Centrosema Brasilianum Research Articles

Pollination ecology in Centrosema brasilianum (L.) Benth. (Fabaceae: Papilionoideae): bee size influences pollen deposition

Here, were observed the interaction between Centrosema brasilianum (Fabaceae, Papilionoideae) and their floral visitors and quantified pollen removal and visitor traits. Aims: for to determine whether the behavior, quantity, and location of deposited pollen on the body of visiting bees differs according to the body size of bees. Methods: the morphological and behavioral attributes of floral and bees observed in interaction were measured in 20 individuals of C. brasilianum. The place of deposit and the amount of polinic charge in each bee were identified. The relationship between the attributes of the interactants and of pollen deposited was determined using simple linear models. Results: Bee behavior and pollen deposition on the body varied according to bee body size. Larger-sized bees with long tongues raised floral keels during visits and pollen deposition occurred on their heads and dorsal surfaces. Smaller individuals with short tongues did not raise the keel, and pollen was deposited on the dorsal surface, but mostly over the wings. Additionally, larger bees had twice as many pollen grains deposited on their body surfaces than smaller bees. Conclusions: we assumed that larger bees may provide a more effective pollination service than smaller bees in C. brasilianum. Implications: Future evaluations should be conducted that include more morphological and behavioral attributes in a larger sample number, which would provide a more nuanced understanding of pollination efficiency, the relationship between different behaviors and body sizes of bees, and the consequences of differential pollen deposition on the reproductive success of C. brasilianum.

Responses of selected tropical forage legumes to imposed drought

Drought tolerance is an important attribute for the establishment of forage legumes in the rangelands of the seasonal semi-arid tropics. This experiment examined the seedling rooting depth, plant biomass, and other growth parameters of 5 perennial tropical legumes in response to different watering and drying regimes. Centrosema brasilianum cv. Oolloo and Macroptilium bracteatum (CPI 55770) produced deeper roots, greater root biomass, and more root nodules than Stylosanthes scabra cv. Seca and Desmanthus virgatus (CPI 79653), however only D. virgatus produced deeper roots and increased biomass in response to the drought treatment. Arachis triseminalis (CPI 91423), C. brasilianum and M. bracteatum flowered during the 9-week course of the experiment, with the latter two species producing pods. Seca, A. triseminalis and D. virgatus show adaptations of drought-tolerance, whilst C. brasilianum and M. bracteatum are adapted to drought avoidance.

Evaluation on dry forage yields and nutritional characteristics of introduced herbaceous legumes in Myanmar

The study was carried out to evaluate the forage yields, nutritive values and in vitro fermentation parameters of herbaceous legumes. Five varieties of introduced herbaceous legumes; Stylosanthes guianensis cv. Ubon stylo, Macrotyloma axillare cv. Archer, Centrosema brasilianum cv. Ooloo, Stylosanthes guianensis cv. Stylo 184 and Macroptilum bracteatum cv. Cadarga were evaluated at the research farm, University of Veterinary Science, Yezin, Myanmar. No fertilizer and no irrigation were applied for cultivation to test drought resistance. Dry forage yield, nutritive values and gas production at four harvesting times were measured with 4×5 factorial arrangement (5 legumes and 4 harvesting time) in randomized complete block design. There was no interaction between legumes and harvesting time on forage yield, nutritive values and fermentation parameters but they were affected by the main effects of legume types and harvesting time. Among the legume forages, the highest dry forage yields were found in Ooloo, Ubon stylo, and Stylo 184, and followed by the DM yield of Archer and Cadarga. The DM yield of the second harvest was significantly higher (p<0.05) than those of the first, third and fourth harvest which were not significantly different from each other. As a chemical composition, the DM content of Archer was lower (p<0.05) than those of other varieties. Among the legumes forages, the lower CP content was found in Cadarga. The higher NDF was observed in Ooloo. Ooloo, Ubon stylo and Cadarga showed higher ADF in comparison with the other two varieties. Among the harvesting time, the lowest DM content was found at the first harvest. The highest CP content was found at third harvest. The NDF content was not significantly different. The lowest ADF content was found in fourth harvest. According to the dry forage yield, Ubon stylo and Ooloo had the highest dry forage yield and in term of nutritive values, Stylo 184 and Archer had higher nutritive values. As the main effect of forages, Stylo 184 and Archer had higher gas production in comparison with the other varieties. As the main effect of harvesting time, the fourth harvest had the highest gas production in comparison with other harvesting time. It could be better for cultivation by application of fertilizer and irrigation to get more forage yield and quality.

Diets selected and growth of steers grazing buffel grass (Cenchrus ciliaris cv. Gayndah)–Centro (Centrosema brasilianum cv. Oolloo) pastures in a seasonally dry tropical environment

Context Liveweight (LW) gain of grazing cattle in the seasonally dry tropics is usually moderate during the wet season (WS) and declines to slow growth or LW loss during the dry season (DS). Cattle growth can often be improved by inclusion of herbaceous legumes into pastures to improve their nutritional quality. Aims A study examined the quality of the diet selected and the growth of young cattle grazing a buffel grass (Cenchrus ciliaris)–Centro (Centrosema brasilianum) pasture in a high-rainfall, seasonally dry, tropical environment in northern Australia to relate the diet selected to cattle growth. Methods During three annual cycles, young steers grazed a grass–Centro legume pasture at moderate stocking rate. LW was measured monthly, and diet attributes (legume content, DM digestibility (DMD) and crude protein concentration) were measured fortnightly by near-infrared reflectance spectroscopy analyses of faeces. Pasture available and species were measured twice annually. Key results The annual LW gain and diet attributes followed a consistent profile through the annual cycles. Following the seasonal break, the diet DMD and crude protein concentration increased abruptly to maxima (means 732 and 184 g/kg respectively), and then declined approximately linearly during the remainder of the WS and the wet–dry transition season (TS); DMD decreased by 0.49, 0.74 and 0.88 g/kg units per day. DMD and crude protein averaged 561 and 61 g/kg respectively during the DS. Centro comprised 86–291 g/kg of the pasture on offer, and averaged 283 and 205 g/kg of the diet during the TS and DS, respectively, but only 58 g/kg during the WS. Cattle selected for Centro during the TS and the DS, but not during the WS. Cattle LW gain reflected diet quality averaging 0.86, 0.59 and 0.12 kg/day during the WS, TS and DS respectively. Conclusions The Centro legume contributed substantially to the diet of growing cattle during the TS and DS, but not during the WS. The LW gains of cattle were moderate during the WS and TS, and low during the DS. Implications Centro in a buffel grass pasture contributed substantially to the diet, but nevertheless annual LW gain was only modest (mean 179, range 159–209 kg/annum).

Phytosociology of the herbaceous-subshrub layer of a rupestrian complex in Serra do Espinhaço, Brazil

ABSTRACT Rupestrian complexes of the Serra do Espinhaco are recognized for their high degree of biodiversity and endemism. However, environmental impacts, particularly from mining, have degraded these environments. The purpose of this study was to describe the herbaceous-subshrub communities that occur in quartzitic (QRC) and ferruginous (FRC) rupestrian complexes in different seasons of the year, with regard to floristic similarity and phytosociological structure. Additionally, the study aimed to identify native species with potential use for the restoration of similar degraded areas. Vegetation was sampled from plots located in the municipality of Conceicao do Mato Dentro, state of Minas Gerais. Five contiguous strata of 10 × 50 m were demarcated in each environment, in which 12 plots of 2 × 1 m (2 m²) were randomly distributed, for a total of 60 plots (sample units) in each physiognomy. The studied communities exhibited few similarities and lower floristic diversity than other rupestrian complexes. Detrended correspondence analysis distinguished the communities of FRC from those of QRC. The species with the highest value of importance in FRC were Bulbostylis fimbriata and Centrosema brasilianum, while in QRC Echinolaena inflexa had the highest values, thus, making them eligible for restoration programs in similar environments.

EVALUATION OF VEGETABLE EXTRACTS FROM THE SEMI-ARID AS NATURAL pH INDICATOR

Given the various difficulties to expose the contents of the subject of chemistry is a constant search for alternative materials to facilitate learning. This may partly be due to chemical science to be a significant practical character. However, due to professional educational institutions and material limitations ends up being passed on to the student of predominantly theoretical way, requiring a high degree of abstraction and consequently in their disinterest the same. In this context , we investigated the use of ethanol extracts of various plants, such as: Jitirana (Ipomoea glabra ), Íxora (Ixora coccínea), Centro (Centrosema brasilianum) and Candlebush (Senna alata) flowers, Beet (Beta vulgaris L.) fruit and Urucum (Bixa orellana) seeds as an acids and bases natural indicator, from laboratory tests capable of identifying properties demonstrate the pH. Initially we evaluated the variation in the coloration of extracts using for this buffer solutions at pH 3, 7 and 12. Among the cited vegetable flowers Jitirana, ixora and Centro presented activities relevant indicator as staining variants between pH 2:13. The extracts of plants were further added in glass tubes containing buffer solutions with a pH ranging from 2 to 13. The change in color of the extracts showed good activity has the same pH indicator.

The voluntary intake in growing pigs of four ensiled forage species

Forage can potentially be food resource for pig feeding in the tropics. The palatability of silages by pigs may be better than that of fresh forage. Foliage silage contains more dry matter than green forage and has a pleasant smell. Thirty commercial pigs (47.0 ± 4.7 kg live weight LW), were used to assess the silage intake capacity of pigs when feeding the legumes Clitoria ternatea, Centrosema brasilianum, Cratylia argentea and the Brachiaria grass hybrid Mulato II. The silages were offered ad libitum as a supplement to a normal balanced diet based on maize and soy bean meal. A crossover design was applied comprising five treatments, Control and the four silage supplements respectively. Daily consumption of dry matter -expressed in g of DMkg-1 metabolic LW- were similar (p>0.05) for diets containing C. argentea, C. ternatea and the Control. Daily consumption of C. brasilianum and Brachiaria was significantly lower (p<0.001). In conclusion, C. argentea and C. ternatea silages have the potential to serve as feed supplement in pig diets.

Effect of five forage legume covers on soil quality at the Eastern plains of Venezuela

At the Eastern planes of Venezuela, large to tracts of pastureland are sustained by low fertility acid soils that often lead to overgrazing, decreased pasture production, invasion by weeds, and soil compaction and erosion. The objective of this study was to evaluate the behavior of local forage legume species and its influence on chemical and biochemical properties of soil with the ultimate goal of identifying which one of these species have the potential to be used as cover in the establishment of a “Ley farming” system. The study was conducted on an Oxisol and used five local species from the genus Centrosema ( Centrosema brasilianum, Centrosema macrocarpum, Centrosema pascuorum, Centrosema rotundifolium and Centrosema molle) which were established as cover for a period of 3 years. Dry matter (DM) and soil samples were collected twice a year, during the dry season (April) and during the rainy season (October). The soil parameters evaluated were total nitrogen, organic matter, calcium, potassium, magnesium, pH, soil respiration, and enzymatic activities that include β-glucosidase, arylsulphatase, phosphatase, urease, protease, dehydrogenase and catalase. The annual average data were used to identify indicators of soil quality through principal component analysis (PCA) that led to calculate a soil quality index (SQI). The results indicated that DM production varied among the different legume covers, showing C. macrocarpum the greatest productivity (1340 kg h −1). The PCA identified seven of the tested soil variables as quality indicators: total nitrogen, pH, calcium, soil respiration and arylsulfatase and β-glucosidase activities. Total nitrogen, P and β-glucosidase activity were the indicators showing the largest changes over time being able to discriminate between treatments. After the 3 year period of the trial the SQI of the soil tested raised from 0.17 (very low quality) to 0.30 (low quality) where C. brasilianun, C. pascuorum and C. molle were established and to 0.40 (moderate quality) where C. macrocarpum and C. rotundifolium were established. Thus, the legume crop covers influenced positively the soil quality. C. macrocarpum was the legume cover that showed the greatest soil improvement, having the best potential to be used as forage cover to establish a “Ley farming” system at the Eastern planes of Venezuela.

Effect of Fallow Species and Fallow Duration on Soil Fertility, Biomass and White Yam (Dioscorea rotundata Poir) Production

ABSTRACT Field experiments were conducted between 2003 and 2006 to study the effect of fallow species and fallow duration on biomass production, soil nutrient contents, weed control and yam production in Umudike, South Eastern Nigeria. The experiment was laid out as a split plot in a randomized complete block design (RCBD), with three replications. The main plot treatments were duration of fallow (1 and 2 years) and the sub plot treatments were eight legume cover crops (Aeschynomene histrix, Centrosema brasilianum, Centrosema pascuorum, Chamacrista rotundifolia, Mucuna georgia, Mucuna ghana, Pueraria phaseoloides and Stylosanthes guanensis) in comparison with natural fallow and natural fallow plus inorganic fertilizer (NPK Mg 12:12:17:2) at 400 kg ha−1. The yam variety used was Dioscorea rotundata (cv. Nwopoko). Biomass production was significantly higher in Stylosanthes guanensis than in the other cover crop species except Aeschynomene histrix at 6 and 12 months after planting (MAP). Stylosanthes guanensis also gave higher biomass than natural fallow at 3 and 4 MAP. Soil P and K were significantly higher after Mucuna ghana than after other legumes and natural fallow. Soil N and P were significantly higher with one than with 2 years of fallow. Weed biomass was consistently lowest in Stylosanthes guanensis than in other legume cover crops except with Chamacrista rotundifolia, Mucuna ghana and Pueraria phaseoloides at 4 MAP and Aeschynomene histrix at 12 MAP. Yam tuber yields obtained with Centrosema brasilianum after 2 years of fallow was significantly higher than the yield obtained with each of the other fallow species and duration except with Aeschynomene histrix after one-year fallow and Centrosema brasilianum, Mucuna georgia and Mucuna ghana after two-year fallow.

Potentials of covercrops for sustainable short fallow replacement in low-input systems of maize production in the humid tropics

A field experiment was conducted from 1999 to 2003, in which the growth of eleven green manure covercrops were studied for biomass production at Umudike, in the humid tropics of south eastern Nigeria. The covercrops were turned into the soil as green manures after three years of fallow and compared with grass cover and NPK fertilizer for production of two maize varieties. Treatments comprised Chamacrista rotundifolia, Pueraria phaseoloides, Aeschynomene histrix, Centrosema pascuorum, Centrosema brasilianum, Stylosanthes capitata, Mucuna pruriens, Mucuna deeringiana, Mucuna veracruz, Crotolaria ochroleuca, Lablab purpureus , natural grass cover and NPK fertilizer. Maize (Zea mays L.) varieties consisted of FARZ-23-Y and TZBR Eldana 2C 3 -W. All possible combination of the maize varieties and the manure treatment were laid out in a randomized complete block design with three replications. Mucuna deeringiana and Mucuna Veracruz gave the significantly highest biomass 3 months after planting in the establishment year. However, Aeschynomene histrix produced the significantly highest biomass 3 years after planting. Mucuna pruiens, Crotolaria ochroleuca and Lablab purpureus did not persist in competition with the native vegetation. Aeschynomene histrix fallow produced significantly higher maize dry matter yield than Centrosema pascuorum, Centrosema brasilianum, Lablab purpureus and grass cover but not other treatments. Average grain yields ranged from 1260.4kg/ha in Mucuna pruriens to 2399.4kg/ha in Aeschynomene histrix fallow in 2002 and from 640.7kg/ha in Lablab purpureus to 1428.2kg/ha in Stylosanthes capitata fallow in 2003. In 2002, grain yields obtained with Aeschynomene histrix improved fallow were statistically similar to those obtained with Chamaecrista rotundifolia, Centrosema brasilianum and NPK fertilizer treatment, but significantly lower in other cover crop fallows. There were generally no statistically significant effects of variety and its interaction with cover crops on maize crop growth and yields. Keywords : cover crops, short fallow, maize, humid tropics Global Journal of Agricultural Sciences Vol. 4(2) 2005: 113-118

Assessment Of Tropical Grasses And Legumes For Phytoremediation Of Petroleum-Contaminated Soils

Phytoremediation is a promising technology for the clean-up of petroleum-contaminated soils, especially in the tropics where climatic conditions favour plant growth and microbial activity and where financial resources can be limited. The objective of this work was to identify tropical plant species from the eastern savannahs of Venezuela suitable for this technology. Three legumes (Calopogonium mucunoides, Centrosema brasilianum, Stylosanthes capitata) and three grasses (Brachiaria brizantha, Cyperus aggregatus, Eleusine indica) were tested for their ability to stimulate microbial degradation in soil contaminated with 5% (w/w) of a heavy crude oil. In greenhouse experiments, plant biomass production and oil dissipation (total oil and grease, and fraction composition) were analysed after 90 and 180 days incubation. Although previously tested on their tolerance to oil contamination, the legumes died within six to eight weeks. The grasses showed reduced biomass production under the influence of the contaminant. Relative growth rates were higher in contaminated soil indicating a delay in plant growth patterns and development. Soil planted with B. brizantha and C. aggregatus showed a significantly lower oil concentration than non-vegetated soil. Furthermore, a positive correlation between root biomass production and oil degradation was found. Concentration of saturated hydrocarbons was always lower in planted than in unplanted soil. B. brizantha also caused a considerable reduction of aromatics. Based on these results, B. brizantha is recommended for follow-up investigations which could further develop the application of phytoremediation of petroleum-contaminated soils in the tropics.

Soil water depletion under various leguminous cover crops in the derived savanna of West Africa

Leguminous cover crops have the potential of making cropping systems in the tropics sustainable if they would not deplete resources such as soil water and nutrients to the detriment of companion crops. Therefore, a study was carried out at Alabata, Ibadan, southwestern Nigeria, to evaluate the effects of leguminous cover crops on soil water suctions in 1993 and 1994 in order to assess the possibility of integrating them into the farming systems of the savanna zone of West Africa. In 1993, 13 leguminous cover crops ( Aeschynomene histrix, Centrosema brasilianum, Centrosema pascuorum, Chamaecrista rotundifolia, Cajanus cajan, Crotalaria verrucosa, Crotalaria ochroleuca, Lablab purpureus, Mucuna pruriens, Psophocarpus palustris, Pseudovigna argentea, Pueraria phaseoloides and Stylosanthes hamata) were planted in a randomized complete block design with four replications . Maize and natural fallow (mainly Chromolaena odorata and Imperata cylindrica) were included as comparisons. Only six of the legumes ( A. histrix, C. pascuorum, C. cajan, C. ochroleuca, M. pruriens, and P. phaseoloides) were included in the measurements in the 1994 new plots. Soil water suctions at various stages of legume growth were measured at daily or weekly intervals (depending on the frequency of rainfall events) using tensiometers installed at 0–15 and 15–30 cm soil depths. Soil water suctions exceeding 10 kPa (theoretical field capacity) were observed mainly between 6 and 12 weeks after planting (WAP), and by 20 WAP when cover crops had matured and rainfall frequency was very low. Soil water suctions were significantly related ( r 2>0.80) to dry matter between 8 and 10 WAP. The studied cover crops were classified in three groups which can be used as a guide for choosing the legumes in tropical farming systems. Soil water depletion was markedly influenced by growth characteristics of legumes and distribution of rainfall during the rainy season. Leguminous cover crops conserved soil water after their growth needs were satisfied.

RELATIVE PALATABILITY AND SEASONAL AGRONOMIC PERFORMANCE OF SELECTED PASTURE LEGUMES FOR SPECIES MIXTURES IN DRY-SUBHUMID WEST AFRICA

Relative palatability and some agronomic traits were studied for nine legumes including Aeschynomene histrix, Centrosema brasilianum (two accessions), Centrosema pascuorum, Chamaecrista rotundifolia, Stylosanthes guianensis (two accessions) and Stylosanthes hamata (two accessions). All species were consumed by cattle but the relative palatability varied according to season. Only the two S. guianensis accessions were positively selected throughout the year. A positive relationship was established between the ability to retain green leaves in the dry season and palatability. Once established, the two C. brasilianum accessions out-performed the other legumes in their ability to stay green and retain leaves in the dry season; related to the ability to retain green leaves under drought conditions, C. brasilianum ILRI 155 was among the most palatable legumes in the dry season. S. guianensis accessions had the highest dry matter (DM) yields and one of them (ILRI 15557) had the highest nutritive value. In contrast with earlier results in the same environment, C. rotundifolia and A. histrix performed poorly in terms of DM productivity. The implications of the agronomic characteristics of the legumes for the management of legume-based pastures in crop/livestock systems are discussed and the concept of legume–legume mixtures, composed of several compatible species, is advocated.

Nitrogen fertilizer replacement indexes of legume cover crops in the derived savanna of West Africa

Legume cover crops are a potential means for overcoming N depletion in the derived savanna of West Africa. A 3-year trial was, therefore, conducted near Ibadan, southwestern Nigeria to measure the N contribution of 13 legume cover crops as compared to urea –N, using a N fertilizer replacement index for a maize test crop. Two series of trials involved the following legume cover crop species: Aeschynomene histrix, Centrosema brasilianum, Centrosema pascuorum, Chamaecrista rotundifolia, Cajanus cajan, Crotalaria verrucosa, Crotalaria ochroleuca, Lablab purpureus, Mucuna pruriens, Psophocarpus palustris, Pseudovigna argentea, Pueraria phaseoloides and Stylosanthes hamata. Trials were undertaken using a complete block design. Cover crops were planted in 1994 (Series 1) and 1995 (Series 2) in separate sites and each series was subsequently slashed and planted for one season with maize (Zea mays) in 1995 and 1996. At the 50% flowering stage, N concentration of above-ground vegetation of cover crops ranged from 21 to 38 g N kg−1. Nitrogen accumulated by 4.5-month old cover crops ranged from 14 to 240 kg N ha−1, depending on species and year. Cover crops increased grain yield of the subsequent maize crop by 25–136% over the control without N application. Nitrogen uptake by the maize crop was higher following cover crops than after maize or natural grass. The N fertilizer replacement index of cover crops for maize ranged from 11 (A. histrix) to 96 kg N ha−1 (C. cajan) in Series 2. Perennial (C. brasilianum, S. hamata, C. cajan, P. phaseoloides and C. verrucosa) and annual (C. rotundifolia, M. pruriens, C. ochroleuca and L. purpureus) species could potentially save 50 to 100 kg N ha−1 for maize crops. The cover crops accumulated more N in the wetter than in the drier year. However, the N fertilizer replacement index was higher for subsequent maize grown in the drier year. The cover crop-N recovery in maize was also higher than the urea-N uptake in the drier year. The N fertilizer replacement indexes can be predicted using the above-ground biomass amount of cover crops at 20 weeks after planting (drier year) or the N concentration at that stage (wetter year).

EFFECTS OF SOIL FERTILITY AND FERTILIZER APPLICATION ON BIOMASS AND CHEMICAL COMPOSITIONS OF LEGUMINOUS COVER CROPS

The biomass and chemical compositions of selected leguminous cover crops Aeschynomene histrix, Cajanus cajan, Centrosema brasilianum, Centrosema pascuorum, Chamaercrista rotundifolia, Crotalaria verrucosa, Lablab purpureus, Psophocarpus palustris, Pseudovigna argentea, Mucuna pruriens, Pueraria phaseoloides, and Stylosanthes hamata were studied in a pot experiment, using soil with two fertility levels. Biomass yield responded to soil fertility levels and fertilizer application. The highest response to soil fertility was observed with C. brasilianum (340%, 200% and 310% more shoots, roots and nodules in high fertility soil than low fertility soil without fertilizer application). The highest response to fertilizer application was with P. palustris (500% more shoots with fertilizer than without in high fertility soil), with C. rotundifolia (410% more roots with fertilizer than without in low fertility soil), and with L. purpureus (1330% more nodules with fertilizer than without on high fertility soil). Legumes grown without fertilizer application allocated more biomass to roots than those with fertilizer application. Chamaercrista rotundifolia, L. purpureus, P. argentea, M. pruriens and C. cajan showed higher N content in roots than in shoots. Soil fertility levels did not affect N content of shoot, while fertilizer application increased it by 30%. Except for C. cajan (only shrub species), all the herbaceous legumes had lower lignin content (6–10%) in the shoots. The mean lignin content in roots was above 20% with no fertilizer, and decreased with fertilizer application compared to the no fertilizer treatment. The polyphenol concentration in shoots was higher than in roots.

Effect of seed size and phosphorus fertilization on growth of selected legumes

A screenhouse experiment was conducted to assess the effects of seed size and phosphorus (P) fertilization on growth of 12 herbaceous and shrub legumes [Arachis hypogaea, Cajanus cajan, Centrosema pascuorum, Centrosema brasilianum, Crotolaria ochroleuca, Glycine max, Lablab purpureus, Mucuna cochinchinensis, Mucuna pruriens var. utilis (black seed), Mucunapruriens (white seed), Pueraria phaseoloides and Vigna unguiculata] grown on a P‐deficient Plinthustalf. Species with large seed size showed higher biomass accumulation, nodulation and higher plant nutrient element content. However, response to P fertilization was higher in small size seeded species. Plant top dry weight was highly correlated with seed weight and seed nutrient element contents. Although P application significantly increased nitrogen (N), P, potassium (K), calcium (Ca), and magnesium (Mg) contents of plant tops, high rate of P fertilization appeared not to be beneficial to the early growth of the species tested on this P‐deficient soil. The use of large seed size with high seed nutrient element contents is highly recommended for fast establish ment of fallow legume species intended for use in production systems on P‐deficient soils.

Phosphorus requirement and nodulation of herbaceous and shrub legumes in low P soils of a Guinean savanna in Nigeria

There is increasing interest to improve the N 2 fixation and P use efficiency of herbaceous and shrub legumes currently being introduced in cereal-based cropping systems in the moist savanna zones of West Africa. Knowledge about N and P nutrition of these legumes can assist in adapting them to new areas where fertilizer use is not feasible by the smallholder farmers. Pot and field experiments were carried out to examine variation among potential herbaceous and shrub legumes for their ability to nodulate and to use P efficiently. These legumes were grown at two P levels (0 and 7 kg P ha −1) in soils collected from two fields with different cropping histories (compound and degraded fields) at Yamrat in the northern Guinea savanna of Nigeria. In the compound field, animal manure and household residues are applied annually whereas in the degraded field, cereals are grown continuously with minimal organic inputs. Significant differences in growth, P content and mycorrhizal infection rate occurred among the different legumes as affected by P and cropping history. Legumes grown in soil from the degraded field responded more to P application than those grown in soil from the compound field. Phosphorus responsive legume species e.g. Mucuna pruriens var. utilis (black seed) and Crotolaria ochroleuca, had a low mycorrhizal infection rate compared to lower P responsive species such as Lablab purpureus and Cajanus cajan. A significant relationship was found between mycorrhizal infection rate and plant growth but not with nodulation of these legumes. All legumes nodulated naturally and the proportion of N derived from atmospheric N 2 ranged from 38% for Centrosema brasilianum to 90% for L. purpureus. Application of P increased the weight of nodules but did not improve the proportion of N 2 fixation. This study showed that species such as L . purpureus has a high N 2 fixing capability and can also adapt to low P soils conditions in the northern Guinea savanna of West Africa.

Regeneration of plants from callus tissue of the pasture legume Centrosema brasilianum

Plants were regenerated from leaf explants of Centrosema brasilianum cultured in vitro. Callus and buds were produced on Murashige and Skoog medium (MS), 0.8% agar, 0.1 mg/l NAA and 1 mg/l BAP. Regeneration of multiple shoots was achieved by transferring callus onto fresh medium containing 0.01 and 1 mg/l of NAA and BAP, respectively. Shoots formed roots upon transfer to MS with 0.01 mg/l NAA. Plantlets were succesfully transferred to soil. Leaf-derived calli of Centrosema arenarium, C. macrocarpum, C. pascuorum, C. pubescens, and C. virginianum did not produce shoots when cultured in vitro.