Environmental conditions in cutting...

Prof. Dr. Károly Hrotkó

SZIU Faculty of Horticultural Science

Environmental conditions in cutting

propagation

Dr. Hrotkó Károly Environmental conditions and rooting of cuttings 2

Different requirements in the phases of technology I. Environmental conditions of stockplants

II. Requirements of rooting cuttings

III. Requirements of rooted cuttings


I. Environmental conditions and stockplants Turgor, water content.

Temperature

Light - shading, etiolation

Nutrition

CO2 enrichment


Water supply of stockplant and water content of cuttings Optimal water supply is required.

Taking cuttings earlier (before 9 am) results higher turgor.

Water deficit of stockplants results low rooting capacity and susceptibility to infections.

Water loss of hardwood cuttings improves the uptake of hormonal soultion.


16.05.2008

0

0,5

1

1,5

2

2,5

3

0:00

3:00

6:00

9:00

12:00

15:00

18:00

21:00

time

sap

flo

w(k

gh-1

)

Érdi V. 4/24 Érdi V. 4/23

Korponay 4/8 Korponay 4/10

26.05.2008

0

0,5

1

1,5

2

2,5

3

0:00

3:00

6:00

9:00

12:0

0

15:0

0

18:0

0

21:0

0 time

sap

flo

w(k

gh

-1)

Érdi V. 4/24 Érdi V. 4/23

Korponay 4/8 Korponay 4/10

Dynamics of transpiration of

leaves on Prunus avium

in May 2008.

(2008. 05. 16. és 2008. 05. 26.)


Water content

influence the

rooting of cuttings;

above 50% more

favorable

Sainte Julien GF 655/2

0

10

20

30

40

50

60

70

80

40 45 50 55 60

Water (%)

Rooti

ng (

%)

Gyökeresedés

Lineáris (Gyökeresedés)

Rooting of plum hardwood cuttings related to

water content of cuttings


Temperature at taking of cuttings Complex effects, related to other conditions (sunshine

hours, hormonal factors, etc.).

Faster growth of shoots on apple and plum at higher temperature; results more thin shoots and higher rooting percentage.

Higher temperature on the day of taking hardwood cuttings of plum results higher rooting. Reason is unknown, probably complex.


PPO-

activity

cold unit

water

content leaf fall POD-activity

phenolics

sproutin

g

rooting

temperature

Effects on rooting of plum rootstocks hardwood cuttings


Marianna GF 8-1

0

10

20

30

40

50

60

70

80

90

-250 0 250 500 750 1000 1250 1500 1750 2000

Cold unit (CU)

ro

oti

ng

(%

)

gyökeresedés

Lineáris (gyökeresedés)

– No direct link

between dayly

average

temperature and

rooting

– Low cold unit

quantity befora

taking cuttings

(below 500 CU) is

more favorable

Temperature and cold unit (CU) on plum rootstocks’

hardwood cuttings


Rooting of plum rootstocks’ hardwood cuttings

Phenolics and

rooting

– favorable:

Fehér besztercei:

above 10 μg/mg

St. Julien GF 655/2:

10-30 μg/mg

Marianna GF 8-1:

15-40 μg/mg

Marianna GF 8-1

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30 35 40 45 50

phenol content in buds (μg/mg)

roo

tin

g (

%)

Gyökeresedés

Polinom. (Gyökeresedés)


POD activity and

rooting

– Low activity is more

favourable

– Fehér besztercei (bud)

St. Julien GF 655/2

(cutting): under 4 U/mg,

Marianna GF 8-1

(cutting): under 3 U/mg

Marianna 8-1

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7

POD activity (U/mg protein)

Rooti

ng (

%)

Gyökeresedés

Lineáris (Gyökeresedés)

Rooting of plum hardwood cuttings


0

10

20

30

40

50

60

70

80

90

9. 1. 10. 1. 11. 1. 12. 1. 1. 1. 2. 1. 3. 1.

taking of cuttings (date)

roo

tin

g (

%)

Fehér besztercei

Sainte Julien GF

655/2

Marianna GF 8-1

Polinom. (Fehér

besztercei)

Polinom. (Marianna

GF 8-1)

Polinom. (Sainte

Julien GF 655/2)


Effect of light on stockplants Daylength

- affetc photosysnthesis: carbohidrate accumulation - fotomorfogenetic effect : increasing daylength affect positive the vegetative growth and rooting of Chrisanthemum.

Wawelength no consistent results: red light stimulate the phytochrom system and rooting, but some results indicate that blue light also positive.


Etiolation and shading of stockplants Etiolation: excluded solar radiation. During preconditioning different level of shading

is more applied in practice. Local etiolation using black strips or Alu folie. Effect

- starch accumulation, - reduced formation of schlerenchima, - reduced lignin production – phenolics may be used for rooting, - etiolated tissue react more efficient to auxine treatments.


Rejuvenalization

grafting subsequently

on seedlings →

Etiolated and shaded

stockplants


CO2 enrichment Increased photosynthese – more shoots appropriate

for cuttings.

Only in closed systems (greenhouse) is possible.

In winter effectivity should be increased usin supplementary lighting.


Nutrition of stockplants Shott mass and its nutrient content is determining

to the regeneration process (related to the anatomy structure too)

Factors of nutrient balance during rooting: + absorption from substrate (no importance!) + assimilation (only leafy cuttings!) - respiration during rooting (increase due auxine application) - leaching due to irrigation, mist application


Principles of nitrogen and carbohydrate metabolism in cuttings Lack of roots – no nitrogen uptake and assimilation

Amino acid sources for root formation: - Amino acid reserve - proteolitic processes (decomposition of proteins)

Carbohydrates: energy reserves and sources for structural carbohydrates (cellulose)

Optimal concentration of non-structural carbohydrates (sugar, starch) is required for rooting

Starch content test on hardwood cuttings (jódos-jódkáli 0,2%)


Importance of Carbohydrate / Nitrogen ratio Carbohydrates: energy reserves and sources for

structural carbohydrates (cellulose)

Indirect effects!

Higher C / N ratio in stockplant shoots is favourable.

Exceed nitrogen reduction decreases the shoot (cuttings) production.

In thin shoots, secondary shoots the C/N ratio and rooting is higher.


Management of stockplant in order to improve C/N ratio in practice Decreased N- supply; increased K and P supply

Root restriction: close planting, root pruning

Pruning back the primary shoots (increased C/N ratio in secondary shoots)

Moving away from shoot basis C/N ratio decreases

Maintaining healthy leaf surface

Positive effect of ringing, etiolation


Rooting of Vitis cuttings of potted plants with excluded nutrients

Missing nutrient in substrate Rooting percent

Nitrogen 91%

Potassium 42%

Phosphorus 37%

Magnesium 35%

Calcium 0%


Role of other nutrients in rooting process Ca - activates peroxidase, essential for growing of root

primordium

Zn - cathalitic effect on triptophan synthesys → formation of native auxine

Mn - activates oxidative enzymes

B - influences the permeability of membrane, sugar transport, activates enzyme, carbohydrate metabolism, metabolism of phenolics, formation of auxine, and nucleic acids


Shoot position and type of cuttings is related to nutrient content Considerable morphological and nutrient content

differences along the shoot from basis to shoot tip. Secondary shoots, branches root better, but

consider plagiotropic shoots. Basal cuttings generally root better:

- more ripe and lignificated shoots, higher C/N ratio, - meristematic cell groups in branch collar, - number of preformed roots considerable decreases towards the shoot tip.

Shoots with flower buds root less (blueberry, Abelia, Ligustrum, Ilex, etc.)


Shoot meristem in shoot tip

Section of subterminal growth

Rhytidom typical to species,

leaf fall, → leafless shoot

Secondary thickening,

lignification

Secondary thickening,

complete cambial ring,

formation of secondary

xylem

schlerenchyma

(lignification starts)


← terminal cutting

← basal cutting

Hradwood cutting


Autovegetatív szaporítások


Effect of storage conditions on rooting of cuttings Requirements during cutting storage depends on

species and cutting type.

Avoid water deficit, mass decrease and disease infection.

Temperature as low as the species can tolarate.

Maximum air humidity, moistured substrate, or covering material.

Decreased oxigen and etilen concentration, increased CO2 level.

Storage length from few days to more month.


II. Environmental conditions during rooting Leaf water content and turgor

Transpiration activity and water supply

Photosynthetic activity and solar radiation


Problems of water management in leafy cuttings: contradicting requirements Reduce the water loss through transpiration activity,

maintaining turgor

Maintaining the photosynthetic activity – required solar radiation

Avoid heat stress in leaves

Optimal temperature in rooting zone


Factors in water management in leafy cuttings Water loss due to transpiration.

Water uptake - no roots , - basal part of tracheas, tracheids are blocked, no water transport, - minimal water uptake through leaves, - more water uptake through basal part of cuttings.

Water deficit→ stomatal conductance reduced→ no CO2 uptake→reduced photosyntesis


How to control water loss of cuttings? Water loss depends on difference in vapour

pressure of leaf and environmental air.

Difference could be deminish - leaf temperature and vapour pressure of leaves - increased vapour content in environmental air, - combination of both factors.

Vapour pressure of leaves is function of - leaf temperature and - difference between leaf temperature and the leaf-air temperature difference (Δt).


Importance of solar radiation When solar radiation intensity is larger than 0,8 J

cm-2 min-1 (Klougart 1975) shading is required. Large fluctuation in solar radiation

in May 250 – 540 J cm-2

in Agust 250 – 2100 J cm-2 (Klougart 1975). Shading reduces insolation at 70-80%. Long wave radiation gets throug PE tent →plant

temperature is higher than under glass, but during the night the temperature decrease more.

White plastic foil reflects 40-60% of solar radiation.


Options in reducing water loss of leafy cuttings in propagation technology Using closed propagation units

(polythene tent, closed systems inside the glasshouse, polythene tent, shading, contact plastic cover, wet cover)

Intermittent mist (open and closed propagation units)

Fog system


Closed propagation units: advantages and shortcomings Simple and cheap (glass, polythene tent, etc.) Heat trap effect → increasing leaf – air vapor pressure

difference → water loss. Shading is required:

- PE-inner cover, modifyed PE foils (vinil-acetate, Al- or Mg-silicate added) long wave radiation in reflected - flies

Additional mist or fog systems could be installed. Contact foil cover: advantageous when radiation and

temperature is controlled, condeansation of vapour contributrs to wetting of leaves. Recommended for less sensitive leaves (evergreens – thick epidermis – danger of drying out is lower).


Double cover inside the polythene tent


Shading is required !


Intermittent mist: benefits and shortcomings Water film on leaves reduces leaf temperature → reduced

leaf vapour pressure – minimal difference in vapor pressure between leaves and air → reduced leaf transpiaration.

Intermittent mist reduces the air temperature due to evaporation → advective cooling of leaves.

High air vapour content (80-95% relative humidity) reduces the Δ RH.

Reduces the temperature in rooting zone – bottom heat is required.

Leaching of nutrients from leaves and cuttings. Applyed in closed propagation units.

(Environmental factors in open systems are less controllable, nowadays are not utilized in practice.)


Propagation unit with intermittent mist and shading


Application of intermittent mist and shading in PE tent and glasshouse


Fog systems High air relative humidity.

Fog systems spray at 40-60 bar pressure water drops of 15 μm size into air, which remain flotating.

Reduces leaching of nutrients.

No temperature decrease in rooting zone.

Larger costs in investment and maintenance .

Applicable for acclimatization of in-vitro plants also.


Propagation unit with fog system


Importance of temperature Optimum temperature at temperate zone plants 18-25

˚C, at tropical and subtropical plants 25-32 °C

Higher temperature at daytime (21-27 °C), lower at night (15 °C) .

Higher temperature increases the shoot growth in contrary root formation; by using bottom heat could be balanced.

At root growth higher roote zone temperature is recommended while for formation of root initials lower temperature is favourable.


Role of light in rooting of cuttings Rooting requires relative low solar radiation.

Cuttings of some herbaceous plants (Chrisanthemum, Pelargonium, Poinsettia) root better at increased solar radiation (116 Wm-2), optimum differrs by species (20-100 Wm-2).

Cuttings of some ornamental plants root better at long-day conditions.

Long day conditons are preferable for growth of rooted cuttings eg. Rododendrons (additional lighting in wintertime is favourable).

Red and fare-red wavelength is favourable for rooting (rooting is linked to phytochrom-system!).


Photosysnthetic activity of cuttings For rooting no highest photosysnthetic activity is

required, too high PAR increase the danger of drying out of cuttings.

After rooting intensive photosynthetic activity is required for growth of cuttings.

Citokinin-formation of cuttings increase the stomatal conductance and the intensity of photosynthesis.


Benefits and shortcomings of different propagation systems in technology Working with cuttings placed on ground is difficult. Replanting, potting of rooted cuttings is not economical. Mist propagation when using high Fe and Mg containing

water cause stayning by salt – cuttings are not attractive. Bottom heat is required when using mist beacause of

temperature decrease in rooting zone. Nutrient leaching from cuttings could not be balanced by

spray with fertilizers. White (milk foil) cover reflects of 40-60% of radiation,

isothermal condition, minimal vapour condensation. Using propagatin trays nutrient sprays after rooting

improves the growth of cuttings.


Improved raising technology Cyclical growth and winter dormancy of woody plants

should be considered.

Optimal environment conditions should be prepared to each growth cycle in propagation units : control of daylength, water supply, temperature, CO2, nutrients, mycorrhiza, substrate, etc.

Lighting, CO2 application to mist system or fog, fertilizers, etc.


St. Julien A hardwood cuttings

in open ground conditions

Environmental conditions in cutting...

Documents

Transcript of Environmental conditions in cutting...