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seed development in flower part 3b
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SEED DEVELOPMENT SEED DEVELOPMENT (MATURATION)(MATURATION)
JULIO MARCOSJULIO MARCOS--FILHOFILHODEPT. OF CROP SCIENCEDEPT. OF CROP SCIENCE
USP/ESALQUSP/ESALQ
INTRODUCTIONINTRODUCTION
Start Start flower induction and differentiationflower induction and differentiation
22
Seed development : a sequence of events Seed development : a sequence of events controlled by the genotypecontrolled by the genotype
Flowering and pollination are not uniform in Flowering and pollination are not uniform in the same plant or within a populationthe same plant or within a population
Maturation: set of successive stages in Maturation: set of successive stages in preparation for successful seed germinationpreparation for successful seed germination
INTRODUCTIONINTRODUCTION
33
Initial studies: aimed at determining Initial studies: aimed at determining phenologicalphenologicaldifferences among species and the optimum harvest differences among species and the optimum harvest timetime
First proposed criteria to identify seed maturity:First proposed criteria to identify seed maturity:
-- Time from planting or seedling emergence to Time from planting or seedling emergence to harvestingharvesting
-- Seed moisture content and morphological Seed moisture content and morphological characteristics to identify seed maturitycharacteristics to identify seed maturity
Delouche (1971) :Delouche (1971) :
Seed maturationSeed maturation is a process that comprises a is a process that comprises a set of morphological, physical, physiological set of morphological, physical, physiological and biochemical events that occur from ovule and biochemical events that occur from ovule fertilization to the moment in which seeds fertilization to the moment in which seeds become physiologically independent of the become physiologically independent of the parent plantparent plant
SEED DEVELOPMENTSEED DEVELOPMENT
44
Dure III (1975)Dure III (1975)
Days after flowering
Embr
yo d
ry w
eigh
t
CELL DIVISION AND ELONGATION
(PHASES I and II)
RESERVE DEPOSITION(PHASE III)
DESICCATION(PHASE IV)
HISTODIFFERENTIATIONHISTODIFFERENTIATION
55
GENERAL PARAMETERS TO CHARACTERIZE SEED GENERAL PARAMETERS TO CHARACTERIZE SEED MATURATIONMATURATION
1960s and 1970s: individual seeds x plant 1960s and 1970s: individual seeds x plant populationpopulation
66
Seed sampling at preSeed sampling at pre--defined intervals and defined intervals and identification of parameters associated identification of parameters associated with maturation progresswith maturation progress
Definition of seed changes in seed technology Definition of seed changes in seed technology researchresearch
SEED MOISTURE CONTENTSEED MOISTURE CONTENT
Dry fruits x Fleshy fruitsDry fruits x Fleshy fruitsFinal dehydration
GENERAL PARAMETERS TO IDENTIFY SEED GENERAL PARAMETERS TO IDENTIFY SEED MATURATIONMATURATION
Ovule fertilization and evolution during Ovule fertilization and evolution during maturationmaturation
77
TIMETIME
Fresh weightFresh weight
Dry weightDry weight
Moisture Moisture contentcontent
Variations in moisture content, fresh weight and dry Variations in moisture content, fresh weight and dry weight during maturation of seed produced in dry (weight during maturation of seed produced in dry (-- -- --) ) or fleshy fruits ( ).or fleshy fruits ( ).((CarvalhoCarvalho and Nakagawa, 2000)and Nakagawa, 2000) 88
R6R6R5R5
SEED SIZESEED SIZE
Soybean pod and seed development (Ritchie et al., 1994)Soybean pod and seed development (Ritchie et al., 1994)
GENERAL PARAMETERS TO IDENTIFY SEED GENERAL PARAMETERS TO IDENTIFY SEED MATURATIONMATURATION
99
R6 R7 R8 1010
SEED SIZESEED SIZE
GENERAL PARAMETERS TO IDENTIFY SEED GENERAL PARAMETERS TO IDENTIFY SEED MATURATIONMATURATION
Species Period (days) Reference
Cotton 21-28 Carvalho (1972)
Soybean 64 Jacinto and Carvalho (1974)
Sorghum 15-20 Nagai (1973)
Wheat 40 Carvalho and Yanai (1976)
Days after flowering necessary for seeds of different species toDays after flowering necessary for seeds of different species to attain attain maximum size during maturation (maximum size during maturation (CarvalhoCarvalho and Nakagawa, 2000)and Nakagawa, 2000)
1111
2 5 8 11
2
4
6
Num
ber o
f ce
lls/s
eed
x 10
-6
number of cells
dry weight
10
40
30
20
(Dry
wei
ght (
mg/
seed
)
EgliEgli FrutFrut development period (Phase I)development period (Phase I) 1212
DRY WEIGHTDRY WEIGHT
SEED MOISTURE CONTENT + DRY WEIGHTSEED MOISTURE CONTENT + DRY WEIGHTMoisture contentMoisture content
Dry weightDry weight
1313EgliEgli
GENERAL PARAMETERS TO IDENTIFY SEED GENERAL PARAMETERS TO IDENTIFY SEED MATURATIONMATURATION
Species Moisture content (%) Reference
Cotton 50-60 Carvalho (1972)Peanut 47-50 Carvalho et al. (1976)Oat 45 Frey et al. (1958)Field bean 38-44 Neubern and Carvalho (1976)Maize 25-30 Hunter et al. (1991)Soybean 50 Andrews (1966)Sorghum 23-30 Kersting et al. (1961)Wheat 40 Carvalho and Yanai, 1976
Seed moisture content of different species at the time they reacSeed moisture content of different species at the time they reach h maximum dry weight during developmentmaximum dry weight during development
1414
Primary root protrusion x Normal seedlingsPrimary root protrusion x Normal seedlings
Germination x Dormancy during maturationGermination x Dormancy during maturation
1515
GENERAL PARAMETERS TO IDENTIFY SEED MATURATIONGENERAL PARAMETERS TO IDENTIFY SEED MATURATION
GERMINATIONGERMINATION
VIGORVIGOR
Initial germination (days) after ovule fertilization in some culInitial germination (days) after ovule fertilization in some cultivated tivated species (species (DeloucheDelouche, 1971), 1971)
SpeciesGermination
(days after anthesis) Rye 05Wheat 05Sorghum 06 to 10Clover 10Cotton 22Soybean 38
1616
Days after sowing
Moisture content
(%)
Seed dry weight
(mg/seed)
Germination(%)
Vigor(mg dry weight /
seedling)78 55.3 20.40 05 5.084 50.6 25.34 28 4.0790 48.1 28.80 77 7.4796 39.8 34.10 37 7.69102 27.2 36.44 11 4.86108 14.1 34.10 09 4.88111 11.0 37.24 06 5.53117 8.8 37.54 81 9.57123 9.9 37.90 83 10.72126 10.7 37.84 65 9.34
Variation of seed moisture content, dry weight, germination and Variation of seed moisture content, dry weight, germination and vigor vigor during wheat maturation, cv. IAS during wheat maturation, cv. IAS --54. (Carvalho and Yanai, 1976)54. (Carvalho and Yanai, 1976) 1717
DETERMINATION OF PHYSIOLOGICAL MATURITYDETERMINATION OF PHYSIOLOGICAL MATURITY
a) Seed maturity is identified by the maximum a) Seed maturity is identified by the maximum dry matter accumulation dry matter accumulation
b) Seed physiological maturity is reached b) Seed physiological maturity is reached when there are no significant increases in when there are no significant increases in seed dry weightseed dry weight
1818
c) Seed physiological maturity occurs when c) Seed physiological maturity occurs when seeds reach maximum dry weight, seeds reach maximum dry weight, germination, and vigorgermination, and vigor
CONCEPTSCONCEPTS
1919
DETERMINATION OF PHYSIOLOGICAL MATURITYDETERMINATION OF PHYSIOLOGICAL MATURITY
Seed physiological maturity = maximum dry weightSeed physiological maturity = maximum dry weightPREVAILING IDEAPREVAILING IDEA
Relative MaturityRelative Maturity, , Morphological MaturityMorphological Maturity, , Mass Mass MaturityMaturity, , Harvest MaturityHarvest Maturity, , Agronomic Agronomic MaturityMaturity, , Time of HarvestTime of Harvest
Determination of physiological maturity in individuals Determination of physiological maturity in individuals or in plant communitiesor in plant communities
MOISTURE CONTENT SIZE
VIGOR
GERMINATION
DRY WEIGHT
2020
Days after sowingDays after sowing Moisture Moisture content (%)content (%)Seed dry weight Seed dry weight
(mg/seed)(mg/seed)6464 72.972.9 61.461.47070 60.560.5 158.4158.47676 56.856.8 171.0171.07979(()) 43.943.9 202.8202.88282 38.238.2 203.8203.88888 21.821.8 194.8194.89494 41.041.0 208.6208.6100100 30.030.0 206.4206.4106106 18.118.1 194.8194.8
Mean values of moisture content and dry weight during maturationMean values of moisture content and dry weight during maturation of of bean seeds, cv Carioca (Neubern and Carvalho, 1976) bean seeds, cv Carioca (Neubern and Carvalho, 1976)
2121
2222
DETERMINATION OF PHYSIOLOGICAL MATURITYDETERMINATION OF PHYSIOLOGICAL MATURITY
Difficult to identify the exact point of seed Difficult to identify the exact point of seed physiological maturity (maximum dry weight)physiological maturity (maximum dry weight)
NEED TO INCREASE PRECISION:NEED TO INCREASE PRECISION:
-- Number of statistical replicatesNumber of statistical replicates
-- Reduce harvesting intervalsReduce harvesting intervals- Additional care in weighing
Use of Use of 14 14 C to monitor reserve accumulationC to monitor reserve accumulation
2323
DETERMINATION OF PHYSIOLOGICAL MATURITYDETERMINATION OF PHYSIOLOGICAL MATURITY
Visual indicators of seed physiological maturity Visual indicators of seed physiological maturity
MAIZE:MAIZE:Black LayerBlack LayerMilk LineMilk Line
Pod and Seed Color Pod and Seed Color SOYBEAN:SOYBEAN:
20
40
60
80
100
Perc
enta
ge
Days after R349 63 77 90
GreenYellowYellow, typical of cultivar
PM
2424
Marcos-Filho (1979)
Black Layer
(Mississippi State University extension service, http://msucares.com/crops/corn/corn2.html)
2525
Mature
Physiological potential
Overripe
ContrerasContreras
Maturation of Maturation of tomatotomato
2626
SpeciesSpecies Mean periodMean period
(days)(days)LettuceLettuce 00OnionOnion -- 44TobaccoTobacco 00MaizeMaize
InbredInbredSingle hybridSingle hybridDouble hybridDouble hybrid
00--55
--1010SoybeanSoybean -- 77TomatoTomato +10+10WheatWheat -- 66
Average and range in days before or after physiological maturitAverage and range in days before or after physiological maturity and seed vigor y and seed vigor of different cultivated species (TeKrony and Egli, 1997) of different cultivated species (TeKrony and Egli, 1997)
(() () (--): days before seed maximum dry weight): days before seed maximum dry weight(+): days after seed maximum dry weight(+): days after seed maximum dry weight
2727
Days after Days after floweringflowering
GerminationGermination(()) Soluble SugarsSoluble Sugars(()) ProteinsProteins(())
FDFD SDSD FDFD SDSD FDFD SDSD
2626 0000 6868 1.11.1 0.10.1 0.570.57 0.090.09
3232 0000 6868 1.51.5 0.20.2 0.510.51 0.180.18
4242 6565 ---- 2.22.2 0.20.2 0.620.62 0.250.25
4848 5454 9393 1.61.6 0.40.4 0.480.48 0.190.19
Percentage germination, leakage of sugar and protein from soybeaPercentage germination, leakage of sugar and protein from soybean seeds, cv n seeds, cv Chippewea, submitted to drying at different maturation stagesChippewea, submitted to drying at different maturation stages
(Adams and Rinne, 1983) (Adams and Rinne, 1983)
(() FD ) FD seed threshing and fast drying immediately after harvest;seed threshing and fast drying immediately after harvest;SL SL slow seed drying still attached to pods.slow seed drying still attached to pods.
(() Germination (%); Seed leachate (mg/seed) ) Germination (%); Seed leachate (mg/seed) 2828
Days after anthesis
Dry weightDry weight
ContrerasContrerasMaturation of tomato
Physiological PotentialPhysiological Potential
2929
SEED MATURITY X HARVEST TIMESEED MATURITY X HARVEST TIME
- Determination of harvest time
-- Delayed harvest: problemsDelayed harvest: problems
3030
Date(L1)
Yield(kg/ha)
Date(L2)
Yield (kg/ha)
09/03/81 5.255 11/03/81 5.104
19/03/81 4.493 01/04/81 4.797
08/04/81 4.398 22/04/81 4.695
05/05/81 3.904 12/05/81 4.440
18/05/81 3.888 05/06/81 4.236
Effect of harvest time on maize seed yield in two locations of Parana state, Brazil (Hadlich, 1983) 3131
RH
RH
RH
RH
RH3232
3333
FIELD WEATHERINGFIELD WEATHERING
YEARYEAR PMPM HTHT 14*14* 28*28*
19731973 9494 8888 5858 5555
19741974 8585 8383 8585 4141
19751975 8989 8585 6666 5757
19761976 8383 2828 1313 0707
19771977 7171 6262 4040 0505
Vigor (accelerated aging) of Kent soybean seeds as influenced by harvest time for five experimental years (TeKrony et al., 1980).
3434PM = physiological maturity; PM = physiological maturity; HT = adequate HT = adequate
harvest time;harvest time; 14 and 28 = days after HT14 and 28 = days after HT
3535
SEED MATURITY X HARVEST TIMESEED MATURITY X HARVEST TIME
-- Harvesting at physiological maturity?Harvesting at physiological maturity?
-- Variations in seed moisture content and Variations in seed moisture content and in plant characteristicsin plant characteristics
-- Visual parameters: Visual parameters: black layer, milk line, black layer, milk line, seed and/or fruit color, glumes and pedicelseed and/or fruit color, glumes and pedicel
SEED MATURITY X HARVEST TIMESEED MATURITY X HARVEST TIME
-- Uniformity of maturationUniformity of maturation
3636
SoybeanSoybean TomatoTomato
CottonCotton
3737
I
II
III
Carrot
Umbel Order
Umbel / Plant
Proportion (%)
Germination (%)
First Count (%)
1000 seeds (g)
Primary 1 11 75 54 2.28Secondary 11 58 65 43 2.15Tertiary 24 31 54 37 1.99
Number of umbels per plant, contribution to plant seed production (%), germination (%), vigor (germination first count - %) and weight of 1000 seeds associated with umbel order in carrot (Nascimento, 1991)
3838
RESERVE ACCUMULATION DURING SEED RESERVE ACCUMULATION DURING SEED DEVELOPMENTDEVELOPMENT
3939
-- Sequence of genetically programmed eventsSequence of genetically programmed events
-- Monocots Monocots endosperm;endosperm; Dicots Dicots cotyledonscotyledons
-- Final yield: Final yield: seed numberseed number + + seed growth rateseed growth rate + + duration duration of seed fillof seed fill
1. NUTRIENT TRANSLOCATION FROM THE PARENT PLANT1. NUTRIENT TRANSLOCATION FROM THE PARENT PLANT
Photoassimilates (sugars, amino acids and other solutes) are transported via phloem
RESERVE ACCUMULATION DURING SEED RESERVE ACCUMULATION DURING SEED DEVELOPMENTDEVELOPMENT
4040
Plant reserve accumulation in endospermic seedsPlant reserve accumulation in endospermic seeds
Nutrient translocation to seedsNutrient translocation to seeds
Short distance transportShort distance transport
NUTRIENT TRANSLOCATION NUTRIENT TRANSLOCATION short distanceshort distance
starchy endosperm
transfer cells
chalazal region
embryo
pedicelphloem
basal endosperm
4141
1. NUTRIENT TRANSLOCATION FROM THE PARENT PLANT1. NUTRIENT TRANSLOCATION FROM THE PARENT PLANT
RESERVE ACCUMULATION DURING SEED RESERVE ACCUMULATION DURING SEED DEVELOPMENTDEVELOPMENT
Plant reserve accumulation in nonPlant reserve accumulation in non--endospermic seedsendospermic seeds
4242
f f
ct
eeh
NUTRIENT TRANSLOCATION NUTRIENT TRANSLOCATION short distanceshort distance
4343
Mature seeds Mature seeds two or three main types of reservestwo or three main types of reservesSynthesis is parallel during seed developmentSynthesis is parallel during seed development
Synthesis occurs in different cellular compartments: starch, in amyloplastslipids, in spherosomesproteins, in cytosol and endoplasmic reticulum
2. NUTRIENT ASSIMILATION2. NUTRIENT ASSIMILATION
RESERVE ACCUMULATION DURING SEED RESERVE ACCUMULATION DURING SEED DEVELOPMENTDEVELOPMENT
4444
Nucleic acidsNucleic acids
2. NUTRIENT ASSIMILATION2. NUTRIENT ASSIMILATION
CarbohydratesCarbohydrates
4545
LipidsLipids
ProteinsProteins
15 4515 304530
10
100
20
30
200
300
mg
0,1
0,3
0,5
0,02
0,04
0,06Dry Weight
Proteins
DNA
RNA
Days after fertilization
mg
whole seed endosperm embryo
MAIZEMAIZE
4646
mg
mg
2. NUTRIENT ASSIMILATION2. NUTRIENT ASSIMILATION
LEGUMESLEGUMES
4747
Accumulation of carbohydrates precedes those of Accumulation of carbohydrates precedes those of lipids and proteinslipids and proteins
10
50
40
20
30
30 7050
Days after flowering
Perc
enta
ge
Proteins
Carbohydrates
Lipids
Changes in carbohydrate, lipid and protein contents during Changes in carbohydrate, lipid and protein contents during soybean seed development (Adapted from Konno, 1979)soybean seed development (Adapted from Konno, 1979) 4848
20
140
100
60
DNA
RNAproteins
cell division cell elongation
10 14 18 22 26Days after flowering
200
1400
1000
600
prot
eins
(mg/
coty
ledo
n)
RN
A (
g/co
tyle
don)
1
7
5
3
DN
A (
g/co
tyle
don)
4949
Stage Dry weight(mg/seed)
M.C.(%)
Proteins(mg/seed)
Oil(mg/seed)
Sugars(mg/seed)
R 4 0.2 78.4 ---- ---- ----R 5 5.9 83.1 2.5 0.1 1.3R 6 123.6 62.4 42.0 26.7 19.3R 7 194.2 51.9 71.9 31.7 30.8R 8 188.3 9.7 73.4 36.2 32.4
Variation in soybean composition during maturation Variation in soybean composition during maturation (Dornbos and McDonald, 1986)(Dornbos and McDonald, 1986)
5050
HORMONESHORMONES
5151
Abscisic acidAbscisic acid
Cytokinins
Gibberellins
AuxinsAuxins
ENVIRONMENTAL FACTORS AFFECTING SEED ENVIRONMENTAL FACTORS AFFECTING SEED DEVELOPMENTDEVELOPMENT
-- Soil FertilitySoil FertilityAdequate supply Adequate supply seed size and weightseed size and weight
- WaterEffects of water deficitsWater excess Time of occurrenceAssociation with temperature stress
5252
Association of water deficit and thermal stress during soybean Association of water deficit and thermal stress during soybean seed filling (Franseed filling (Frana Neto and Krzyzanowski)a Neto and Krzyzanowski)
5353
APROSMAT, 2006
water deficitwater deficit
alternate dry and humid
periods
5454
-- Temperature Temperature
ENVIRONMENTAL FACTORS AFFECTING SEED ENVIRONMENTAL FACTORS AFFECTING SEED DEVELOPMENTDEVELOPMENT
5555
Critical value: 35Critical value: 35ooC during seed fillingC during seed filling
Forced maturationForced maturation and greenish seedsand greenish seeds
5656
ColorGermination (%) Tetrazolium 1-3 (%) Emergence (%)
Initial 3 months Initial3
monthsInitial 3 months
Yellow 88 87 75 73 87 88
Green 60 19 52 20 58 38
Soybean: presence of green seeds and effects on germination and vigor (Scheren and Tolentino Jr, 2005)
5757
ENVIRONMENTAL FACTORS AFFECTING SEED DEVELOPMENT
-- LightLightPhotosynthesis x plant and seed performancePhotosynthesis x plant and seed performanceRetention of flowers and fruitsRetention of flowers and fruits
-- Seed position on the plantSeed position on the plant
5858
Seed 4Seed 4--stage developmental pattern: cell division, stage developmental pattern: cell division, cell elongation, reserve accumulation, desiccationcell elongation, reserve accumulation, desiccation
Seeds do not germinate while attached to the parent plant
During most of seed development:Formation and activity of enzymes involved in
synthesis processes, managed by m-RNA5959
ENVIRONMENTAL FACTORS AFFECTING SEED DEVELOPMENT
METABOLISM REVERSION FROM DEVELOPMENT TO METABOLISM REVERSION FROM DEVELOPMENT TO GERMINATIONGERMINATION
6060
Metabolic reversion from synthesis to hydrolysisMetabolic reversion from synthesis to hydrolysis
Synthesis and activity of ABASynthesis and activity of ABAHigh concentration during embryogenesisHigh concentration during embryogenesis
Synthesis and activity of ABASynthesis and activity of ABADecrease during late maturation desiccation Decrease during late maturation desiccation
Management by mManagement by m--RNARNA
HORMONE INFLUENCE HORMONE INFLUENCE
cyt gib aux
ABA
Fertilization Maturity
Seed dry weight
6161
Does drying play a role in this switch?
synthesissynthesis mobilizationmobilization
Desiccation is the Desiccation is the triggertrigger to switch to metabolism to switch to metabolism reversionreversion
Henk Hilhorst 6262
DESICCATION TOLERANCE DURING SEED DESICCATION TOLERANCE DURING SEED MATURATIONMATURATION
Desiccation during seed maturation:developmental pattern, driving seed embryo to a
quiescent stage in preparation for germination
Desiccation Tolerance:Desiccation Tolerance:The ability to recover biological functions after The ability to recover biological functions after
drying to equilibrium with moderately dry air and drying to equilibrium with moderately dry air and then resume normal function when rehydratedthen resume normal function when rehydrated
6363
This ability depends on the ability to maintain membrane structure and prevent protein denaturation
DESICCATION TOLERANCE DURING SEED DESICCATION TOLERANCE DURING SEED MATURATIONMATURATION
Desiccation Tolerance:Desiccation Tolerance:Intolerant Phase:Intolerant Phase:Cell division and elongation + part of reserve Cell division and elongation + part of reserve
accumulation period accumulation period
Premature and rapid desiccation:Damage to enzyme and protein synthesisLoss of cell turgidity, damage to cell membranes,enzymes, proteins and nucleic acid structure
6464
Tolerant Phase:Final phase of reserve accumulation
DESICCATION TOLERANCE DURING SEED MATURATIONDESICCATION TOLERANCE DURING SEED MATURATIONPROTECTIVE SUBSTANCES OR MECHANISMS PROTECTIVE SUBSTANCES OR MECHANISMS
-- LEA (LEA (late embryogenesis abundantlate embryogenesis abundant) Proteins) Proteins
-- Antioxidant systemsAntioxidant systems
-- Soluble sugars: raffinose, stachyose, sucroseSoluble sugars: raffinose, stachyose, sucrose
-- Heat shockHeat shock proteinsproteins
-- Slow dryingSlow drying6565