dwarfing in ornamentals

Pratiksha Kumari 20306Division of Floriculture and Landscaping

(use of shrubs as potted plants)

IMPORTANCE OF DWARFING Control of plant growth imp in modern plant

production.

Short, homogenous plants, more robust

Easy to harvest, transport and sell.

Compact growth desirable, difficult to obtain by

traditional breeding.

Cereals, grasses, fruit trees and ornamentals, are

regularly treated chemically to control their stature

and flowering time.Indian Agricultural Research Institute, New Delhi

IMPORTANCE OF DWARFING FOR ORNAMENTAL SHRUBS

• Dwarf ornamental shrubs, used as permanent

landscaping, pot plants.

• Require little care compared to seasonal bedding

plants or large ornamental shrubs.

• Same foliage and flowers as large shrubs.

• Typically 1-3 feet tall, use lesser water and

fertilizer.

Indian Agricultural Research Institute, New Delhi

DWARFING TECHNIQUES:

Synthetic Growth regulators

Photopeiodic control

Thermoperiodic control

Water Stress

Breeding approaches



CASE STUDY-I

Effects of Water Stress and Selected Plant Growth Retardants on Growth

and Flowering of ‘Raspberry Ice’ Bougainvillea

(S. Ma and M. Gu )


Acta Horticulture ;2012. 937, 237-242.


Needs a lot of labor-intensive pruning (as potted plant).

PGRs alternatives to frequent prunning

Daminozide, paclobutrazol and chlormequat reported to be effective in controlling plant height.

to examine the effects of WS, daminozide and chlormequat on growth and flowering of ‘Raspberry Ice’ bougainvillea.

MATERIALS AND METHODS Plant Materials and Culture

195 12-cm tall ‘Raspberry Ice’

bougainvillea cuttings used

Every 3 cutting were potted up in 20 cm

pots

Plants irrigated as necessary with water-

soluble fertilizer 200 mg (20−4−6)

Prunned to 15cm in height .



• Plants treated with 2-week, 3-week and 4-week WS

• Tap water (150 ml) provided to each WS plant after that .

• Saucers placed under pots to ensure the 150 ml water was fully absorbed

Water Stress Application

PGR Application-Daminozide (1,250, 2,500, and 3,750 ppm)

Chlormequat (300, 600, 900 ppm)

Daminozide/chlormequat (800/1,000, 1,250/1,250,

and 2,500/ 1,500 ppm)

Foliar sprayed with a trigger sprayer at 20 mL PGR

solution/pot .

Control plants were not subject to PGR or WS

treatment.


RESULTS :Growth • Water stress showed significant impact on both plant height

and width

• PGR treatments did not

Flowering• All treatments show higher %age of flowering (33.3% to 60%).

• Daminozide as foliar spray, more flowers/pot than other

treatments .


Treatments Height (cm) Width (cm)

Control 30.8 84.9

WS 22.5 66.5

Daminozide 27.9 87.0

Chlormequat 33.0 87.0

Daminozide/Chlormequat

30.7 92.9

Table of WS and PGR applied to growth of “Raspberry Ice” Bougainvillea in 2009

WS (2 week, 3 week, 4 week water stress combined) Daminozide (1,250,2500, and 3750mg/L treatments combined)Chlormequat (300, 600, and 900 mg/L treatments combined)Daminozide/Chlormequat (800/1000,1250/1250,2500/1500 mg/L treatments combined)

CASE STUDY-II


Use of uniconazole to control height of Hibiscus rosa sinensis

(Steven E. Newman et.al)

HortScience; 1989 24(6):1041



For growing in pots and for

landscaping dwarf plants

preferred.

Chloromequat chloride

induce shortened internodes &

darken green leaves (Wilkins

and Kotecki, 1985).

Research evaluates the

effectiveness of Uniconazole

for control of plant height,

width, leaf distortion and no of

breaks/ plant

METHOD:Rooted cuttings of hibiscus rosa sinensis l. Cv ‘brilliant’ selected

Plants fertilized weekly with 200 mg n/ Litre (20N-8.6P-16.6K) at each

irrigation.

Plants pinched and flower buds were removed

Plants sprayed with uniconazole at 0, 10, 15, or 20 mg a.i./ Litre.

Ten plants treated at each of the given rates.


RECORDING OF OBSERVATIONS:

Data collected 77 days after treatments

were applied, when all hibiscus plants were in

full flower.

plant height (from the potting mediun

surface)

width (the average of two measurements

taken perpendicular to each other ),

stem length, leaf distortion, number of

breaks, and days to flower.Indian Agricultural Research Institute, New Delhi

RESULTS :Plant height

Height were reduced by all application rates of uniconazole,

with the main effect on height occurring at rates <15 mg./litre

0 5 10 15 200

1020304050607080

Uniconazole(mg a.i./litre)


Width plant width was reduced linearly for each unit increase in concentration

0 5 10 15 2005

1015202530354045

plant width(...


Leaf distortion significantly increased with increased application rates of uniconazole . where 1=no distortion to 10=severe

0 5 10 15 200123456789

10

leaf distortion

Uniconazole (mg a.i./liter)


Number of breaks It is increased with increased uniconazole application

0 5 10 15 200

5

10

15

20

25

no of bre...


INFERENCES :

Maximum reduction in plant height with Uniconazole

application at 15 mg/litre.

Leaf distortion maximum at 15 mg/L. plants treated with

10 mg/L were of high quality with minimal levels of

distortion and curling

15 - 20 mg/L severe distortion and of poor quality.

Uniconazole @ 10 mg a.i./L controlled height

promising method for height control and plant quality

improvement .



CASE STUDY-III

Application of growth regulators to Ornamental shrubs for use as

interior decoration( Joustra M. K. et.al)

Acta Horticulturae ;1989 251:359-369.


Screening of shrubs for indoor

performance have started

The need for regulation of

growth and / or flowering have

become evident.

Aspects of such experiments on

Clematis , Hydrangea

macrophylla, Rhododendron

(azalea) , Skimmia sps, Hibiscus

rosa sinensis, Choisya ternata,

Viburnum tinus, Vaccinium vitis,

briefly discussed here.


CLEMATIS

• Branching of clematis ‘Capitan Thuilleaux’ can be improved with dikegulac-Na and promalin (1:1 6-BAP+GA4+7)

• 14 mL promalin/L spray solution is sufficient to get good branching .• For compact growth of clematis cvs paclobutrazol gives good results .

HYDRANGEA MACROPHYLLA

• Plant height of hydrangea macrophylla Cv was effectively controlled by daminozide , ancymidol, or by paclobutrazol

• Not by chlormequat.• Gibberelin together with lightning speeded up flowering .• Only ancymidol and paclobutrazol stimulated inflorescence initiation of plants.


RHODODENDRON (AZALEAS )

• Retardation of growth by daminozide, chlormequat, or by paclobutrazol.• Branching induced by spray application of mefluidide.• Application of acifluorfen as a soil drench promote more shoot.

SKIMMIA SPECIES

• Skimmia plants perform very well indoor .• So studies have been conducted on the effect of GA and CT on growth and • branching of the second flush of this plant.


CHOISYA TERNATA

• Growth can be retarded by the use of paclobutrazol, but not with other GRs.• Since flowering than is also delayed with this application means other than

use of GRs have to be worked on.

VIBURNUM TINUS

• Heavy growth retardation was observed in treatment with paclobutrazol and high conc of daminozide or ethephon.

• Initiation of flowering during early stage of growth can also be achieved by the use of paclobutrazol


VACCINIUM VITIS

• Treating of plants with a combination of daminozide and ethephon ,together with a cold treatment just before forcing to flowering resulted in compact growth of the plants.

• This method offers good possiblity of using vaccinium as pot plant.


• Application of growth retardant chlormequat immediately after topping

• And a second spray when the plants reach 5cm height

HIBISCUS ROSA SINENSIS


•Use of growth regulators in dwarfing of ornamental shrubs for use

as pot plants can be undertaken.

•There are many side-effects associated with use of GRs, so before

their use proper study must be conducted.

•There are many GRs which along with suppressing growth also

promote the formation of flower buds.

•Study on interaction of climatic factors and GRs treatment still

needs attention.

•Breeding on dwarfing can also sometimes overcome the use of GRs.

dwarfing in ornamentals

Documents

new delhiuse of shrubs

growth water stress

hibiscus plants

control plants

plant growth imp

plant heightheight

width pgr treatments

homogenous plants