4.1. INTRODUCTION I. INTRODUCTION AND PRINCIPLES 4.1. INTRODUCTION 4.1. INTRODUCTION 4.2. PARAMETERS OF SEED QUALITY 4.1.

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1 UNIVERSITY OF SÃO PAULO ESCOLA SUPERIOR DE AGRICULTURA LUIZ DE QUEIROZ Brazil 4.1. INTRODUCTION IMPORTANCE OF SEED QUALITY I. INTRODUCTION AND PRINCIPLES 4. SEED QUALITY Ana Novembre ESALQ Piracicaba, Brazil SEED QUALITY RESULTS FROM GENETIC, PHYSICAL, PHYSIOLOGICAL AND PHYTOSANITARY CHARACTERISTCS OF THE SEEDS 4.1. INTRODUCTION IMPORTANCE OF SEED QUALITY HIGH QUALITY SEEDS SHOULD HAVE: CAPACITY TO PRODUCE NORMAL SEEDLINGS EXPECTED FIELD EMERGENCE AND UNIFORMITY POTENTIAL STORABILITY 4.1. INTRODUCTION IMPORTANCE OF SEED QUALITY QUALITY EVALUATION SHOULD DETERMINE SEED LOT VALUE FOR SOWING, TO ASSURE: GENETIC IDENTITY AND PURITY OF SEED SEED LOTS WITHOUT CONTAMINANTS (WEED SEEDS, MICROORGANISMS AND INSECTS) SEED ABILITY TO PRODUCE VIGOROUS AND HEALTHY PLANTS 4.1. INTRODUCTION IMPORTANCE OF SEED QUALITY QUALITY EVALUATION SHOULD DETERMINE SEED LOT STORAGE CAPACITY 4.2. PARAMETERS OF SEED QUALITY a) VARIETAL IDENTITY AND PURITY BREEDING PROGRAMS NEW CULTIVARS SEED PRODUCTION OBJECTIVE: BREEDER SEED QUALITY EVALUATION SHOULD DETERMINE SEED LOT VALUE FOR TRADING CERTIFIED SEED SEED MULTIPLICATION WITHOUT GENETIC ALTERATIONS

2 4.2. PARAMETERS OF SEED QUALITY b) PHYSICAL (INTEGRITY OF THE SEED, SEED FORMATION AND WATER CONTENT) MOISTURE CONTENT OF SEEDS AND BIOLOGICAL PROCESS SEEDS, % WATER EFFECTS GERMINATION WELL-DEVELOPED AND HIGH DENSITY SEEDS HAVE HIGHER QUALITY SEED PHYSICAL INTEGRITY IS RELATED TO MECHANICAL HARVEST, SEED CLEANING AND TRANSPORTATION AND STORAGE. SEEDS WITHOUT MECHANICAL DAMAGE MAINTAIN SEED QUALITY SEED MOISTURE CONTENT REGULATES ALL BIOLOGICAL PROCESSES IN SEED DETERIORATION MOST SEED SPECIES STORAGE LONG-TERM STORAGE 4.2. PARAMETERS OF SEED QUALITY c) PHYSIOLOGICAL (VIABILITY AND VIGOR) SEED VIABILITY REFERS TO THE CAPACITY OF A SEED TO GERMINATE AND PRODUCE A NORMAL SEEDLING SEED VIGOR COMPRISES THOSE SEED PROPERTIES WHICH DETERMINE THE POTENTIAL FOR RAPID, UNIFORM EMERGENCE, AND DEVELOPMENT OF NORMAL SEEDLINGS UNDER A WIDE RANGE OF FIELD CONDITIONS (AOSA, 1983) 4.2. PARAMETERS OF SEED QUALITY c) PHYSIOLOGICAL (VIABILITY AND VIGOR) SEEDS HAVE MAXIMUM QUALITY AT PHYSIOLOGICAL MATURITY. AFTER THAT, SEED STORAGE SUCCESS DEPENDS ON ENVIRONMENTAL, HARVEST, POSTHARVEST AND STORAGE CONDITIONS MATURATION PARAMETERS WATER SEED SIZE DRY MATTER GERMINATION 4.2. PARAMETERS OF SEED QUALITY d) PHYTOSANITARY ATTRIBUTES (INSECTS- AND SEED-BORNE DISEASES) HEALTH OF SEEDS REFERS PRIMARILY TO THE PRESENCE OR ABSENCE OF DISEASE-CAUSING ORGANISMS, SUCH AS FUNGI, BACTERIA, VIRUSES, AND INSECTS EMBRYO MATURE SEED INSECTS AND FUNGI GENERALLY REDUCE SEED QUALITY

3 4.3. RELATIONSHIP OF SEED QUALITY AND PRODUCTION FACTORS GENERAL CONDITIONS AFFECTING SEED QUALITY FACTORS KNOWN TO AFFECT THE GROWTH OF THE PARENT PLANT INFLUENCE SEED QUALITY (quality of initial seed, temperature and photoperiod, herbicide and pesticides) HARVESTING AND PROCESSING CONDITIONS (mainly mechanical damage, the extent of damage depends on seed species and seed moisture content; adverse effects are magnified during storage) 4.3. RELATIONSHIP OF SEED QUALITY AND PRODUCTION FACTORS GENERAL CONDITIONS AFFECTING SEED QUALITY POSTHARVEST STORAGE CONDITIONS (seed moisture and drying, storage temperature, insects and storage fungi, Aspergillus sp. and Penicillium sp.) 4.3. RELATIONSHIP OF SEED QUALITY AND PRODUCTION FACTORS a) FIELD PRODUCTION AFFECTS PURITY AND VARIETAL IDENTITY PURITY VIABILITY AND VIGOR PHYSICAL INTEGRITY OF SEEDS SEED SIZE WEED SEEDS AND INSECTS AND FUNGAL PRESENCE OR ABSENCE Seed borne disease affecting plant growth in the field Seed-borne pathogen (seed transmitted)

4 4.3. RELATIONSHIP OF SEED QUALITY AND PRODUCTION FACTORS SEED BORNE DISEASE AFFECTING PLANTS IN THE FIELD, AND SEED HARVEST, PROCESSING AND STORAGE; PURITY AND HEALTH OF SEED LOT b) PROCESSING AFFECTS PURITY VIABILITY PHYSICAL INTEGRITY OF SEEDS SEED SIZE WEED SEEDS AND INSECTS AND FUNGAL PRESENCE OR ABSENCE DRY AND HOT SEASON DURING SOYBEAN SEED PRODUCTION AFFECTS SEED PROCESSING 4.3. RELATIONSHIP OF SEED QUALITY AND PRODUCTION FACTORS c) STORAGE AFFECTS MOISTURE CONTENT VIABILITY AND VIGOR WEEDS SEEDS AND INSECT AND FUNGAL PRESENCE OR ABSENCE PURITY Sorghum seed germination with variations of relative humidity (RH) and temperature (T) during storage period UH T Storage (Months) ( C)

5 Incidence of Sitophilus oryzae on stored wheat seeds TEMPERATURE ( C) SEEDS MOISTURE CONTENT GERMINATION, VIGOR AND SEED PATHOLOGY FROM Euterpe oleracea SEEDS WITH DIFFERENT MOISTURE CONTENT (Nascimento, 2005). Seed Water moisture content 43,4 37,4 30,3 26,1 21,0 15,1 11,9 G 92 a 88 a 80 b 42 c 07 d 00 e 00 e Seedling emerg. index 0,020 ab 0,023 a 0,018 b 0,016 b 0,016 b 0,000 c 0,000 c Seedling emerg. 93 a 89 ab 85 b 48 c 11 d 00 e 00 e Seedl. size (cm) 15,7 a 15,2 a 15,3 a 10,5 b 9,0 b 0,0 c 0,0 c Dry mattter g/seedling 0,440 a 0,399 a 0,272 b 0,144 c 0,021 d 0,000 e 0,000 e Penicillium sp. 00 d 00 d 00 d 06 d 14 ab 08 bc 20 a Aspergillus sp. 00 b 00 b 00 b 00 b 00 b 08 a 00 b F. solani 54 a 60 a 50 a 50 a 22 b 04 c 02 c F. moniliforme 12 ab 10 ab 16 a 00 b 04 ab 02 ab 02 ab a) SAMPLING OBJECTIVE TO OBTAIN A SAMPLE SIZE SUITABLE FOR TESTS; THE SAMPLE MUST REPRESENT THE QUALITY OF THE SEED LOT FROM WHICH IT WAS DRAWN a) SAMPLING SEED LOT SEED LOT IS A SPECIFIED QUANTITY OF SEED AND PHYSICALLY IDENTIFIABLE SEED LOT SAMPLES PRIMARY SAMPLE COMPOSITE SAMPLE SUBMITTED SAMPLE WORKING SAMPLE a) SAMPLING Primary sample is a small portion taken from one point in the lot Composite sample is formed by combining and mixing the primary samples taken from the lot Submitted sample is a sample submitted to the testing station (Minimum size is specified in ISTA Rules) Working sample is a sub-sample taken from the submitted sample in the laboratory on which one of the quality tests described in ISTA Rules is conducted

6 Without partitions SOIL DIVIDER CONICAL DIVIDER (BOERNER TYPE) With partitions EQUIPMENTS FOR SAMPLING SEED LOT (TRIERS) Seeds that have not been rendered free-flowing, the primary samples must be drawn by hand MECHANICAL DIVIDERS CENTRIFUGAL DIVIDER (GAMET TYPE) SAMPLING INTENSITY (seed in containers of more than 100kg or from streams of seed entering containers) LOT SIZE UP TO 500kg AT LEAST 5 PRIMARY SAMPLES (P.S.) 501 3,000kg 1 P.S. FOR EACH 300kg, BUT NOT LESS THAN 5 P.S. 3,001 20,000kg 1 P.S. FOR EACH 500kg, BUT NOT LESS THAN 10 P.S. 21,000 AND ABOVE 1 P.S. FOR EACH 700kg, BUT NOT LESS THAN 40 P.S. (ISTA, 1999) SAMPLING INTENSITY (seed in containers up to 100kg capacity) 1-4 containers: 3 primary samples from each container 5-8 containers: 2 primary samples from each container 9-15 containers: 1 primary sample from each container containers: 15 primary samples total containers: 20 primary samples total 60 or more containers: 30 primary samples total (ISTA, 1999) a) SAMPLING LOT AND SAMPLE WEGHTS (ISTA, 1999) Minimum sample weights Species Maximum weight of lot (kg) Submitted sample (g) Working sample for purity analysis (g) Sorghum bicolor Zea mays

7 b) PURITY ANALYSIS OBJECTIVE IS TO DETERMINE: a) The composition of the sample being tested and, by inference, the seed lot composition b) The identity of the various species of seeds and inert particles constituting the sample b) PURITY ANALYSIS WORKING SAMPLE PURE SEEDS %; Predominant species and pieces of seed units larger than ½ their original size OTHER SEEDS (by number; any species other than pure seed) Result is % Pure Seed SUBMITTED SAMPLE INERT MATTER (%; seed and all other matter not defined as pure seed or other seeds) WORKING SAMPLE PURE SEEDS c) VIABILITY - GERMINATION TEST OBJECTIVE TO DETERMINE THE MAXIMUM GERMINATION POTENTIAL OF A SEED LOT INERT MATTER OTHER SEEDS PURITY TEST - Brachiaria brizantha cv Marandu SEED GERMINATION IS THE EMERGENCE AND DEVELOPMENT OF THE SEEDLING, WHICH SHOWS POTENTIAL TO DEVELOP INTO A PLANT UNDER FAVORABLE SOIL CONDITIONS

8 c) VIABILITY - GERMINATION TEST WORKING SAMPLE PURE SEED PRESCRIPTIONS FOR SEED GERMINATION: WATER, TEMPERATURE, OXYGEN AND LIGHT, MAINLY FOR DORMANT SEEDS c) VIABILITY - GERMINATION TEST GERMINATION METHODS (ISTA, 1999) SPECIES Prescriptions for: Additional directions (including dormancy break) Substrate Temperature First Final C county count (days) (days) Sorghum bicolor TP;BP 20-30; Prechill Zea mays BP; S 20-30; 25; c) VIABILITY - GERMINATION TEST EVALUATION: Normal seedlings (%; show the potential for continued development into satisfactory plants under favorable environmental conditions) Abnormal seedlings (%; do not show the potential for continued development into satisfactory plants under favorable environmental conditions) Ungerminated seed: dormant, dead and other categories (%; seeds which have not germinated at the end of the test period) Result is related to % of Normal Seedling

9 c) VIABILITY - TETRAZOLIUM TEST OBJECTIVE TO MAKE A QUICK ESTIMATE OF SEED VIABILITY PRINCIPLE A colorless tetrazolium solution is used as an indicator living cells with the formation of a red, stable and non-diffusible substance, named Formazan. Thus, it s possible to distinguish the red-colored living tissues from the colorless dead ones c) VIABILITY - TETRAZOLIUM TEST SEED SAMPLES (2x100; 4x50; 2x50) INDIVIDUAL SEED EVALUATION Result is related to % Viable Seeds SEEDS ARE HYDRATED (6 to 24 h) CONDITIONED IMMERSED IN OR 0.5 OR 1.0% TETRAZOLIUM SOLUTION d) MOISTURE CONTENT OBJECTIVE a a b b TO DETERMINE THE MOISTURE CONTENT OF THE SEED (% OF WEIGHT OF THE ORIGINAL SAMPLE) Figura 1. Teste TETRAZOLIUM de tetrazólio: sementes viáveis TEST (a) e não viáveis (b). VIABLE SEEDS (a) NON-VIABLE SEEDS (b) SUBMITTED SAMPLE MOISTURE-PROOF CONTAINER d) MOISTURE CONTENT OVEN METHOD: 103 ± 2 C/17h; 130 ± 3 C/4; 2; 1h THE DETERMINATION SHALL BE CARRIED OUT IN DUPLICATE ON TWO INDEPENDENTLY DRAWN WORKING SAMPLES WORKING SAMPLE WEIGHT (ISTA, 1999) Diameter of containers (cm) < 8 Working sample (g) 4 a

10 e) SEED HEALTH OBJECTIVE TO DETERMINE THE HEALTH STATUS OF A SEED SAMPLE AND BY INFERENCE THAT OF THE SEED LOT HEALTH OF SEEDS REFERS PRIMARYILY TO THE PRESENCE OR ABSENCE OF DISEASE-CAUSING ORGANISMS SUCH AS FUNGI, BACTERIA, VIRUSES, AND INSECTS e) SEED HEALTH HEALTH TESTING OF SEEDS IS IMPORTANT FOR THREE REASONS: Seed-borne inoculum may give rise to progressive disease development in the field Imported seed lots may introduce diseases into new regions. Test to meet quarantine requirements may therefore be necessary Seed health testing may clarify seedling evaluation and causes of poor germination or field establishment and thus supplement germination testing f) VIGOR SEED VIGOR IS THE SUM OF THOSE PROPERTIES THAT DETERMINE THE ACTIVITY AND PERFORMANCE OF SEED LOTS OF ACCEPTABLE GERMINATION IN A WIDE RANGE OF ENVIRONMENTS (ISTA, 1999) f) VIGOR CHARACTERISTICS ASSOCIATED TO: Rate and uniformity of seed germination and seedling growth Emergence ability of seeds under unfavorable environment Performance after storage, particularly the retention of the ability to germinate VIGOR TESTS ACCELERATED AGING TEST (AA) PURE SEEDS ARE EXPOSED TO: TEMPERATURE (41 C TO 45 C) RELATIVE HUMIDITY (100% OR 76%) SEED EVALUATION: MOISTURE CONTENT AND GERMINATION 24 TO 120h

11 VIGOR TESTS COLD TEST PURE SEEDS ARE EXPOSED TO: TEMPERATURE (10 C) MOISTENED SUBSTRATUM 4 TO 7 DAYS + 7 DAYS AT NORMAL AMBIENT CONDITIONS SEED EVALUATION: SEEDLING EMERGENCE COLD TEST SEEDLING EMERGENCE COLD TEST (PAPER TOWEL + SOIL) GERMINATION TEST VIGOR TESTS CONDUCTIVITY TEST WEIGH REPLICATES OF 25 OR 50 PURE SEEDS: DISTILLED WATER: 25, 50 OR 75mL TEMPERATURE (20 C; 25 C OR 30 C) IMMERSE SEEDS FROM 3 TO 24h VIGOR TESTS CONDUCTIVITY TEST SEED EVALUATION: ELECTROLYTE LEAKAGE (µscm -1 g -1 seed); MOISTURE CONTENT CONDUCTIVITY METER

12 VIGOR TESTS VIGOR TESTS SEEDLING GROWTH TESTS SPEED OF SEED GERMINATION SEEDLING SIZE DRY MATTER OF SEEDLINGS SEEDLING GROWTH TESTS SEEDLING SIZE Pa Nascimento, 2005 VIGOR TESTS TETRAZOLIUM TEST SEEDS ARE HYDRATED (6 to 24 h) SEED SAMPLES (2x100; 4x50; 2x50) CONDITIONED IMMERSED IN OR 0.5 OR 1.0% TETRAZOLIUM SOLUTION INDIVIDUAL SEED EVALUATION Result is related to % Viable and Vigorous Seeds 4.5. IN HOUSE SEED QUALITY CONTROL MAIN PROCEDURES SOYBEAN SEEDS 4.5. IN HOUSE SEED QUALITY CONTROL MAIN PROCEDURES SOYBEAN SEEDS BEFORE HARVEST MOISTURE CONTENT AND TETRAZOLIUM TESTS, WEEKLY DURING HARVEST MOISTURE CONTENT, MECHANICAL DAMAGE AND TETRAZOLIUM TESTS DURING PROCESSING MOISTURE CONTENT, MECHANICAL DAMAGE AND TETRAZOLIUM TESTS DURING STORAGE MOISTURE CONTENT, MECHANICAL DAMAGE AND TETRAZOLIUM TESTS

13 4.5. IN HOUSE SEED QUALITY CONTROL MAIN PROCEDURES SOYBEAN SEEDS BEFORE SELLING MOISTURE CONTENT, PURITY, SEED WEIGHT, MECHANICAL DAMAGE, GERMINATION, TETRAZOLIUM, SEEDLING EMERGENCE AND SEED PATHOLOGY TESTS WHEN IN DOUBT??? SAND GERMINATION TEST CONDUCTED FILLED SEED NORMAL SEEDLING PARTIALLY FILLED SEED ABNORMAL SEEDLING EMPTY SEED DEAD SEED SEED FORMATION AND GERMINATION OF SEED (X-RAY TEST) SIMILARITY IN HILUM COLOR FROM TWO SOYBEAN SEED CULTIVARS AFFECTING VARIETAL PURITY BRS Gralha BRS Celeste

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