There is large variation among cultivars of groundnut in ability to nodulatc and fix nitrogen (N), and in seasonal and diurnal patterns of nitrogenase activity. Total N uptake, or total dry matter production, may be a useful index in ranking cultivan for N2-fixing ability.

Certain cultivars of Arachis hypogaea ssp. hypogaea var.

bpogaea formed up to 13% of their total nodule number on the

hypocotyl, and some cultivars even nodulated on the stem above the crown of the plant. In contrast, cultivars from A. hypogaea ssp. fastigiata var. fasrigiata and var. vulgaris formed few nodules on the. hypocotyl. Non-nodulating plants have been observed in 13 crosses. Genetic analysis indicates that two independent recessive genes are involved. Some progeny of these crosses also form a few big nodules, a trait which seems to be controlled by the host plant

Dart, P J

Gibbons, R W

Nambiar, P T C

Nigam, S N

ICRISAT Open Access Repository

Transgressive segrcgatiotl was observed for all the characteristics studied among the 16 lines of ). 3 plants grown in the field. The ranges in values of the characters studied f'or the parents and the F plants are shown in Table I .  Most of the segregates flowered 2 days earlier than their parents except line 9, which took 40 days to t'lower, as did 'Bossier'. Lines 4,6,9, and I 1  were shorttr in stature than 'Bossier', and all of them had lowtt seed yields than their parents. Among them, lines 9 and I 1  had less nodulation (nodule mass between 2 and 3 mg/ plant) and low nitrogenase activity (2.2~1 mol C2H4 produced /plant per h), while line 6 showed extensive nodulation (191 mg nodule tissue/ plant) and moderate to high nitrogenase activity (7.32 u mol Iq produced! plant per h ). Two lines (Nos. 3 and 16) showed both high yierd and good N21'ixation (see Table I). Given the promising nature of these results additional crosses between cvs. Bossier and IH 92 have been made and are being advanced to the F3 generation for detailed testing of both agronomic traits and ability to fix N2. With the high cost of' fertilizer N to countries such as Tanzania, it is imperative that luture soybean breeding programs consider BNF as a prime criterion in the development and selection of new cultivars. REFERENCES Auckland. A.  K .  ( 1970) Soya bean improvement in East Africa. In: Cropimprovement in East Africa. C. 1,. A. 1-eakey (Ed.). Commonwealth Agricultural Bureaux, England. Pp. 1 29- 1 56. Chowdhury. M.S. (1977) Response of soybean to Rhizobium inoculation at Moroporo. 7'an;liinia. 1tt: Biological nitrogen fixation in farming systems of the tropics. Ayanaha and P.J. Dart (Eds.). Wiley, New York, NY, USA. Pp. 245- 253. .ue, T.A. (Fd.)  ( 1978) Selecting and breeding legumes for enhanced nitrogen ' fixation. Prcr. workshop, Boyce Thompson Institute, Cornell Univ., Ithaca, NY. USA. Mrnbap, E.T. ( 1975) Highlights of soybean production in Tanzania. In: Soybean production. protection and utilization, D.K. Whigham (Ed.). INTSOY Series, No. 6. Univ. ol' Illinois, Urbana, IL, USA. Pp. 252-255. Sachansky. S. ( 1977) 7i.(h). Grain Legume &11. 7, 15-17. BNF Techno1og.y for Tropical Agriculture GENETIC MANIPULATION OF NODULATION IN GROUNDNUT P.T.C. Nunbiu, P.J. Dart, S.N. Nitam and R.W. Gibbons' Summary There is large variation among cultivars of groundnut in ability to nodulatc and fix nitrogen (N), and in seasonal and diurnal patterns of nitrogenase activity. Total N uptake, or total dry matter production, may be a useful index in ranking cultivan for N2-fixing ability. Certain cultivars of Arachis hypogaea ssp. hypogaea var. bpogaea formed up to 13% of their total nodule number on the hypocotyl, and some cultivars even nodulated on the stem above the crown of the plant. In contrast, cultivars from A. hypogaea ssp. fastigiata var. fasrigiata and var. vulgaris formed few nodules on the. hypocotyl. Non-nodulating plants have been observed in 13 crosses. Genetic analysis indicates that two independent recessive genes are involved. Some progeny of these crosses also form a few big nodules, a trait which seems to be controlled by the host plant. INTRODUCTION The number of nodules formed by legumes, and their effectiveness, is governed by both plant and Rhizobium genes, with large differences in nodulation and nitrogen (N2) fixation already reported for cuitivars of soybean (Vorhees, 1915). peas (Holl & LaRue, 1976) cowpea (Zary, et al., 1978) and groundnut (Wynne, Elkan & Schneeweis, 1980; Nambiar & Dart, 1980). I t  may be possible to increase N2 fixation in legumes by genetic manipulation. This paper summarizes our efforts to establish genotypic differences in N2 fixation among groundnut cultivars and understand the genetics of non-nodulation in groundnut. -ck I CP No. S d ~ 1 ~ ~ 1 ~ ~ ~ ~ u t a n c h e r u .  .) P. 0.  Andm Pradtilh SO2 324, India BOTANICAL VAHlATION IN ARACHIS H YPOGAEA L. The genus A ruchis belongs to the tribe Aeschynomeneae (Leguminosae, subtribe, Papilionoideae) with 22 described and possibly 40 undescribed species (Gregory, Krapovickas & Gregory, 1980). There is a great diversity within the genus. For example plant type varies from upright forms to prost rate types with runners, and the growing period required extends from short-duration annual to perennial. The cultivated groundnut, A. hypoguea, is an annual tetraploid (4n = 40). Based on morphology, the species is subdivided into subspecies hypogaea, which includes var. hypogaea, and var. hirsuta, and subspecies fastigiata which includes var. fastigiata and var. tlgaris (Krapovickas, 1973). The hypogaea ssp. includes longduration, ternately branched "Virginia types," mostly with runner and spreading bunch growth habits while the fastigiata ssp. includes short-duration, sequentially branched types mainly with an upright branch habit, the "Spanish" and "Valencia types." The cultivated groundnut is grown throughout the tropics and subtropics between latitudes 40°N and 40°S, where rainfall during the growing season exceeds 500 mm. The crop grows best in well-drained, sandy loams, and tolerates air temperatures between 20°C and 40°C. The crop duration varies with the location and season of cultivation - the Spanish and Valencia types normally mature 90 to 1 10 days after planting, while the Virginia types mature 130 to 150 days after planting. VARIATION IN N2 FIXATION AMONG GROUNDNUT CULTIVARS NZ fixation in groundnut is closely related to photosynthesis (Nambiar & Dart, 1980). Figure I shows seasonal variation in hi2 fixation among nine groundnut cultivars. In general, the Virginia types ('Florunner', MK 374, 'Florigiant', M 13, and 'Kadiri 7 1-1') formed more nodules and fixed more N2 n the Valeacia ('Ganpapuri', MH 2, and PI 59747) and Spanish (Ah 8189) ss. A similar trend was o bsertred in field experiments in North Carolina by ~ i n n t  e  (11. (1980). In all the cultivars, N2 fixation started at around 25-30 days after planting with signxicant genotypic differences apparent by 30days, and with 00 interaction between sampling date and cultivar ranking until after 50 days, a time that generally corresponds to early pod frliing. Cultivar difference6 in pod filling and partitioning also become evident at this growth stage (McCloud et a/., 1980), and in turn affect energy supply to the nodules. This rn4y explain the cultivar x sampling-time interaction for nitrogcnase activity per plant that could be observed from the fourth sampling on. In most cu4tivan nodule senescence started during this stage of plant growth, along with @ ~cclinc in N2 fixation per plant. Fiftywjwa selected germplasm Lines were scrmntd u co three seasons (1977- 1979) for nodulation and N2 fixation using the eoetyltne reduction arsay Figure I .  Nitrogenase activity per plant of selected groundnut cult ivars during the. post-rainy season. 1980. Virginia cv. M K 374 is M K-374 T Gangapuri J M-13 r: Kadiri 7 1-1 PI 259747 A Days after planting . MK-374 Florunnrr Florigiant A A r g r n t ~ n r  L , 1 - * - .J presented in both figures lor 20 40 60 xo  roo 120 comparison. Days after p l an t~ng  (Dart, Day & Harris, 1972). Plants were sampled 20-25 days after flowering. The data was analyzed by the Scott-Knot method (Gates & Bilbro, 1978) and the clusters formed were grouped as high, medium, or low in BNF traits (see Table 1). Three- to five-fold differences in nodulation and N2 (C2H2) reduction were observed among these groundnut genotypes. A Virginia type, N C  Ac 282 1, ranked high over three tests and a Valencia type, NC Ac 2654, ranked high during two tests, while a Spanish type Ah 3275, was clustered as low during four tests. Crosses have been made between the cultivars of the high and low groups in order to estimate the heritability of N2 fixation in groundnuts. Wyne et al. (1980) reported high heritability for such traits in 30 F4 lines derived from a cross between cv. 922 (Spanish) and cv. NC 6 (Virginia) in fields at Raleigh. However they observed that correlations between p a r e d  and general combining ability effects for N2 fixation were nonsignificant for progenies of a diallel cross grown in the glasshouse, indica~irc that rimplc evaluation of lints for capacity to fix N2 may not I b r .  identdh ,urrcrior Dartnts for use in breeding Dromrm (Isleib et al., 1 M ) .  TABLE 1 : Variatio~i n the noduktion and N2 (C2H2) fixation of groundnut cultivus over three seasons of testing. N o d u -  N1a% N o ~ u -  N l w  NO&- N l ~  No&- N,w  b l ion lation h t  ion h t h  Ah 3277 Ah 3275 N o .  42 1 19 1 44 I-\ AC 888 Ah 61 Ah 3272 N o .  3527 Faupur-1-5 No. 418 N C  Ac 1337 NC Ac 5 16 NC Ac 945 NC Ac 699 148-74-3-1 2-ti No. 1780 N C  As 738 TC; 17 No. 3270 NC Ac 5 1 TG 8 Ah 42 N C  Ac 265 1 NC Ac 1 0 2  NC Ac 524 CAUC l NC Ac 2734 NC Ac 495 Spancrou NC A r  1286 NC Ac 17149 Ah  1069 ffidiri 71.1 19 2600 Sl'""lsh bpanld  V Y I C ~ U  Spanish Spanish Spanish Sprnlsh Spanist~ Sprnuh Spanuh Spanish Valcncia Vrlenc~a V d r n c v  Span~sh Span~sh Spanish Valencu Span~sh S p r n i l  Valenc~a Vdcncu Valcncm Spanish Valrncu Vdencu Spanish Valencu Spanish Spanish Vdcncia Vdencia Spanish Virginia SprniJI Virginia Sprnirh sprnirh Spanish Valencia spmish spuridr spuridr Vi-n sprn* splnirh sp.nirh Spanish VlkafiB Sp.nhh v- V U  Groundnut shows a marked diurnal periodicity in C2H 2 reduction (Nambiar & Dart, 1980). A preliminary survey of nitrogenase activity in 14 groundnut lines selected for differences in foliage production, showed a significant interaction between lines and time of measurement of nitrogenase activity. This suggests that, if cultivars with less diurnal variability in N2 fixation can be found, they may have larger overall daily fixation. There are difficulties in relating the nodulation and N2 fixation scores of groundnut lines obtained from sampling at a particular stage of the growth cycle to their overall seasonal activity. Moreover, such methods are destructive and. hence, not useful for examining early generation populations in a breeding program. An alternate method is to use the total N uptake of the crop at harvest as an indication of N2 fixation. Nitrogenase activity through the season and total N2 uptake by two cultivars grown at ICRISAT are shown in Figure 2 and Table 2. Cv. Kadiri 71-1, a Virginia runner, nodulated better and fixed more N2 than the dwarf Valencia-type cv. MH 2. The differences in N2 fixation rates are not reflected in the pod yield, but are evident in the total dry matter produced, and total N harvested. 0Kadir1 71-1 1 0 ,  c M H - 2  - - Post-rainy season -Rainy season ?,, 80 - * C 9 m . .' 60 '. 1 .* b1 rr , U 40,- - % Figure 2. Nitrogenase activity a 2 0 -  per plant of the cv. Kadiri 7 1- 1 I and  cv. M H 2 during the  post- I l - - - L  ---1 I . _ _ _ _ I d  rainy and  the  1980 rainy 40 80 120 seasons. Davs after planting TABLE 2: Dry matterproduction bycvs.Kadiri71-1 andMH2 duringpost- rainy season. Cultivars Pod weight Top weight Total dry Harvest N index @e/ha) (kg/ha) matter (kg ~+=d/kg tops) (kgFPi-da~) Kadiri 7 1 -1 2426 4103 43 MH 3db 1833 1041 24 t h  HYPOCOTYL AND STEM NODULATION Host genotype and Khizobium strain have been shown to influence the distribution of nodules in legumes (Caldwell, 1966). In groundnut, cultivars belonging to the botanical variety hypogaea form more nodules in the hypocotyl region than do those from var. fastigiata and var. vulgaris. Nodules on the hypocotyl of var. hypogaea accounted for 13.4% of the total number of' nodules per plant while in the other botanical groups they only accounted for 0.5- I .O%. These hypocotyl nodules form 40-60 days after planting and only develop when the soil around the hypocotyl is moist. Some rllltivars such as cv. MK 374 (var. hypogaea) also nodulate on the stem. ing the pod filling stage the nodules on the hypocotyl and stem remained plnK while many nodules on the roots turned green, indicating senescence. Selecting for these traits in breeding material might increase N2 fixation during the pod filling and maturation stages. GENETICS OF NODULATION Host plants unable to form nodules have been observed in soybeans and peas (Williams & Lynch, 1954; Holl & LaRue, 1976). Recently Gorbert & Burton (1979) reported non-nodulating lines of Arachis hypogaea in the progenies of a cross 487A- 1-1-2 x PI 262090. Non-nodulating groundnut lines have also been reported from Georgia (R.O. Hammons, personal communication). During the 1978 rainy season, F2 progenies from three crosses in the rust screening nursery at ICRISAT segregated for non- nodulation. All the parents of the crosses nodulated normally. Later, during the rainy season 1979, non-nodulating lines were found in 10 additional crosses (see Table 3). Genetic analysis for nod ulation vs. non-nodulation showed that a pair of independent, recessive genes control non-nodulation (Nigam et al., 1980). It ~teresting to note that one of the parents in most of the crosses is a rust- resistant Valencia cultivar - either cv. PI 259747, cv. NC Ac 17090, or cv. EC 76446 (292). Any of these parents crossed with cultivars NC 17, Shantung Ku No. 203, or NC Ac 2731, always segregated for non-nodulation, but cv. PI 259747 crossed with cv, NC Ac 17090 or cv. EC 76446 (292) did not produce non-nodulating plants in the F2 generation, nor did cv. NC Ac 2731 when crossed with cv. Shantyng Ku No. 203. This indicates that one set of genes for non-runfkbtion in present in cvs. PI 259747, NC Ac 17090, and EC 76447 (292) @,another set in cvs. NC 17, Santung Ku No. 203 and NC Ac 2731. S.gn@ ~ ~ d u i a t i n g  segregants formed only a few nodules, which were much h r ~ r  $48 '  those formed by either parents or the normally nodulating F2 pla$s:~k character is not stabk genetically. For example, a p h t  with three big h n o d ~ i a  in the FS generation segregated in the F6 pa&raon into normal 9oc#ibi&u, , .  non-nodulating and "big nodulew types. Rhitobium isolates from TABLE 3: Crosses producing pmgeny that fail t o  nodulate. Shantung Ku No. 203 x NC Ac 1 7 142 NC Ac 273 1 x NC Ac 17090 NC Ac 273 1 x EC 76446 (292) t$C Ac 2768 x NC Ac 17090 NC 17 x NC Ac 17090. Shantung Ku No. 203 x NC Ac 17090 Shantung Ku No. 203 x EC 76446 (292) Shantung Ku No. 203 x PI 259747 NC 17 x EC 76446 (292) NC-Fla-14 x NC Ac 1 7090 RS-I 14 x NC AC 17090 NC 17 x PI 259747 NC Ac 2731 x PI 259747 the big nodule type formed normal nodules on the parent plants under sterile conditions. Moreover. big nodule segregants were observed in F2 populations grown in controlled conditions and inoculated with a single strain that forms normal nodules on the parents. These observations indicate that the big nodule trait is essentially a plant character. We are using the non-nodulating groundnut lines in experiments to measure N fixation by groundnut, with the N uptake by the non-nodulated plants providing an estimate of the mineral N uptake by the nodulated plants. REFERENCES Caldwell, B. E. (1966) Crop Sci. 6, 427-428. Dart, P. J . , Day, J . M . & Harris, D. (1972) Assay of nitrogenase activity by acetylene reduction. Internat. Atomic Energy Agency (IAEA). Pub. no. 149. Pp. 85-100. Daggar, J . E . ( 1935) J. Arner. Soc. Agron. 27, 286288. Gates. C . E . & Bilbro, J . D . (1978) Agron. J. 70,462-465. Gorbert, D . W . & Burton, J . C . ( 1979) Crop Sci. 19, 727-728. Gregory, W . C., Krapovickas, A. & Gregory, M . P. (1980) Structure, variation evolution, and classification in Arachis. In: Advances in legume sciena, R. J. 9 mefield & A. H . Bunting (Eds.) Royal &rtmical Gardens, Kew, EngLud. +&. -93. Holl, F.B. & LaRue, T.A. (1976) Host genetics and nitrogen f d o n .  h World soybean research, L . D . Hill (Ed.). Interstate Printem & Pubtirhenr, Inc. Chicago, IL, USA. Pp. 156-163. Isleib, T. G., Wynne, J . C., Elkan, G.H., & Schnceweis, T.J. (1980) Peanut Scf. 7, 101-105. Krapovickas, A.  ( 1973) The origin, variability and spread of the groudnut (Arachir hypogaea) . In: Agricultural genetics: Selected topics. R . Moav (Ed.). National Council for Rcs. and Devel. Jersusalem, Israel. Pp. 135-151. McCloud, D. E., Duncan, W. G., McGraw, R. L., Siborle, P.K., Ingram, K.T., I Dreyer, J., & Campbell, I. S . (1980) Physiological basis for increased yield potential in peanuts. In= Proc. Internat. Workshop on Groundnuts, R. W. Gibbons (Ed.). ICRISAT, Patancheru, A. P., India. Pp. 125-132. Nambiar, P . T . C . & Dart, P . J . (1980) Studies on nitrogen fixation by groundnut at#, ICRISAT. lo: Proc. Internat. Workshop on ~ r o u n d n k ,  R. W. ~ i &  (Ed.). ICRISAT, Patancheru, A.P., India. Pp. 110-124. Nigam, S.N., Arunachalam, V., Gibbons, R. W., Bandyopadhyay, A. & Hambiar. P.T.C. (1980) Oleagineux 35, 453455. Nutman, P. S . ( 1969) Proc. Roy. Soc. B. 172,4 17437. Voorhees, J . H . (19 15) J. Amer. Soc. Agron. 7, 139-140. Williams, L . F . & Lynch, D . L. (1 954) Agron. J. 46, 28-29. Wynne, J . C., Elkan, G . H . & Schneeweis, T. J . (1980) I n c r ~ n i t r o g e n  fmtioa of the groundnut by strain and host selection. In: Proc. Internat. Workshop on Groundnuts, R . W . Gibbons (Ed.). ICRISAT, Patancheru, A. P., India. Pp. 95- 109. Zary, K , W., Miller, J . C., Weaver, R. W., & Barnes, L. W. (1978) J. Amer. Soc. Hort. Sci. 103. 806808. 

Genetic Manipulation Of Nodulation In Groundnut

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