Ever since its introduction into India from Indonesia in the eighteenth century, clove, the high-value and much sought after spice, has been defying attempts to develop improved varieties. However, clove growers can, hope for a change soon, thanks to the discovery of a source of dwarfing gene and one producing king cloves, much bolder than the present day clove.
Originally, only a few plants had come from abroad, therefore, India did not have adequate genetic diversity in clove plantations for breeding new varieties. Crop improvement was done largely through selection of elite mother trees based on their regular and heavy bearing nature and then propagated vegetatively.
As a result, the total production of this tree spice continued to lag far behind the demand, estimated annually at around 4,000 tonnes. Though precise figures about the actual output are not available, it is believed to be around 1,500 tonnes from a total plantation area of around 1,855 hectares. The commercially important part of the clove tree is the dried, aromatic, fully grown, but unopened, bud of the flower.
The clove clones available at present in the country have trees appearing different in terms of shape, bearing habits, canopy and season of bearing fruits but their overall productivity levels are almost same. Despite some variations in the seed shape and dimensions of clove, the weight of, say 100 fruits or 100 seeds, turns out to be almost similar in different trees.
In a bid to conserve the available genetic diversity and increase it further, the Calicut-based Indian Institute of Spices Research (IISR) launched a programme for collection, cataloguing and evaluation of clove germplasm. It has already collected nearly 220 germplasm samples from within the country and abroad.
However, the real breakthrough came when IISR scientists came across distinctly different types of clove trees growing in a plantation in Kanyakumari district of Tamil Nadu. Two of the plants, located at the Black Rock Estate, are dwarf and bushy. They are 16 years old and yet only about two metres tall. The width of their canopy is around five metres. The main trunk is only 0.6 metre in height, with profuse branches starting just 60 cm above the ground level. Each tree bears annually about three kg dry reddi-sh brown cloves, relatively smaller in size than the normal ones.
The tree bearing cloves of a size much larger than the normal one discovered in the same estate in Kanyakumari is 25 years old and has a height of about 10 metres with a cylindrical canopy. The fruits are dark reddish brown and resemble the ordinary cloves. The diameter of the head of the flower bud is 0.7 cm, compared to an average 0.5 cms for ordinary cloves. Similarly, the length of the flower bud of the king clove tree is 1.4 cm, against 1.3 cms for the ordinary one.
The IISR scientists propose to utilise the genes of these dwarf and king clove plants in their breeding programme. They feel that the dwarf gene source has potential to lead to a new dwarf variety of cloves having compact canopy size. This would help accommodate more number of plants per unit area, facilitating higher production.
Besides, it would be much easier to harvest the flower buds and carry out other farm operations in dwarf plantations. They are expecting a similar kind of revolution in clove production as had occurred in the case of wheat with the discovery of Norin 10 dwarfing gene or in rice after the availability of "Dee-gee-woo-gen" dwarfing gene.
