The success of any breeding programme depends on the proper evaluation and exploitation of the available gene pool. Hence, a massive gene bank was established at CCRI with collections from both indigenous and exotic sources. The indigenous collections were made between 1925 and 1940 by surveying the existing plantations for vigorous, disease-resistant Arabica and Robusta plants and over 250 collections were established at CCRI. These collections formed the base for developing early Indian selections. After 1940, exotic collections from all coffee-growing countries, including Ethiopia, the home land of Arabica coffee, were introduced into the gene bank. Presently, there are about 300 surviving collections of Arabica, 73 types of Robusta and 17 different species of coffea. All these collections have been thoroughly assessed and some of the collections, with useful agronomic traits were exploited in breeding programmes.
The main objectives of varietal improvement in Arabica coffee are to evolve superior genotypes through breeding for:
• Rust tolerance
• High productivity
• Wide adaptability
• Improved quality
Recently, focus has also been on breeding for pest and drought tolerance and low caffeine.
Variability in Arabica
Arabica is a polymorphic species (having many forms). Variability in Arabica and its hybrids relate to various agronomic traits like plant size (dwarf, semi-dwarf, tall); branching habit (erect, spreading, drooping); fruit size (small, medium, bold);fruit ripening ( early, late); quality traits and yield potential. Besides, a wide spectrum of resistance from complete susceptibility to total resistance to leaf rust pathogen is also seen. By utilizing this variability, CCRI has successfully released 13 elite selection by employing the standard breeding strategies like inter-varietal hybridization followed by pedigree selection (Sln.2.Sln.3), pure line selection (Sln.1, Sln.4, Sln.8), interspecific hybridization followed by backcross breeding (Sln.6),double crosses( Sln.10),multiple crosses (Sln.7.3) and introgressive breeding (Sln.5A, Sln.5B,Sln. 9, Sln.12 and Sln.13) using spontaneous tetraploid interspecific hybrids like Devamachy and Hybrido De Timor (HDT).
Arabica varieties from CCRI
Arabica coffee (COFFEA ARABICA L) is a small tree in its original habitat, but grows like a shrub with bushy growth when trained. Arabica produces superior quality coffee but is susceptible to diseases like leaf rust and pests like white stem borer. This necessitated the systematic breeding efforts for genotypes with respect to leaf rust resistance, high yielding potential, wide adaptability and superior quality. So far CCRI has developed 13 Arabica selections for commercial cultivation of which, seven selections are popular among the growers and cultivated on commercial scale. A brief description of different Arabica selections developed by CCRI is as follows:
The S.288 was the first selection releases during 1936-37 and this variety was developed by pure line selection from S.26, a putative natural hybrid between C. Arabica and C. liberica. The plants of S.288 exhibited tall phenotype with vigorous growth and manifested resistance to leaf rust race 1 and 2, and was found superior to other varieties like ‘chiks’ and “kents’ under cultivation then. Fruits are round with broad disc and orange yellow to red in colour, popularly known as ‘golden drops’. This selection is known for its general adaptability and is a moderate yielder(800 to 1000 kg ha-1) but produces high percentage of defective beans(20 to 30%). The liquor quality is rated as Fair Average Quality.
It is a hybrid of S.31 and S.22. Initially this was recommended for cultivation, because of its hybrid vigor and resistance to leaf rust. But, seed distribution was withdrawn subsequently, because of high bean abnormalities.
This selection was released during 1945-46 and is the most widely adaptable and cultivated variety in India. S.795 was developed from the cross between S.288 and ‘kents’ coffee with the main objective of minimizing bean abnormalities in S.288. The plants of S.795 are vigorous and wide spreading with profuse growth and a yield potential of 1500 to 2000 kg ha-1. Leaves are oblong, broad and young leaves (tip) are bronze in colour. The fruits are round to oblong with broad honey disc and the number of fruits varies from 12 to 16 per cluster. Beans are oblong, bold with 60 to 65% ‘A’ grade and liquor is balanced with good body, good acidity and fairly good flavor. The S.795 showed resistance to leaf rust race 1 and 2, prevalent at the time of release, but later fell susceptible to new virulent races 7,8,12 and 16.
This is a composite selection of three Ethiopian Arabica collections viz. Cioccie, Agaro and Tafarikela. Among these, Cioccie and Agaro exhibit semi-erect branching while Tafarikela shows drooping nature. All the three collections are tall types and moderate yielders with yield potentiall of 1000kg ha-1. The young leaf (leaf tip) colour is green in Cioccie, bronze in Agaro and dark bronze in Tafarikela. Fruits are long, bold, orange red with projected honey disc, occasionally with persistent calyx in Agaro and Cioccie. Beans are bluish green, long and bold with 65% ‘A’ grade and excellent liquor quality. On the other hand, fruits are relatively small in Tafarikela and ripen early compared to all Arabica varieties. Cioccie and Agaro are resistant to leaf rust races I, II and VIII. Through Tafarikela is susceptible to rust, it exhibits horizontal resistance showing very less rust build up under field conditions. Because of the specific resistance, Sln.4 was given for commercial cultivation during late 1960s as a strategy to check the devastation of race VII on S.795 plantations.
Sln.5 (Sln.5A and Sln.5B)
Sln.5 includes two separate families of cross bred lines involving Devamachy and S.881 (a wild Arabica collection from Rume Sudan) and Devamachy and S.333. Devamachy is a spontaneous Robusta x Arabica hybrid collected from a private estate in Coorg and characterized by intermediate plant phenotype to Arabica and Robusta eith good vegetative vigour but low fruit set. The plant of Devamachy x S.881 (Sln.5A) show vigorous vegetative growth with erect branching habit. The leaves are relatively small, narrow, elongated and leathery with wavy margin. Young leaves (leaf tip) are generally green in colour and the plant exhibit field resistance to leaf rust. Even though rust susceptibility is seen in some plants, defoliation is not common. Fruits are round to oblong, variable in size with long peduncles (stalks) and 8 to 12 per cluster, relatively late in ripening. Sln.5A is a consistent yielder with production potential of 1200 to 1500 kg ha-1 but beans are medium in size with high percentage of ‘B’ grade beans (~40%). Adaptable to hot and humid climate, it performs well across different elevations. Sln.5A is a very popular and the most cultivated variety in non-traditional coffee areas especially in Andhra Pradesh.
Devamachy x S.333 line (Sln.5B) is characterized by uniform, medium sized, semi-drooping plants. Leaves are elongated, medium in size and young leaves are light bronze in colour. The plants also exhibit higher resistance to leaf rust with a yield potential of 1500 kg ha-1. Fruits are round, bold with round navel, 12 to 16 per cluster, normal in ripening. Beans are bluish grey, round, bold in size with 60 to 65% ‘A’ grade and liquor in both Sln.5A and Sln.5B is FAQ to FAQ+ in quality. Being adaptable to different Arabica growing regions, it performs well in medium to high altitudes.
This was developed by crossing Robusta cv.S.274 and ‘kents’ Arabica. Progenies from the 2nd backcross to ‘kents’ were found to be vigorous with Arabica type of appearance and Robusta type of tight clusters. Bushes are tall, vigorous with spreading branches and medium to long inter nodal length. Leaves are broad, thick and young leaves are bronze in colour. Fruits are bold, round, arranged in tight clusters with 16 to 20 fruits per cluster and ripening is relatively late. The yield ranges between 1200 and 1500 kg ha-1 and beans are bluish grey, round and bold with 60 to 65% ‘A’ grade and liquor quality is FAQ to FAQ+. The Sln.6 is well adapted to mid altitudes and shows a mixed type of rust reaction with about 80% of plants manifesting high tolerance to rust. A particular progeny of Sln.6 raised at Swarnagiri estate (Coorg) from the seed supplied from CCRI became popular because of its proven performance, high uniformity, consistent yield and tolerance to rust.
Sln.7 is derived from multiple crosses involving ‘San Ramon’, a dwarf mutant and tall Arabicas like Sln.795, Agaro and Hibrido de Timor (HDT). The original ‘San Ramon’ mutants were very compact in branching habit, with closer internodes and deep roots but highly susceptible to rust. Of the progeny of the mutant, 70% were dwarf type and 30% were tall types. In order to improve resistance to leaf rust and to exploit the dwarf phenotype for high density planting, San Ramon was crossed with S.795 and Sln.7.1 was developed. Dwarf type in Sln.7.1 was crossed HDT and Sln.7.3 developed. The dwarfs in Sln.7.3 are suitable for high density planting (1.2×1.2m, 1.5×1.2m) with a yield potential of over 1500 kg ha-1 but with annual variations for production. Sln.7.3 is a late ripener, drought tolerant and suitable for marginal areas. It is however, susceptible to virulent races of leaf rust. The liquor quality of the variety is rated as FAQ to above FAQ
It is a pure line selection of ‘Hibrido de Timor’ popularly known as HDT. The HDT is a naturally originated Robusta x Arabica hybrid identified in Timor Island (in South East Asia) and was introduced into India in 1960. The plant phenotype closely resembles Arabica and possesses high vertical resistance to leaf rust. Plants show compact growth and drooping branches. It is a moderate yielder (1000 to 1200kg ha-1) and produces medium to bold beans. Cup quality is similar to Arabica (FAQ to FAQ+). Sln.8 is suitable for cultivation in medium altitudes.
With the objective of exploiting HDT as a source of rust resistance, several crosses were made between HDT and other tall Arabicas such as Tafarikela, S.795, Geisha, S.12 Kaffa and Bourbon. Among these, HDT x Tafarikela showed high resistance to leaf rust under field conditions and on an average (23 years) yielded 1700 kg ha-1 at CCRI. Hence, this combination has been given as Sln.9 for commercial cultivation. The plants of Sln.9 are tall, vigorous with drooping branches and medium to long internodes. Leaves are broad, elliptic, young leaves are dark bronze in colour. Fruits are bold, dark red, oblong and12 to 16 per cluster and show early ripening. Beans are bluish green, round, bold with 60 to 65% ‘A’ grade beans and liquor quality is excellent with strong body, possessing distinct flavour in cup. Sln.9 manifests fairly good tolerance to leaf rust and is drought hardly and widely adaptable across all the coffee regions. For these reasons, Sln.9 has gained popularity among growers.
‘Caturra’ is a semi-dwarf mutant of Arabica coffee (Bourbon). It has high yielding potential but is highly susceptible to rust resistance, it was crossed with Cioccie and S.795. The respective progenies were again crossed to evolve the double cross hybrid, Sln.10. The plants of Sln.10 are compact and semi dwarf in nature with profuse bearing habit and manifest resistance to common race of rust but are susceptible to virulent races. Fruits are bold and produce nearly 65% ‘A’ grade beans. Cup quality is similar to S.795.
This is a derivative of the interspecific hybridization between C. Arabica and C. eygenioides and spontaneously obtained by amphiploidy. Bushes resemble Arabica with erect to semi-erect habit and thin branches. Leaves are narrow, linear, small and young leaves given in colour. Fruits are small, oblong, 10 to 15 per cluster, golden red in colour and late ripening. The plants are resistant to leaf rust and moderately tolerant to drought. It is a moderate yielder with a yield potential of 1000 to 1200 kg ha-1 and produces more ‘B’ grade beans (30 to 40%). Cup quality is similar to Arabica. Sln.11 exhibit better adaptability to hot and humid climate
A semi-dwarf genotype derived from a cross between caturra and HDT, Sln.12 was released for commercial cultivation in India in 1985. Its bushes are compact and vigorous with profuse branches and close internodes, and are thus suitable for high density planting. Leaves are medium in size and elliptical. The young leaves are green in colour. The variety is an early bearer and fruits are dark red, round, bold, 12 to 18 in tight clusters. The plants exhibit high resistance to leaf rust in the initial years. However, resistance broke down in later years due to appearance of several new rust races. This hybrid has the potential to yield an average of 2000 kg ha-1. Under different management conditions, the yield ranged from 1000 to 3000 kg ha-1 indicating its potential to respond to intensive cultivation. Beans are bluish green, round, bold with over 60% ‘A’ grade and liquor quality is FAQ to FAQ+ with pleasant aroma and taste. The Sln.12 variety requires intensive management practices for realizing consistent yields. Widely adaptable across all the coffee regions, it is suitable for cultivation in high elevation areas (above 1200m MSL). In lower elevations, the plants exhaust fast due to become susceptible to coffee leaf rust and coffee white stem borer.
The variety ‘Chandragiri’, released in 2007, is derived from the cross Villasarchi x HDT. Plants are semi-dwarf in phenotype with vigorous growth, thick primaries and close nodes. Leaves are broad, thick, dark green in colour. Fruits are oblong, flat, elongated, 12 to 18 in number and borne in loose clusters, normal in ripening. Beans are bluish green, long and bold with 20 to 25% MNEB, 20 to 25% ‘AA’, 30 to 35% ‘A’ grade and liquor is FAQ to FAQ+ This variety manifests high field tolerance to leaf rust with yield potential of 1500 to 1800 kg ha-1. ‘Chandragiri’ variety is best suited for cultivation at higher elevations (100m MSL and above).
Robusta varieties from CCRI
The second most commercially important coffee species in India is ‘Robusta’ (coffea canephora). The ravages of leaf rust and white stem borer on Arabica coffee encouraged Indian planters to introduce Robusta coffee in 1930-1906. Robusta is a native of Central Africa and is predominantly a low land coffee that adapted readily to the Indian soils. Robusta coffee possesses several useful characters like tolerance to leaf rust, white stem borer, nematodes as well as the potential to give consistent yields. Because of these reasons, the cost of Robusta cultivation is relatively lower compared to Arabica. On the other hand, an inability to cope with long drought, late cropping, late stabilization of yields and inferior bean and liquor quality compared to Arabica are some of negative aspect of Robusta Coffee. Self-incompatibility and the limited gene pool are bottlenecks for Robusta improvements in our country. Keeping these aspects in view, improvements of Robusta was undertaken by CCRI. As a result of this work, three superior Robusta cultivars were developed and given for commercial cultivation.
Selection 1R (S.270, S.274)
These are the seeding progenies of two individual high yielding mother plants. Both these types are vigorous and grow into moderately large trees. Leaves are large, broad, light green, waxy with smooth margins. The fruits are medium bold, round to oblong with pronounced navel and borne in tight clusters of 30 to 50 fruits each. Ripening is usually late compared to Arabica and outturn ratio is 5:1. Beans are medium to round and green to greyish in colour when wet processed. The progeneis produce nearly 43% ‘A’ grade beans. The cup is neutral with a quality rating of FAQ to good. These two genotypes have recorded yields of nearly 1000 kg ha-1 on an average over 35 years under rain fed conditions. Among the two progenies, S.274 produces more bold beans compared to S.270. Because of this trait and also due to its wide adaptability, S.274 has become more popular with a yield potential of 2500 to 3000 kg ha-1 under irrigated conditions and 1000 to 1500 kg ha-1 under rain fed conditions.
Selection 2R (BR series 9, 10, 11)
Seventeen superior plants which have yielded twice the family mean yield were identified from the initial twelve single seedling progenies (S.267 to S.278), and named as ‘Balehonnur Robusta’ (BR), named for the eponymous town in Karnataka’s Chikmagalur district. Based on the progency performance of these plants, BR 9, 10 and 11 were found to be superior in production and as such seed mixture of these clones was issued for commercial cultivation as Sln.2R. Clones were also issued for establishment of bi/polyclonal gardens. This selection resembles S.274 in growth habit, yield potential and bean/cup characteristics. However, in these clones, high degree of stability for ‘A’ grade beans and other characters are seen. It is important to note that only seed mixture of the three clones BR 9, BR 10 and BR11 should be used for planting. Individual BR clones should not be planted separately as this may result in poor fruit set due to self-incompatibility.
Selection 3R (CxR)
This is a hybrid variety developed through interspecific hybridization involving C. congensis and C. canephora (Robusta). C.congensis is a species closely related to both Arabica and Robusta with compact bush, drooping branches and better bean quality than Robusta. F1 was backcrossed to both the parents (Robusta and Congensis) and established further progenies. In the back cross progeny to Robusta, selection was made and through sib-mating the commercial CxR hybrid was evolved.
The hybrid plants are intermediate to both parents in size with compact secondary growth giving drooping appearance. Each branch consist of 9 to 12 bearing nodes. This hybrid can be planted in closer spacing of 2.7 x 2.7m or 2.4 x 2.4 m (9×9 ft or 8×8 ft) compared to pure Robusta S.274 which requires a wider spacing of 3x3m (10 x 10 ft). Fruits are 30 to 40 per node in tight clusters, orange to crimson red with prominent and projected navel. This variety is an early, uniform rippner and easy to harvest with an out turn ratio of 4:5:1. Beans are medium to bold, golden brown and 60 to 65% represent ‘AB’ grade of soft, neutral with light to fair acidity and good cup quality. The yield potential is 1000 to 1500 kg ha-1 under rainfed conditions and 2000 to 2500 kg ha-1 under irrigated conditions.
Region specific suitability of station bred selections
Based on the adaptability and proven performance, the CCRI selections recommended for different regions are detailed below.
In general, It has been observed that the semi-dwarf Arabica varieties like cauvery/catimor and chandragiri have wider adaptability for different agro-climatic regions, respond well for intensive cultivation practices and amenable for new planting designs such as hedge row planting and paired row planting, aimed at mechanization of certain farm operations. However, cultivation of these varieties in low elevations leads to physiological stress and early debilitation of the plants leading to high susceptibility to leaf rust and thereby vulnerable for white stem borer infestation. Hence, cultivation of the semi-dwarf varieties can be preferred only at higher elevations (above 1200m MSL for Cauvery and above 1000m MSL for Chandragiri) for assured performance.
As durability of resistance in semi-dwarf genotypes can be challenged by the new rust race that evolve after the introduction and expansion of any new variety in field, rust management has to be carried out as an essential operation. Among the semi-dwarf varieties, the chandragiri variety has definite advantage with respect to superior grade percentages. In this variety, on an average, over 70% of the beans belong to ‘A’ grade, of which 25 to 30% belongs to ‘AA’ grade with superior bean density, contributing for value addition. Procurement of seeds from authentic source such as Coffee Board Research Department is very important to avoid indiscriminate advancement of generations and to retain genetic vigour of the population.