STAND ESTABLISHMENT:STAND ESTABLISHMENT:

Influencing Influencing factorsfactors

ATM

Frank J. Dainello, PhDFrank J. Dainello, PhDExt. HorticulturistExt. HorticulturistCom. Veg. CropsCom. Veg. CropsDept of Hort. Sci.Dept of Hort. Sci.

STAND ESTABLISHMENTSTAND ESTABLISHMENT

““the sins of planting the sins of planting will haunt you all will haunt you all season”season” AnonymousA thought worth remembering!!A thought worth remembering!!

3 Phases of Established3 Phases of Established

n

3. Seedling establishment

STAND ESTABLISHMENT

1. Seed bed preparation/planting

2. Seed germination & emergence

Establishment –Establishment –Phase IPhase I

nSTAND ESTABLISHMENT

1. Seed bed preparation/planting

SEEDBED PREPERATIONSEEDBED PREPERATION

““The facet ofThe facet of stand establishment stand establishment in which the greatest in which the greatest sins are committed!”sins are committed!”

SEEDBED PREPERATIONSEEDBED PREPERATION

•The seedbed is to the crop as the The seedbed is to the crop as the foundation is to the housefoundation is to the house•Improper preparation leads to Improper preparation leads to uneven emergence, lack of uneven emergence, lack of uniformity of stands, weed and uniformity of stands, weed and pest problemspest problems•Reduce yieldReduce yield•Increased production costIncreased production cost

SEEDBED PREPERATION• Year round undertaking

–Employ practices to enhance tilth and structure• Immediate crop destruction• Keep weeds under control• Build organic matter• Pay attention to rotations

SEED PLACEMENTSEED PLACEMENT IMPACTS STAND IMPACTS STAND ESTABLISHEMTESTABLISHEMT

Lateral placementLateral placement

Depth

D

epth

placemen

tplacem

ent

TOO DEEP:TOO DEEP: Increased soil Increased soil impedance pressureimpedance pressurereduced gas exchangereduced gas exchangerisk of water logging risk of water logging and or crusting effectand or crusting effect

TOO SHALLLOW:TOO SHALLLOW:risk of insufficient risk of insufficient moisture for imbibitionmoisture for imbibitionrisk of high risk of high temperature injurytemperature injury

Depth: Depth: 3 times the seed width3 times the seed width

PLANTING

OVER SEEDING CAN CAUSE PROBLEMS WITH

UNIFORMITY/QUALITY

Poor in-row spacing

Establishment- Phase IIEstablishment- Phase II

2. Seed germination & emergence

PHASE 2

GERMINATIONGERMINATION

• The process by which a The process by which a viable(living) seed imbibes viable(living) seed imbibes water, triggering respiration, water, triggering respiration, protein synthesis and other protein synthesis and other metabolic activities which metabolic activities which cause radicle emergence.cause radicle emergence.

GERMINATIONGERMINATION

Seeds are considered to have Seeds are considered to have germinated once radicle germinated once radicle emergence has occurredemergence has occurred

Germinated seed

(Radicles emergenced)

GERNIMATION GERNIMATION (ENVIRONMENTAL FACTORS)(ENVIRONMENTAL FACTORS)

• Moisture Moisture – Seed contentSeed content– Soil contentSoil content

• TemperatureTemperature

• Oxygen/gas exchangeOxygen/gas exchange

SEED MOISTURE SEED MOISTURE CONTENTCONTENT

• Seeds stored 4 - 5 % moisture contentSeeds stored 4 - 5 % moisture content

• Water needed to active metabolic processesWater needed to active metabolic processes

• Excess moistureExcess moisture– inhibits gas exchange(stops metabolic

processes)– leakage of sugars, organic and amino acids– increase pathogen susceptibility(substrate)

Oxygen & Gas Exchange

• Seeds are living organisms.

• Oxygen needed in metabolic process for germination to occur in vegetables

• Water logged soils force oxygen out of soil microclimate and stops processes

– can cause physiological breakdown – decay as a result of pathogenic attack

Moisture & GerminationMoisture & Germination• Moisture stress

– The greater the deficit the slower the germination and radicle emergence

– Greater negative effect on seed with poor vigor

• More advanced germination the greater the impact of moisture stress– some evidence for cycling wetting and drying

prior to planting enhances germination.

GERMINATIONGERMINATION(Soil physical properties)(Soil physical properties)

• Soil moisture content

• Soil temperature

• Soil insect and disease pressure

• Soil impedance

FACTORS IMPACTING FACTORS IMPACTING GERMINATION & EMERGENCEGERMINATION & EMERGENCE

•Soil temperature

TEMPERATURE & GERMINATION

• Generally the higher the temperature the better Generally the higher the temperature the better the germination for most vegetablesthe germination for most vegetables– warm temperatures increases respiration rate and warm temperatures increases respiration rate and

other metabolic processesother metabolic processes• Each species has an optimum temperature range Each species has an optimum temperature range

above or below which germination is reduced or above or below which germination is reduced or inhibitedinhibited– temperature impact pathogen activity which can temperature impact pathogen activity which can

have a detrimental effect on germinationhave a detrimental effect on germination

INFLUENCE OF SOIL TEMPERATURE ON GERMINATION

CROP Min Max Opt. Range

Cabbage 40 100 85 45-95

Carrot 40 95 80 45-85

Onion 35 95 75 50-90

Pepper 40 95 85 45-90

Watermelon 60 105 95 70-90

INFLUENCE OF SOIL TEMPERATURE ON EMERGENCE

CROP Min.days (F) Max days (F) Cabbage 4 @ 86 15 @ 50 Carrot 6 @ 77 51 @ 41 Onion 4 @ 77 136 @ 32 Pepper 8 @ 77 25 @ 59 Watermelon 3 @ 95 12 @ 68

SOIL TO SEED CONTACTSOIL TO SEED CONTACT

• Onset of germination delayed at soil Onset of germination delayed at soil matrix potentialsmatrix potentials

• Highest germination % between Highest germination % between -0.3 -0.3 & -0.1& -0.1

• Soil matrix potentials outside of this Soil matrix potentials outside of this rangerange – DELAYED GERMINATION – DELAYED GERMINATION

SOIL TO SEED CONTACTSOIL TO SEED CONTACT

• Germination ultimately determined by:– the impedance of the soil matrix

• due to surface and colloidal forces

– the contact of the seed with soil moisture

• irrespective of the initial difference between the water potential of the seed interior and the soil

SOIL FACTORS IMPACTING SOIL FACTORS IMPACTING GERMINATION & EMERGENCE GERMINATION & EMERGENCE

• Soil impedance – the pressure or barrier effect soil has on emergence.

SOIL IMPEDANCESOIL IMPEDANCE • Emergence force of seed hypocotyls will Emergence force of seed hypocotyls will

determine how effective a specie is in over determine how effective a specie is in over coming the negative effect of soil coming the negative effect of soil impedance.impedance.

• Small seeded crops such as carrots lack Small seeded crops such as carrots lack good emergence forcegood emergence force

• Crust and/or deep planting very disastrous Crust and/or deep planting very disastrous to crops lacking good emergence forceto crops lacking good emergence force

EMERGENCE VIGOR

• The ability of a hypocotyls to rapidly emerge through the soil profile and emerge above the soil surface.

FACTORS IMPACTING FACTORS IMPACTING GERMINATION & EMERGENCEGERMINATION & EMERGENCE

•Soil insect and disease pressure

Establishment- Establishment- Phase IIIPhase III

Seedling establishment

PHASE 3

SEEDLING ESTABLISHMENTSEEDLING ESTABLISHMENT

• The time from seedling emergence from the soil until 2 – 4 true leaf stage

• Impacted by» Insects» Diseases» Soil moisture and temperature» Wind Desiccation» Sand basting» Hail» Chemical injury

STAND ESTABLISHMENTSTAND ESTABLISHMENTGOALGOAL

• TO REDUCE THE TIME REQUIRED FOR SEED GERMINATION TO SEEDLING ESTABLISHMENT

n

3. Seedling establishment

STAND ESTABLISHMENT

1. Seed bed preparation/planting

2. Seed germination & emergence

3 COMPONENTS OF STAND 3 COMPONENTS OF STAND ESTABLISHMENTESTABLISHMENT

1.1.Good Soil ConditionsGood Soil Conditions

2.2.Viable SeedsViable Seeds

3.3.Favorable MicroclimateFavorable Microclimate

GOOD SOILGOOD SOIL CONDITIONSCONDITIONS

(COMPOENT # 1)

IDEAL SEED BED SOIL IDEAL SEED BED SOIL CONDITIONSCONDITIONS

• Well pulverized

• Free of clods and plant residue

• Firm and level

• Provide good soil to seed contact

MEANS of ACHIEVING GOOD MEANS of ACHIEVING GOOD SOIL to SEED CONTACTSOIL to SEED CONTACT

• Ovoid working soil when wetOvoid working soil when wet• Ovoid excessive disking, causes compaction Ovoid excessive disking, causes compaction

restricts root growth & yieldrestricts root growth & yield• Pulverize soil to the point that it is free of Pulverize soil to the point that it is free of

clods and debrisclods and debris

– Rotovators are ideal implements

VIABLE SEEDSVIABLE SEEDS

(COMPOENT # 2)

SEEDSSEEDS• Embryonic orEmbryonic or New plants New plants

– plant in miniature -plant in miniature -

• Contained in a Dispersing structuresContained in a Dispersing structures– protected in a cover (the seed coat) until protected in a cover (the seed coat) until

a self sufficient autotrophic organism a self sufficient autotrophic organism can be establishedcan be established

VIABLE SEEDVIABLE SEED

• Seed Having The Ability Seed Having The Ability To Germinate and To Germinate and develop into a seedling develop into a seedling once planted!once planted!

FACTORSFACTORS INFLUENCING SEED INFLUENCING SEED VIABILITYVIABILITY

1. Seed coat (testa)2. Food reserves3. Dormancy4. Condition under which seed

produced5. Storage conditions

SEED COAT CHARACTERISTICSSEED COAT CHARACTERISTICS

• Surface area

• Nature of the surface

• Mucilage content

• Thickness

• Porosity

• Thickness or Porosity– can impede water uptake

– restrict radicle emergence

– impact gas exchange•These then interact to slow or stop respiration and other metabolic processes associated with germination

SEED FOOD RESERVES

• Quantity determined by the quality of the seed crop – Growing conditions

– Harvest

– Storage

CONDITIONS UNDER WHICH SEED CROP IS GROWN

• Stressed plants are weak plants which in turn produce unviable or poor germinating seed

SEED DORMANCY

• The failure of seed to germinate even under apparently favorable conditions– Due to a inherent blocking

mechanism within the seed

SEED DORMANCY

• Causes:

–Chilling requirement

–Excessive temperature

–Inhibitors

–Seed coat thickness

(COMPOENT # 3)

FAVORABLEFAVORABLE ENVIRONMENTENVIRONMENT

ROOT ZONE MICROCLIMATE (POST ROOT ZONE MICROCLIMATE (POST GERMINATION TEMPERATURE & GERMINATION TEMPERATURE &

MOIUSTURE STRESS)MOIUSTURE STRESS)

• Radicle injury or death

• Hypocotol injury or death

• No, or poor or uneven stands

• reduced yield

INFLUENCE TEMPERATURE ON EARLY GROWTH

CROP Min. F Max F Range

Cabbage 40 75 60-65Carrot 45 75 60-65Onion 45 85 55-75Pepper 65 95 70-85Watermelon 65 95 70-85

INFLUENCE INFLUENCE OFOF

MICROCLIMATEMICROCLIMATEONON

STAND ESTABLISHMENTSTAND ESTABLISHMENT

Non CoveredNon CoveredStd. bedsStd. beds

CoveredCoveredTrenchesTrenches

Fruit nearing Fruit nearing maturitymaturity

No fruit

SEEDING RATE

– Inadequate rates, poor stands due to Inadequate rates, poor stands due to lack of potential seedlings emerginglack of potential seedlings emerging

– Excessive rates, over crowding weak Excessive rates, over crowding weak spindly plantsspindly plants

SUMMARY: Major factors impacting good stand

establishment

• Seed QualitySeed Quality

• Proper Seedbed Preparation Proper Seedbed Preparation

• Seedbed Moisture Seedbed Moisture

• Soil temperature Soil temperature

• Soil impedanceSoil impedance

• Soil borne pathogensSoil borne pathogens

Department Department OfOf

Horticultural Horticultural SciencesSciencesProgramProgram

AA

AATTMM

“TheThe sins of sins of

plantingplanting willwill

haunthaunt youyou allall

season !”season !”