«Andean roots and tubers: Ahipa, arracacha, maca and yacon M. Hermann and J. Heller, editors Promoting the conservation and use of underutilized and ...»
2.3 History Ahipa or ajipa is, as mentioned, probably the most interesting of all the cultivated yam bean species: (1) from the systematic view because of the absence of known wild ancestral material, (2) from the morphological view because of the presence of genotypes with an erect, short growth habit, and (3) from the agronomic view because of the daylength neutrality, short growth season (5 months) and its considerable adaptability to climatic variation. The distribution is limited to Andean valleys in Bolivia and possibly Peru. There is no definite evidence of the presence of the crop in Peru, but owing to the proximity of the northern Bolivian landraces it may be Promoting the conservation and use of underutilized and neglected crops. 21. 23 assumed that Peruvian material exists. The recorded history of P. ahipa in cultivation indicates that in contrast to the other two cultivated species this species has never been associated with shifting cultivation. The earliest indications of a Pachyrhizus species used as a crop in South America are remains of tuberous roots found among the plant residues in the ‘mummy bundles’ of the Paracas Necropolis, the southern coast of Peru, belonging to the Nasca culture (Yacovleff 1933; Towle 1952; Ugent et al. 1986).
Accordingly, substantial evidence exists that a plant resembling P. ahipa or a plant belonging to the Jíquima cultivar group (a morphologically distinct group from coastal Ecuador within the P. tuberosus complex, Sørensen et al. (1997)) was known and cultivated by at least one of the Indian cultures of pre-Columbian South America.
Information in the manuscripts of Oviedo (1535) also confirms the existence of preColumbian cultivation. Although some authors, e.g. Yacovleff and Muelle (1934) and Hawkes (1989), have identified these remains and depictions as belonging to P. tuberosus, the typical growth habit and morphology of the inflorescences and the legumes allow for a positive determination as P. ahipa or the Jíquima in agreement with Ugent et al. (1986). Sauer (1950) mentions the crop as one of the common elements in the cropping systems of the terraced Andean fields of Peru, i.e. none of the three cultivar groups belonging to the P. tuberosus are cultivated at altitudes above 1800 m asl; the Jíquima is a lowland cultivar, whereas the main cultivation of P. ahipa takes place above 2000 m asl.
Ahipa (Pachyrhizus ahipa (Wedd.) Parodi) 3 Origin of the cultivated species and geographical distribution The distribution area of the three cultivated species within Pachyrhizus extends from 21° N in Mexico to 25° S in Bolivia/northern Argentina.
Pachyrhizus ahipa is found sporadically in cultivation in Bolivia and in a few localities in the provinces of Jujuy and Salta in Argentina in subtropical Andean valleys along the eastern side of the range. The latter genotypes probably originate from seeds introduced from the southern part of Bolivia. Bolivian farm labourers working in Argentina recall importing seed material from Bolivia when visiting relatives and the genotypes are of the erect bushy type found in the Bolivian province of Tarija (Parodi 1935; Burkart 1952; Sørensen 1990; Ørting 1996b; Ørting et al. 1996;
Ing. Agr. R. Neuman pers. comm. and pers. observ.). Altitudinal range: fertile subtropical valleys between 1000 and 3000 m asl (Fig. 2).
The only herbarium specimens known to the authors are from the provinces of Sorata and Tarija in Bolivia and Jujuy Argentina. No herbarium specimen of Peruvian origin has been seen nor has any reference to such material been found by the authors.
Today the cultivation of P. ahipa in Peru is either extinct or possibly restricted to a few valleys in the area around Tarapoto (Dr C. Arbizu, pers. comm.); hence, the locating and conserving of any remaining Peruvian germplasm is urgently needed.
There are no records of plants undoubtedly wild, a wild progenitor of P. ahipa has yet to be identified and the geographical origin is still obscure. Brücher (1977,
1989) states that the likely location must have been in the 'ceja de montañas' in the Andean region; however, recently Ing. Agr. J. Rea (pers. comm.) has claimed to have found a wild P. ahipa near Sorata, Bolivia, i.e. the locality where the type specimen was collected by G. Mandon (no. 747, 1856). Nevertheless, until material of this genotype becomes available for morphological and molecular analyses the phylogeny of this species cannot be finally determined. Another possible location where a wild progenitor may be found is the Peruvian valleys of Apurimac, Ene and Mantaro owing to the climatic and edaphic conditions according to Dr D. Debouck (pers. comm.) Not surprisingly the germplasm of Bolivian origin — representing 26 of the 31 available accessions — has been found to have the greatest diversity seen. Even the 13 landraces/primitive cultivars from the two departments of La Paz and Cochabamba possess a remarkable degree of genetic/morphological variation in earliness, growth rate of both vegetative and reproductive shoots and internodal lengths. The single Argentinean landrace/cultivar seen from the northern province of Salta has several distinguishing traits: very short, erect bushy growth and reduced seed set and good tuber growth. The landraces/cultivars of known origin most strongly resembling the Salta cultivar have been collected in the southern Bolivian departments of Tarija (in the village of Carapari) and Chuquisaca (along the Pilaya and Pilcomayo rivers). A thorough survey of the southern Bolivian/northern Argentinean germplasm conducted in 1996 revealed that all germplasm of this area Promoting the conservation and use of underutilized and neglected crops. 21. 25 has determinate growth habit, i.e. P. ahipa landraces with indeterminate growth habit have only been observed in the northern parts of Bolivia (Fig. 2).
4 Properties of the species The developmental stages (V0-R9) of the genus - also applicable to the species P. ahipa (see Fig. 6) - according to Grum (1990) and Sørensen et al. (1993) are presented in Table 1.
Table 1. The developmental stages of Pachyrhizus, based on morphology and physiological changes according to Grum (1990) and Sørensen et al.
4.1 Biological nitrogen fixation Like other members of the legume family, Pachyrhizus has an efficient symbiosis with nitrogen-fixing Rhizobium and Bradyrhizobium bacteria. These bacteria provide the plants with a source of nitrogen and, as a result, there is no requirement for an additional supply of nitrogen fertilizer. In contrast to many of the grain legumes, a substantial amount of the fixed nitrogen is returned to the soil if the vegetative aboveground parts are left in the field. The crop therefore forms an integral part of a sustainable land-use system, both in an ecological sense and from a socioeconomic standpoint. Recent studies (Kjær 1992; Halafihi 1994; Halafihi et al. 1994) have been conducted under both greenhouse and field conditions to examine the efficiency of the biological nitrogen fixation Field collecting of indigenous strains of Rhizobium and Bradyrhizobium was carried out in 1993 in Central and South America. Subsequent isolation of the collected material and evaluation in 1993-94 under greenhouse conditions have been completed in order to select Pachyrhizus genotypes and bacteria strains with high potential for nitrogen fixation (Grum 1997). The emphasis of this research is the improvement of the host plant range, thus providing a simple technology within the reach of the agriculture in developing countries.
Castellanos et al. (1997) conducted the first field test quantifying the actual amount of nitrogen fixed by two accessions of P. ahipa (reproductively pruned and Promoting the conservation and use of underutilized and neglected crops. 21. 27 harvested after 154 days): 58-80 kg N/ha (or 60-76 g N/t biomass per day), and three cultivars of P. erosus (reproductively pruned harvested after 154-168 days): 162-215 kg N/ha (or 84-107 g N/t biomass per day). Approximately 50% of the harvested N, i.e. ±130 kg/ha or close to 800 kg protein/ha (N x 6.25), accumulated in the tuberous root in P. erosus, i.e. a value which equals or outyields the amount of protein harvested in grain legumes. The amount of N in the residue, i.e. hay; of P. erosus was 120-150 kg/ha, twice the amount recorded in the P. ahipa residue. The N amounts recorded in the residue of P. erosus are higher than the quantity recorded in practically all grain legumes (the plant population of both species in the trials was 110 000 plants/ha and the plants were reproductively pruned).
4.2 Chemical composition of the used parts The tuberous root of the Andean yam bean is the only part used. The seeds are not used because of their rotenone/rotenoid content (neither as food nor as insecticide).
The possibility of using the insecticidal compounds will be treated later in this subsection. Here it is enough to mention that the rotenone (and rotenoids) ingredient is not found in toxic amounts in the tuber or in any other part of the plant except for the seeds. Other ingredients of the seed, e.g. protein, starch and fatty acids, have yet to be analyzed.
The current knowledge of the chemical composition of the tuber is based on the analyses of 19 different non-reproductively pruned accessions (6 plants per accession) grown in a trial under greenhouse conditions in Denmark (Ørting 1996a).
The dry matter content ranged from 15% (minimum) to 20% (average) to 30%. In the subsequent analyses the tubers were freeze-dried and ground to meal. From this material 25 samples were selected and analyzed by the reference method for protein (Smith et al. 1985), starch (Krisman 1962; Shannon 1968) and sugar (Dubois et al.
1956). Additional calibration was carried out by Dr W.J. Grüneberg. The estimation of the amylose, i.e. the amylopectin fraction of the starch, was conducted according to Somogyi (1945) and Nelson (1944) (see Table 2). The analyses repeatedly demonstrated that the starch consists of nearly pure amylopectin (96 to 99.9%).
Initially, saccharose, glucose, fructose, mannose, arabinose, xylose, maltose and several malto-oligosaccharides were analyzed separately. Later the analyses of the sugars were reduced to the determination of the total sugar content, saccharose and reducing sugars, in agreement with Somogyi (1945) and Nelson (1944). A determination of the lipid content and composition was not conducted for the abovementioned material, as in preliminary investigations on both protein and lipid the lipid content was found to be below 1% (Dr A. Borcherding, pers. comm.) The tuber flour of all 120 plants (material from the greenhouse trial in Denmark, Ørting 1996a) was screened by using Near-Infrared Analysis (NIRS) (Burns and Ciurczak 1992). The principles of calibration of NIRS-equipment with regard to rapid screening of plant material were described in detail by Tillmann (1996). The P. ahipa NIRS calibration was based on the reference analysis of the abovementioned 25 samples and on available reference calibrations for Vicia faba L. material. The results Ahipa (Pachyrhizus ahipa (Wedd.)Parodi) Table 2. Protein, starch and sugar content (on a dry matter basis) in tuberous roots of 19 P. ahipa and 2 P. tuberosus (Chuin cultivar group) accessions
of these analyses demonstrating the level and the variation in the nutritional composition of Andean yam bean tuber are presented in Table 2. Whether the resulting yam bean calibration may also be used to evaluate large progenies in breeding programmes has yet to be verified in future experiments.
An additional common generic characteristic of Pachyrhizus is the presence of an insecticidal compound called rotenone (C23H22O6). This ingredient is to be found in the mature seeds, but not in toxic amounts in the tuber itself or in any other part of the plant. As is clearly demonstrated in Sørensen (1990,Table 2) practically all studies of the insecticidal compounds and their properties have been conducted on one Promoting the conservation and use of underutilized and neglected crops. 21. 29 species only, P. erosus (until the recent examinations by Lackhan (1994) and Scramin (1994)). Few analyses evaluating the compounds with insecticidal or fungicidal properties in P. ahipa have been conducted so far. The examinations published by Hansberry et al. (1947) included the species P. erosus, ‘P. strigosus’ Clausen (considered conspecific with P. erosus according to Sørensen (1988), P. ahipa and P. tuberosus. This extension of the material analyzed did increase the knowledge of the properties of the genus in general; however, the differences between the species identified by Hansberry and his associates were remarkably few. The recent analyses carried out in Brazil (Scramin 1994) and in Trinidad (Lackhan 1994) both included P. ahipa. These analyses are therefore valuable and will possibly lead to renewed commercial interest in the exploitation of the insecticidal properties of the Andean yam bean.
4.3 Nutritional In the areas of origin the Andean yam bean tuber is regarded as both healthy and nutritious. The brown skin may easily be peeled away, leaving a white (often with purple subepidermal stripes), juicy and crisp flesh. The tuber is always eaten raw and there are no reports on antinutritional factors in the Andean yam bean tuber.
The tubers have a protein content of 8-18% (dry weight) based on recent analysis of 19 accessions, i.e. a high content in comparison with that of traditional root crops (pers. observ.). About 80% of the protein is water-soluble (Dr A. Borcherding, pers.
comm.). No information on the amino acid composition is currently available for the Andean yam bean tuber. However, an amino acid composition similar to that of the Mexican yam bean (= P. erosus) (investigated by Evans et al. (1977)) is to be expected.