Seed Testing - Purity And Germination 674b

Seed Science and Technology

LABORATORY EXCERCISE Seed Testing - Purity and Germination Introduction Seed testing is the cornerstone of all other seed technologies. It is the means by which we measure the viability and all the physical factors that regulate the use and maintenance of seeds. Everything that is done with seeds should have some test information to guide the work and ensure high quality. Seed tests tell if a crop of seeds is worth collecting, if handling procedures are correct, and how many potential seedlings are available for regeneration. Seed testing is related to health status of seed. Sowing healthy seeds of high quality is our concern to improve crop yields thus increasing food production. It has a great concern to farmers and seed producing agencies where the diseases is high and average yields are low and where more food is needed to feed the ever-increasing population. So, it is important to test the seeds for disease organism before they are sown in the field and to avoid harmful organisms travelling from infected to non-infected areas within a country or across international boundaries. Objectives 1. To expose students to various types of test in determination of seed quality. 2. To provide hands-on for students to perform seed testing. 3. To expose students the importance of seed testing and the parameters to be taken during seed testing. Materials Various types of seeds: green beans, black eyed peas, soy beans, ladyfinger, long beans, red beans, Brassica spp., vines, unknown seeds, inert matter. Methodology Seed physical purity test is the most fundamental and the first test to be carried out in seed testing, as the subsequent tests are made only on the pure seed component. Seeds provided by the lecturer were divided into smaller portion but representing whole seed sample and not bias. Seeds were weight and by using forceps and thin ruler, seeds were divided into various components accordingly (pure seeds, other seeds, and inert matter). Finally, each component was weight and percentages of each component were calculated. According to Seed Testing Rules of Association of Official Seed Analyst (AOSA) and International Seed Testing Association (ISTA), filter papers, blotters, paper towels, cellulose papers, sponge rok sand, vermiculite, terralite, or a mixture of 50 percent sand and perlite or vermiculite, or soil are acceptable substrata for germination various seed. In this germination test, rolled paper towel germination technique and sand germination technique were employed. For rolled paper towel germination test, fifty pure seeds were used. Five seeds were arranged per lane, in ten lanes, on moistened kitchen towel. To facilitate observation, wax paper was used when rolling the kitchen towel. Similar amount of seeds were used in sand germination test. Sand was washed and put on the container. Five long lanes were produced using a ruler and ten seeds were arranged per lane.

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Seed Science and Technology

For both tests, samples were incubated at room temperature, away from direct sunlight. Moisture of the medium was maintained and data was collected in two days interval for ten days. Percentage of germination, contamination, and dormancy were calculated. For moisture content determination, three aluminium foils (“boat”) were prepared and filled with ten pure seeds each. Seeds were then dried in the oven at 103°C for 18 hours. Weight of seeds before and after drying was identified and moisture content of seeds was calculated. Results See the appendix Discussion Seed Purity Test Seed purity denotes the composition of a particular seed lot. It is based on physical determination of the components present and include percentage by weight of pure seeds (working sample represented by the crop species of which the lot is being tested), other crop seeds (seeds other than seed being tested), weed seed (seeds present from plants considered as weed), and inert matter (materials that is not seed) (Copeland, 2001). Seed packet tested in this experiment containing 93.31% pure seeds (mung bean seeds), 6.21% other crops seeds, 0.48% inert matters, and no weed seeds. According to Copeland (2001), amount of other seeds is better to be below 5%. Although no weeds are found this sample, other crop seeds may cause detrimental effect to livelihood of pure seeds (in of competition of soil nutrients and space) if it was “accidently” grown in the same place with the pure seed. This batch of seeds has moderate quality and it is advisable to buy a seeds with at least 95% purity. The purity test is perhaps the most complex and exacting of all tests for seed quality. A seed analyst must have a comprehensive knowledge of seed structure and function and must be able to identify a wide array of differing species. Seed Germination Test Germination has been defined as “the emergence and development from the seed embryo of those essential structures which, for the kind of seed tested indicate its ability to develop into a normal plant under favourable, conditions in soil” (Sweedman and Merritt, 2006). Germination test used to ratify the seeds that follow those rules. The seedlings lacking of an essential structure, showing weak or unbalanced development, decay or damage or damage affecting the normal development of seedling are not considered or calculated in germination percentage. Factors that can affect the performance of seed in germination tests include: diseased seed, old seed, mechanically damaged seed, seed stored under high moisture and excessive heating of seed during storage or drying (Basra, 2006). In rolled paper towel germination test, 98% of seeds germinate after 4 days of incubation (appendix: Figure A), while for sand germination test, 90.6% of seeds germinate within 6 days (appendix: Figure B and Figure C). This demonstrating mung beans tested in this

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Seed Science and Technology

experiment has very good value to money – it germinates fast and grows fast – indicating seeds are very good in quality and vigour. This seeds is suitable for large-scale cultivation. Differences in germination percentage recorded in two methods employed demonstrated the importance of choosing correct approach when executing germination test. Rolled paper towel method suitable for most small and medium size seeds. It is a good method to test germinability of seeds but not seed vigour. The rolled paper towel was placed in slanted position to save space and avoid damages of seeds or embryos. Germinability of seeds is somewhat determined by the quality of sand used in sand germination test. Fine, smooth sand (e.g. river sand) is excellent choice. Sand should be washed thoroughly before use. In seed testing, results are always wanted urgently and the germination test unfortunately is not rapid. While result for some crop species (e.g. Brassica, Hordeum, Phaseolus) are available in seven days, other agricultural and horticultural species require ten, 14, 21, or 28 days. Some tree or shrub species require up to 30 days after pretreatment for three to four months (e.g. Rosa spp. and Pyrus spp.) (Schmidt, 2007). Germination test is somewhat expensive and exerts considerable pressures on time, labour, and money (Basra, 1995). Seed Moisture Content Test Average moisture content of mung bean seeds tested in this experiment is 10.74%. This value is high compared to critical moisture content for mung beans that fit for long torage (through cryopreservation), mentioned by Bennets and Cocks (1996) which is at 6.3%. Availability of high moisture content stimulate the enzyme production thus assisting breakdown of food storage in seeds, and this metabolic activity releasing heat that will leads to fungal growth. Seeds will die. Seeds must be properly dried to maintain its viability over a long period. This seeds, however, safe for short term or mid term storage (Brink and Belay, 2006) Moisture content is an indirect quality parameter since it is known that it has a crucial influence on storage and longevity. Analysis with a high or a low moisture figure can thus suggest a different storage fate. High demand for exactness is relevant for agricultural crops used for consumption, because it is influences nutrient quality. Less exactness can be accepted in connection with reproductive material of forest seed. Seeds may be absorb or release moisture according to the balance with atmospheric humidity (relative humidity), so to eliminate error caused by varying humidity, seeds should be packed in waterproof material as quickly as possible after sampling and should maintained within this packaging until the working sample for moisture content determination has been taken out. Moisture analysis should be done as quickly as possible to prevent errors caused by absorption from the air (Karrfalt, 2001). These three tests have provided sufficient information to the farmers about the quality, germinability, and suitable storage condition for the seeds. Viability test can be done if requested.

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Seed Science and Technology

Conclusion From this experiment, we become aware and understood about various methods in determining seed quality, performing seed testing, and significance of each steps involved. References Basra, A.S. 1995. Seed Quality: Basics Mechanism and Agricultural Implication. Haworth Press, Binghamton, New York, USA. Basra, A.S. 2006. Handbook of Seed Science and Technology. Haworth Press, Binghamton, New York, USA. Bennet, S.J. and Cocks, P.S. 1996. Genetic Resources of Mediterranean Pasture and Forage Legumes. Kluwer Academic Publisher, Netherlands. Brink, M. and Belay, G. 2006. Plant Resources of Tropical Africa – Cereals and Pulses. PROTA Foundation, Wageningen, Netherlands. Copeland, L.O. 2001. Principle of Seed Science and Technology. Kluwer Academic Publishers, Netherlands. Karrfalt, R.P. 2002. Seed Testing. USDA Forest Services National Tree Seed Laboratory, Georgia, USA. Schmidt. L. 2007. Tropical Forest Seed. Forest Genetic Resources, Copenhagen, Denmark. Sweedman, L. and Merritt, D. 2006. Australian Seeds: A Guide to Their Collection, Identification and Biology. CSIRO Publishing, Collinwood, Australia. http://www.bpi.da.gov.ph/Services/seedtesting.html (291009) http://164.100.10.50/Seed/Stl/html%20pages/Germination%20Testing.htm (311009)

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Seed Science and Technology

APPENDIX SEED MOISTURE CONTENT (MC) TEST Species Origin Method used Date/Time in Date/Time out

: Vigna radiata (mung bean) : Malaysia : 103°C for 18 hours for more : 261009/1030 hours : 021109/1045 hours

Formula for moisture content calculation % MC = (M2-M3)/(M2/M1) x 100 M1 : Weight of dish (g) M2 : Weight of dish and sample (g) M3 : Weight of dish and sample after oven drying (g) Dish A M1 0.249

M2 2.118

M3 1.919

Calculation (0.199/1.869)(100)

% MC 10.65%

Dish B M1 0.252

M2 2.274

M3 2.059

Calculation (0.215/2.022)(100)

% MC 10.63%

Dish C M1 0.222

M2 2.199

M3 1.983

Calculation (0.216/1.977)(100)

% MC 10.93%

Average seed MC: (10.65 + 10.63 + 10.93)/3 = 10.74%

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Seed Science and Technology

SEED PURITY TEST Species Origin Date

: Vigna radiata (mung bean) : Malaysia : 261009

Total weight of seeds: 482.954 g Seed Species/Variety Weight (g)

% from Total Weight

Mung bean

450.681

(450.681/482.954)(100) = 93.31%

Black eyed peas

22.539

(22.539/482.954)(100) = 4.67%

Soy beans

0.867

(0.867/482.954)(100) = 0.18%

Ladyfinger

1.777

(1.777/482.954)(100) = 0.37%

Long bean

1.157

(1.157/482.954)(100) = 0.24%

Red bean

0.206

(0.206/482.954)(100) = 0.04%

Brassica spp

0.275

(0.275/482.954)(100) = 0.06%

Vines

1.242

(1.242/482.954)(100) = 0.26%

Unknown seeds

1.891

(1.891/482.954)(100) = 0.39%

Inert matter

2.319

(2.319/482.954)(100) = 0.48%

% Component % Pure seed: 93.31%

% Other crops: 6.21%

% Inert matter: 0.48%

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Seed Science and Technology

SEED GERMINATION TEST METHOD: ROLLED PAPER TOWEL GERMINATION 3010 4 50 50 49 47 196 49 98

0211 6 50 50 49 47 196 49 98

0411 8 50 50 49 47 196 49 98

0611 10 50 50 49 47 196 49 98

Date (2009) 0211 0411 0611 Days 0 2 4 A 0 40 39 B 0 25 28 C 0 36 37 D2 0 45 47 Total 0 146 151 Average 0 36.5 37.75 % 0 85.9 88.8 1 2 dead or dormant; our group

0911 6 39 30 37 48 154 38.5 90.6

1111 8 39 30 37 48 154 38.5 90.6

1311 10 39 30 37 48 154 38.5 90.6

Group

Date (2009) Days A B C2 D Total Average %

2610 0 0 0 0 0 0 0 0

2810 2 50 50 49 46 195 48.7 97.5

Seeds removed 1 (mould) 3 (dead1)

Total seeds 50 50 50 50 200

Group

METHOD: SAND GERMINATION Seeds removed 1 (mould) 10 (mould) 1 (mould) 2 (dead1) 2 (mould)

Total seeds 40 40 40 50 170

FIGURES ROLLED PAPER TOWEL GERMINATION TEST

Figure A: Mung bean seeds germinate into normal plantlets after 4 days of incubation.

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Seed Science and Technology

SAND GERMINATION TEST

Figure B (top) and Figure C: Mung bean seeds germinate into normal plantlets after 6 days of incubation.

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