Tephrosia Vogelii Hook Research Articles

Effectiveness of Packaging Integrated with Plant Extracts in Controlling Maize Weevil <i>Sitophilus zeamais</i>

Maize weevil Sitophilus zeamais is one of the storage pests that compromise both quality and quantity of stored maize grains. In Malawi, most smallholder farmers use botanicals like Tephrosia vogelii Hook and Lantana camara to manage S. zeamais. This study was conducted to investigate the effectiveness of packaging integrated with plant extracts in controlling this pest. Ziploc bags, paper cartons, grass jars, paper envelopes and polyethylene terephthalate (PET) water bottles are the common packaging and storage materials for these botanical pesticides used by small holder farmers. This study involved preliminary experiments in which plant extracts within packaging materials were tested, for their efficacy against S. zeamais for five months. PET water bottle provided significant (p<0.01) control over other treatments to store the maize seeds against S. zeamais. Thereafter, the effect of botanicals packaged and stored for one month in PET water bottle was studied on grain damage caused by the weevils. The inhibition effect of the botanicals on grain damage was significant (p<0.01). This study obtained vital information that can be utilized by farmers as a sustainable way to manage storage pests.

Analysis on safety assessment of Tephrosia vogelii Hook to Apis cerana cerana

Tephrosia vogelii Hook was excellent insecticidal plant, it was introduced into China and planted over a large area in Guangdong province. The main active components of T. vogelii was rotenone and it widely found in leaves and pods of T. vogelii. This paper study of the safety assessment of T. vogelii flowers to worker bees. In this paper, the content of rotenone in T. vogelii petal, nectar, pollen, pistil, and stamen samples were investigated by HPLC, and tested the toxicity of T. vogelii flowers for Apis cerana cerana during 24 h. The dissipation and dynamic of rotenone in A. c. cerana different biological compartments were investigated under indoor conditions during 24 h. The results showed, The LT50 of T. vogelii flowers to worker bees were collected from the eastern, western, southern, northern and top were 13.95, 24.17, 12.55, 26.48, and 18.84 h, the haemolymph of worker bees have the highest content of rotenone, the least accumulation of rotenone in workers bee's thorax, and the rate of dissipation was slowly during the whole study. In conclusion, the results showed the T. vogelii create security risks to worker bees under some ecosystems.

Brown Stink Bug Mortality by Seed Extracts of Tephrosia Vogelii Containing Deguelin and Tephrosin

ABSTRACT Extracts of the seeds of Tephrosia vogelii Hook. f. were studied in relation to its chemical composition and toxicity to the brown stink bug Euschistus heros (F.). The extracts were obtained in ethyl acetate and ethanol in the sequence according to the polar nature of the solvents. Extracts were sprayed in concentration of 1.0, 2.5, 5.0, 7.5 and 10% on third-instars nymphs and adults, and mortality was recorded. Presence two rotenoids in ethyl acetate was detected, with analyzed with gas chromatography-mass spectrometry (GC-MS). Crude fraction analyses confirmed the presence of these rotenoids (tephrosin - 2.71% in ethyl acetate and 3.66% in methanol; and deguelin - 10.46% in ethyl acetate and 1.22% in methanol) and three other rotenoids in small amounts. Eight days after applications, ethyl acetate caused more stink bugs mortality and on less time than ethanol extract, because great quantity of rotenoids, as polarity. Concentrations above to 1 and 2.5% of the ethyl acetate extracts caused mortality above 80% of the nymphs and adults of E. heros, respectively. Concentration were considered high, thus chemist analyzes demonstrated high rotenoids presence. In conclusion, seed T. vogelli extracts, rich in deguelin and tephrosin (3:1), cause mortality of E. heros, however, high concentration are necessary.

EFIKASI INSEKTISIDA NABATI EKSTRAK DAUN Tephrosia vogelii Hook. TERHADAP Crocidolomia pavonana (F.) dan Plutella xylostella (L.) SERTA PENGARUHNYA PADA Diadegma semiclausum (Hellen)

[EFICATION OF BOTANICAL INSECTICIDE OF Tephrosia vogelii Hook. f. LEAF EXTRACT AGAINTS Crocidolomia pavonana (F.) AND Plutella xylostella (L.) AND ITS EFFECT TO Diadegma semiclausum (Hellen)]. The active fraction of hexane extract of Tephrosia vogelii (Tv) leaves was evaluated for this insecticidal activity on second-instar larvae of Crocidolomia pavonana and Plutella xylostella as well as for the safety to the adults of Diadegma semiclausum parasitoid. Fraction (fr) 2-4 of Tv from column chromatography (CC) had strong insecticidal activity on C. pavonana and P. xylostella. In the test with C. pavonana, the fraction was more active by feeding than by contact. Based on LC50 at 72 hours since treatment (HST), fr 2-4 CC Tv was 1.8 times more toxic to P. xylostella than to C. pavonana. The fr 2-4 CC Tv showed strong antifeedant effect against C. pavonana larvae. At equal test concentrations, the treatment with fr 2-4 CC Tv caused much lower mortality in D. semiclausum parasitoid adults than in its host larvae, P. xylostella. In contrast, an organophosphate profenofos, included in this study as a positive control, was much more detrimental to D. semiclausum than to P. xylostella. In the semifield experiment, fr 2-4 CC Tv had comparable effect with profenofos and bioinsecticide Bacillus thuringiensis in reducing the population of C. pavonana larvae on broccoli plants.

Comparative Efficacy of Insecticidal Plants on the Management of Groundnut Bruchid (Caryedon Serratus)

Laboratory study was conducted to determine the efficacy of insecticidal plant extracts Azadirachta indica A. (Juss), Lantana camara L. (Verbenaceae), Eupatorium odoratum L. (Asteraceae), Tephrosia vogelii Hook, Afromomum melegueta K.M. (Schumann) and Ocimum gratissimum (L) leaves against groundnut bruchid beetle (Caryedon serratus), and a synthetic insecticide (Cypermethrin) (10EC)) under ambient condition of temperature and relative humidity (30°C and 72%). One hundred grams of shelled groundnut was weighed into jute bags and treated with powders of the insecticidal plants. Both treated and untreated bags of groundnut were then infested with newly emerged adult of C. serratus (20 per bag) and covered. The experiment was laid out in Completely Randomized Design (CRD) and replicated four times. Parameters assessed included number of egg oviposited, number of eggs hatched (eclosion) and number of adults that emerged from each treatment, total developmental period (egg – adult), sex ratio of the emerged adults and finally percentage germination of the treated seeds. Data collected were analyzed using analysis of variance and treatment means were separated using Duncan multiple range tests at P ≤ 0.05 level of significance. Results showed that A. indica, L. camara, T. vogelli, A. melegueta and O. gratissimum treated seeds significantly recorded lowest mean number of eggs, reduced damage by C. serratus and increased germination percentage compared with E. odoratum and control. In conclusion, A. indica, L. camara, T. vogelli, A. melegueta and O. gratissimum have the potentials as alternatives to synthetic insecticides in the management of C. serratus by resource poor farmers.

English

Essential oils are complex mixtures of odours and steam volatile compounds which are deposited by plants in the subcuticular space of glandular hairs, in excretory cavities and canals or exceptionally in heart wood. Essential oils have been found to have no specific biological functions in plants, but constitute many compounds that are insect repellents or act to alter insect feeding behavior, growth and development, ecdysis (moulting) and behavior during mating and oviposition. Others possess antifungal, insecticidal and antiseptic properties. Essential oils of leaves of Tagetes minuta L. (Asteraceae), Fuerstia africana T.C.E. Friers (Labiaae), Tephrosia vogelii Hook. f. (Leguminosae) and Sphaeranthus ukambensis were obtained by steam distillation using the Clevenger apparatus (Guenter, 1949). Compounds in the essential oils were identified by gas chromatography-mass spectrometry (GC-MS). The characteristic volatiles isolated from the four plants were identified as follows: major constituents of the essential oils from F. africana included the following: limonene (39.1%), (Z)-β-ocimene (30.5%), targetone (26.2%), E -targetone (59%), λ-terpinene (26.2 %), peripitenone 23.7%, ocimene allo (22.8%) and Z-targetone (100%). The compounds with the highest relative abundance value in the essential oils included Z-targetone, E-targetone and (Z)-β-Ocimene. Analysis of T. minuta also revealed a number of compounds which included mycene (20.1%), verbinene (8.0%), Z-ocimenone (35.2%), E-caryophylene (25.5%), α-Humelene (11.8%), germacrene D (21.4%) and camphene (2%). The major constituent of T. minuta was Z-ocimene, caryophylene E and mycene. Essential oils from T. vogelii as revealed by the GC-MS analysis were pinene α (32.7%), limonene (35.1%), copaene α (22.9%), β -elemene (36.7%), Z-nerolidol (77.7%), δ-cadinene (67.6%), α humelene (69.6%) and -4-α-ol-(β)copaene (65.7%). The highest proportion of the essential oils constituted Z- nerolidol δ-cadinene, α-humelene and 4-α-ol-β. Copaene. The compounds in essential oils obtained from S. ukambensis were α-copaene (23.8%), β-bourbonene (25.5%), α-gurjunene (14.3%), cymene<2, 5-dimethoxy-para (87.7%), α -humelene (100%), λ- muurolene (17.9%), λ-cadinene (77.3%), caryophylene oxide (54.7%) and δ-cadinene (61.9%). The major compounds contained in essential oils from S. ukambensis were α-humele, λ-cadinene, δ-cadinene and cymene<2, 5-dimethoxy-para. The compounds which were common in the four test plants included: α-pinene, α-humele, ocimene allo and (E) β-ocimene. Each of the test plant secreted essential oils constituting numerous volatiles known to exhibit acaricidal, insecticidal and/or arthropod repellent properties. These plants may be useful sources of compounds for use in the control of arthropods of medical, veterinary and agricultural importance. Key words: Essential oils, GC-MS, Tagetes minuta, F. africana, T. vogelii, S. ukambensis

COMPARATIVE EFFICACY OF INSECTICIDAL PLANTS ON THE MANAGEMENT OF GROUNDNUT BRUCHID (CARYEDON SERRATUS)

Laboratory study was conducted to determine the efficacy of four insecticidal plant extracts Azadirachta indica A. Juss., Lantana camara L. (Verbenaceae), Eupatorium odoratum L. (Asteraceae), Tephrosia vogelii Hook against the groundnut bruchid beetle (Caryedon serratus), and a synthetic insecticide (Cypermethrin) (10EC)) under ambient condition of temperature and relative humidity (30°C and 72%). Two hundred grammes of unshelled groundnut was weighed into jute bags and treated with powders of the insecticidal plants. Both treated and untreated bags of groundnut were then infested with newly emerged adult of C. serratus (20 per bag) and covered. The experiment was laid out in a Completely Randomized Design (CRD) with four replications. Parameters assessed included number of egg oviposited, number of eggs hatched (eclosion) and number of adults that emerged from each treatment, total developmental period (egg – adult), sex ratio of the emerged adults and finally percentage germination of the treated seeds. Data collected were analyzed using analysis of variance and means were separated using Duncan multiple range tests at 5% level of significance. The lowest mean number of eggs was laid in A. indica, L. camara and T. vogelli treated seeds compared with the control which recorded the highest number. Similarly, results obtained showed that L. camara, T. vogelii, and A. indica powder significantly reduced damage by C. serratus and increased germination percentage compared with E. odoratum and control. In conclusion, L. camara, T. vogelii, and A. indica have the potentials as alternatives to synthetic insecticides in the management of C. serratus by farmers.

Toxicity and repellent effects of leaf extracts of four Kenyan plants against nymphs and adults of Rhipicephalus appendiculatus (Neuman 1901)

Ticks are important arthropod vectors of diseases of man and farm animals in Africa and in spite of the efforts to control them using synthetic acaricides, they continue to be amongst the leading vectors of disease-causing agents. Unfortunately, over-reliance on synthetic acaricides for tick control has led to problems including acaricide resistance, environmental pollution, and acaricide residues in products destined for human consumption. These problems highlight the need for alternative tick control methods that are environment friendly and yet effective. In the current study, the repellency and toxic effects of essential oils extracted from four Kenyan plants namely;Tagetes minuta L.(Asteraceae), Fuerstia. africana T.C.E. Friers (Lamiaceae), Tephrosia vogelii Hook. f. (Leguminosae) and Sphaeranthus ukambensis against the ixodid tick Rhipicephalus appendiculatu were determined. Essential oils were extracted by steam distillation from fresh plants using Clevenger apparatus. Host seeking nymphs (2-3 weeks old)and adult ticks were used and fumigant toxicity bioassay was done using four concentrations (0.1µ/ml, 0.01 µ/ml, 0.001 µ/ml, and 0.0001µ/ml) of the essential oils, each in four replicates and with ten ticks per replicate. In the control experiment, ticks were exposed to n- hexane. Mortality was recorded every 48 hours for 2 weeks. In repellency bioassay, a Y tube olfactometer and same concentrations as above were used. Treated paper discs were placed in one arm and control (discs treated with hexane) in the other. Ticks were introduced at the main arm and allowed to make choices on the direction of movement. Ticks on the two arms were counted after 30 minutes. The essential oils showed dose dependant mortality and repellency values. The highest repellency value for R. appendiculatus adults was observed with T. vogelii (93.8% at 0.01µ/ml) while for the nymphs, both S. ukambensis and T. vogelii recorded the highest repellency values of 100% and 95% respectively both at 0.1µ/ml concentration. Essential oils from Fuerstia. africana recorded the highest mortality values for nymph (97.8% at 0.1µ/ml) and adult (53.2 % 0.1µ/ml) Rhipicephalus appendiculatus . The present study has demonstrated that Tephrosia vogelii, Tagetes minuta and Sphaeranthus ukambensis have repellent and toxic effects on Rhipicephalus appendiculatus and therefore can

Distinct chemotypes of Tephrosia vogelii and implications for their use in pest control and soil enrichment

Tephrosia vogelii Hook. f. (Leguminosae) is being promoted as a pest control and soil enrichment agent for poorly-resourced small-scale farmers in southern and eastern Africa. This study examined plants being cultivated by farmers and found two chemotypes. Chemotype 1 (C1) contained rotenoids, including deguelin, rotenone, sarcolobine, tephrosin and α-toxicarol, required for pest control efficacy. Rotenoids were absent from chemotype 2 (C2), which was characterised by prenylated flavanones, including the previously unrecorded examples (2S)-5,7-dimethoxy-8-(3-hydroxy-3-methylbut-1Z-enyl)flavanone, (2S)-5,7-dimethoxy-8-(3-methylbut-1,3-dienyl)flavanone, (2S)-4′-hydroxy-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone, (2S)-5-methoxy-6″,6″-dimethyl-4″,5″-dihydrocyclopropa[4″,5″]furano[2″,3″:7,8]flavanone, (2S)-7-hydroxy-5-methoxy-8-prenylflavanone, and (2R,3R)-3-hydroxy-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone. The known compounds (2S)-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone (obovatin 5-methyl ether) and 5,7-dimethoxy-8-(3-hydroxy-3-methylbut-1Z-enyl)flavone (Z-tephrostachin) were also found in C2. This chemotype, although designated Tephrosia candida DC. in collections originating from the World Agroforestry Centre (ICRAF), was confirmed to be T. vogelii on the basis of morphological comparison with verified herbarium specimens and DNA sequence analysis. Sampling from 13 locations in Malawi where farmers cultivate Tephrosia species for insecticidal use indicated that almost 1 in 4 plants were T. vogelii C2, and so were unsuitable for this application. Leaf material sourced from a herbarium specimen of T. candida contained most of the flavanones found in T. vogelii C2, but no rotenoids. However, the profile of flavonol glycosides was different to that of T. vogelii C1 and C2, with 6-hydroxy-kaempferol 6-methyl ether as the predominant aglycone rather than kaempferol and quercetin. The structures of four unrecorded flavonol glycosides present in T. candida were determined using cryoprobe NMR spectroscopy and MS as the 3-O-α-rhamnopyranosyl(1→6)-β-galactopyranoside-7-O-α-rhamnopyranoside, 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside, 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside-7-O-α-rhamnopyranoside, and 3-O-α-rhamnopyranosyl(1→2)[(3-O-E-feruloyl)-α-rhamnopyranosyl(1→6)]-β-galactopyranosides of 6-hydroxykaempferol 6-methyl ether. Tentative structures for a further 37 flavonol glycosides of T. candida were assigned by LC–MS/MS. The correct chemotype of T. vogelii (i.e. C1) needs to be promoted for use by farmers in pest control applications.

Fatty acid composition of seed oils from selected wild plants of Kahuzi-Biega National Park and surroundings, Democratic Republic of Congo

Oils were extracted from seeds of Carapa grandiflora Sprague (Meliaceae), Carapa procera DC. (Meliaceae) , Cardiospermum halicacabum Linn (Sapindaceae) , Maesopsis eminii Engler (Rhamnaceae) , Millettia dura Dunn (Fabaceae) , Myrianthus arboreus P. Beauv. (Cecropiaceae) , Myrianthus holstii Engl. (Cecropiaceae) , Pentaclethra macrophylla Benth (Mimosaceae) , Podocarpus usambarensis Pilger (Podocarpaceae) , Tephrosia vogelii Hook. (Fabaceae) and Treculia africana Decne (Moraceae) collected from a forest in Kahuzi-Biega National Park and the surrounding areas in Democratic Republic of Congo. Fatty acids in the oils were determined by gas chromatography to detect potential sources of various quality oils. Twenty-four fatty acids were detected in the seed oils and the most abundant were palmitic (16:0), stearic (18:0), oleic (18:1n9), linoleic (18:2n6) and α-linolenic (18:3n3) acids. Four fatty acids with trans double bonds and two fatty acids with non-methylene separated double bonds were detected in oils from C. halicacabum, M. dura and T. vogelii . There were remarkable occurrences of very long chain fatty acids, particularly lignoceric and behenic acids. M. eminii, P. usambarensis, T. vogelii and M. dura seed oils have potential for use in foods because of the contents of essential fatty acids. The oils from C. grandiflora, C. procera, M. arboreus, M. holstii and P. usambarensis showed a high potential for use in the cosmetic industry due to their fatty acids profile and high unsaponifiable matter content.

In-situ Fertilizer Industry for Small Scale Farmers: The Case of Tephrosia vogelii Fallow and Minjingu Phosphate Rock in Eastern Tanzania

Tephrosia vogelii Hook. f. is among the best leguminous shrubs in enhancing soil fertility especially in improvedfallow situations in eastern and southern Africa. The objective of this study was to assess the influence of Minjinguphosphate rock (MPR) application and prevailing weather on survival, dry matter, N and P accumulations ofTephrosia vogelii fallow, and maize yields in subsequent season. Tephrosia vogelii fallow was grown for 22 monthson acidic P deficient ferralsol amended with 0 or 80 kg P ha-1 at fallow establishment. The survival of T. vogeliiplants was monitored over 22 months. Fallow nutrient accumulation was assessed by measuring the quantityand quality of litter commencing at 12 months. The quality of leaves was monitored from 6, 12, 18 and 22 months,while the quantity and quality of stems were assessed at 22 months. Foliar quantity was measured at 22 months.Long dry season significantly (p &le; 0.05) reduced survival by about 50% in the first 6 months and up to 80% at 22months. Litter dry weight and stem biomass, were significantly increased (p &le; 0.05) by MPR application. Foliar Pconcentration was significantly increased by P application up to 12 months only. The total N and P accumulatedin the litter and stems during the 22 months were significantly increased (p &le; 0.05) by MPR application. In the 22months period, the total N accumulated in the three plant components were 65.7 and 133.5 kg ha-1 for control andMPR treated plots, respectively. The corresponding values for P were 3.4 and 11.3 kg ha-1. These accumulations ledto improvement of maize yields in the subsequent season by 147% relative to natural fallow. Improved fallows ofT. vogelli can be used as In-situ fertilizer industry for small scale farmers in the tropics.

Ethno-medical and veterinary uses of &lt;i&gt;Tephrosia vogelii&lt;/i&gt; hook. F.: a review

All parts of Tephrosia vogelii Hook. f. (Fabaceae) is used in tropical Africa for numerous ethno-medical and traditional veterinary practices. The leaf is ichthyotoxic and has been used as insecticide, rodenticide and anthelminthic. It has also been used as abortifacient and to induce menses. The leaf macerate is purgative and emetic, while the sap is used to treat diarrhoea. The leaf-sap and root scrapings are used as ear and tooth ache remedies, respectively. Extracts from the roots have been used as molluscicide. The plant extracts have also been used in the treatment of tuberculosis, typhoid fever and localized fungal infections. The biological activities are due mainly to rotenoids isolated from the plant. In conclusion, T. vogelii has a great potential in the therapy and prophylaxis of animal and human diseases. Nigerian Veterinary Journal Vol. 28 (3) 2007 pp. 24-39

Insecticidal Effects of Tephrosia. vogelii Hook (Leguminosae) Leaf Powder and Extracts on Sitophilus zeamais Motsch, Callosobruchus macuIatus F. and Tribolium castaneum Herbst.

Laboratory bioassays were conducted to investigate the effects of the powder, aqueous and ethanol extracts of Tephrosia vogelii Hook leaf on Sitophilus zeamais Motsch (Curculionidae), Callosobruchus maculatus F. (Bruchidae) and Tribolium castaneum Herbst (Tenebrionidae) in the laboratory at 30 ± 1 -c and 70 ± 2 % RH. Mortality data were recorded and probit analysis run to determine the toxicity of the various formulations. The results showed that the extracts were more toxic to each of the test insect species than the leaf powder. The LC50 values obtained for the powder were 10.13 g/kg for C. maculatus; 19.82 g/kg for S. zeamais and 6.85 g/kg for T castaneum. The LC50 values obtained for the ethanol extract were 0.037 g/L for C. maculatus, 0.071 g/L for S. zeamais and 0.08 g/L for T castaneum while for the aqueous extract the LCso values were 1.209 g/L for C. maculatus, 0.744 g/L for S. zeamais and 2.025 g/L for T. castaneum. C. maculatus was the most susceptible of the three test insect species to the ethanol extract. The results indicate that T. vogelii leaf products could be used to protect cowpea, maize or groundnut against C. maculatus, S. zeamais and T. castaneum infestation during storage.

The role of maize-legumes-cassava intercropping in the management of maize ear borers with special reference to Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae)

The effects of intercropping maize with cowpea, lima bean, soybean, three leguminous cover crops (Tephrosia vogelii Hook F., Canavalia ensiformis L., Sesbania rostrata Bremek. & Oberm.) and cassava on the infestation of Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae) and other lepidopteran ear borers were studied. Field experiments were conducted in four locations in Benin using a 4x2 pattern of maize-legumes or maize-cassava planting. Intercropping reduced the number of eggs (by >25%) and larvae (by 17.9–53%) of M. nigrivenella compared with the monocrop. Maize-C. ensiformis and maize-T. vogelii proved to be the most effective combinations for reducing M. nigrivenella populations in the different locations. Grain loss and ear damage, which were significantly correlated with the number of insects in the ear, were significantly affected by the intercrops, with losses abated by 47–84% in the four sites. No parasitized larvae were found in any of the locations.

Effect of Insecticidal Plant Materials, Lantana camara L. and Tephrosia vogelii Hook, on the Quality Parameters of Stored Maize Grains

The effect of ground powders of two tropical plants, Lantana camara L. and Tephrosia vogelii Hook, on the level of insect damage and the grain quality parameters of stored maize were evaluated for five months. The evaluations were aimed at generating natural product treatments suitable for post-harvest grain protection and as sustainable alternatives to synthetic insecticides in the control of the maize weevil, Sitophilus zeamais Motschulsky. Three rates (1.0, 2.5 and 5.0% w/w) of each plant powder, a synthetic insecticide, Actellic Super 2% dust at 0.05% w/w and an untreated control were used as treatments. Results showed that the plant powders significantly minimised the magnitude of depression in percent grain moisture content albeit at a lesser rate with high concentration and had no effect on the percent germination of maize grains when compared to the controls. The botanical treatments and synthetic insecticide were equally effective in reducing insect damage by 25%, but the level of damage was independent of the concentration applied. Grain colour and odour were unaffected by the botanicals. Results are discussed with regard to the use of botanicals by small-scale farmers as cost-effective and sustainable alternatives to synthetic insecticides in maize grain storage. Key Words: botanicals, indigenous knowledge, grain storage, grain quality parameters, synthetic insecticides, insect damage, seed viability, food safety Journal of Food Technology in Africa Vol.9(1) 2004: 29-35

Root recovery of five tropical tree and shrub species by sieves of different mesh sizes

Accurate quantitative assessment of roots is key to understanding the belowground plant productivity as well as providing an insight of the plant-soil interactions. In this study, root recoveries by sieves of different mesh sizes (2.0, 1.0, 0.5 and 0.25 mm) were measured for five tropical tree and shrub species grown in monoculture stands: crotalaria (Crotalaria grahamiana Wight and Arn.), pigeonpea [Cajanus cajan (L.) Millsp.], sesbania [Sesbania sesban (L.) Merr.], tephrosia (Tephrosia vogelii Hook F.), siratro [Macroptilium atropurpureum (DC.) Urb.] and tithonia [Tithonia diversifolia (Hemsl.) Gray]. Root samples were take from 0-15 cm soil depth. Recovery of coarser roots (>1.0 mm) ranged from 70 to 93% and 90 to 98% of the cumulative root length and biomass respectively. The proportion of root length of the finer roots ( 0.25 mm) are used, a correction factor could be useful for root length measurements but not root biomass measurements for a particular species in each site and for a specific study.

Crop Damage by Nematodes in Improved-fallow Fields in Western Kenya

The rotation of leguminous shrubs and crops is being tested on farms and recommended as a means of improving soil fertility and increasing crop yield in eastern and southern Africa, including western Kenya. However, this improved fallow practice may also increase the nematode population in the soil. An experiment was conducted to monitor the effects of plant-parasitic nematodes on crops after improved fallow. Soil was collected from a maize (Zea mays L.)/bean (Phaseolus vulgaris L.) field, a natural fallow, a Crotalaria (Crotalaria grahamiana Wight & Arn.) fallow, a Tephrosia (Tephrosia vogelii Hook. f.) fallow and a Crotalaria — Tephrosia mixed fallow and used to fill plastic pots placed in a shade. Three successive crop cycles of 2 months were tested in these pots using maize and beans, the most important staple foods in western Kenya. In the first cycle, beans grew poorly on the Tephrosia and Crotalaria — Tephrosia soil due to the high incidence of root knot nematodes, Meloidogyne spp., while maize did not suffer any loss. Although the populations of root knot nematodes reduced drastically in the second and third cycles, both maize and beans experienced heavy losses on the soil under improved fallow probably due to the spiral nematodes, Scutellonema spp., which became dominant in the nematode communities. Despite the use of fertilisers (N, P, K), both crops became highly sensitive to spiral nematodes in the third cycle because of the degradation of the soil physical properties. The study showed that the benefits of improved fallows in terms of crop production may be limited by the high number of plant-parasitic nematodes they help develop in the process.

Do Species Mixtures Increase Above‐ and Belowground Resource Capture in Woody and Herbaceous Tropical Legumes?

The rotation of crops with planted, N2‐fixing legumes is a promising agroforestry innovation for replenishing soil fertility in the tropics. We postulated that woody and herbaceous legumes with different growth and rooting patterns could be mixed to optimize above‐ and belowground resource capture. The objective of this study was to evaluate the effect of species interactions on resource utilization by legumes grown in mixtures on a Kandiudalfic Eutrudox in western Kenya. Four woody legume shrubs—pigeonpea [Cajanus cajan (L.) Millsp.], sesbania [Sesbania sesban (L.) Merr.], crotalaria (Crotalaria grahamiana Wight and Arn.), and tephrosia (Tephrosia vogelii Hook F.)—grown in monoculture and mixed stands were evaluated for light interception, soil N and water uptake, and biomass production. Siratro [Macroptilium atropurpureum (DC.) Urb.] and groundnut (Arachis hypogaea L.) were undersown in woody legume stands. Total aboveground biomass production ranged from 9 to 13 Mg ha−1 for monoculture and 8 to 15 Mg ha−1 for mixtures of woody legumes. Total N in woody‐legume stands ranged from 100 to 178 kg N ha−1. Biomass and plant N were not significantly different among woody‐legume treatments. However, undersowing siratro as a supplement increased stand productivity and recycled biomass N. Species complementarity in topsoil and subsoil utilization of mineral N was observed in crotalaria + sesbania and pigeonpea + tephrosia mixed stands. Dense soil cover created by siratro led to better conservation of soil water. Results indicated that the tested mixtures provide a better risk management strategy through compensatory growth potential. Greatest opportunities for intensifying resource utilization appear to exist through undersowing a creeping legume with an open‐canopy woody legume.

Utilisation of soil organic P by agroforestry and crop species in the field, western Kenya

A field experiment in western Kenya assessed whether the agroforestry species Tithonia diversifolia (Hemsley) A. Gray, Tephrosia vogelii Hook f., Crotalaria grahamiana Wight & Arn. and Sesbania sesban (L) Merill. had access to forms of soil P unavailable to maize, and the consequences of this for sustainable management of biomass transfer. The species were grown in rows at high planting density to ensure the soil under rows was thoroughly permeated by roots. Soil samples taken from beneath rows were compared to controls, which included a bulk soil monolith enclosed by iron sheets within the tithonia plot, continuous maize, and bare fallow plots. Three separate plant biomass samples and soil samples were taken at 6-month intervals, over a period of 18 months. The agroforestry species produced mainly leaf biomass in the first 6 months but stem growth dominated thereafter. Consequently, litterfall was greatest early in the experiment (0–6 months) and declined with continued growth. Soil pH increased by up to 1 unit (from pH 4.85) and available P increased by up to 38% (1 μg P g−1) in agroforestry plots where biomass was conserved on the field. In contrast, in plots where biomass was removed, P availability decreased by up to 15%. Coincident with the declines in litterfall, pH decreased by up to 0.26 pH units, plant available P decreased by between 0.27 and 0.72 μg g−1 and Po concentration decreased by between 8 and 35 μg g−1 in the agroforestry plots. Declines in Po were related to phosphatase activity (R2=0.65, P<0.05), which was greater under agroforestry species (0.40–0.50 nmol MUB s−1 g−1) than maize (0.28 nmol MUB s−1 g−1) or the bare fallow (0.25 nmol MUB s−1 g−1). Management of tithonia for biomass transfer, decreased available soil P by 0.70 μg g−1 and Po by 22.82 μg g−1. In this study, tithonia acquired Po that was unavailable to maize. However, it is apparent that continuous cutting and removal of biomass would lead to rapid depletion of P stored in organic forms.

Changes in phosphorus concentrations and pH in the rhizosphere of some agroforestry and crop species

The aim of this work was to assess whether agroforestry species have the ability to acquire P from pools unavailable to maize. Tithonia diversifolia(Hemsley) A. Gray, Tephrosia vogelii Hook f., Zea mays and Lupinus albusL. were grown in rhizopots and pH change and depletion of inorganic and organic P pools measured in the rhizosphere. Plants were harvested at the same growth stage, after 56 days for maize and white lupin and 70 days for tithonia and tephrosia, and the rhizosphere sampled. The rhizosphere was acidified by tithonia (pH change −0.3 units to pH 4.8) and lupins (−0.2 units to 4.9), alkalinised by tephrosia (+0.4 units to pH 5.4), and remained unchanged with maize growth. Concurrent with acidification in the rhizosphere of tithonia there was a decline in resin-P (0.8 μg P g−1). However, there was also a decline in NaOH extractable inorganic P (NaOH-Pi) (5.6 μg P g−1 at the root surface) and organic P pools (NaOH-Po) (15.4 μg P g−1 at 1.5 mm from the root), which would not be expected without specific P acquisition mechanisms. Alkalinisation of tephrosia rhizosphere was accompanied by changes in all measured pools, although the large depletion of organic P (21.6 μg P g−1 at 5 mm from the root) suggests that mineralisation, as well as desorption of organic P, was stimulated. The size of changes of both pH and P pools varied with distance away from the rhizoplane. Decline of more recalcitrant P pools with the growth of the agroforestry species contrasted with the effect of maize growth, which was negligible on resin-P and NaOH-Pi, but led to an accumulation of P as NaOH-Po (14.2 μg P g−1 at 5 mm from the root). Overall the depletion of recalcitrant P pools, particularly Po, suggests that the growth of tithonia and tephrosia enhance desorption and dissolution of P, while also enhancing organic P mineralisation. Both species appear to have potential for agroforestry technologies designed to enhance the availability of P to crops, at least in the short term.