Thursday, 11 May 2017

STARCH CONTENT DETERMINATION FROM CASSAVA SAMPLES

Starch is a soft, white and tasteless powder that is insoluble in cold water, alcohol or other solvents. Starch is one of the most abundant substance in nature, a renewable and unlimited resource. Starch is produced from grains or root crops. Starch is the main constituent of cassava and about 25% starch may be obtained from matured and
good quality tubers. Determination of starch content in different cassava varieties, aids breeders to know the cassava varieties with high or low starch content. It also aids the institute NRCRI to know the particular cassava variety required by some consumers. For example, low starch content cassava varieties is recommended for diabetic patients and high starch content of cassava varieties is required in making products like garri and starch.

2.3       DRY MATTER DETERGMINATION FROM CASSAVA ROOT TUBERS

Conclusion: The weight of 10g of the sample is composed of water and dry matter, when dried in oven, the weight reduces. The higher the dry matter of a particular cassava genotype, the longer the shelf life of that cassava genotype in a dry state but the lower the dry matter, the shorter the shelf life of that cassava genotype. Cassava genotype with high dry matter are recommended for production of garri.

2.4 PLANT TISSUE CULTURE LABORATORY


Plant tissue culture laboratory is a branch of the Biotechnology programme in the National Root Crops Research Institute. This unit makes use of certain techniques  to maintain or grow plant cells, tissues or organs in-vitro under sterile conditions on a nutrient culture media of known composition. This technique is widely used to produce clones of plants and the method is known as Micro propagation. Plant tissue culture relies on the fact that plant cells have the ability to regenerate a whole plant from single cells (totipotency). Pieces of stems or roots can often be used to generate a new plant on a culture medium with their required plant nutrient.

2.4.1 SECTIONS AND EQUIPMENTS FOUND IN PLANT TISSUE LABORATORY

In National Root Crops Research Institute, the plant tissue culture laboratory has six sections, namely:
1. ANTE ROOM: This is a small room found before entering the main laboratory where foot wears from outside is exchanged with the one used inside the laboratory (slippers). The essence is to reduce the amount of pathogens that enter into the laboratory and the major purpose is to prevent inflow of external from outside the laboratory.
2. PREPARATORY ROOM: This is a large room found in the middle of the laboratory and it is where most of the laboratory work is done, like preparation of different medium for culturing our ex-plant. Most of the equipment and reagents are kept here.
i. Hot Air Box: Used for dry sterilization. It is used for drying of glass wares and other materials needed for practical work. The holding period varies according to the giving  
ii. sterilization temperature attend. For example 160oC for 45mins, 170oC for 20mins after which the materials are allowed to cool for about 2hrs. This is to prevent glass wares from breaking.
iii. pH Meter: Used in the determination of accurate pH of a medium, liquid samples and specimens.
iv. Distiller: Used for the distilling water.
v. Dryer: For drying glass wares after washing.
vi. Refrigerators and Freezers: Used for storing, maintaining reagents and also for storing of Stock Solution between sub-culturing period. It is also for storing sterile media to prevent dehydration.
vii. Canister: Used to store petri dishes for dry sterilization.
viii. Racks: It is used storing test tubes.
ix. Microwaves: Used for melting solid medium.
x. Hot Plate Magnetic Stirrer: For heating and stirring of medium.
xi. Sensitive Weighing Balance: Used for weighing salt and other reagents in sandy form.
xii. Automatic Dispenser: Used for dispensing required volume of medium uniformly into culture vessels.
xiii. Dry Cabinet (Desiccant): is used for drying glass wares, surgical instruments and media.
xiv. Glass Measuring Cylinder: It is used in measuring the volume of liquid.
xv. Test tubes: They are used as culture vessels, also for mixing and dilution of solution.
xvi. Forceps: Used for inoculating and transferring culture from one specimen bottle or culture plate to another.
xvii. Air Conditioner: Used for providing the media and reagents prepared with conducive environment to avoid denaturation by heat.

3. AUTOCLAVE ROOM:

 It is a room were the autoclave is kept. Autoclave is used for wet  
4. sterilization (Steam Sterilization). For medium we sterilize for 15 minutes at 121oC and 1.05kg/cm2 or 15psi (pound per square inch). 
5. ASEPTIC MANIPULATION ROOM: It is a room where initiation and sub culturing are done. In this room, we work under sterile environment (Aseptic Condition). We first  do surface sterilization (Swab) with 70% ethanol before work is done here. We have the following equipment.
i. Laminar Air Flow: It provides a sterile environment used for initiation  and sub culturing. It is in the larminal air flow that ex plants are inoculated into the culture medium under aseptic conditions.
ii. Mechanical Shaker: Used for shaking the ex plants inside the culture bottles.
iii. Binocular Microscope: Used to view and excise ex plants during meristem initiation.
6. CULTURE ROOM: This is also known as incubation room. This room is used for incubation of initiated and cultured plantlet. This room has shells of fluorescent light which helps to re-enact the outside condition of solar energy from the sun. It is also air conditioned which helps to maintain the temperature of the room that is 28oC±2 (Minimum of 26oC and Maximum of 30oC). The photo period of this room is 16hrs light and 8hrs darkness, light intensities of 2000 to 3000 flux of light with 250 bulbs are provided. The plants are heterotrophic.
7. WASHING ROOM: This is where culture vessels and glass wares are washed. 

2.4.2 COMMMON TERMS USED IN PLANT TISSUE CULTURE

i. Micro-Propagation: invitro clonal propagation of plant from shoot or nodal explants, usually with an accelerate proliferation of shoots obtained through sub culture.
ii. Callus: a mass of undifferentiated parenchymatous cells either in nature or in culture. 
iv. Plantlet: a small rooted plant or germinating embryo 
v. Ex vitro: Condition of growth inside the culture vessel.
vi. In Vitro: Condition of growth inside the culture vessel.
vii. Ex Plant: tissue taken from its original plant (Mother plant) and transferred to an artificial medium for growth.
viii. Clone: A population of cells derived from a single cell from mitotic divisions. It is also commonly used to denote a population of plants derived from a single individual. 
ix. Node: It is a region of the stem from where a leaf bearing an auxiliary bud arise.
x. Toti potency: Ability of a plant parts (cell) to regenerate whole plants when cultured or intended.
xi. Aseptic Techniques: Procedures/measures taken in the prevention of bacteria, fungi, micro plasmas and other micro organisms into the cells, tissues and also prevent cross contamination of the other culture.
xii. Surface Sterilization (SWAB): It is the disinfection of plant materials by the use of sterilant for invitro culture.
xiii. Culture: Growing cells, organs, tissue or whole plant (Nodal Segments) in Nutrient medium under aseptic conditions.

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