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1.
A survey of allozyme variation in cultivar-groups of cowpea [Vigna unguiculata (L.) Walp.] was undertaken by examining 21 enzyme systems encoded by 36 loci in 271 accessions representing the five cultivar-groups. Very low levels of variation were found within accessions, which is typical of self-pollinating species. Little variation was also found among accessions. Compared with other legume crops, V. unguiculata is depauperate in allozyme variation. We found an average of 1.61 alleles per locus with 42% of the loci polymorphic and a total heterozygosity of 0.061. Of the variation present, 90% was found within cultivar-groups, while 10% was among cultivar-groups. Data analyses revealed continuous variation among cultivar-groups and geographic regions with the accessions failing to segregate into discrete morphophysiological or geographic clusters. However, evolved cultivar-groups (cv.-gr. Melanophthalmus and cv.-gr. Sesquipedalis) appear to be less diverse than their putative primitive cultivar-group progenitors. Due to the lack of availability of critical material, no clear center of origin can be established. However, the data presented suggest that Northeast Africa could be a possible center of domestication. Received: 18 February 1999 / Accepted: 4 November 1999  相似文献   

2.
Summary The effects of K and Mg application on dry matter yield and uptake of K, Mg and Ca in cowpea were studied in greenhouse at Haryana Agricultural University, Hissar (india). Dry matter yields of leaves, stems and roots increased by 17, 30 and 27 per cent over control due to application of 150 ppm K and 17, 16 and 26 per cent by 40 ppm Mg respectively. Potassium application has antagonistic effect on Ca concentration of leaves, stems and roots and synergistic on root Mg concentrations upto 25 ppm K. However, Mg had a synergistic effect on concentration of K upto 20 ppm Mg and antagonistic at 40 ppm Mg in all plant parts. Uptake of K, Mg and Ca increased by Mg application, but K increased only K uptake.  相似文献   

3.
D akora , F.D. & V incent , J.M. 1984. Fast-growing bacteria from nodules of cowpea ( Vigna unguiculata (L.) Walp.) Journal of Applied Bacteriology 56 , 327–330.
First plating from nodules of cowpea frequently yielded fast-growing large colonies, either apparently uniform or associated with small colony forms typical of the expected slow-grower ( Bradyrhizobium ). Most cultures from single large colonies nodulated both cowpea and siratro ( Macroptilium atropurpureum ), but all such nodules revealed Bradyrhizobium alone or associated with a fast-growing form. Six of nine plants inoculated with a mixed inoculum of slow and fast forms had nodules occupied by both although in no case was the fast-grower able to secure solo invasion. Most of the fast-growing forms shared some internal antigens with Rhizo-biurn meliloti and/or R. trifolii ; none reacted with antiserum to Bradyrhizobium CB 756.  相似文献   

4.
The cowpea (Vigna unguiculata (L.) Walp.) cultivars TVu 354 and Solojo were grown in solution culture at 10 to 1000 M Ca supply. The Ca supply did not vary by more than 10% during the experiment. The pH value was kept constant within 0.1 units at 4.0 by automatic titration. The cultivar TVu 354 proved to be much more Ca-efficient than Solojo. At 10 M Ca supply Solojo died, whereas TVu 354 was hardly affected in dry matter production. The differences in Ca efficiency were independent of the P supply. They could not be explained by differences in Ca uptake or Ca concentrations in the plant tissue. Short-term studies using 45Ca, both in the dark and in the light, indicated better transport of Ca from the roots to the shoots and within the shoots to the younger leaves in the Ca-efficient cultivar TVu 354. However, the main reason for the differences between the cultivars in sensitivity to low Ca supply were differences in the Ca requirement of the plant tissue to maintain tissue organization and function. Sequential fractionation of the freeze-dried leaf tissue with hot water, 0.5 M NaCl, 1 M CH3COOH, and 2 M HCl did not reveal cultivar differences in Ca binding state. The results clearly show that considerable genetic potential in tolerance to low Ca supply exists in cowpea. However, a better understanding of the physiological/biochemical reasons for low internal Ca requirement is needed.  相似文献   

5.
A chimeric plant was observed in the F2 generation of a cross between a mutant cultivar, Ife BPC, and a germplasm line, TVu 2, in cowpea, Vigna unguiculata (L.) Walp. The chimeric plant had four lateral branches, one of which was intensely variegated, while the others were mostly green with few white sectors. F3 progeny from the intensely variegated branch of this plant were all variegated, while seed derived from the mostly green branches produced only green progeny. In subsequent generations, the descendants of the variegated branch bred true for the variegated trait, while those of the mostly green branches were also true-breeding for green colour. No pure-green or pure-white shoots were observed in any of the variegated plants examined in this study. Consequently, no pure-green or pure-white seedlings were produced from seeds harvested from the variegated plants. The results of reciprocal crosses between variegated and normal green plants indicate that variegation is inherited in a strictly uniparental maternal fashion. This is the first report of a cytoplasmically inherited mutation affecting foliage colour in cowpea. Received: 10 March 2000 / Accepted: 16 May 2000  相似文献   

6.
Summary Rhizobium strains CIAT 301, CIAT 79 and SLM 602 were tested and found effective in the nodulation and nitrogen fixation of cowpea cv. MI-35 (Vigna unguiculata (L.) Walp) plants in growth chamber experiments. Fresh weight of nodules increased with plant age initially and stabilized in 20–30 days from planting, followed by a secondary flush of nodule growth after 30 days. Apparent nitrogen fixation per gram nodule fresh weight reached a maximum in 20–30 days after planting and then decreased, even though a flush of new nodules was produced.  相似文献   

7.
8.
Cowpea (Vigna unguiculata (L.) Walp.) nodules have been investigated by means of cytochemical and immunocytochemical procedures at the ultrastructural level in order to assess the role of the uninfected cells in ureide biogenesis. Uricase activity in the nodules was shown by cytochemical methods to be localized exclusively in the numberous large peroxisomes confined to the uninfected cells; the small peroxisomes in the infected cells did not stain for uricase. Uricase was also localized in the peroxisomes of uninfected cells by immunogold techniques employing polyclonal antibodies against nodule-specific uricase of soybean. There was no labeling above background of any structures in the infected cells. The results indicate that the uninfected cells are essential for ureide biogenesis in cowpea. Although tubular endoplasmic reticulum, the presumptive site of allantoinase, increases greatly in the uninfected cells during nodule development, it virtually disappears as the nodules mature. The inconsistency between the disappearance of the tubular endoplasmic reticulum from older nodules and the high allantoinase activity reported for older plants remains to be explained.Abbreviations DAB 3,3-diaminobenzidine - ER endoplasmic reticulum - GARG goat anti-rabbit immunoglobulin G - IgG immunoglobulin G - kDa knodalton - Mr apparent molecular mass - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis  相似文献   

9.
Anthropogenic contamination with Cu is an important issue and it is necessary to understand how Cu toxicity influences the uptake/acquisition of nutrients by plants. An experiment was conducted with soil-grown cowpea (Vigna unguiculata (L.) Walp.) to investigate the interaction between Cu toxicity and P deficiency. Plant performance was related to the activity of Cu2+ at the outer surface of the root plasma membrane, {Cu2+} 0 o , which was calculated from properties of the soil solution. The addition of Cu to the soil was found to reduce growth of plant shoots by inducing Cu toxicity, which was associated with a reduction in the shoot tissue Fe concentration. The critical value (50% reduction in shoot growth) determined for {Cu2+} 0 o in this soil-based experiment (3.8 μM) corresponds well to values determined previously. Importantly, regression analyses indicated that although the alleviation of P deficiency improved overall growth, the P-status of the plant did not influence the apparent toxicity of the Cu. This result was unexpected, given that Cu inhibits the growth of roots hairs; these being important for the uptake of immobile nutrients such as P. This study advances our understanding of Cu toxicity and its impact upon nutrient uptake.  相似文献   

10.
11.
Summary Waterlogging pot-grown cowpea plants for eight days (24–32 from sowing) during the period of rapid vegetative growth when symbiotic nitrogen fixation rates are also increasing at maximum rate had effects on anatomical, morphological and physiological attributes of the legume system viz reduced nodule production and increased nodule cortication, stimulated adventitious root formation at, or near, the water table but killed older submerged roots and nodules, caused the main stem to become hypertrophic just above the water line, accelerated senescence of the lowermost leaves and delayed branch formation. After re-draining the rooting medium nodule growth and symbiotic fixation activity occurred at the expense of rapid recovery by the host plant. The physiological basis for these findings in relation to identifying cowpea cultivars more tolerant of waterlogged soils is discussed.One of a series of papers describing work undertaken in a collaborative project with the International Institute of Tropical Agriculture, Nigeria, sponsored by the U.K. Ministry of Overseas Development.  相似文献   

12.
An in vitro regeneration system was developed in cowpea [Vigna unguiculata (L.) Walp.] Blackeye. Among several explants studied, shoot initiation response was observed from shoot apices of 3–5-day-old seedlings. The optimal medium for maximum shoot initiation comprised MS salts, B5 vitamins, 8.88 μM N 6-benzylaminopurine, 1 gl-1 casein hydrolysate, 342 μM L-glutamine, 3% sucrose, 0.3% phytagel, adjusted to pH 5.8. A shift in pH from 5.8 to 7.0 had no effect on shoot initiation and on number of shoots per explant. The highest shoot initiation frequency (77%) was obtained using this preferred medium, reaching a maximum of eight shoots per explant. For shoot elongation, 14 μM gibberellic acid was supplemented in the shoot initiation medium. Presence of indolebutyric acid in the rooting medium had no effect on root induction. The regenerated plants were fertile and developed normally.  相似文献   

13.
Shoot regeneration via organogenesis was achieved from axenic cowpea [Vigna unguiculata subsp. unguiculata L. (Walp.) Verde.] hypocotyls and cotyledons of advanced breeding lines and varieties. Cotyledons and embryos were excised from green immature pods. The apical parts of the embryos were removed and the hypocotyls were transferred to regeneration media. Cotyledons and hypocotyls were tested on media with gradients of several hormonal and putrescine combinations. Cowpea cotyledons and hypocotyls exhibited a pattern of shoot formation that occurred in three distinct phases. Multiple shoots developed within 45 days from the wounded region of the primary hypocotyl and cotyledons in different media containing a high cytokinin concentration. The induced plant explants were then grown for 20 days in low-intensity light (10 μmol m–2 s–1) on the same medium and numerous shoot buds emerged de novo from the upper part of the hypocotyl and the wounded part of the cotyledons. These buds had no apparent vascular connection with the parent tissues. The plant regeneration capability of this procedure was tested with several cowpea genotypes, five of which (83D-442, 86D-1010, 93K-624, Vita 3 and Ife Brown) responded positively with shoot development and were able to form roots and whole plants. Some somaclonal variation was observed. Received: 14 June 1996 / Revision received: 14 December 1996 / Accepted: 25 January 1997  相似文献   

14.
Cowpea (Vigna unguiculata) is a promiscuous grain legume, capable of establishing efficient symbiosis with diverse symbiotic bacteria, mainly slow-growing rhizobial species belonging to the genus Bradyrhizobium. Although much research has been done on cowpea-nodulating bacteria in various countries around the world, little is known about the genetic and symbiotic diversity of indigenous cowpea rhizobia in European soils. In the present study, the genetic and symbiotic diversity of indigenous rhizobia isolated from field-grown cowpea nodules in three geographically different Greek regions were studied. Forty-five authenticated strains were subjected to a polyphasic approach. ERIC-PCR based fingerprinting analysis grouped the isolates into seven groups and representative strains of each group were further analyzed. The analysis of the rrs gene showed that the strains belong to different species of the genus Bradyrhizobium. The analysis of the 16S-23S IGS region showed that the strains from each geographic region were characterized by distinct IGS types which may represent novel phylogenetic lineages, closely related to the type species of Bradyrhizobium pachyrhizi, Bradyrhizobium ferriligni and Bradyrhizobium liaoningense. MLSA analysis of three housekeeping genes (recA, glnII, and gyrB) showed the close relatedness of our strains with B. pachyrhizi PAC48T and B. liaoningense USDA 3622T and confirmed that the B. liaoningense-related isolate VUEP21 may constitute a novel species within Bradyrhizobium. Moreover, symbiotic gene phylogenies, based on nodC and nifH genes, showed that the B. pachyrhizi-related isolates belonged to symbiovar vignae, whereas the B. liaoningense-related isolates may represent a novel symbiovar.  相似文献   

15.
Summary When pot-grown cowpea plants experienced a large diurnal variation in root temperature (33°C day–19°C night) during reproductive growth, floral morphology was markedly affected. Petals were constricted in such a way as to restrict self-pollination hence seed yields were drastically reduced. These abnormal flowers were very similar to those mediating mechanical male sterility in cowpea, a genetically inherited, recessive, outcrossing mechanism identified in field populations.  相似文献   

16.
17.
This study calculated the compositional nutrient diagnosis (CND) norms of cowpea (Vigna unguiculata (L.) Walp.), as well as identified significant nutrient interactions of this crop growing in an irrigated calcareous desert soil. Three genotypes were distributed in rows in a 2-ha field. The soil showed high heterogeneity in its chemical properties. For statistical analysis, 86 foliar composite samples from healthy plants were used. Preliminary CND norms were developed using a cumulative variance ratio function and the 2 distribution function. Means and standard deviations of row-centered log ratios VX of five nutrients (N, P, K, Ca, and Mg) and a filling value R, which included all nutrients not chemically analyzed. Preliminary CND norms are: VN*=0.174±0.095, VP*=–2.172±0.234, VK*=–0.007±0.267, VCa*=–0.022±0.146, VMg*=–1.710±0.132, and VR5*=3.728±0.084. These CND norms are associated with dry bean yields higher than 1.88 t ha–1, and are associated with the following foliar concentrations: 26.2 g N kg–1, 2.5 g P kg–1, 22.9 g K kg–1, 21.6 g Ca kg–1, and 4 g Mg kg–1. Cowpea plants growing in desert calcareous soils took up lower amounts of N, P, and K than those considered as optimum in a previous report. Six interactions were strongly indicated for cowpea through principal component analyses: positive for Ca–Mg, and negative for N–Ca, N–Mg, Ca–P, Mg–P, and K–P. Furthermore, two interactions were identified using simple correlations, negative N–P and positive K–Ca.  相似文献   

18.
LUSH  W. M.; EVANS  L. T. 《Annals of botany》1980,46(6):719-725
To test the proposition that photoperiodic controls synchronizethe flowering of cowpeas, Vigna unguiculata (L.) Walp. [V. sinensis(L.) Savi], the day-length requirements for floral initiationand for flowering were investigated in several short-day accessions.No evidence was found of different critical photoperiods atdifferent stages of development, but exposure to only 2–4short days was required for floral initiation compared withabout 20 for development to open flowers. Pod setting was increasedafter exposure to even one short day more than the number requiredfor flower opening. Floral buds at higher nodes appeared to require fewer shortdays for development to flowering than buds at the lower nodes,and displayed faster rates of development. Inflorescence budsdid not resume development if they were exposed to 15 or morelong days following inflorescence initiation. Thus, any tendencytowards synchronous flowering in cowpeas is not due to the criticalday-length for flower development being shorter than that forflower initiation, but could be the result of cumulative photoperiodicinduction of plants and the more rapid development of later-formedflowers. Vigna unguiculata (L.) Walp., cowpeas, flower initiation, flower development, fruit set, photoperiodism  相似文献   

19.
Summary The differential response of six cowpea (Vigna unguiculata (L.) Walp) cultivars to liming was assessed in a greenhouse trial using an Ultisol (Typic Paleudult) from southeastern Nigeria. Lime rates from 0 to 5.0 t/ha were applied to give a range of soil pH, determined in 11 soil/water from 4.25 to about 7.0. Without liming, relative dry matter yields of tops ranged between 46.6 and 76.8 percent. Significant yield responses to the first lime increment (0.5 t/ha) were observed particularly in the less tolerant cultivars and maximum yields were generally obtained with application of 1.6 to 2.5 t/ha lime.Among the six cultivars, TVu 4557 and Ife Brown were most tolerant, Vita-1 and Vita-3 were moderately tolerant, and TVu 1977-OD and TVu 4552 were least tolerant to soil acidity. The latter two cultivars were the most poorly nodulated when grown in the unlimed soil. The first lime increment enabled excellent nodulation to be achieved in all cultivars. Nitrogen analyses on tops confirmed the visual symptoms of nitrogen deficiency in two cultivars (Vita-1, TVu 1977-OD) grown in the unlimed soil. Analysis of data on chemical composition of plant tops and chemical soil characteristics gave indications that aluminium toxicity is the major growth limiting factor for cowpeas in this soil.This study, albeit with a limited range of cowpea germplasm clearly indicates that cowpea possesses considerable potential as a grain legume on strongly acid soils (pH<5.0), even in circumstances where lime is not available. Low rates of lime (0.5 t/ha or less) will greatly expand the available choice of cultivars.  相似文献   

20.
In cowpea typical Mn toxicity symptoms are brown speckles on mature leaves representing depositions mainly in the cell walls and formation of non-constitutive callose. The histochemical charecterization of the brown speckles indicates the presence of oxidized Mn. However, the reducing agent hydroxylamine hydrochloride only slightly while thioglycolic acid almost completely decolorized the speckles. Brown boron-deficient roots treated with hydroxylamine hydrochloride and thioglycolic acid showed the same pattern of decoloration suggesting that the brown color of the Mn toxicity symptoms derives mainly from oxidized phenolics. To evaluate the effect of light on the formation of brown speckles by high Mn concentrations and non-constitutive callose in leaves, three approaches were used: (i) comparison of shaded and unshaded plants at different Mn supplies via the roots, (ii) local application of Mn to leaves in the light and in the dark, (iii) local application of Mn to leaves in the dark with subsequent light and dark treatments. Shading of whole plants (i) aggravated formation of both brown speckles and callose at similar Mn concentrations in the leaves. When the Mn application and the light treatments were locally confined (ii, iii), light had no effect on formation of either brown speckles or callose. The present results are in contradiction to the available reports in the literature showing aggravation of Mn toxicity by high light intensities.  相似文献   

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