The Response of Groundnut (Arachis hypogaea L.) to Timing of Irrigation

A timing-of-irrigation experiment was conducted in controlled-environmentglasshouses, in which a finite quantity of water was appliedto four stands of groundnut (Arachis hypogaea L.) at differentstages of the growing season. Irrigation schedules were broadlydivided into two periods; sowing to pod initiation and pod initiationto final harvest. Within these periods two levels of soil moisturedeficit were imposed by withholding or applying limited amountsof irrigation at regular intervals. Shoot dry matter yields were hardly affected but pod yieldswere more than 4-fold lower in early- than in late-irrigatedstands. Thermal time was used to separate the effects of temperatureand water stress on developmental processes. The degree-dayrequirement for peg initiation was similar in all treatmentsbut late-irrigation delayed pod development by about 200 °Cd.The effect of timing of irrigation on pod yield operated mainlythrough its influence on the duration of pod production, whichwas closely linked to the rate and duration of canopy expansionlate in the season. The insensitivity of pod yield to earlymoisture deficits reflected the extreme plasticity of growthand development in groundnut, since most processes resumed ratessimilar to the pre-stress levels in early-irrigated stands oncestress was released. Key words: Groundnut, irrigation, growth, development     

Groundnut (Arachis hypogaea L.) cultivars for cultivation on calcareous soils

Summary Studies of incubation experiments showed that the phosphorus turnover under aerobic decomposition in soil starts with a non-biological process, which is rapid and probably due to chemical fixation. The present study allowed a distinction to be made between chemical fixation and biological immobilisation of added phosphorus with special reference to the effects of addition of energy material in the process of biological turnover. Invariably, both glucose and cellulose additions resulted in an increase in phosphorus immobilisation. Comparatively, cellulose acted slowly on phosphorus turnover, with the prospect of more immobilisation in long term experiments. re]19730416     

The Response of Groundnut (Arachis hypogaea L.) to Timing of Irrigation: II. 14C-PARTITIONING AND PLANT WATER STATUS

Finite quantities of water were applied at different growthstages of groundnut stands (Arachis hypogaea L.) grown in controlledenvironment glasshouses. Soil moisture deficits were imposedbetween sowing and pod initiation or between pod initiationand final harvest by withholding or applying water. Effectson assimilate production and partitioning and plant water relationswere examined. Leaves were the primary sites of ¹⁴CO₂ fixation, though theircontribution generally declined late in the season, whereasfixation by stems was initially low but increased sharply whenstress was released in the late-irrigated stands. ¹⁴C-fixationby stem apices and pegs also rose sharply following irrigationof the late-stressed stands. Leaves were the primary source of assimilates, though translocationtended to decrease as the season progressed, even in the late-irrigatedstands. Stems were initially the major sinks, but their sinkactivity disappeared almost completely when stress was releasedin the late-irrigated stands. Assimilate import by stem apicesdeclined progressively and pod sink activity was negligiblein the late-stressed stand, but both increased markedly whenearly-season stress was released. Leaf water status showed marked diurnal variation, whereas pegsshowed less variation and maintained much higher turgor levels,largely because of their lower solute potentials. Marked osmoticadjustment occurred in expanding but not in mature leaves, allowingthem to maintain higher turgor levels during periods of severestress. This adjustment was rapidly lost when stress was released.The observed changes in assimilate production and partitioningpreceded detectable changes in bulk turgor levels. Implications for growth, development and yield are discussed. Key words: Groundnut, irrigation, partitioning, water status     

Utility of EST-derived SSR in cultivated peanut (Arachis hypogaea L.) and Arachis wild species

Background  

Lack of sufficient molecular markers hinders current genetic research in peanuts (Arachis hypogaea L.). It is necessary to develop more molecular markers for potential use in peanut genetic research. With the development of peanut EST projects, a vast amount of available EST sequence data has been generated. These data offered an opportunity to identify SSR in ESTs by data mining.     

The Effect of Groundnut rosette assistor virus on the Agronomic Performance of Four Groundnut (Arachis hypogaea L.) Genotypes

The effect of Groundnut rosette assistor virus (GRAV), in the absence of the other two agents (Groundnut rosette virus and its satellite RNA) of the groundnut rosette disease virus complex, was evaluated on the agronomic performance of four groundnut (=peanut) genotypes (CG‐7, ICGV‐SM‐90704, JL‐24 and ICG‐12991) with different botanical characteristics. All genotypes infected with GRAV showed mild yellowing/chlorosis of leaves and the symptoms persisted throughout their growth period. ELISA absorbance values indicated lower amounts of GRAV antigen in ICGV‐SM‐90704 than in the other genotypes. The reduction in leaf area due to GRAV infection varied between 15.5% and 21.7%, whereas the plant height was decreased between 11.3% and 13.4% among the four genotypes. GRAV infection caused 28.4%, 16.9%, 21.7% and 25.5% reduction in the dry weight of haulms in CG‐7, ICGV‐SM‐90704, JL‐24 and ICG‐12991 respectively. Plants infected with GRAV showed greater reduction in seed weight in CG‐7 (52.2%), followed by JL‐24 (46.1%), ICG‐12991 (40.7%) and ICGV‐SM‐90704 (25.7%). These results provide evidence for the first time that GRAV infection, without GRV and sat RNA, affect plant growth and contribute to yield losses in groundnut.     

Responses to Saturation Deficit in a Stand of Groundnut (Arachis hypogaea L.) 1. Water Use

Stands of groundnut were grown in computer-controlled glasshouseson water stored in an undisturbed soil profile. The maximumsaturation vapour pressure deficit (D) of the air was either1.0, 2.0, 2.5, or 3.0 kPa, and the mean air temperature was27 °C. Transpiration (E), determined from the soil water balance, wasstrongly dependent on D, because D influenced both the fractionof incident solar radiation intercepted by foliage (f) and thetranspiration rate per unit f (E/f). When D exceeded 2 kPa,canopy expansion was restricted and f reduced during early growth,but differences in f diminished as the canopies closed. E/fincreased with D, implying that any restriction of transpirationthrough stomatal closure at large D was outweighted by a steeperhumidity gradient from leaf to air. In all treatments E/f decreased as the soil profile dried. Saturationdeficit per se had little influence on the proportional reductionin E/f with time, even though soil water deficit was considerablygreater at large D. This lack of response occurred because plantscompensated for the greater evaporative demand by extractinglarger amounts of water from deep in the profile. Groundnut, Arachis hypogaea L., humidity, rooting depth, transpiration     

Genetic diversity of Bradyrhizobium strains isolated from Arachis hypogaea

Rhizobia are used exclusively in agricultural systems for enhancing the ability of legumes to fix atmospheric nitrogen. Knowledge about the indigenous population is necessary for the selection and application of inoculant strains. In this study, we have assessed the genetic diversity of Bradyrhizobium strains isolated from the host plant, Arachis hypogaea along the coastline of Tamil Nadu. Different populations collected from varying environmental conditions were analysed for salt and pH tolerance. Genetic diversity among the strains was studied using RAPD markers and PCR-RFLP of 16S rDNA and nifD genes. The approaches used in this study yielded consistent results, which revealed a high degree of heterogeneity among strains and detection of two distinct genetic groups.     

RFLP variability in peanut (Arachis hypogaea L.) cultivars and wild species

Summary RFLP variability was studied in eight U.S. peanut cultivars, representing the four market types, and in 14 wild Arachis species accessions, using random genomic clones from a PstI library. Very low levels of RFLP variability were found among the allotetraploids, which included the U.S. cultivars and Arachis monticola, a wild species. The diploid wild species were very diverse, however. RFLP patterns of the allotetraploids were more complex than the diploids, and the two constituent genomes could usually be distinguished. On the basis of RFLP band sharing, A. ipaensis, A. duranensis, and A. spegazzinii appeared most closely related to the diploid progenitor species of the allotetraploids. A dendrogram of relationships among the diploid wild species was constructed based on band sharing.     

Response of two peanut (Arachis hypogaea L.) cultivars to boron and calcium

The response of two peanut cultivars (Tainan 9 and SK 38) to applications of six boron (B) rates (H₃BO₃ at 0, 0.12, 0.25, 0.5, 1 and 2 kg B ha^–1) at two calcium levels [nil (-Ca) or CaSO₄ at 100 kg Ca ha^–1 (+Ca)] to a B-deficient Oxic Paleustult was studied in a pot experiment. Without added Ca, both cultivars had low seed yields and gave only small responses to B. Similarly, without added B, both cultivars had low seed yields and did not respond to Ca. But, with added Ca or B, they responded strongly to B and Ca, respectively. In both cultivars, deficiencies of Ca or B depressed seed dry weight by depressing seed size by over 75%. Boron deficiency further depressed seed dry weight by decreasing the number of seeds per plant by decreasing the number of seeds per pod in Tainan 9, and the number of pods per plant in SK 38. Seed dry weight was depressed more than pod dry weight, so that both Ca and B deficiencies severely depressed the shelling %. With added Ca, tainan 9 responded to lower levels of B than SK 38, reaching maximum seed dry weight at 0.12 kg B ha^–1. At this low level of B. SK 38 yielded only half the seed dry weight of Tainan 9. But SK 38 continued to respond to increasing levels of B to 2 kg ha^–1, producing a maximum seed yield 40% higher than Tainan 9. The results indicate that where all other nutrients are adequate, SK 38 will yield better than Tainan 9 on soils with high B, but worse on soils with low B. The implications of these findings for the selection of peanut cultivars are discussed.     

The Deamidase of Groundnut Plants (Arachis hypogaea)

The deamidase enzyme system present in extracts of groundnutplant tissues has been studied. The distribution of the enzymewithin the different organs of the plant were determined, andsome of the properties of the enzyme present in leaf extractsare recorded. From its substrate specificity the enzyme is probablybest regarded as a -methyleneglutaininase, although it catalysesthe hydrolysis of glutamine at about one-fifth of the rate of-methyleneglutamine. The enzyme may play an important role inthe over-all nitrogen metabolism of the plant, as well as controllingthe relative concentrations of -methyleneglutamine and -methyleneglutamicacid in the different organs. The properties of the enzyme havebeen compared with those recorded in the literature of glutaminasesand asparaginases, and certain common features are apparent.The new deamidase was, however, more stable to certain denaturingtreatments than were the other types of deamidase.     

Micropropagation in Peanut (Arachis hypogaea L.)

Multiple shoots in Arachis hypogaea L. could be induced from the de-embryonated cotyledons (DC), embryo-axes (EA) and mature whole seeds (MWS) in MS medium supplemented with different levels of benzylaminopurine (BAP). DC was the most suitable explant with 57.9 % induction and more than 40 shoots per explant in 31.6 % of cases. Though EA and MWS had high percent induction at or above 30 mg dm^–3 BAP, only 10 – 14 shoots per explant were observed. In DC, multiple shoots were confined to the proximal end and in EA they originated from the axillary bud region. Histological studies on DC confirmed the origin of shoots from the region of attachment with the embryo. Shoots could be rooted in MS medium containing 2 g dm^–3 charcoal and 200 mg dm^–3 casein hydrolysate. Sixty percent of the rooted plantlets could be established in the field.     

Diallel analysis in groundnut (Arachis hypogaea L.)

Summary An 8 × 8 full diallel experiment based on 4 bunch plus 4 spreading types of groundnut (Arachis hypogaea L.) was conducted over three environments. For both number of pods and pod yield, additive, nonadditive and reciprocal cross effects were detected and these were also influenced by changes in environments. For number of pods additive genetic variance was predominant whereas it was approximately equal to non-additive genetic variance for pod yield. Graphical analysis revealed the presence of strong non-allelic interaction for number of pods whereas for pod yield absence of dominance and/or presence of non-allelic interaction was evident.Part of Ph.D. Thesis of the first author     

Boron mobility in peanut (Arachis hypogaea L.)

In most plant families, boron (B) is phloem immobile. For plants such as peanut which bury their fruit, the mechanism for B delivery and the B source for fruit and seed growth remains enigmatic. Therefore, this study aimed to establish evidence of B retranslocation in peanut and to identify its importance in plant development. In a sand culture experiment, the increase in B contents in new organs after B withdrawal and the corresponding decline in B contents in older organs was evidence of B redistribution. In a foliar ¹⁰B experiment, the ¹⁰B abundance of treated-leaves decreased and ¹⁰B was detected in leaves and flowers formed after the application of foliar B. Application of ¹⁰B to the roots for a period also provided evidence for the retranslocation of ¹⁰B accumulated during the first growth period. The ¹⁰B abundance in older plant parts declined and ¹⁰B appeared in new organs (flowers, pegs, leaves) that had developed after the ¹⁰B supply had been replaced by ¹¹B. In the fourth experiment, foliar application of B reduced hollow heart, a symptom of B deficiency in seeds, in cv. TAG 24 from 39 to 8% and in Tainan 9 from 63 to 18%. These experiments all provide evidence for B retranslocation in peanut, but further work on the relative importance of the xylem and phloem pathways for B loading into the fruit is needed.     

Response of groundnut (Arachis hypogaea L) toRhizobium inoculation in the field: Problems and prospects

Summary A successfulRhizobium inoculant strain needs to be more competitive than native soil rhizobia in forming nodules and to be effective in fixing nitrogen. Persistence of the strain from one season to the next will be an added advantage, since it eliminates the need to inoculate every season. Earlier studies indicated that groundnut,Arachis hypogaea, seldom responds toRhizobium inoculation in soils already containing rhizobia which nodulate groundnut. However, the results of seven years of research at ICRISAT have opened up the prospect of inoculating groundnut in such soils. These experiments indicate that inoculating with sufficient numbers of an effectiveRhizobium strain, NC 92, applied as a liquid slurry below the seed, increased yields of certain groundnut cultivars. Similar results were reported from other research centres in India. Inoculation with NC 92 for two consecutive seasons increased the proportion of nodules formed by this strain, from 25–32% in the first season to 41–54% in the second season, indicating that this strain can persist in the field for the following season. This paper also discusses results of experiments relating to host cultivar specificity and some possible problems in applying this information to farmers' fields. Strain NC 92 also produces a siderophore, an iron chelating compound, which may help in the iron nutrition of the plant.

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Resumen Respuesta del maní (Arachis hypogaeaL.)a la inoculación con Rhizobiumen el campo. Problemas y perspectivas.La inoculación conRhizobium para tener exito debe de realizarse con una cepa que sea competitivamente mejor que las cepas nativas del suelo en cuestión, en relación a la habilidad para formar nódulos y a la eficacia en la fijación de nitrógeno. La persistencia de la cepa de una temporada para otra es una caracteristica deseable ya que elimina la necesidad de reinocular cada temporada. Estudios previos indicaban que el maní (Arachis hypogaeae) raras veces responde a la inoculación conRhizobium en suelos que ya contienenRhizobium especificos. Sin embargo los resultados de siete años de investigaciones en ICRISAT han abierto nuevas perspectivas para la inoculación del maní en dichos suelos. Esta experiencias indican que la inoculación, en cantidades suficientes de una cepa deRhizobium eficaz (NC 92) aplicada en forma de liquido viscoso bajo la semilla incrementa el rendimiento de ciertos cultivars de mani. Resultados semejantes se han observado en otros centros de investigación en India.La inoculación de la cepa NC 92 durante dos años consecutivos incrementó la proporción de nódulos formados desde 25–32% en la primera temporada hasta 41–54% en la segunda indicando pues la persistencia de dicha cepa en el suelo de una a otra temporada. Este trabajo también evalua los resultados de investigaciones relacionando la especificidad del inóculo con la posible problemática que conlleva la aplicación de esta informacion por el agricultor.

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Résumé Réponse de l'arachide (Arachis hypogeaL.)à l'inculation de Rhizobiumdans les champs. Problèmes et perspectives.Pour être couronnée de succès, une souche deRhizobium inoculée doit supplanter les rhizobiums natifs du sol en ce qui concerne la formation de nodules et doit fixer l'azote efficacement. La persistance de la souche d'une saison à l'autre, rendant inutile la répétition saisonnière de l'inoculation, est un avantage supplémentaire. Des études antérieures ont montré que l'arachide (Arachis hypogea) ne répond que rarement à l'inoculation dans des sols contenant déjà des rhizobiums capables de noduler cette plante. Cependant, les résultats de sept années de recherches éffectuées à l'ICRISAT ont ouvert des possibilités quant à l'inoculation dans ce type de sols. Ces expériences montrent qu'une bouillie liquide d'une souche efficace deRhizobium (NC 92), répandue en quantité suffisante sous les graines, augmente le rendement de certains cultivars d'arachide. Des résultats similaires ont été rapportés par d'autres centres de recherches en Inde. L'inoculation de NC 92 pendant deux saisons consécutives a augmenté la proportion des nodules formés par cette souche de 25 à 32% pour la première saison, et de 41 à 54% pour la seconde, ce qui indique que cette souche peut persister dans le sol d'une saison à l'autre. Dans cet article sont également discutés les résultats d'expériences concernant la spécificité de l'hôte et quelques problèmes concernant l'utilisation de ces informations par les agriculteurs. La souche NC 92 produit aussi un sidérophore, agent complexant du fer pouvant jouer un rôle dans le métabolisme de ce métal chez la plante.

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Submitted as ICRISAT J. A. No. 475.     

Characterization of Two Strains of Cowpea Mild Mottle Virus Naturally Infecting Groundnut (Arachis hypogaea L.) in India

Two viruses were isolated from commercial groundnut plants showing mild mottle (MM) and severe mottle (SM) symptoms in the Rayalaseema area of Andhra Pradesh State, India. The host range of both the isolates was restricted to Fabaceae. The physical properties of both isolates were: DEP 10^-6 to 10^-7. TIP 70–85 C and LIV 5–8 days. Partially purified virus preparations contained slightly flexuous filamentous particles. In ELISA and gel diffusion tests both isolates reacted similarly with anusera to the carlaviruses cowpea mild mottle, cassia mild mosaic and potato M. Particle morphology. sedimentation coefficient, and estimated sizes of the coat proteins and RNAs gave additional evidence that the viruses were carlaviruses. Bemisia labaci transmitted only the MM isolate and the two isolates also differed in electrophoretic mobility of intact particles and amino acid composition of the coat proteins. The isolates are identified as distinct strains of cowpea mild mottle virus.     

Absence of Root Hairs in Non-Nodulating Groundnut, Arachis hypogaea L.

Root hairs observed at the site of lateral root emergence innodulating groundnut cultivars were found to be absent in non-nodulatinggroundnut lines. In a segregating F₂-population of the crossNC 17 x PI 259747 a strong association was observed betweenthe presence of root hairs and nodulation, and the absence ofroot hairs and non-nodulation. Key words: Root hairs, Arachis hypogaea, Non-nodulation     

Jasmonic Acid-Mediated-Induced Resistance in Groundnut (Arachis hypogaea L.) Against Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae)

Jasmonic acid (JA) acts as a signal molecule to induce resistance in plants against herbivores and its levels are elevated in plants after wounding or insect damage. Groundnut is an important crop in many tropical and subtropical regions worldwide, but there is surprisingly little knowledge on its induced defenses against herbivores. The effect of JA as a spray on induced resistance in three groundnut genotypes, namely, ICGV 86699 (resistant), NCAc 343 (resistant), and TMV 2 (susceptible), against Helicoverpa armigera was studied. The activity of oxidative enzymes [peroxidase (POD) and polyphenol oxidase (PPO)] and the amounts of other host plant defense components [total phenols, hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and protein content] were recorded at 24, 48, 72, and 96 h after pretreatment (1 day) with JA followed by infestation with H. armigera (PJA + HIN) and H. armigera infestation with simultaneous JA application (HIN + JA) to understand the consequences of induced resistance in groundnut. The plant damage, larval survival, and larval weights were also recorded. There was a significant increase in POD and PPO activities and in the amounts of total phenols, H₂O₂, MDA, and proteins in PJA + HIN- and JA + HIN-treated plants as compared to the plants treated with JA and infested with H. armigera individually and to untreated control plants. Among all the genotypes, the strongest induction of defense was observed in the ICGV 86699 genotype. It is concluded that pretreatment with JA and its application during low levels of insect infestation can increase the levels of host plant resistance against herbivorous insects and reduce the pest-associated losses in groundnut.     

Genetic and phenetic analyses of Bradyrhizobium strains nodulating peanut (Arachis hypogaea L.) roots.

Seventeen Bradyrhizobium sp. strains and one Azorhizobium strain were compared on the basis of five genetic and phenetic features: (i) partial sequence analyses of the 16S rRNA gene (rDNA), (ii) randomly amplified DNA polymorphisms (RAPD) using three oligonucleotide primers, (iii) total cellular protein profiles, (iv) utilization of 21 aliphatic and 22 aromatic substrates, and (v) intrinsic resistances to seven antibiotics. Partial 16S rDNA analysis revealed the presence of only two rDNA homology (i.e., identity) groups among the 17 Bradyrhizobium strains. The partial 16S rDNA sequences of Bradyrhizobium sp. strains form a tight similarity (> 95%) cluster with Rhodopseudomonas palustris, Nitrobacter species, Afipia species, and Blastobacter denitrificans but were less similar to other members of the alpha-Proteobacteria, including other members of the Rhizobiaceae family. Clustering the Bradyrhizobium sp. strains for their RAPD profiles, protein profiles, and substrate utilization data revealed more diversity than rDNA analysis. Intrinsic antibiotic resistance yielded strain-specific patterns that could not be clustered. High rDNA similarity appeared to be a prerequisite, but it did not necessarily lead to high similarity values between RAPD profiles, protein profiles, and substrate utilization. The various relationship structures, coming forth from each of the studied features, had low compatibilities, casting doubt on the usefulness of a polyphasic approach in rhizobial taxonomy.     

Somatic embryogenesis from the axillary meristems of peanut (Arachis hypogaea L.)

Developmental anomalies in the plumule meristem of peanut (Arachis hypogaea L.) somatic embryos resulted in poor shoot differentiation and reduced plant recovery. Existing meristems with caulogenic potential have never been tested for embryogenesis in peanut. The present experiment was designed to test the mature zygotic embryo axis derived plumule with three meristems for somatic embryogenesis. Embryogenic masses and embryos developed from the caulogenic meristems in the axils. Exposure of 2 weeks in primary medium with 90.5 μM 2,4-D suppressed the shoot tip differentiation temporarily which then regained the ability to form the shoot on withdrawal of 2,4-D. Exposure of 4 weeks in primary medium with 90.5 μM 2,4-D suppressed the shoot tip differentiation irreversibly. No shoot formation was noted from the tips in any of the cultures which were in secondary medium with 13.6 μM 2,4-D. Development of somatic embryos directly from axillary meristems was confirmed histologically. Conversion frequency of these embryos was 11%. Thus, in this report, we describe a method to obtain somatic embryos from the determined organogenic buds of the axillary meristem, by culturing the nodal explant vertically on embryo induction medium. It also displays the possibility of obtaining both embryogenic and organogenic potential in two parts of the same explant simultaneously. The possibility of extending this approach for genetic transformation in in vivo system through direct DNA delivery or Agrobacterium injection in meristems can also be explored. Using Agrobacterium rhizogenes, we have demonstrated the possibility of gene transfer in the axillary meristems of seed-derived plumule explant.     

Partial characterization of an allergenic glycoprotein from peanut (Arachis hypogaea L.)

A concanavalin A-reactive glycoprotein allergen has been isolated from peanut (Arachis hypogaea). The allergen was separated by affinity chromatography and purified by gel permeation and ion-exchange chromatography. The monomeric molecular weight is 65,000 and the pI is 4.6. The presence of one cysteine residue per molecule results in some dimer formation. Concanavalin A-reactive glycoprotein is a potent allergen for peanut-sensitive patients in both in vivo and in vitro tests. It is allergenically stable, on in vitro examination, at temperatures of up to 100 degrees C and over the pH range 2.8-10. Removal of the carbohydrate moiety failed to eliminate the allergenicity. Concanavalin A-reactive glycoprotein is identified in the crossed immunoelectrophoretic pattern as a major antigen of peanut protein extract but its structural characteristics indicate that it is probably not a component of the major storage-protein complex, arachin.