Pigeon Pea Leaf Research Articles

Assessment of the Incidence of Pigeon Pea Leaf Webber, Grapholita critica (Meyr.) and Roller, Caloptilia soyella (Van.) in Relation to Weather Variables in the Bundelkhand Region of Uttar Pradesh

Background: Pigeon pea (Cajanus cajan, Mayer) is the member of Asian Cajanus crop and also reffered as Tur and Arhar and commonly grown in Kharif session in Indian subcontinent.). In India, around 250 known species of insect pests have been identified to affect pigeon pea crops at different growth stages. The leaf webber and leaf roller are notable insect pests that pose a significant threat to pigeonpea, particularly during its vegetative stage. The leaf webber and leaf roller, among various insect pests, are notably visible and pose a threat to pigeonpea. These insects target the pigeonpea plant during its vegetative stage. Specifically, the leaf webber, identified as Grapholita (Pammene) critica, Meyrick (Lepidoptera: Tortricidae), has been acknowledged as a significant constraint affecting pigeonpea production. The aim of this investigation is to assess the relationship between the incidence of leaf roller and leaf webber and various abiotic factors, including temperature, relative humidity, wind velocity and rainfall. Methods: The research, spanning Kharif 2021-22 and 2022-23, at Entomological Research Block in BUAT, Banda. It aimed to observe leaf roller and leaf webber incidence in pigeon pea alongside weather conditions. ‘IPA-203’ pigeon pea variety was manually sown in 200 m2 plots on July 12, 2021 (first year) and July 18, 2022 (second year). Standard agronomic practices were adhered to and no insecticides were used on the crop. Result: Over the two-year observation period, the larval population of G. critica on pigeon pea plants commenced during the 34th SMW, peaking at 4.90 larvae plant-1 in the 45th SMW. Simultaneously, C. soyella infestation initiated in the 34th SMW, steadily increasing until the 42nd SMW, reaching its peak larval count at 3.03.

IN VITRO EVALUATION OF SUPPRESSING EFFECT OF SOME MEDICINAL PLANT LEAF EXTRACTS ON RADIAL MYCELIA GROWTH OF Fusarium oxysporum f.sp. lycopersici

The experiment was conducted to evaluate the effect of six medicinal plant extracts namely Azadiracta indica (Neem), Ocimum tenuiflorum (Tulshi), Cajanus cajan (Pigeon pea), Cynodon dactylon (Durba grass), Lawsonia inermis (Mehandi) and Cliotoria ternatea (Thunkuni) at different concentrations (10, 50, 100 and 200 mg/L) on the radial mycelial growth of Fusarium oxysporum f.sp. lycopersici. The experiment was conducted following Completely Randomized Design (CRD) with five replications. Radial mycelial growth, inhibition percentages and colony characters were recorded. The radial mycelial growth was maximum (90mm) of Neem leaf extracts at 10 mg/L which was statistically similar with Tulshi at 10 mg/L and control treatment. Lowest radial mycelial growth was found in Pigeon pea (18.80 mm) leaf extracts at 200 mg/L. The highest radial mycelia growth inhibition (79.11%) was observed on Pigeon pea at 200 mg/L.

Management of Alternaria Leaf Blight in Pigeonpea through Host Plant Resistance and Micronutrient Application

Background: Pigeonpea [Cajanus cajan (L.) Millsp] is one of the primary grain legume crops grown in India for its high quality vegetable protein, animal feed and fodder. It is affected by various fungal and viral diseases. Among these, leaf blight caused by Alternaria alternata is one of the most destructive diseases and recently the disease of minor importance becomes major one in Tamil Nadu. Use of resistant cultivar is the most effective, economically viable and eco-friendly tool for combating the plant diseases. The micronutrients play a key role in many physiological and biochemical functions of the plants which influences plant pathogenic interaction. The micronutrients viz., Zn.Mn,Cu and Fe found to have greater impact on reducing the plant disease severity. Developing integrated disease management strategy involving disease resistant variety, micronutrient and fungicide application would be the best sustainable method for controlling the pigeonpea leaf blightMethods: Twenty four pigeonpea genotypes along with two local varieties viz., CO5 and CO6 were evaluated in the field for their resistance against Alternaria alternata leaf blight disease, consecutively for three years from 2015-16 to 2017-18 using the disease resistance scale ranging from 0 to 9. Field experiments were also conducted for three consecutive Kharif season from 2015 to 2018 to evaluate the efficacy of the foliar application of different micronutrients and combination fungicide viz., carbendazim 12% + mancozeb 63% on the incidence of leaf blight disease. Result: A total of 24 pigeonpea genotypes were screened for their resistance against leaf blight under field condition. Among these, four genotypes viz., BDN2, IPA 8F, IPA 15F and MA6 were found resistance and nine genotypes were moderately resistant and remaining 11 genotypes showed susceptible reaction to leaf blight. The results of the field experiment on micronutrient and fungicide application revealed that foliar spraying of MnSO 4 @0.2% on 30 days after sowing and carbendazim 12%+ mancozeb 63%@ 1g / lit on 45 days after sowing recorded the lowest leaf blight incidence of 8.1 PDI (Per cent Disease Index) with the highest disease reduction of 76.9% as against 35 PDI in the untreated control plot. The above treatments also recorded the highest grain yield of 905 kg/ ha as against 703 kg/ in the untreated control.

A COMPARATIVE EVALUATION OF LEAF MEALS OF PAWPAW (C. Papaya), SWORDBEAN (C. gladiata), JACKBEAN (C. ensiformis) AND PIGEONPEA (C. cajan) AS FEED INGREDIENTS AND YOLK COLOURING AGENTS IN LAYERS' DIETS

Leaf meals of the above-named tropical plants at 0.2,3,4 and 5% dietary levels were investigated for their values as feed ingredients and egg yolk pigmenters in white maize based layer diets. Each diet was fed as 5 replicates of 15 hyaline layers for 14 weeks. Pawpaw leaf meal (RM) at 4% and 5% dietary levels significantly (P<0.05) depressed feed intake without affecting egg production and body weights. It, however, had no colouring affecting egg yolk. Sword Bean leaf meal (SBIM), jackbean leaf meal (JBM) and pigeon pea leaf meal (PPLM) compared favourably with the control group in terms of feed intake, egg production and body weights, SBLM exceptionally improved egg yolk colour, scoring 4, 5, 8 and 12 on the Roche egg yolk colour fan at 2,3,4 and 5% dietary levels respectively. JBLM and PPLM only gave a score of 4 and 5% dietary level. SBLM appears to be very high in biological available xanthophylls and should be considered for development as commercial egg yolk pigmenter.

Seasonal patterns of insect pest in major pigeonpea and chickpea growing agro-climatic zones of India and their management inferences

A pest scout data in pigeonpea (leaf webber, plume moth, pod borer) and chickpea (pod borer) crops including daily insect pest counts for three successive seasons (2015/16—2017/18) at western and eastern plateau hills (agro-climatic zones) of India was analysed for spatio-temporal dynamics. Longer infestation (different crop phenological growth stages) behaviour of leaf webber and pod borer in pigeonpea and chickpea, respectively influenced their increased mean counts (incidence). Weekly mean counts of leaf webber, plume moth and pod borer in both the crops varied significantly between the seasons. Linear incremental change in mean counts of leaf webber and pod borer on pigeonpea and chickpea, respectively was observed across the seasons (inter-seasonal). Intra-seasonal built-up of plume moth (pigeonpea) and pod borer (pigeonpea and chickpea) mean counts was also noticed. On pigeonpea, leaf webber and plume moth mean counts never reached an economic threshold level (3 larvae/plant), but crossed the advisory level (1.5 larvae/plant). It was observed that there was incremental rise in pod borer mean counts and crossing economic threshold level over seasons in chickpea (1 larvae/m row length), while it was not the case in pigeonpea (1 larvae/ plant). Furthermore, survival and management strategies of leaf webber, plume moth and pod borer in pigeonpea and pod borer in chickpea were discussed.

English

The study was conducted with the objective of measuring feed intake, digestibility, and growth performance of Begait sheep fed hay basal diet and supplemented with different levels of Tsara (Pterocarpus lucens) leaves, Pigeon pea (Cajanus cajan) leaves and concentrate mixture on iso-nitrogenous basis to supply 66.60 g/day crude protein (CP) on dry matter (DM) basis. Twenty five yearling male Begait sheep with initial body weight (BW) of 24.2±1.1 kg (Mean±standard deviation, SD) were used in a randomized complete block design (RCBD) based on their initial BW. The hay was fed to all sheep on ad libitum basis. Treatments were hay alone (T1), or supplemented with 400 g DM Tsara (P. lucens) leaf (T2), 320 g DM pigeon pea (C. cajan) leaf (T3), 360 g DM mixtures of Tsara (P. lucens) and pigeon pea (C. cajan) leaves (T4) and 300 g DM concentrate mixture (75% rice bran and 25% sesame seed cake; T5). The study consisted of 90 days feeding and 7 days of digestibility trials. Hay DM intake ranged from 850 to 985 g/day and was the highest for T1, while total DM intake was the highest for T2 (1299 g/day), lowest for T1 (985 g/day) and intermediate for the other three treatments (1143-1202 g/day). The CP intake was higher (P T2 (72%) > T4 (65%) while the value for T3 (66.4%) was similar with that of T2 and T4. The average daily gain (ADG) was 31, 85, 52, 54 and 107 g/day (SEM = 1.83) in the order of T5 > T2 > T3 = T4 > T1. In conclusion, based on the biological performance results supplementation of concentrate mixture (T5) and Tsara (T2) (P. lucens) leaf induced a comparable response of feed intake, digestibility and body weight gain and were better than the supplemental feeds that contained Pigeon pea and are therefore recommended. Key words: Average daily gain, feed conversion efficiency, nutrient intake.

English

The study was conducted with the objective of determining the carcass characteristics of Begait sheep fed hay basal diet and supplemented with different levels of Tsara (Pterocarpus lucens) leaves, pigeon pea (Cajanus cajan) leaves and concentrate mixture on iso-nitrogenous basis to supply 66.60 g/day crude protein on dry matter (DM) basis. Twenty five yearling male Begait sheep with initial body weight (BW) of 24.2±1.1 kg (Mean±SD) were used in a Randomized Complete Block Design (RCBD) based on their initial BW. The hay was fed on ad libitum basis to all sheep. Treatments were hay alone (T1) or supplemented with 400 g DM Tsara leaf (T2), 320 g DM pigeon pea leaf (T3), 360 g DM  mixtures of Tsara and pigeon pea leaves (T4) and 300 g DM concentrate mixture (75% rice bran and 25% sesame seed cake; T5). The study consisted of 90 days feeding trial and carcass evaluation at the end. The average final body weight was 32.2, 31.6, 27.76, 28 and 26.88 kg (standard error of mean, SEM = 0.38) in the order of T5 > T2 > T3 = T4 > T1. Hot carcass weight of 14.9, 14.3, 11.3, 11.2 and 9.5 (SEM = 0.33) followed almost a similar trend to that of the final body weight except that values for T2 and T5 were similar. In conclusion, based on the biological performance results supplementation of concentrate mixture (T5) and Tsara (T2) induced a comparable response and were better than the supplemental regimes that contained pigeon pea and are therefore recommended. Key words: Begait sheep, dressing percentage, edible offal components, empty body weight hot carcass weight, non-edible offal components, rib eye muscle area, slaughter weight. &nbsp

Experimental, theoretical modeling and optimization of inhibition efficiency of pigeon pea leaf extract as anti-corrosion agent of mild steel in acid environment

This study is on the application of pigeon pea leaf (PPL) extract as anti-corrosion agent for mild steel in acid environment (HCl solution). The work involves investigation of the corrosion inhibition process using combination of experimental, theoretical modeling and optimization studies. The chemical compositions and functional groups of the extract were identified using gas chromatography mass spectrophotometer (GC-MS) and Fourier transform infrared (FTIR) spectroscopy respectively. For the response surface methodology (RSM), Design Expert software was used for the optimization of the inhibition efficiency. Scanning electron microscopy (SEM) was used to inspect the surface morphology of the mild steel. The inhibition efficiencies of 87.13%, 91%, 92.1% and 90.7% were obtained from the experimental studies of thermometric, gravimetric, potentiodynamics polarization and electrochemical impedance spectroscopic techniques respectively. A quadratic model showing the relationship between inhibition efficiency and inhibition variables was generated. The model was scrutinized with various criteria, which include coefficient of determination (R2 = 0.9733), p value (<0.0001), adequate precision (22.44), adjusted R2 (0.9485) and coefficient of variation (4.98). The RSM model adequately predicted the optimum inhibition efficiency of 91% at inhibitor concentration of 0.9 g/L−1. The theoretical modeling reveals that 1-Tridecene and Luteolin were the most active constituents of pigeon pea leaf responsible for the inhibition process. Polarization study revealed that pigeon pea leaf extract acted as a mixed-type inhibitor. Furthermore, the inhibition process was in accordance with Langmuir isotherm. Spectra of the corrosion particles and SEM analysis confirmed the physical attachment of the extract species on the mild steel surface.

Approach to study of pigeonpea leaf webber [Grapholita critica (Meyr.)] damage dynamics and its relation to weather

Investigation of the published data of a field experiment on assessment of damage due to leaf webber (Grapholita critica (Meyr.)Torticidae:Lepidoptera) under seven different sowing periods at weekly intervals between June IV to August II weeks of 2013-14 at Gulbarga (Karnataka) and observations on leaf webber damage recorded on weekly basis between 32 and 42 standard meteorological weeks (SMW) was done to demonstrate appropriate analytical methodology for an improved understanding of seasonal dynamics of G. critica damage and its relation to weather. Approach to analyses included reporting of calendar (SMW) based observations of G. critica damage on crop age basis, one way ANOVA for testing differences in damage levels amongst sowing periods, SMWs and crop age besides description of relations of damage with crop age and weather variables. Seasonal damage levels of G. critica for sowing periods were non-significant but significant (P less than 0.05) across SMWs and crop age with reduced damage during early and late crop stages irrespective of sowing periods. Seven and four weeks of higher damage and the best fit of polynomial relations of second order in respect of crop age over calendar based periods signified crop stage dependent damage due to G. critica. While MLR revealed significant influence of all weather and crop age variables (R2: 0.79), non-parametric regression revealed that less than 30°C of maximum temperature and greater than 23°C of minimum temperature to be favourable for G. critica damage. Crop age and calendar based observations have their importance for an area wide and field basis management of G. critica respectively.

Separation of pinostrobin from pigeon pea [Cajanus cajan (L) Millsp.] leaf extract using a cation exchange resin for catalytic transformation combined with a polyamide resin

An efficient continuous system for separation of pinostrobin from pigeon pea leaf extract using a cation exchange resin column (fixed-bed column reactor) connected to a polyamide resin column (fixed-bed column separator) was developed in this study. An NKC-9 cation exchange resin, with a styrene divinyl benzene matrix and –SO3– functional groups, was used as a catalyst to transform pinostrobin chalcone into piostrobin, with a dynamic transformation efficiency of 97.67±1.82%. A polyamide resin column was used to adsorb pinostrobin from the pigeon pea leaf extract solution after the transformation reaction, and the most optimal condition was identified. After adsorption equilibrium, 30–70% ethanol was injected into the polyamide resin column as a desorption solvent, from which 50–70% ethanol eluates were collected as the final product and 30–40% ethanol was used to wash out impurities. This system greatly improved production, yielding a 24.67-fold increase in pinostrobin content in the dry product from 2.32±0.16% to 57.23±1.18%, and a final recovery of pinostrobin of 151.12±1.53%.

First Report of Tobacco streak virus Infecting Pigeon Pea (Cajanus cajan) in India

Pigeon pea is an important pulse crop grown in diversified cropping systems in India. In the rainy season of August 2011 and September 2012, pigeon pea cv. LRG 30 plants with leaf necrosis having wrinkled margin on one side were observed in Kadiri mandal of the Anantapuram district of Andhra Pradesh (A.P.), India. Symptoms included necrotic spots on young leaves followed by wilting of leaves, petiole and branch/axillary shoot proliferation, with small leaves having mosaic symptoms. Symptomatic leaves were sap-inoculated onto 10 seedlings of cowpea (cv. Pusa Komal) using 0.01 M phosphate buffer (pH 7.0). Localized necrotic lesions developed in all the inoculated plants after 2 days post inoculation. Field symptoms were reproduced on healthy pigeon pea upon back inoculation using single lesions of infected cowpea leaves. In direct antigen coating (DAC)-ELISA, all the infected pigeon pea and cowpea leaf samples were positive to a polyclonal antiserum specific to Tobacco streak virus (TSV) supplied by ICRISAT, India. Total RNA was extracted using infected pigeon pea and healthy leaf samples by TRI Reagent (Sigma). Reverse transcription (RT)-PCR was carried out using primers specific to the coat protein (CP) gene of TSV (1). A product of the 700-bp DNA fragment was obtained in field-infected pigeon pea samples but not in healthy controls. The amplicon was cloned into PTZ57R/T using the Ins TA clone PCR kit (Fermentas). Recombinant clone was sequenced in both directions and the CP gene sequence obtained was deposited in GenBank (KF220492). Sequence analysis of the CP gene of TSV from pigeon pea shared 98 to 100% identity with Indian TSV isolates originating from different hosts including groundnut (FJ355948), mung bean (FJ749259), and sunflower (DQ864448), and 88 to 92% similarity with TSV type isolate (white clover: X00435) both at nucleotide and amino acid levels. TSV belongs to the genus Ilarvirus of family Bromoviride and has a wide host range. TSV is pollen borne, assisted by thrips causing mechanical injury (2). To our knowledge, this is the first report of TSV on pigeon pea in India and was widespread in Anantapuram, Kadapa, Kurnool, and Mahbubnagar districts of A.P. Yield loss depends on the stage of infection as early infection resulted in complete failure of the crop. TSV was prevalent on many legume crops such as black gram, green gram, and groundnut in A.P, Tamil Nadu, Karnataka, and Maharashtra states (3). TSV infection of pigeon pea may pose a serious implication for pulse production.

Expression of drought responsive genes in pigeonpea and in silico comparison with soybean cDNA library

Pigeonpea, a drought tolerant, semi-arid pulse crop has been investigated for the expression of differentially expressed genes (DEGs) under drought stress. The cDNA library of soybean leaf tissue retrieved from the Unigene database of the NCBI, were compared for in silico expression using IDEG6 web statistical tool. A list of 52 non-redundant DEGs consisting of 11 up-regulated and 41 down-regulated was obtained. Among these, more photosynthesis and light harvesting proteins were down-regulated in drought stress conditions. Pathways were assigned based on KEGG database, revealing 32 genes involved in 17 metabolic pathways. Homologous sequences of six up-regulated genes namely, ADF3, APB, ASR, DLP, LTP1, and UGE5 were then used for quantitative reverse transcription PCR (qRT-PCR) in pigeonpea. The qRT-PCR result revealed the significant up-regulation of dehydrin-like protein (DLP) (5.02 log2 fold) and down-regulation of acid phosphatase class B family protein (APB) (9.43 log2 fold) and non-specific lipid transfer protein 1-like (LTP1) (18.81 log2 fold) in pigeonpea water-stressed leaf sample compared to well-watered leaf samples. No significant difference was observed in the stressed root compared to the stressed pigeonpea leaf sample except that APB showed an up-regulation of 11.35 log2 fold change.

Antioxidant Activities of Extracts and Main Components of Pigeonpea [Cajanus cajan (L.) Millsp.] Leaves

Antioxidant activities of the aqueous and ethanol extracts of pigeonpea [Cajanus cajan (L.) Millsp.] leaves, as well as petroleum ether, ethyl acetate, n-butanol and water fractions and the four main compounds separated from the ethanol extract, i.e. cajaninstilbene acid (3-hydroxy-4-prenylmethoxystilbene-2-carboxylic acid), pinostrobin, vitexin and orientin, were examined by a DPPH radical-scavenging assay and a β-carotene-linoleic acid test. In the DPPH system, the antioxidant activity of the ethanol extracts was superior to that of the aqueous extracts, with IC50 values were 242.01 and 404.91 µg/mL, respectively. Among the four fractions, the ethyl acetate one showed the highest scavenging activity, with an IC50 value of 194.98 µg/mL. Cajaninstilbene acid (302.12 µg/mL) and orientin (316.21 µg/mL) showed more efficient radical-scavenging abilities than pinostrobin and vitexin. In the β-carotene-linoleic acid test, the inhibition ratio (%) of the ethyl acetate fraction (94.13%±3.41%) was found to be the highest, being almost equal to the inhibition capacity of the positive control BHT (93.89%±1.45%) at 4 mg/mL. Pinostrobin (>500 µg/mL) and vitexin (>500 µg/mL) showed insignificant antioxidant activities compared with cajaninstilbene (321.53 µg/mL) and orientin (444.61 µg/mL). In general, the ethyl acetate fraction of the ethanol extract showed greater activity than the main compounds in both systems, such results might be attributed to the synergistic effects of the components. The antioxidant activities of all the tested samples were concentration-dependent. Based on the results obtained, we can conclude that the pigeonpea leaf extracts may be valuable natural antioxidant sources and are potentially applicable in both medicine and the healthy food industry.

Evaluation of the nutritive potential of pigeon pea (&lt;i&gt;Cajanus cajan&lt;/i&gt;) grain and leaf meals on growth performance of pre-pubertal rabbits

The study investigated the effect of including pigeon pea grain and pigeon pea leaf meals in the pre-pubertal rabbit diets that had maize offal as the main energy source. Eighteen pubertal rabbits of age range 5-6 weeks and weight range 482-486 gm at the commencement of the experiment were randomly allocated to experimental diets 1, 2 and 3 respectively containing 0% pigeon pea, 15% Pigeon pea grain meal and 15% Pigeon pea leaf meal, in replacement of maize offal. The final live weight (1375.1g for diet 1,1487.5g for diet 2 and 1347.38g for diet 3), daily weight gain (11.6g for diet 1, 13.00g for diet 2 and 11.21g for diet 3) and feed: gain: ratio 6.50 vs. 5.20 vs. 5.31 for diets 1,2 and 3 respectively were not significantly (P > 0.05) affected by the dietary treatments. However, the daily feed intake 65.3g vs. 59.50 g for Diets 2 and 3 respectively ware similar but significantly (P 0.05) among the dietary groups. It was concluded that 15% Pigeon pea grain meal inclusion in rabbit diet with maize offal rather than maize, as the main energy base, resulted in better performance of weaner rabbits. Keywords : Pigeon pea leaf meal; grain meal, pre-pubertal rabbit, haematology , muscle composition Bowen Journal of Agriculture Vol. 5 (1&2) 2008: pp. 102-108

Foliar sprays of concentrated urea at maturity of pigeonpea to induce defoliation and increase its residual benefit to wheat

The pigeonpea ( Cajanus cajan (L.) Millsp.) crop retains appreciable amounts of green foliage even after reaching physiological maturity, which if allowed to defoliate, could augment the residual benefit of pigeonpea to the following wheat ( Triticum aestivum L.) in a pigeonpea–wheat rotation. The effect of addition of leaves present on mature pigeonpea crop to the soil was examined on the following wheat during the 1999/2000 growing season at Patancheru (17°4′N, 78°2′E) and during the 2001–2003 growing seasons at Modipuram (29°4′N, 77°8′E). At Patancheru, an extra-short-duration pigeonpea cultivar ICPL 88039 was defoliated manually and using foliar sprays of 10% urea (30 kg/ha) and compared with a millet ( Pennisetum glaucum (L.) R.Br.) crop, naturally senesced leaf residue and no-leaf residue controls. At Modipuram, the effect of 10% urea spray treatment on mature ICPL 88039 was compared with the unsprayed control. At both locations, the rainy season crops were followed by a wheat cultivar UP 2338 at four nitrogen levels applied in a split plot design, which at Patancheru were 0, 30, 90 and 120 kg N ha −1 and at Modipuram 0, 60, 120 and 180 kg N ha −1. At Patancheru, urea spray added 0.5 t ha −1 of extra leaf litter to the soil within a week without significantly affecting pigeonpea yield. This treatment, however, increased mean wheat yield by 29% from 2.4 t ha −1 in the no-leaf residue pigeonpea or pearl millet plots to 3.1 t ha −1. At Modipuram, the foliar sprays of urea added more leaf litter to the soil than at Patancheru. Here, increase in subsequent wheat yield due to additional pigeonpea leaf litter was 7–8% and net profit 21% more than in the unsprayed control. The addition of pigeonpea leaf litter to the soil resulted in a saving of 40–60 kg N for the following wheat crops in both the environments. The results demonstrated that pigeonpea leaf litter could play an important role in the fertilizer N economy in wheat. The urea spray at maturity of the standing pigeonpea crop significantly improved this contribution in increasing wheat yield, the effect of which was additional to the amount of urea used for inducing defoliation. The practice, if adopted by farmers, may enhance sustainability of wheat production system in an environmentally friendly way, as it could reduce the amount of fertilizer N application to soil and enhance wheat yield.

Production of a Host‐Specific Toxin by Germinating Spores of Alternaria tenuissima Causing Leaf Spot of Pigeon Pea

Production of a host‐specific toxin by Alternaria tenuissima, the cause of pigeon pea leaf spot, was investigated in spore‐germination fluids (SGF). The SGF selectively induced necrosis on pigeon pea leaves in a deteched leaf assay. Necrotic lesions were observed when a toxin from SGF was applied onto detached young leaves of the pigeon pea cultivar Bahar at concentration as low as 5 ng/ml. The resistant line Tanzania and nonhosts tolerated at least 20,000 times higher concentration of the toxin. The differential activity of the toxin on hosts and nonhosts of the fungus, as well as on susceptible and resistant cultivars or lines, suggested host‐specific property of the toxin. At a concentration of 10 ng/ml, the toxin induced susceptibility of pigeon pea leaves to a non‐pathogenic isolate of Alternaria alternata. The toxin possibly plays a role as a disease determinant of A. tenuissima, because the toxin was released from germinating spores as early as 3 h of incubation andthe, amount detected within 9 h was about 6 times of the concentration required for necrotic toxicity.

Dry matter yield and chemical composition of pigeon pea ( C. cajan) leaf meal and the nutritive value of pigeon pea leaf meal and grain meal for laying hens

Three studies were conducted to determine: (1) the yield of leaf meal of pigeon pea in the southeastern agricultural zone of Nigeria; (2) the value of pigeon pea leaf meal (PPLM) as a feed ingredient and egg yolk colouring agent in layers' diets; (3) the value of pigeon pea grain meal (PPGM) as a protein and energy source for layers. Dry matter yields of PPLM were 2.30, 2.36 and 2.68 t ha −1 for 4-, 6- and 8-week cutting intervals, respectively. Crude protein content increased with more frequent cutting intervals and crude fibre with less frequent cutting intervals. Up to 7.5% PPLM in diets did not adversely affect layer performnce, but 10% was needed to give a yolk colour score of 8 on the Roche colour fan in white maize-based layers' diets. At dietary levels >20%, PPGM depressed feed intake and egg production.

Título en español

En pruebas de laboratorio y de campo, la hojarasca de gandul (Cajanus cajan (L.) Huth.) se asoció con necrosis de la punta de la raíz, supresión del crecimiento y germinación pobre de soya, habichuelas lablab, gandul y de ciertas malezas locales. La hojarasca de gandul albergó y sirvió de sustrato a especies de hongos de los generos Pythium, Fusarium y Rhizoctonia, las cuales a menudo se asocian con síntomas similiares en otras plantas. Mediante una extracción de la hojarasca de gandul con hidróxido de potasio, se logró eliminar los hongos patógenos. Sin embargo, los extractos diluidos y con pH ajustado (pH = 6.2), en igual forma causaron los síntomas típicos de necrosis de la punta de la raíz, supresión del crecimiento y pérdida de germinación. Las especies de malezas variaron en su sensitividad a la hojarasca de gandul. Las gramíneas fueron inhibidas más que las dicotiledóneas. La germinación, brotación y supervivencia del bledo (Amaranthus dubius Mart. ex Thell.) aumentó con los residuos de la hojarasca de gandul. La acumulación de la hojaraca comenzó con el cierre del cultivo, sombreando las hojas inferiores de la planta y por consiguiente su muerte y caída. En predios de la costa sur de Puerto Rico, donde se sembró el gandul densamente, el bledo llegó a ser la maleza predominante bajo el dosel de los arbustos al momento de la cosecha. El rendimiento de residuos de tallos fue mayor que el de las raíces u hojas. El índice de cosecha fue bajo (26% basado en rendimiento de vainas y 15% basado en rendimiento de semilla). En el laboratorio, el umbral mínima para poder detectar inhibición en la planta causada par la hojarasca de gandul, fue de 5 a 1 0 g de hojarasca por metro cuadrado de superficie y aproximadamente 25 g equivalentes a la hojarasca al usar extractos sacados con hidróxido de potasio. Durante la cosecha, la hojarasca de gandul sobrepasó 150 g por metro cuadrado, cantidad similiar a los niveles óptimos necesarios para la inhibición de las plantas hallados en pruebas de laboratorio (100 a 200 g de hojarasca por metro cuadrado).