Annals of Botany 70 11-17, 1992

Biological Nitrogen Fixation in ahipa (Wedd.) Parodi

S0REN KJ/ER Botanical Section, Department of Botany, Dendrology and Forest Genetics, Royal Veterinary and Agricultural University, Rolighedsvej 23, DK-1958 Frederiksberg C (Copenhagen), Denmark

Accepted 15 January 1992 Downloaded from https://academic.oup.com/aob/article/70/1/11/129022 by guest on 29 September 2021 The patterns of growth and N, fixation capability in (Wedd) Parodi inoculated with Bradyrhuobium ' Pachyrhizus Spec 1' strains (LiphaTech) were investigated in a zero-N culture system under greenhouse conditions The P ahipa plant is day-neutral with respect to reproductive development Competition occurred between the two storage organs (legume and tuber) and prevented high tuber yield in P ahipa The symbiotic effectiveness of the association was high, as the profuse nodulation provided the inoculated with adequate amounts of N Nodules were present throughout the cycle of P ahipa The change in rate of N, fixation (RNF) and relative growth rate (RGR) was almost paraJlel dunng ontogenesis The developmental pattern of N, fixation activity revealed that 65 % of total N, fixation occurred after N began to accumulate in the reproductive (pod wall plus seed) tissue Dunng pod filling allocation of N compounds to the seeds exceeded N, fixation, the pod walls being the pnmary source of redistnbuted N, followed by the leaves

Key words: Pachyrhizus ahipa (Wedd ) Parodi, ahipa, tuber crop, dinitrogen fixation, dry matter and N partitioning, reproductive growth

(1989) observed that in P erosus nodules were present INTRODUCTION through flowering and pod maturation Furthermore, they Leguminous root crops in Third World countries have observed that remobihzation of vegetative tissue N to the received renewed attention as potentially high-yielding root tuber occurred some time after pod maturation The capacity crops of good nutritional value (National Research Council, to sustain a high N, fixation capability dunng pod filling 1979) The tuber-bearing genus Pachyrhizus Rich ex DC may be the cause for these observations (, tnbus ) includes five species native to The objectives of the present study were to investigate the Central America and northern to central South America ontogenetic patterns of growth, N2 fixing capability, and (Serensen, 1988) Unlike the other members of the genus, P mineral N uptake by P ahipa Such information would ahipa is bushy, non-climbing, fast maturing and insensitive provide a basis for investigations on the interspecific hybrid to photopenod (National Research Council, 1989) P ahipa characters of Pachyrhizus spp regarding patterns of growth was known and cultivated by the Incas in pre-Columbian and increased reliance on biologically fixed N in agricultural time according to Yacovleff(1933) and Ugent, Pozorski and plant production Pozorski (1986) The cultivation of P ahipa is very limited today, restricted to Andean valleys in and Peru MATERIALS AND METHODS between 1500 and 2500 m above sea level (Sorensen, 1990) A closely related species, (L ) Urban is P ahipa plants were cultured in greenhouse from 7 Apr to native to Mexico and Central America and has many 21 Oct 1990 at the Royal Veterinary and Agricultural morphological characteristics in common with P ahipa University in Copenhagen Daily maximum and minimum Interspecific breeding between cultivars of P ahipa and P greenhouse air temperature were on average 28 °C and erosus was studied by Serensen (1990) for the stability of 18 °C, respectively The climate computer system was the various genetic characters and valuable agricultural hybrids DGT/Volmatic system LCC1220 The symbiotic association between the legume P erosus Seeds of a uniform size (mean d wt 370 ±20 mg), cultivar and indigenous strains of was investigated AC 102 from Bolivia, were immersed in 70% ethanol with by Vansuyt and Zinsou (1989) The Bradyrhizobium strains 0-01% Tween 20, then surface sterilized by using 3% were infective in vertisols (pH 8 4) and neutral ferralhtic Korsohn (Ferrosan A/S) for 30 min, while the stenlant soils (pH 6 9), but not in acid ferralhtic soils (pH 4 6) The solution was agitated The seeds were nnsed three times in influence of favourable soil fertility on the nodule func- sterilized water and pregerminated in Petn dishes 3—4 d tioning with P erosus as host plant was studied by Lynd and at 25 °C in the dark and transferred to 145 mm diameter Purcino (1987) They found that adequate soil levels of pots Seedlings were thinned to one plantlet per pot 2 weeks phosphorus, calcium and potassium increased nodule mass after sowing and nitrogenase activity considerably Vansuyt and Zinsou Nutrient solutions were prepared with deminerahzed

0305-7364/92/070011 +07 S03 00/0 © 1992 Annals of Botany Company 12 Kjar—Nitrogen Fixation in Pachyrhizus ahipa Downloaded from https://academic.oup.com/aob/article/70/1/11/129022 by guest on 29 September 2021

FIG 1 Development of underground parts in Pachvrhizus ahipa (Wedd ) Parodi plants growing in N-free culture solution with Bradyrhizobium 'Pachyrhizus Spec 1' (LiphaTech) ( —N + I) A, Plantlet growing in N-free culture solution without Bradyrhizobium (treatment — N —I) 20 d after emergence (DAE) Bar = 11-0 mm B, Plantlet showing 'root curling' originating from the infection of roothairs (20 DAE) Bar = 11-Omm C, Apical part of the root showing the profuse nodulation (45 DAE) Bar = 5 5 mm D, Necrosed nodule together with young spherical nodules (85 DAE) Bar = 55 mm E, Indeterminate nodules with terete branches (148 DAE) Bar = 55 mm F, Representative tubers in plants (185 DAE), that may develop to 0-5 kg fresh weight Bar = 27 4 mm water A basal nutnent solution was used containing 1 0 mM solution with mineral N Control plants (designated -N-I) KHjPO4,3 8mMCaSO4 2H2O,0 9 mMMgSO4 7H,O, 1/tM without Bradyrhizobium and exogenous N were cultivated KC1, 54 fiM Fe-III-Na-EDTA, 46 ;tM H,BO3, 12 fm MnSO4, as a reference The pH was adjusted to 6 5 with 01 M K.OH 0 8 fiM ZnSO4, 0 3 /tM CuSO4 and 0 5 /tM Na2MoO4 2H,O On 7 Apr 1990, pregerminated seeds of the —N + I The test plants were grown in three different N regimes N- treatment were inoculated with a peat-based culture control plants received the basal nutnent solution adding containing two Bradyrhizobium strains (120B2 and 120B6) 2 5 mM Ca(NO3)2 and no inoculum (designated +N —I) isolated from P erosus in Thailand (Dr R Stewart Smith, Inoculated plants with Bradyrhizobium 'Pachyrhizus Spec LiphaTech, pers comm ) Each pot received approx I x I08 1' (LiphaTech) were fed with the N-free basal nutnent viable Bradyrhizobia solution (designated -N + I), 2 5 mM CaSO4 2H;O was The +N —I plants were cultured without mineral N till +I added to equalize the Ca concentration of the nutnent 19 d following seedling emergence On 6 May 1990, 19 d Kjcer—Nitrogen Fixation in Pachyrhizus ahipa 13 after seedling emergence (DAE) nodules were observed on to the root was narrow and non-girdling, occasionally the — N + I plants, and the nutrient solution containing clusters of nodules developed Nodules were present and 2 5 CaCNOj);, was added to the +N-I plants active (red colouring by leghaemoglobin) through flowering The artificial growth medium vermiculite (grade 4 and pod setting Senescence of the first developed nodules 3-8 mm) was immersed in nutrient solutions for 48 h The was observed during pod development 85 DAE (Fig 1 D) pots were placed on 05 1 nutrient solution reservoirs, and a The root system of the control plants ( —N —I) developed 7-mm thick and 120-mm long wick made of synthetic extended primary roots without nodules (Fig 1 A) ceramic fibre (Fred Johansen A/S) was provided to obtain Patterns of development The initiation of fertile shoots a capillary nse of the nutrient solution from the reservoir occurred during early vegetative growth (fourth trifoliate The reservoirs were covered with non-transparent white leaf) After floral initiation, a rapid formation of leaves polyethylene to exclude light Autoclaved coarse granite occurred during the development of inflorescences, which gravel serving as a biological barrier was used to cover the led to the accumulation of leaf and stem matter until the growth medium to a depth of 20 mm The nutrient solution beginning of pod setting (Fig 2 A, B) Anthesis was lengthy reservoirs were adjusted daily to 0 5 1 capacity During plant (6 weeks), characterized by a high abscission-rate of flower Downloaded from https://academic.oup.com/aob/article/70/1/11/129022 by guest on 29 September 2021 growth pots were spread to minimize canopy interference buds, flowers and immature pods Tubenzation appeared to The pots were arranged in a completely randomized be initiated during flowering The active tuber growth was design Eight replicate pots of the treatments ( + N —I and delayed till after pod dryness, due to the 'strong sink' of the — N + I) were sampled on five occasions during the first 71 d pods During pod development disintegration of nodules after emergence (DAE), and four replications of the treatments ( + N-I and —N + I) were sampled from 85 (A) DAE to 185 DAE on six occasions, le a total of 11 70 samplings during the experiment The reference — N —I were sampled on seven occasions till 99 DAE The leaf area 60 of the plants was determined in all 11 samplings The leaf area ot the leaflets was measured by an area meter (Model 50 Li-3000) Plants were separated into root, nodules, tuber, stem, leaves, pod wall and seed The dry matter content of the various plant parts was £ 40 determined by drying samples at 80 °C in a well-aerated CL oven for 20-48 h until constant weight was attained The 30 dried material was finely ground and total N content was Q determined by a micro Kjeldahl digestion with subsequent o 20 colonmetnc NH4-N determination by the phenol-hypo- chlonte method (Hinds and Lowe, 1980) 10 The relative growth rate (RGR), rate of N2 fixation (RNF) and rate of N assimilation in the reproductive tissue 0 (RNA-reprod ) were calculated as 100 V//A VA VA VA VA V/\ V A V

where qy and qt were the experimental values (total plant gS weight, total plant N, reproductive tissue N) at harvest " times /, and tt, respectively All data of the treatments o 60 ( + N-I and -N + I) are means of eight (20-71 DAE) and "o four (85-185 DAE) replicates, respectively The standard o error of the mean is indicated ±s e f 40 o Q. O I RESULTS 20 General observations _ Nodulation The number of days from inoculation to formation of nodules was approx 30 d, due to a slow rate 20 34 45 57 71 85 99 121 134 148 185 of germination and development of the crop Nodules were Days after emergence initially formed near the apical portion of the roots and FIG 2 Growth analysis of Pachyrhizus ahipa (Wedd) Parodi plants mainly on the primary roots (Fig 1 B, C) As the root growing in N-free culture inoculated with Bradyrhizobium ' Pachy- system developed, nodules appeared on lateral roots Having rhizus Spec 1'strains (LiphaTech)(-N + I) A, Total dry matter (DM) per plant, B, Dry matter partitioning Data represent the mean of persistent menstems the growth habit of the nodules was eight replicates (20-71 DAE) and four replicates (85-185 DAE) Mean indeterminate The nodule shape was spherical when young, se = 12% Arrows indicate the period of anthesis (g) Root, (Bj) later terete branches developed (Fig 1 E) The attachment nodules, (0) tuber, (B) stem, (B) leaves, (0) pod wall plus seed 14 Kjcer—Nitrogen Fixation in Pachyrhizus ahipa TABLE 1 Development of nodules in Pachyrhizus ahipa {Wedd) Parodi plants inoculated with Bradyrhizobium Pachyrhizus Spec V (LiphaTech) {-N +1) Data represent the mean + s e with eight replicates 20-71 d after emergence (DAE) and four replicates 85-185 DAE

Nodule dry matter (DM) and total N

'S after % of total rgence DM(g) N(mg) plant N

34 CM5±O-O2 10-2±l 0 15 45 0-37±0-O4 28 3±3 8 19 57 0-66 ±0-08 583±68 16

71 0 83 ±0-07 585±5-O 13 Downloaded from https://academic.oup.com/aob/article/70/1/11/129022 by guest on 29 September 2021 85 1 26±0-17 95 1 ±93 12 99 1 16±OO3 79 1 ± 1 8 8 121 0-80 ±0 24 49 6 ± 15 8 5 134 1 12±0-O6 71 9±32 6 148 l-O3±O17 734±148 5 185 0 66±0-09 524±77 3

3000

20 34 45 57 85 99 121 134 148 185 0 20 40 60 80 100 120 140 160 180 200 Days after emergence Days after emergence FIG 3 Growth analysis of Pachyrhizus ahipa (Wedd) Parodi plants FIG 4 Leaf area development of Pachyrhizus ahipa (Wedd) Parodi growing in N-free culture with Bradyrhizobium ' Pachyrhizus Spec 1' plants growing in N-free culture with Bradyrhizobium 'Pachyrhizus strains (LiphaTech) ( —N + I) A, Total nitrogen (N) per plant, B, N Spec 1' (LiphaTech) (-N + I) (A-A) Data represent the mean of partitioning Data represent the mean of eight replicates (20-71 DAE) eight replicates (20-71 DAE) and four replicates (85-185 DAE) Mean and four replicates (85-185 DAE) Mean s e =13% Arrows indicate s e were between 2 and 20 % Arrows indicate the period of anthesis the period of anthesis Symbols as in Fig 2

and the dry matter content was 16% The nitrogen content and leaf senescence were observed The cycle of the plant was 0-8 % on a d wt basis, and the crude protein content was not completed after pod dryness, as the shoots remained was 5% (6 25xN) still functional, a second floral initiation occurred and the The nodule mass increased till early pod setting, 85 DAE active tuber growth started P ahipa is generally single (Table 1) At the initiation of anthesis (45 DAE) nodules tuberous, but may produce several tubers per plant The made up 19% of total N and 9% of the total dry matter epidermal cortex of the tubers is smooth and grayish- The nodule fraction of total N and total dry matter was brown The tubers are usually plump and elongated in reduced to 3 and 1%, respectively, at final harvest (185 shape (Fig 1 F) DAE) The leaves made up 45 % of the total dry matter and 53 % of the total N at anthesis (Figs 2B and 3B) During anthesis Growth of P ahipa inoculated with Bradyrhizobium and pod setting (45-99 DAE) the total dry matter and total The growth of P ahipa plants inoculated with Brady- N of the leaves were reduced to 12 and 20%, respectively reached a maximum at 99 DAE (40 ± 2 g dry Total N in the leaves constituted an increasing part during matter) (Fig 2 A) Dry matter accumulation resumed and the final reproductive growth (121-185 DAE) The leaf area the dry matter amounted to 68 ± 9 g per plant at the final reached a maximum of 2000 cm2 at the beginning of pod harvest, of which 38±4 g was found in the reproductive setting 85 DAE (Fig 4) At pod filling leaf senescence tissue The mean fresh tuber yield was 67 ± 12 g per plant started and the leaf area decreased by approx 30% to Kjcer—Nitrogen Fixation in Pachyrhizus ahipa 15

6

20 40 60 80 100 120 140 160 180 200 Downloaded from https://academic.oup.com/aob/article/70/1/11/129022 by guest on 29 September 2021 Days after emergence FIG 6 Comparison of leaf matter nitrogen (N) between the treat- ments of Pachyrhizus ahipa (Wedd ) Parodi plants — N +1, growing in N-free culture with Bradyrhizobium 'Pachyrhizus Spec 1' (LiphaTech) (A-A), +N — I, fertilized with 5 mM nitrate without Bradyrhizobium (D-D), —N —I, growing in N-free culture without Bradyrhizobium, I e control (V-V) Data represent the mean of eight replicates (34-71 DAE) and four replicates (85-185 DAE) Data of the -N-I treatment are single observations

62% of the accumulated total N and 56% of the accumulated total dry matter The relative growth rate (RGR) and the rate of N2 fixation (RNF) changed almost in parallel dunng on- togenesis (Fig 5A) The relative N allocation rate to -0 02 0 20 40 60 80 100 120 140 160 180 200 reproductive tissue (RNA-reprod) dunng pod setting Doys after emergence (56-99 DAE) was faster than RNF in the whole plant, I e N FIG 5 Growth analysis of Pachyrhizus ahipa (Wedd ) Parodi plants was mobilized from vegetative organs to the reproductive growing in N-free culture with Bradyrhizobium 'Pachyrhizus Spec 1' tissue (Fig 5B) The concentration of N in the leaves (LiphaTech) (-N + I) A, Relative growth rate (RGR) (——) and declined from 4 9 to 3 6% dunng pod filling (71-121 DAE) rate of N, fixation (RNF) ( ), B, Rate of N, fixation (RNF) ( ) (Fig 6) The leaf area was reduced by approx 30 % dunng and the rate of N assimilation in the reproductive tissue (RNA- pod filling and the N content of the vegetative organs reprod) ( ) Data represent the mean of eight replicates (20'—71 DAE) and four replicates (85-185 DAE) Arrows indicate the period declined from 300 to 200 mg N of anthesis

Symbiotic Nt fixation 1350 cm2 per plant After pod dryness the shoot growth As culture conditions were essentially N-free, whole plant resumed, and at the final harvest 185 DAE the leaf area was N accumulation was a direct indication of the symbiotic N2 2350 cm2 fixation About 9% of the total N, fixation took place P ahipa produced one or several tubers per plant The dunng preflowenng (0-45 DAE), 40 % dunng the 6 weeks of tuber initiation occurred in secondary thickened roots, flowenng (45-85 DAE), 65% dunng the 11 weeks of pod where the activities from anomalous cambia may be development (57-148 DAE) and 12 % dunng the 5 weeks of responsible for the growth of the mature tuber as in P active tuber growth (148-185 DAE) erosus (Dabydeen and Sirju-Charran, 1990) The active The rate of N, fixation increased rapidly reaching a tuber growth started after pod dryness The tuber dry maximum from the third to sixth week after seedling matter accounted for 16% of the total dry matter and 6% emergence (Fig 5 A) This was also the time of maximum of the total N at the final harvest 185 DAE (Figs 2B and RGR and rapidly increasing leaf area (Fig 4) At the 3B) initiation of pod setting, 56 DAE, there was a steep decrease The accumulation of dry matter and total N in the in the rate of N8 fixation, but dunng the later stages of pod reproductive tissues were slow dunng the first four weeks of setting N2 fixation resumed The rapid allocation of anthesis (Figs 2 and 3) The penod of rapid increase in nitrogenous compounds to the seeds induced leaf senescence reproductive tissue dry matter and total N was quite short in the subtending leaves of the pods, and reduced the N2 (71-99 DAE) The reproductive tissue made up 70% of the fixation to a minimum After pod dryness the reduction in total dry matter and 64 % of the total N 99 DAE At the the rate of N, fixation was probably due to diminishing final harvest 185 DAE the reproductive tissue contained radiant energy 16 Kjcer—Nitrogen Fixation in Pachyrhizus ahipa

DISCUSSION In agreement with Serensen (1990), P ahipa plants were day-neutral The storage sink of the reproductive tissue competed immediately with the aenal parts, as the allocation of assimilates to the vegetative tissue decreased dunng anthesis and early pod development Dunng reproductive growth the dry matter and N accumulation were controlled

Q by the development of the reproductive tissue, which served as an active sink The active tuber growth was delayed till after pod dryness in agreement with observations in P erosus (Zinsou and Venthou-Dumaine, 1988) After fruit maturation tuber growth resumed The competition between

the two storage organs (legume and tuber) prevented high Downloaded from https://academic.oup.com/aob/article/70/1/11/129022 by guest on 29 September 2021 20 40 60 80 100 120 140 160 180 200 tuber yield in P ahipa Studies earned out dunng short day Days after emergence conditions (Zinsou and Venthou-Dumaine, 1988, Paull, FIG 7 Comparison of the accumulation of dry matter (DM) between Chen and Fukuda, 1988) reported the active tuber growth in treatments of Pachyrhizus ahipa (Wedd) Parodi plants —N + l, growing in N-free culture with Bradyrhizobium ' Pachyrhizus Spec I' P erosus to be under control of the flowenng process The (LiphaTech) (A-A)> +N —I, fertilized with 5 mM nitrate without active tuber growth in P erosus started (4-6 weeks after Bradyrhizobium (•—•). —N —I, growing in N-free culture without sowing) dunng early anthesis Once P erosus was induced Bradvrhizobium, l e control (V-V) Data represent the mean of eight to develop tubers and flowers, vegetative growth ceased replicates (20-71 DAE) and four replicates (85-185 DAE) Data of the treatment —N —I are single observations Mean s e = 11 % Flower removal ensures continued tuber development in P ahipa and P erosus Throughout the Mexican Baji'o region, flowers are removed by hand to encourage the development of large and sweet tubers in P erosus (Heredia, 2000 1985) This practice improves the quality and doubles the tuber yields of P erosus (Heredia, 1985) Field tnals in Tonga with P ahipa accessions revealed its potential as a 1500 - high yielding root crop (M Grum, pers comm ) When the fertile shoots were removed by hand, fresh tuber yields of P ahipa increased substantially According to Zinsou, Venthou-Dumaine and Vansuyt (1987) foliar applications 1000 with 50 ppm gibberellic acid (GAJ may triple tuber yields in P erosus by partial or total inhibition of the reproductive development 500 The developmental pattern of N, fixation activity between P ahipa and Bradyrhizobium 'Pachyrhizus Spec 1' strains revealed the following (1) high rates of N2 fixation till 0 20 40 60 80 100 120 140 160 180 200 anthesis, (2) declining N2 fixation dunng pod setting, (3) Days after emergence rates of N, fixation were reduced to zero dunng pod filling, FIG 8 Comparison of nitrogen (N) accumulation between treatments (4) plant growth and N, fixation resumed after pod dryness of Pachyrhizus ahipa (Wedd ) Parodi plants — N + I, growing in N- The decline in the rate of N, fixation is often associated with free culture with Bradyrhizobium ' Pachyrhizus Spec 1' (LiphaTech) the competitive demands of reproductive tissue for photo- (A-A), +N — I, fertilized with 5 mM nitrate without Bradyrhizobium synthates, as they restnet the carbohydrate supply to the (D-D). —N —I, growing in N-free culture without Bradyrhizobium, nodules (Herndge and Pate, 1977) In contrast, Fujita, I e control (V-V) Data represent the mean of eight replicates (20-71 DAE) and four replicates (85-185 DAE) Mean se = 12% Data of Masuda and Ogata (1988) inferred that the rates of N£ the — N —I treatment are single observations fixation of Glycine max (L ) Merr were controlled by the export rate of the fixed-N from nodules, and not by the status of the photosynthate supply to the nodules The strong sink of the reproductive tissue appeared to be the Symbiotic effectiveness most important factor regulating the rates of N2 fixation of Theoretically, P ahipa plants fertilized with optimum P ahipa levels of N will provide a measure of the potential growth P ahipa maintained the N, fixation capability to supply under the actual experimental conditions (Gibson, 1980) A adequate amounts of N to plant growth and storage organs, comparison of the inoculated plants (—N + I) with the N except dunng the penod of most rapid allocation of N to the fertilized plants ( + N — I) showed no significant difference in seeds In this phase the allocation of nitrogenous compounds the accumulation of dry matter dunng ontogenesis (Fig 7) to the seeds exceeded N, fixation (Fig 5B) As a Dunng anthesis and pod setting (34-99 DAE), P ahipa consequence, redistnbution of N occurred dunng pod plants fertilized with 5 mM nitrate accumulated significantly filling, the pod walls being the primary source of redistn- (P < 0 05) less N than plants with Bradyrhizobium (Fig 8) buted N followed by the leaves (Fig 9) Kjcer—Nitrogen Fixation in Pachyrhizus ahipa 17

1200 Fujita K, Masuda T, Ogata S 1988 Dinitrogen fixation, ureide concentration in xylem exudate and translocation of photo- synthates in soybean as influenced by pod removal and defoliation 1000 - Soil Science and Plant Nutrition 34 265-275 Gibson AH. 1980. Methods for legumes in glasshouses and controlled E 800 - environment cabinets In Bergersen FJ,ed Methods for evaluating biological nitrogen fixation Chichester John Wiley, 139-184 Heredia ZA. 1985. Guia para cultivar jicama en el Bajio Follelo para 600 - Productores 15 Mexico Secrctana de Agriculture y Recursus Hidraulicos, 1-11 Herridge DF, Pate JS. 1977 Utilization of net photosynthate for £ "00 - nitrogen fixation and protein production in an annual legume Plant Phvsiologv 60 759-764 200 - Hinds AA, Lowe LE. 1980. Application of the Berthelot reaction to the determination of ammonium-N in soil extracts and soil digests Communications in Soil Science and Plant Analysis 11 469-475 Lynd JQ, Purcino AAC 1987. Effects of soil fertility on growth, tuber Downloaded from https://academic.oup.com/aob/article/70/1/11/129022 by guest on 29 September 2021 20 40 60 80 100 120 140 160 180 200 yield, nodulation and nitrogen fixation of yam bean (Pachvrhizus Days after emergence erosus (L) Urban) grown on a typic eutrustox Journal of Plant FIG 9 Redistribution of nitrogen (N) fr°m pod wall to seed in Nutrition 10 485-500 Pachyrhizus ahipa (Wedd ) Parodi plants growing in N-free culture with National Research Council. 1979. 1 Root Crops Yam Bean In Bradyrhizobium 'Pachyrhizus Spec 1' (LiphaTech) ( —N + I) Repro- Tropical Legumes resources for the future Washington, DC ductive tissue (pod wall + seed) (A-A) and pod wall (V-V) Data National Academy Press, 21-27 represent the mean of eight replicates (45-71 DAE) and four replicates National Research Council 1989. Ahipa In Lost crops of the Incas (85-185 DAE) Mean se =12% little-known plants of the Andes with promise for worldwide cultivation. Washington, DC National Academy Press, 38—45 Paull RE, Chen NJ, Fukuda SK. 1988. Planting dates related to The symbiotic efficiency of the association between P tuberous root yield, vine length, and quality attributes of yam bean HorlScience 23 326-329 ahipa and Bradyrhizobium ' Pachyrhizus Spec 1' was high, Sercnsen M. 1988. A taxonomic revision of the genus Pachvrhizus as the profuse nodulation provided the plant with adequate (Fabaceae-Phaseoleae) Nordic Journal of Botany 8 167-192 amounts of N The dry matter production and N ac- Serensen M. 1990. Observations on distribution, ecology and cultivation cumulation of symbiotic dependent plants ( — N + I) and of the tuber-beanng legume genus Pachvrhizus Rich ex DC plants relying on exogenous N ( + N —I) were of the same Wagemngen Agricultural University Papers 90 1-38 Ugent D, Pozorski S, Pozorski T 1986. Archaeological manioc magnitude (Mamhot) from Coastal Peru Economic Botany 40 78-102 Vansuyt G, Zinsou C 1989 Preliminary investigations on indigenous strains or Rhizobium nodulating yam bean (Pachvrhizus erosus ACKNOWLEDGEMENTS Urban) in Guadeloupe In Degras L, ed Proceedings of the 25th Caribbean Food Crops Societv Meeting, Guadeloupe, 2-8 July The skilled technical assistance of Mrs M Rappold is 1989 Publication INRA Antilles-Suyane, 497-507 gratefully acknowledged as are Drs M Serensen, E S Yacovleff E. 1933. La jiquima, raiz comestible extinguida en el Peru Jensen and J K. Schjornng for fruitful discussions and Revista Museo Nacional 2 51—66 critical reading of the manuscript Zinsou C, Ventbou-Dumaine A. 1988 Effects of different sowing dates on the growth and development of yam bean (Pachyrhizus erosus Urban) In Proceedings of the 24th Caribbean Food Crops Society, Jamaica, 15-20 August 1988 LITERATURE CITED Zinsou C, Ventnou-Dumaine A, Vansuyt G. 1987. Croissance et Dabydeen S, Sirju-Cbarran G. 1990 The development anatomy of the developpement du Pachyrhizus erosus (Urban) 1 Effets de l'acide root system in yam bean, Pachvrhizus erosus Urban Annals of gibberellique et du chlorure de chlorocholine en jours courts Botany 66 313-320 Agronomie 7 677-683 Downloaded from https://academic.oup.com/aob/article/70/1/11/129022 by guest on 29 September 2021