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Demand for new high-yielding rubber clones

Demand for new high-yielding rubber clones

TA News Bureau

Recent studies show that there is a rise in demand for high-yielding climate-resilient and environment-optimised Hevea rubber clones. The demand has shown an upsurge in view of reforestation, carbon sequestration etc. Rubber scientist Mallinath Priyadarshan says this needs to be handled carefully. While rubber ensures income to the planter, it cannot be at the cost of forest cover. Also, the government needs to ensure that the benefit of rubber cultivation reaches all parts of the country, especially for the low income groups, he says in an interview to Tyre Asia. His book Biology of Hevea Rubber is to be published by Springer this year

Striking a balance between the rising interest in high-yielding climate-resilient and environment-optimised Hevea rubber clones and the larger interest of the planter is absolutely necessary for the good of the plantation sector. “The two is of prime importance,” says Rubber scientist Dr Mallinath Priyadarshan, a well-known rubber breeder and plantation consultant who had served as a Deputy Director at the Rubber Research Institute of India.
He notes that there is notable awareness on increasing the area under rubber after deforestation. Like jhuming (shifting cultivation) in areas of north-east India, swidden (land cleared for farming by burning away vegetation agriculture) has long been the dominant farming system in Montane Mainland Southeast Asia (MMSEA).
“Today, the ecological bounty of this region is threatened by the expansion of settled agriculture, including the proliferation of rubber plantations,” the scientist explains.
Citing examples, he said in the biodiverse rich Xishuangbanna Prefecture, Yunnan Province, China, there is a rapid increase in rubber plantation from 8 per cent to 22 per cent of total area between 2002 and 2010. The issue is further complicated as rubber is now being increasingly cultivated in physical environments that are marginal in terms of long-term viability.
In the current conception of REDD+ (Reduce Emissions from Deforestation and forest Degradation), landscapes involving swidden qualify almost automatically for replacement by other land-use systems because swiddens are perceived to be degraded and inefficient with regard to carbon sequestration, asserts Dr Priyadarshan.
REDD+ was first negotiated under the United Nations Framework Convention on Climate Change (UNFCCC) since 2005, with the objective of mitigating climate change through reducing net emissions of greenhouse gases through enhanced forest management in developing countries. However, swiddening in some cases may be carbon-neutral or even carbon positive, compared with some other types of land-use systems.
“Agricultural policies and institutions have affected land use in the region over the last several decades and the impact these policies have had on the livelihoods of swiddeners and other smallholders is conspicuous,” the rubber scientist asserts.
A deeper and more systematic analysis of the multiple consequences for the design of successful REDD+ policies in MMSEA, and other areas of the developing world is the need of the hour, he feels.
REDD+ policies should be structured not so much to ‘hold the forest boundary’ but to influence the types of land-use changes that are occurring so that they support both sustainable livelihoods and environmental services, including but not limited to carbon. On the other hand, a mature rubber plantation would qualify as “forest” as per the Clean Development Mechanism (CDM) definition.

Great uncertainty

Meta-analysis of over 250 studies reporting above- and below-ground carbon estimates for different land-use types indicated great uncertainty in the net total ecosystem carbon changes that can be expected from many transitions, including the replacement of various types of swidden agriculture with oil palm, rubber, or some other types of agroforestry systems, Dr Priyadarshan points out.
These transitions are underway throughout Southeast Asia, and are at the heart of REDD+ debates. As some transitions may negatively impact other ecosystem services, food security, and local livelihoods, the entire carbon and non-carbon benefit stream should also be taken into account before prescribing transitions with ambiguous carbon benefits.
“The need is to demarcate areas suitable for rubber, in order to curtail indiscriminate extension of rubber cultivation.” he demands.
Truly, when you extend rubber cultivation to non-traditional areas (above 150 north and south of equator), climate resilient and environment optimised clones are a must, he agrees.
But he, however, says while in traditional areas the yield may range between 1600 to 1800kg /ha, the non-traditional areas can give a productivity of 1100 kg only. “Climate resilient and environment optimised clones can surely give much better yield,” he points out.
Breeding new clones for non-traditional areas is of prime importance. “I worked as a Plant Breeder in Tripura for 18 years and fully understand its importance. I have dealt with all these aforesaid topics in some detail in my latest book on Biology of Hevea Rubber to be published by Springer this year.
The Kyoto protocol was adopted on Dec 11, 1997 but came into force on Feb 16, 2005 after undergoing complex ratification processes. During 17th COP (Conference of Parties) at Durban, it was decided that the Green Climate Fund (GCF) would become an operating entity of the financial mechanism of the UNFCCC. GCF is expected to be the centrepiece of Long Term Financing under UNFCCC with a goal of raising $100 billion per year by 2020.
This resource mobilisation has to become a reality during the years to come. Under the Kyoto protocol of the UNFCCC, signatory countries must decrease emissions of CO2 to the atmosphere, or increase rates of removal and storage. “The plans are meticulous, but are we there yet?” asks Dr Priyadarshan.
Commenting on the need to have close cooperation between breeders and genomic specialists to develop innovative techniques for breeding Hevea rubber in the future, says they are now work on two parallel lines.
“Even genomic specialist-turned plant breeders are shying away from addressing how much their studies can address the issues of society and planters. “This situation needs to change” Dr Priyadarshan asserts.
One fine example is involvement of genomic specialist in reducing the time of breeding cycle of Hevea. Enumerating suitable molecular markers for effective selection of clones at the juvenile stage is one option.

Genetic markers

Transcriptome (the set of all messenger RNA molecules in one cell or a population of cells) analysis of bark is an upcoming area for marker-assisted selection during juvenile stage that can revolutionise breeding Hevea rubber.
RNA sequencing (RNA-seq) of bark validated 78 single-nucleotide polymorphisms (SNPs) in 36 genotypes. This new dataset represents a powerful information source for rubber tree bark genes and will be an important tool for the development of microsatellites and SNP markers for use in future genetic analyses such as genetic linkage mapping, quantitative trait loci identification, investigations of linkage disequilibrium and marker-assisted selection.
Characterisation and cross-amplification of microsatellites from wild Hevea species has augmented the possibility of transferability of these microsatellites to Hevea brasiliensis, he notes.
Lately, there has been a comparative evaluation between self-rooting juvenile clones (JCs) and bud-grafted (donor) clones (DCs) at transcriptome level. Genes, especially encoding epigenetic modifications, are differentially expressed in JCs and DCs. Genes involved in carbohydrate metabolism, hormone metabolism and reactive oxygen species scavenging were up-regulated in JCs of CATAS 7-33-97 and Haiken 2, indicating that the JCs provide sufficient molecular basis for the increased rubber yield.
Comparative trial between self-rooting JCs and DCs, proved self-rooting JCs exhibited better performance in rubber yield. Such investigations clearly indicate the intricateness of stock-scion interactions. No doubt, such investigations can gain a perfect juvenile selection system in Hevea in the years to come. Scientists at Chinese Academy of Tropical Crops at Haikou must be congratulated for such advancements.
“Here, what I mean is that the barrier between plant breeder and the genomic specialist must completely vanish,” Dr Priyadarshan demands. “The genomic specialist must analyse the genotypes raised by the plant breeder. Selections thus made are to be evaluated in planter’s field by the plant breeder. For this, Genomics should become plant breeding curricula,” he suggests.
Dr Priyadarshan states that the initial production of high-yielding clones has given 1600kg/ha against 496kg/ha of unselected seeding is a breeding revolution. In this context there is a need to go for high-yielding clones. But these issues should be examined in the context of the International Treaty on Plant Genetic Resources for Food and Agriculture, the first legally binding international agreement that explicitly recognises farmer’s rights. The idea is solely to ensure higher returns to the planters and ensuring high yielding clones at definite intervals.
Take India for example, the spectrum of geo-climates over the length and breadth of the country is a challenge before the breeders to ensure location specific clones, once the areas suitable for rubber is demarcated (which was done long back). Data from clone evaluation trials can help to take the way forward.
Seeing the subject in the perspective of the planter, it is important to allow him to participate in the breeding programmes. Here, Participatory Plant Breeding (PPB) is truly inspirational. It is a collaborative venture between breeders and farmers which may include marketers, processors, consumers and policy makers.
Planter can assist the breeder through raising open-pollinated seedlings (poly cross), which can be subjected to selection at juvenile stage. The phenomenon of natural selection of embryos (gametic selection) under a given environment works handy to have seedlings with specific adaptation from where such selections can be made. The selection and a posteriori evaluation of clones for their parentage is the work of genomic specialist, he feels.
Plantations with multi-clones are vital to raise poly cross seedlings. The newer concept of Breeding without Breeding (BwB) allows the assemblage of full-sib (FS) and half-sib (HS) families from naturally pollinated seed orchards without conducting any crosses.
“This scheme circumvents artificial mating, focusing instead on a subset of randomly sampled, maternally known but paternally unknown offspring to delineate their paternal parentage,” Dr Priyadarsan says.
This method calls for highly informative molecular markers (Single Sequence repeats-SSRs) for pedigree reconstruction and to unravel the parentage, he adds.

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