The Banana Plant: Morphology, Propagation and Breeding

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The Banana Plant: Morphology, Propagation and Breeding

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Training on Increasing the Capacity of Research Technicians in Breeding. IITA-Ibadan, Nigeria.July 27-August 14, 2015.

Amah Delphine, IITA Nigeria


Plan

1. Introduction2. Classification3. Growth cycle4. Morphology• Pseudostem and foliage• Inflorescence• Flowers• Bunch

5. Propagation6. Breeding7. References and further reading


Introduction• Bananas are giant perennial herb mostly cultivated for their fruits.– Perennial: new stems (suckers) continuously grow from the base of the mother plant to replace the

aerial stems which die off. – Herb: no woody components and aerial parts dies once bunch is harvested.

• Fruits may be eaten raw, steamed, roasted, fried or processed into flour.• They contribute to food and income security to millions of people especially in the tropics.• FAO estimates for world production in 2013 is about 145 Mt.


Classification

• ‘Bananas’ refers to all members of the genus Musa comprising wild and edible types e.g. plantains (a well-defined group of starchy bananas).

• Monocots belonging to the Eumusa section of the genus Musa (several species), family Musaceae, and order Zingiberales.

• Inter- and intra- specific hybrids from two ancestral species M. acuminata colla (A genome) and M. balbisiana colla (B genome) 2n=2x=22 chromosomes.

• Edible bananas of Eumusa have 22, 33, or 44 sets of chromosomes corresponding to diploids, triploids and tetraploids respectively. Ploidy is important for classifying hybrids from breeding programs.


Question

Name a popular banana in your country, mention its form(s) of consumption and describe how you will identify it.


Classification• Form of consumption: desert, cooking and beer

types• Genomic composition:

– AAA desert, highland beer and cooking bananas– AAB plantains and desert bananas– ABB cooking bananas– AA wild and edible types– BB wild types

AAA-EAHBABB AAA BB wild

AA

AAB


Classification• Height of pseudostem:

– Giant (≥3m, >40 leaves), Medium (2.1-2.9m, 32-40 leaves), Small (≤2m, <32 foliage leaves)

• Inflorescence type (plantains):– French, False horn, Horn

French HornFalse horn


Growth Cycle

Vegetative phase - leaf emergenceTwo phases of development; Vegetative and reproductive phase


Growth CycleReproductive phase - bunch emergence


Morphology (rhizome)Rhizome (or corm) - true stem of the plant, has extremely short internodes covered by closely packed leaf scars, differentiated into central cylinder and cortex, ground tissue is starchy parenchyma. It is a storage organ sustaining growth of the bunch, and developing suckers. The terminal growing point (meristem) is a flattened dome from which leaves are formed and later becomes the inflorescence. The root system is adventitious and mostly confined to the upper 40cm of the soil. Roots originate in groups of 3-4 from the corm as primary roots branching off to secondary and then tertiary roots.

It is important for the rhizome to remain completely below the surface of the soil. A phenomenon known as high mat arises when the rhizome is ‘climbing out’ of the soil resulting to plant instability and yield decline due to exposure of roots.


Morphology (suckers)

Suckers - lateral outgrowths from vegetative buds found on the rhizome opposite the leaf base. Propagation is by suckers and four different types of suckers are distinguished;Peeper - small sucker which has just emerged through the soil Sword sucker - narrow leaves and a broad rhizome base; ideal type of planting materialWater sucker - broad leaves, smaller rhizome and weaker connection to mother plant; not ideal as planting material.Maiden sucker - full grown sucker bearing foliage leavesSeveral suckers are produced on the rhizome and the whole unit or clump is known as a mat. When a sucker is planted and the first bunch is harvested this is known as the plant crop. After harvest, the mother plant is cut down and a follower or daughter sucker is selected to produce the second harvest: first ratoon, the third harvest: second ratoon and so on. Water sucker

Peeper

Sword sucker

Maiden sucker


Morphology (Pseudostem and foliage)

Pseudostem - looks like a stem or a trunk, formed by overlapping leaf sheaths, serves as a vascular connection between leaves, roots and fruits. Pseudostem height, aspect and colour are used to distinguish between varieties.

The distal end of the elongating leaf contracts into a narrow petiole which continues into the leaf becoming the mid rib. The mid rib divides the blade into two lamina halves with pinnately arranged parallel leaf veins. The lamina develops inside the pseudostem as a rolled cylinder (cigar leaf) and unfolds after emergence. Older leaves senesce and die and new leaves emerge every 7-10 days. The final leaf to emerge is a smaller flag leaf which curves to protect the emerging inflorescence.

Scale leaves are first produced from the central meristem of developing suckers followed by narrow sword leaves and then broad leaves with wider laminae and finally full-sized leaves by 6 months.


Morphology (Inflorescence)

• inflorescence is a complex spike with a stout peduncle on which flowers are arranged in nodal clusters.

• each node comprises two rows of flowers subtended by a bract which protects the young flowers.

• flowers are predominantly unisexual, the plant monoecious and dichogamous

• proximal nodes bear female flowers (about 5-18)

• distal nodes contain male flowers tightly enclosed in bracts which form a conical structure (male bud).

• hermaphrodite, or neutral flowers, may be present on the rachis (stalk between the female flowers and the male bud).

• peduncle elongates as flowers open in sequence.


Question

What do you understand by - monoecious?- dichogamous?Is selfing possible in banana?


Morphology (flowers)

Male flowers have a smaller ovary, slender style, 5 stamens with long anthers that may or may not produce pollen.

Female flowers have an inferior elongated trilocular ovary with 3 fused carpels bearing 6 petal (5 free and 1 fused) surrounding a thick style and non-functional staminodesOvaries of female flowers later become the fruit or finger.

Female flower Male flower


Morphology (bunch)• The ovaries of the female flowers develop into

seedless fruits by pathenocarpy. • Aborted ovules are seen as small brown flecks in

centre of fruit.• Nodal clusters of rows of female flowers is the

hand and individual fruits developed from female flower is the finger.

• Number of hands per bunch and fingers per hand is determined at flower initiation by the no. of female flowers produced influenced by; genome group, crop cycle, temperature, plant vigour, level of management.

• Bunch position, appearance and shape are used to distinguish varieties.

• Weight of bunch is taken at harvest to determine yield.

• Other post-harvest traits – no. of hands, finger length, finger circumference, peel/pulp ratio, pulp color/texture, dry matter content, nutrient content.


Question

What are the major constraints to increased banana production?


Propagation principle

• A well developed plantain plant

has a corm with clumps of meristems of different ages and stages of development.

• Beside the main apical meristem, there are several lateral meristems found opposite the bases of the leaf sheaths

• When the apical meristem is destroyed lateral buds develop from lateral meristems on corms.

• Principle employed for macropropagation and field decapitation techniques for clean planting material production


Micropropagation

Sword suckers Explant preparationShoot tip initiation

Establishment and proliferation

Multiple bud formationRooted plantlets

Shoot tip culture


MicropropagationMicropropagation• Over 1000 plantlets from a single plant

in a year• Disease-free planting material • Uniform planting material;

synchronized harvests• Faster field establishment with higher

yields• Planting material can be obtained all

year round

Conventional propagation• Only 5-10 suckers from single plant in

a year• Often infected planting material• Non-uniform planting material;

staggered harvests• Slower field establishment with lower

yields• Limited availability of planting material


Nematode

Weevil

PestsDiseases

Biotic Constraints

Black Sigatoka

Bunchy top disease


Breeding objectives

- Taste and consumer acceptability- High and stable yields

- Disease and pest resistance (black sigatoka, nematode, weevil)

- Short stature- Earliness


Breeding bottlenecks

- Low reproductive fertility- Parthenocarpy- Triploidy- Slow propagation- Large space requirement (6m2/plant)- Long generation time (about 2 years from

seed to seed)


Breeding scheme

3x landrace X 2x wild or improved

4x hybrid X 2x wild or improved

3x secondary triploid

2x doubling(oryzalin)

Several black Sigatoka resistant PITA and BITA hybrids developed and are being distributed for testing.


Breeding PITAs

• 3x landrace OL

2x wild PL

3x landrace BT 2x wild

C4

4x hybrid 1658-4(PITA 7)

2x hybrid 2829-62

3x hybrid – 23688-2 (PITA 21)


Pollination - bagging

Male parentFemale parent


Pollination

male flowers

female flowers

7.30-10.30am


Question

Why do we pollinate at 7.30 – 10.30 am?


Ripening and seed extraction


Embryo culture

embryo extractionembryo germination

bud proliferationroot developmentacclimatization


Evaluation

Source: Pillay & Tenkouano 2011


References and further reading

1. IPGRI-INIBAP/CIRAD Descriptors for banana (Musa spp.) 1996.

2. Pillay M. and Tenkouano A. eds. Banana breeding: progress and challenges. CRC Press, 2011.

3. Robinson J. C. and Galán Saúco V. Bananas and plantains. Vol. 19. Cabi, 2010.

4. Swennen R. Plantain cultivation under West Africa conditions: A reference manual. IITA, 1990.

5. Swennen R. and Ortiz R. Morphology and growth of plantain and banana. IITA, 1997.


Thank you.

The Banana Plant: Morphology, Propagation and Breeding

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Transcript of The Banana Plant: Morphology, Propagation and Breeding