1. Agric Technique Manager, SoGB estate, Grand Bereby, Ivory Coast
Usefulness of in vitro micropropagation for establishing plantations of industrial rubber clones
The aim of this presentation is to provide a testimony of SOCFIN experience in acclimatization and establishment of micropropagated rubber clones
Aurélien MASSON
Agric Technique Manager, SoGB estate, Grand Bereby, Ivory Coast

2. THE SOCFIN GROUP Started in 1909
Started in 1909
Rubber and Oil Palm plantations in Africa and Asia
Total of ha
ha planted with rubber trees; 3 M of hevea plants produced in 2014
Rubber R&D field activities based in Ivory Coast (SoGB estate, ha of rubber)

3. CLONAL PROPAGATION BY BUDGRAFTING
Only way for mass propagating rubber tree clones since 1920.
DISADVANTAGES: Coexistence of two genotypes within the same plant
Graft incompatibility: within clone variability, reduction of vigor and of latex production, anticipated mortality and bark necrosis syndrome
Physiological ageing of the scions
Contrary to fruit or seed crops, preference is given to growth and vigor for rubber trees

4. PRODUCTION OF MICRO AND MACRO CUTTINGS
Project in collaboration with University of Gent since 2006
SoGB has been the private company field testing rooted (micro)cuttings of mature rubber tree genotypes at an industrial level
=> Hypothesis: better field performance (faster growth, higher yield) than bud grafted trees
Trials have been carried on since 1990’s to establish self rooted rubber trees at SoGB
Picture : 19 year old microcutting at SoGB
JUVENILITY OF STOCK PLANT
Key requisite for succeeding in propagation by rooted cuttings

5. MATURE GENOTYPE REJUVENATION
Rubber trees are amongst few tree species to be rejuvenated by somatic embryogenesis
2- In vitro production
of somatic embryos
UGent
3- In Vitro Micropropagation
1- Immature fruit
collection
SoGB
4- Acclimatization to ex-vitro conditions

6. bottleneck 1: SOMATIC EMBRYOGENESIS bottleneck 2: TRANSPORTATION
CURRENT LIMITATIONS
bottleneck 1: SOMATIC EMBRYOGENESIS
Very low germination rate : 0.15 %
Genotype dependent protocol, many genotypes being still totally recalcitrant up to now
bottleneck 2: TRANSPORTATION
Logistic - formalities
Travel time
Cost
Volume / Quantity of plantlets
Best option: to have the laboratory where the trees are growing (SOCFIN lab under construction in Indonesia)

7. Successive steps for mass producing industrial rubber clones by rooted cuttings
IN VITRO PLANTLETS
ACCLIMATIZATION
NURSERY
RAISING, HARDENING
PLANTING
STOCK PLANTS
ROOTED
CUTTINGS
RAISING, HARDENING
PLANTING

8. MICROCUTTINGS ACCLIMATIZATION
plantlets acclimatized at SoGB since 2012
Average 75% survival rate
Acclimatization requires 6 weeks
High discrepancies of survival rates between batches due to:
Seasonal effect
Transportation conditions
Poor plantlet quality: heterogeneity in physiological condition and development

9. NURSERY AND FIELD PLANTING
MICROCUTTINGS
NURSERY AND FIELD PLANTING
HARDENING AND RAISING:
The plantlets need to be raised for 4 months for reaching a plantable size
High losses in nursery : plantlets are very fragile, prone to waterlogging, lezard and snail damages
Some plantlets survive after acclimatization but don’t resume growth in the nursery
Substantial growth differences within and between batches of plantlets
PLANTING:
40 ha planted
Agronomic performance under assessment
Up to now, this in vitro propagation system remains uneconomic
=> Hybrid SE/rooted cutting system may overcome the economic aspect

10. MACROCUTTINGS STOCK PLANT
Microcuttings are managed to be used as stock plant for producing rooted cuttings
This procedure is also applicable to macrocuttings (same juvenile-like characteristics)
Overall productivity is still too low (1.5 to 2.5 cuttings per month per stock plant), with noticeable seasonal variations (light intensity, rain)
variations of productivity between stock plants
Stock plants are still producing cuttings with good rooting ability after 2 years

11. MACROCUTTINGS ROOTING AND NURSERY
15 days under 100% RH are needed to get the first adventitious roots
15 more days in the green house to 3 months under shade are necessary to get a ready for planting Hevea cutting (1 new leaf stage)
75% average rooting success for the 2 industrial clones tested so far, in absence of noticeable difference of rooting ability

12. ROOTED CUTTING ISSUED INDUSTRIAL CLONES FIRST FIELD OBSERVATIONS
True-to-typeness
Shorter nursery period than grafted plants
Container-grown cuttings are more convenient than grafted plants produced polybags
Expected advantages found in the literature:
Faster growth, tapering trunk
Higher latex yields (+30%)
Absence of bark necrosis

13. SHORT TERM PROSPECTS To mass clonally produce a wider range of clones
To establish more field comparative grafted vs rooted cutting trials
Improve the efficiency of nursery techniques for producing more rooted cuttings from mature clones at a cheaper cost than from tissue culture