12% Surround

3% SurroundControl

Source:Dr. David Michael Glenn USDA, ARS, West Virginia, USA

-3

-1

1

3

5

7

9

11

13

15

900

1800 30

012

0021

00 600

1500

2400 90

018

00 300

2000 50

014

0023

00 800

1700 20

011

00

Phot

osyn

thes

is (g

CO

2/m

2/hr

)

Hour

Irrigated September 13-20 2007Control irrigated #1 control irrigated #23% Surround irrigated 3% Surround irrigated #212% Surround irrigated 12% Surround irrigated #2

Source:Dr. David Michael Glenn USDA, ARS, West Virginia, USA

In summer the use particle film (kaolin particles) applied in high light condition (clear sky)

-Increase reflection of UV and IR -Reduce leaf temperature-Increase stomatal conductance-Increase whole-canopy photosynthesis and transpiration

12kg = 38US$

Concentration: 10%/12%

Effects on sap flow

heated probe

non-heated probe

H2O

Water reducetemperature

Sap flow measure differences between heated andnon-heated probe

May to July (winter dry season)(104days)

Plant leaf area: 5m2

Kaolin particles: 0.70 L h m-2 x 5m2 = 3.5 L h-1 plant-1 x 8h = 28 L H2O plant-1 day-1

Control: 0.32 L h m-2 = 1.60 L h plant x 8h = 12.8 L H2O plant-1 day-1

Maximum light = 2300µmol m-2 s-1 = 1000 W m-2

-0,50

0,00

0,50

1,00

1,50

2,00

2,50

hora

22:0

013

:00

15:3

017

:00

18:0

020

:30

21:3

015

:30

17:3

020

:30

11:3

011

:00

14:3

013

:00

11:3

011

:00

12:3

015

:00

19:3

016

:00

17:3

018

:30

10:0

012

:30

16:3

09:

3013

:30

15:3

018

:30

13:3

08:

0020

:30

13:3

012

:30

11:0

017

:00

16:0

011

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016

:00

11:0

012

:30

15:0

018

:00

13:0

015

:30

14:3

013

:30

17:0

010

:00

15:0

012

:00

17:0

013

:00

15:3

012

:30

15:0

017

:00

11:3

014

:00

10:0

012

:00

14:0

0

Sapf

low

(L m

-2h-1

)Control Kaolin

I think that Kaolin particles is important to papaya:

- Can reduce midday photosynthesis depression (stomatal effects is so important to increase yield in papaya). The photosynthetic capacity of a papaya genotype also influences papaya fruit quality (Salazar, 1978).

-Can control aphids (Aphids are the predominant means by which papaya ring spot virus (PRSV) is transmitted)

-Reduce canopy temperature (Prolonged droughts, associated with high temperatures, adversely affect fruit production because the condition induces abortion of floral and fruit structures, leading to sterile phases or fruiting skips along the stem)

-Increase scatter light inside the greenhouse

-Kaolin particles reduce dew formation on leaves

Action of Particle Films Against Insects and Mites

850 X

Untreated

Treated

1. Repellent2. Oviposition Deterrent3. Feeding Inhibitor4. Acute Mortality5. Chronic Mortality

6. Impedes Grasping (Fall-Off)7. Paralysis or Altered Behavior8. Host Camouflaging 9. Restricts Movement or Infestation

Process

Inside the greenhouse light is verylimitant

Kaolin particles reduce dew in papayaleavesCan reduce disease!

Microspray irrigation applying above the canopy during summer (12h to 14h). Evaporative cooling reduce VPDleaf-air, increase stomatal conductance, increase transpiration andphotosynthesis

When the airtemperature insidethe canopy reached35ºC the microsprayirrigation system was turned on

10,0

10,5

11,0

11,5

12,0

12,5

13,0

8:50 10:12 12:39hora

trans

pira

ção

(mm

ol m

-2s-1

)

controle microaspersão

3,0

3,5

4,0

4,5

8:50 10:12 12:39hora

défic

it de

pre

ssão

de

vapo

r (kP

a)

controle microaspersão

17

18

19

20

21

22

23

8:50 10:12 12:39hora

taxa

foto

ssin

tétic

a líq

uida

(m

ol m

-2s-1

)

controle microaspersão

0,30

0,35

0,40

0,45

0,50

8:50 10:12 12:39hora

cond

utân

cia

esto

mát

ica

(mol

m-2

s-1 )

controle microaspersão Microsprayirrigationincreased

5 fruits plant-1

Greenhouse can provides adequate environmental conditions to cultivate papaya.-protection against excessive light (sunburn, photoinhibition, high leaf temperature, high VPDleaf-air)-protection against wind and hail- Exclusion of PRV vector

Baixinho de Santa Amália genotype

0

1

2

3

4

5

6

7

8

greenhouse full sunlight greenhouse full sunlight

VPD

leaf

-air

(kPa

)

Treatments

0900 h1200 h

winter summer

0

500

1000

1500

2000

8:09 9:44 12:42

fluxo

de

fóto

ns fo

toss

inté

ticos

(m

ol m

-2s-1

)

hora

E SOL

0

500

1000

1500

2000

09:15 10:22 11:46 13:45

fluxo

de

fóto

ns fo

toss

inté

ticos

(m

ol m

-2s-1

)

hora

E SOL

summerwinter

30% Light reduction

PPF

PPF

Full sunlight ● GreenhouseFull sunlight ● Greenhouse

0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

greenhouse full sunlight greenhouse full sunlightStom

atal

con

duct

ance

(mol

m-2

s-1)

Treatments

0900 h

1200 h

winter summer

0

5

10

15

20

25

greenhouse full sunlight greenhouse full sunlight

Rate

of n

et p

hoto

synt

hesis

(

mol

m-2

s-1)

Treatments

0900 h1200 h

winter summer

0

1

2

3

4

5

6

7

8

greenhouse full sunlight greenhouse full sunlight

VPD

leaf

-air

(kPa

)

Treatments

0900 h1200 h

winter summer

45

47

49

51

53

55

E SOLgreenhouse full sunlight

Spad reading

220

240

260

280

300

320

7:56 9:35 12:32

RC

/CS

hora0,55

0,60

0,65

0,70

0,75

0,80

0,85

07:56 09:35 12:32

Fv/F

m

hora

150

180

210

240

270

300

330

360

07:56 09:35 12:32

ET/C

S

hora

Full sunlight ● Greenhouse

2004/2005 Greenhouse Full sunlight

Plant Height (cm) 183.8 a 144.2 b

Trunk diameter (cm) 13 a 10 b

Leaf number plant-1 35.3 a 29.4 b

Leaf area plant (m2) 0.2 a 0.15 b

Number of fruits plant-

19.7 a 6.5 b

Fruit weight plant-1 3.53 kg a 2.12 kg b

Average fruit weight 364.7 g a 326.1g b

Commercial production

Martelleto et al 2008

Light quality and intensity can affect leaf anatomy in papaya plant

Full sunlightShade 50% < R/FR Buisson e Lee, 1993

Sun leaf Shade leaf

Leaf thickness (µm) 137 119

Specific leaf mass (mg cm-2) 4,7 2,8

Leaf area (cm-2) 292 162

Chlorophyll content (µg cm-2) 3.57 5.16

Petiole lenght (mm) 207 148

Stomata density (mm-2) 465 330

Degree air space 0.29 0.33

Buisson e Lee, 1993

Under conditions of low light intensity and lowred:far red light , leaf lobing was dramaticallyreduced.

Change in spectral quality also resulted in a reduction in the ratio chlorophyll a to b

High Leaf lobing can reduce leaf temperature in sun leaf

Motorcycle radiator

The papaya photosynthetic capacity can be linked to non stomatal limitation in soil field capacitycondition.

As exemple:-Nitrogen leaf concentration

15 g kg-1DM 35 g kg-1DM

18 g kg-1DM 37 g kg-1DM

Valor SPAD 6,6

Valor SPAD 26,6

Valor SPAD 39,8

Valor SPAD 41,2

15 g kg-1DM 35 g kg-1DM

18 g kg-1DM 37 g kg-1DM

Eliemar CampostriniCampost@uenf.brFisiologia VegetalUENF/CCTA

SPAD reading = 60

SPAD reading = 30

Sunrise Solo

Golden

45 Spad reading

1 Spad reading

0

5

10

15

20

25

30

0 10 20 30 40 50 60 70

Apot

(m

ol O

2m

-2.s-1

)

Spad reading

3-4 leaf

6-7 leaf

Golden

0

2

4

6

8

10

12

14

16

0 10 20 30 40 50 60 70

Apot

(µm

olO 2

m-2

s-1)

Spad reading

3-4 leaf

6-7 leaf

Solo

Blade Leaf: Optimal N concentration 50 g Kg-1

(Marinho 2002)

Petiole: Optimal N concentration 11 g Kg-1

(Caliman Company, Brazil)

Soil and air water

1) Air water:

2) Soil water:

Papaya exhibits both stomatal and non stomatal response to soil water deficits and thesource of the response signals are both hydraulic and non-hydraulic in nature

Threshold VPD values to papaya:VPDair = < 1kPa (esair – eair)VPDleaf-air= < 2kPa (esleaf –eair)

Valor SPAD 6,6

Valor SPAD 26,6

Valor SPAD 39,8

Valor SPAD 41,2

Baixinho de Santa Amália genotype70L potsGreenhouseMaximum PAR 1200µmol m-2 s-1

Severe water stress: ψleaf =-0,8MPaRegular irrigated plants: ψleaf =-0,6MPa

ATP

ADP + Pi

H+

Cl-

K+

H2O

(-20kPa)(--68kPa)

(-20kPa)(--68kPa)

Tainung

Red Lady

Sunrise

Tainung

Red Lady

Sunrise

Marler e Mickelbart, 1998

Field-grown papaya

Strategies to increase effective use of water in papaya

-Regulated deficit irrigation (RDI)-Partial rootzone drying (PRD)

15L potsSubstrate soil, sand andcattle manure (2:1:2)The plants were kept at field capacity (FC) until they were 96 days old.

Strategies to increase effective use of water in papaya

-Regulated deficit irrigation (RDI)-Partial rootzone drying (PRD)

-Gas exchange-Chlorophyll fluorescence-Growth (central vein lenght, root dry biomass, stem dry biomass, leaf dry biomass, total dry biomass, root volume)-Proline-Carbon isotope discrimination-Agronomic water use efficiency-Thermal imaging

Av MinMax

RH VPD

TempPAR

The plants were kept at field capacity (FC) until they were 96 days old.

NI PRD14 days after plantingmaximum stress

14 days after plantingmaximum stress

NI

NI

FI

DAT

VPD

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0 3 6 9 12 14 16 17 21

g s(m

ol H

2O m

-2s-1

)

Days after treatment

CIIPSRRDINI

PRDFI

0

0,1

0,2

0,3

0,4

0,5

0,6

CI IPSR RDI NI

gs (m

ol m

-2 s-

1)

0

2

4

6

8

10

12

0 3 6 9 12 14 16 17 21

E (m

mol

H2O

m-2

s-1)

Days after treatment

CI

IPSR

RDI

NI

High VPD

Low VPD

High VPD

y = 12.69x + 0.72R² = 0.5369

FIy = 11.092x + 1.4987

R² = 0.7368PRD

y = 10.871x + 1.6225R² = 0.722

RDI

y = 10.543x + 0.7411R² = 0.715

NI

0

2

4

6

8

10

12

14

0 0,2 0,4 0,6 0,8 1

Tran

spira

tion

(mm

ol m

-2s-

1)

Stomatal conductance (mol m-2 s-1)

FIPRDRDINI

FI

PRD

0

5

10

15

20

0 3 6 9 12 14 16 17 21

A (µ

mol

CO2

m-2

s-1)

Days after treatment

FI

PRD

RDI

NI

4

6

8

10

12

14

16

FI PRD RDI NI

A (µ

mol

m-2

s-1)

0

24

68

10

121416

1820

0 50 100 150 200

Phot

osyn

thes

is(

mol

m-2

s-1)

Soil water potential (kPa)

FIRDINI

Photochemical efficiency of PSII PI=(RC/ABS) x (TR/DI) x (ET/(TR-ET))

(RC/ABS): Active RC density on a Chl basis

(FV/F0): Performance due to trapping probability Fv/F0=TR/DI

(ET/(TR-ET): Performance due to electron-transport probability

Fv/Fm= TR/ABS

y = 0.281x + 12.816R² = 0.9695 FI

y = 0.1678x + 12.876R² = 0.8736 PRD

y = 0.2068x + 13.101R² = 0.8998 RDI

6

8

10

12

14

16

18

20

0 5 10 15 20 25

Leaf

num

ber

Days after treament

FINIPRDRDI y = 0.8018x + 61.052

R² = 0.9566 FI

y = 0.7248x + 58.33R² = 0.9617 PRDy = 0.5561x + 61.358

R² = 0.9666 RDI50

55

60

65

70

75

80

85

0 5 10 15 20 25

Hig

h nu

mbe

r

Days after treament

FINIPRDRDI

0

100

200

300

400

500

600

700

CI IPSR RDI NI

Root

vol

ume

(cm

3)

FI NI

RDI PRD0,40

0,60

0,80

1,00

1,20

1,40

1,60

FI NI PRD RDI

Leaf

are

a (m

2)

FI FI

NI Dry side of PRD

root dead(7 days withoutirrigation)

young root5 days withirrigationafter 7 dayswithoutirrigation

Carbon isotope discrimination

-30,5

-30

-29,5

-29

-28,5

-28

-27,5CI IPSR RDI NI

δ13C

b b b

a

>Ci/Ca (≈0,7) = < δ‰

<Ci/Ca (≈0,3) = > δ‰

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

CI IPSR RDI NI

Ci/C

a

a

b

c

bc

Ca

Ci

0

1

2

3

4

5

FI PRD RDI NI

AWU

E (g

tota

l DW

.L-1

)

b

b

a a

Agronomic water use efficiency

Treatment

Water economyin relation FI AWUE

Transpirationrate

(%) (g DM L-1) (L H2O g DM-1)FI - 3.12 0.322

PRD 50% 4.55 0.217RDI 50% 4.57 0.217NI 55.14% 2.46 0.400

C3 crops1 to 6 g DM L-1 H2O

C4 grasses10 to 30 g DM L-1 H2O

Arkley (1982)

Treatment L H2O m-2 day-1

FI 1.63

PRD 0.84

RDI 0.78

NI 1.17

Treatment Volume waterapplied per

plant per day

TranspirationL H2O per m2

leaf per day per plant

Transpiration L H20 per plant

per day

Leaf aream2

age

Whole canopysummer

16.0 2.5 10 4.0 5 months

Whole canopywinter

10.0 4.2 15 3.5 5 months

FI 2.3 1.63 2.3 1.41 3 months

PRD 1.1 0.84 1.1 1.30 3 months

RDI 1.1 0.78 1.1 1.40 3 months

NI 1.0 1.17 1.0 0.85 3 months

Thermal imaging

Field condition

20 monthsCaliman companyBrazilhttp://www.caliman.com.br/pt/

Field condition

ET0

Field condition

01020304050607080

Rain

fall

(mm

)

1nd gas exchangemeasurements

July

01020304050607080

Rain

fall

(mm

)

2nd gas exchangemeasurements

October

3 days after rainfall

13 days after rainfall

70%

70%

Dr. Thomas MarlerUniversity of GuamGuam

Flooding

Papaya is considered a species sensitive to low oxygen availability in the soil (hypoxia), which is commonly caused by waterlogging(Ogden et al., 1981; Malo and Campbell, 1986)

Reduced oxygen can occur as a result of tropical storms that saturate the soil for several days, flood irrigation, as well as micro-irrigation practices that create microenvironments of reduced soil oxygen

A completely flooded soil can cause death to papaya plants in 2 d (Wolf and Lynch, 1940; Khondaker and Ozawa, 2007) or 3 to 4 d(Samson, 1980)

Khondaker and Ozawa (2007) constructed chambers that controlled soil gas composition atambient (20%), 18% and 11% oxygen; under soil oxygen at and below 18%, A, chlorophyll content, large and small roots, and shoot dry matter wereall decreased

20% O2 18% O2 11% O2

20% O2 18% O2 11% O2

Box 1: 20% O2Box 2: 18% O2Box 3: 11% O2

Papaya, considered sensitive to hypoxia, responds with accentuatedsenescence (chlorotic leaves), leaf fall and does not recover after hypoxicconditions are removed (Marler et al., 1994).

These studies indicate that papaya is sensitive to small reductions in soiloxygen content and it is likely that micro-irrigation saturation of a smallportion of the soil is having some negative effects. Consequently, awelldrained soil is essential for high productivity.