 15oc and 25oc.
· Mix with special plunger and start timing.
· Take the first reading (silt + clay) after 40 seconds of timing. At the completion of the 40 seconds the bouycous hydrometer careful into the center of the suspension and release it gentle so that it does not rotate nor move up or down to violently. Take the reading on the scale to the nearest 0.5 unit.
· Take another reading for clay after 2 hours.
· Finally, obtain a blank reading by preparing 1 liter of 0.5% calgon solution (dilute the stock solution ten times) and adjust the temperature to 20oc.
· Insert a bouycous hydrometer and take the reading.
This is an I.T Report on Agriculture