San Ramon Hybrids

San Ramon

Fruit Clusters

San Ramon Hybrids
San Ramon is a dwarf mutant of Bourbon coffee (Coffea arabica L.) first spotted in Costa Rica. Original San Ramon, thus, is as highly susceptible to leaf rust (caused by Hemileia vastatrix B. et Br.) as Bourbon itself. However, the dwarf stature of San Ramon (Dwarfness and Compactness) permits high density planting. Thus the concept of improving San Ramon by incorporating resistance genes from the then available progenies of S.795 came into being. The first crosses were effected in the year 1958 at the Central Coffee Research Institute (CCRI) of India, to incorporate resistance to the prevalent races I and II conditioned by the gene SH3 available in these materials. Seed from the F1 hybrid lines were given for trials under the name of Sln.7.1. Later, the F1 lines were crossed with Ethiopian Arabica varieties Cioccie and Agaro to obtain resistance against race VIII of the rust fungus conditioned by the gene SH4 available in these collections, in the year 1963. Seed from the resulting hybrid lines was distributed as Sln.7.2. Subsequently, selected plants of Sln.7.2 were crossed with Hibrido de Timor (HDT) to impart maximum possible resistance to leaf rust by transferring the resistance genes of HDT (later identified to be SH6, SH7, SH8 and SH9) in the year 1972. Some efforts were devoted to plant only desirable dwarfs in the progeny plots of this cross. Seed from these hybrids was distributed under the name of Sln.7.3. The cross of Sln.7.3 with selected plants of Sln.6 (Robarbica, an indigenous artificial hybrid of Robusta x Arabica) is aimed at rendering the descendant hybrids extra resistant to leaf rust. This hybrid is named as Sln.7.4. However, there is segregation of resistant and susceptible types in the F3 generation (Resistant 65.6% and susceptible 34.4%). There is also segregation of plant types into tall and dwarf. Among the dwarfs there are four types of plants. These are: a) extreme dwarfs, b) conical shaped dwarfs with short internodes, c) conical shaped plants with slightly longer internodes and d) open type plants with slightly longer internodes. Only the last type of plants in San Ramon hybrids is desirable for cultivation as they are the most amenable for various cultural operations. Presently, seed from resistant plants of this progeny is given out as Sln.7.4.
Improvement of San Ramon mutants has taken place only in India. In the course of improvement of rust resistance, the quality of the produce is not compromised and selection for bold bean size and good cup quality rendered this material resistant to rust as well as producing good quality coffee. The quality aspects and agrotechniques for cultivating this variety are reviewed in the document.
The document is available with the author and can be obtained by mail order/request to santaram_2000@yahoo.com.

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