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a CIAT, Apartado Aéreo, 6713, Cali, Colombia
b Dep. of Plant Sciences, North Carolina State Univ
* Corresponding author (m.blair{at}cgiar.org).
Two common bean (Phaseolus vulgaris L.) germplasm lines with climbing growth habit and yellow seed type, MAC56 (Reg. No. GP-271, PI 644088) and MAC57 (Reg. No. GP-272, PI 644089) were released by the International Center for Tropical Agriculture (CIAT) for tropical mid-altitude growing conditions (1200 to 1800 masl). These novel mid-altitude climbing beans (MAC series) with type IVa growth habit are tolerant of higher temperatures (up to 24°C seasonal average) compared to traditional, type IVb growth habit, climbing beans from the Andean gene pool which are generally found at cooler temperatures (16–20°C seasonal average) (Evans, 1973; Woolley et al., 1991). The new germplasms have fast growth rates, maturing much earlier than traditional climbing beans. They also have good climbing ability but without the aggressive growth of the IVb types (Checa et al., 2004). Both MAC56 and MAC57 belong to the "Canario" commercial seed class that is native to Peru, Mexico, and some other countries of Latin America and Africa (Voysest et al., 1994; Voysest, 2000; Pallottini et al., 2004).
MAC56 and MAC57 are advanced generation F8-derived breeding lines from the cross Doré de Kirundo/LAS399 where Doré de Kirundo (G21715 from the CIAT germplasm bank) is a large seeded, type III growth habit landrace from Burundi that produces yellow grain; and LAS399 is an improved breeding line from Colombia produced by joint research between ICA (Instituto Colombiano de Agricultura) and CIAT at the "La Selva" Agricultural Research Station in Rionegro, Antioquia. LAS399 has type IVb growth habit, flowers and matures at 67 and 140 d, respectively, is resistant to anthracnose [caused by the pathogen Colletotrichum lindemuthianum (Sacc. & Magnus) Lams.-Scrib.], and produces large red grain of the Radical commercial seed class (up to 60 g per 100 seed weight). LAS399 was developed from the cross of two landraces (G12670/G12666) and was tested in Colombia under the VEF-EP (Vivero Equipo Frijol– Ensayo Preliminar) multi-locational nursery in the 1990s. The hybridization and selections required to develop the MAC56 and MAC57 lines were performed at CIAT headquarters (Palmira, Colombia) using pedigree and mass selection. Individual plant selections were made based on seed color and type IVa climbing bean growth habit in the F2 and F5 with mass selection performed on intervening and subsequent generations to the F8 when harvests were bulked. The line was tested from 2002 to 2006, in yield trials planted in three different elevation sites in Colombia (Darién, Palmira, and Popayán).
The mean seed yield of MAC56 from 2002 to 2006 at the moderate-elevation/rainfall site (Darién, 1450 masl, 20°C seasonal average temperature, 1288-mm average yearly rainfall) was 2000 kg ha–1 with a range from 1264 to 2765 kg ha–1over six seasons (given bimodal yearly rainfall at this site, the line was tested in 2 yr over both the March–June and September–January growing seasons). The mean seed yield of MAC57 at this same site was 2627 kg ha–1 with a range of 1193 to 3791 kg ha–1over four seasons. In comparison, control genotypes LAS399 and ICA Viboral yielded less than 1500 kg ha–1 at this site. At the higher elevation site (Popayán, 1800 masl, 18°C seasonal average temperature, 2477-mm average yearly rainfall) the average yield of MAC56 was 1658 kg ha–1 with a range of 1320 to 2016 kg ha–1. Meanwhile, the average yield of MAC57 was 2106 kg ha–1 with a range of 1899 to 2400 kg ha–1. Finally, at the lower elevation site (Palmira, 1000 masl, 24°C seasonal average temperature, 970-mm average yearly rainfall) the mean seed yield for MAC56 was 1207 kg ha–1over three seasons with a range of 721 to 1874 kg ha–1; MAC57 was not tested at this lower elevation site. Lower yields in Palmira were due to susceptibility to pod borer (Lepidoptera: Epinotia opposita Heinrich) that was not controlled in one season so as to observe differences in tolerance to this insect pest; however, MAC56 was remarkably higher yielding than the check genotypes LAS399 and ICA Viboral that produced almost no yield at this location due to a lack of heat tolerance.
MAC56 and MAC57 were tolerant to angular leaf spot [caused by the pathogen Phaeoisariopsis griseola (Sacc.)] in Darién and anthracnose in Popayán. However, both MAC56 and MAC57 were susceptible to Bean common mosaic virus and Bean common mosaic necrosis virus (BCMV and BCMNV) in all three sites. Therefore, the lines are being used in crosses to develop resistance to these viruses (CIAT, unpublished). MAC56 and MAC57 flowered at 38 and 40 d after planting (DAP), respectively, in Palmira; at 42 and 43 DAP in Darién; and at 50 and 52 DAP in Popayán. Maturity was reached at 80 and 84 DAP in Palmira for MAC56 and MAC57, respectively, while in Darién the genotypes matured at 98 and 100 DAP and in Popayán at 109 and 112 DAP.
While both MAC56 and MAC57 produce yellow grain typical of the "Canario" commercial class, MAC56 is medium yellow and has a brilliant (waxy) seed type, while MAC57 has a light yellow grain and a non-brilliant (non-waxy) seed type. Both genotypes have the large seed size characteristic of many Andean gene pool commercial climbing bean varieties with MAC56 producing 100 seed weights of 50.7 g in Darién, 50.5 g in Palmira, 54.0 g in Popayán (average of 51.7 g) and MAC57 producing slightly smaller grain (average of 45.5 g). At lower elevation sites seed size is smaller with MAC56 and MAC57 producing 100 seed weights of 46.6 and 38.9 g, respectively. Cooking quality in preliminary trials is good with both MAC56 and MAC57 producing a light red sauce.
MAC56 and MAC57 have been tested in regional trials in the Andean region (Ecuador, Peru, and Bolivia) as well as in Eastern and Southern Africa (Kenya and Malawi) and found to perform similarly at mid-elevation sites. Photoperiod sensitivity is low given that the lines adapt to mid latitudes; however, differential response at these sites in winter versus summer planting may indicate some sensitivity. No adaptation differences were observed in Colombia for the first versus second season plantings. MAC56 and MAC57 should be useful germplasm for tropical to sub-tropical countries of Latin America (such as Ecuador, Peru, and Mexico) and Eastern and Southern Africa (such as Zambia) where yellow beans are preferred and where climbing beans are grown or have potential to be grown at mid-elevation sites. They may also be useful as varieties for home consumption, local marketing, and export. These germplasm lines are different from the ‘Enola’/‘Azufrado Peruano’ varieties that fall under the restrictive patent on yellow seeded field beans in the United States (U.S. Patent No. 5894,079) as they are larger seeded, produced on climbing beans rather than bush beans and originate from a cross of Burundian and Colombian germplasm rather than as a selection from Mexican germplasm (Pallottini et al., 2004).
In conclusion, MAC56 and MAC57 are novel climbing bean lines selected for yield potential in mid-altitude areas of Colombia and the tropics. Compared to more aggressive climbing beans that are predominantly grown in highland environments in the Andean region of South America, MAC56 and MAC57 are type IVa climbing beans that can be grown at mid-elevation sites in a wider range of countries including those of Eastern and Southern Africa. These climbing beans have been tested in monoculture and would adapt well to various trellis or staking production systems that have become popular in several areas of the Andean (Colombia, Ecuador, and Bolivian inter-montane valleys) and Great Lakes (Rwanda, Burundi, Uganda, and Kenya) regions of South America and Africa at elevations of 1200 to 2600 masl. MAC56 and MAC57, despite their less aggressive growth habit and shorter growth duration, reach the yield potential of climbing beans which is in the range of 1200 to 4000 kg ha–1.
Limited quantities of seeds are available from the corresponding author. We ask that appropriate recognition of source be given when this germplasm contributes to the development of a new cultivar and that FAO regulations on material transfer of the germplasm lines be followed.
Acknowledgments
The research was supported in part by funds from Fontagro (IICA/Inter-American Development Bank) and by CIAT. The authors wish to thank Y. Viera for field plot management.
Footnotes
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Received for publication September 9, 2006.
References
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