Rice Bean Research Articles

Evaluation of Vigna germplasms for resistance to mungbean yellow mosaic virus using agro inoculation

A total of twenty two germplasm lines of Vigna spp. were subjected to agroinoculation to confirm their level resistance/susceptibility against Mungbean Yellow Mosaic Virus (MYMV) using Agrobacterium construct of MYMV strain VA 239. The results showed that twelve mungbean and one urdbean germplasms were found to be highly susceptible (HS) and the rest from both mungbean and urdbean showed susceptible (S) to strain VA 239. One rice bean germplasm (TNAU Yellow) showed complete resistance. The accumulation of the viral genome in the host was confirmed by PCR amplification by using gene-specific primer. The screening results concluded that the resistant germplasm can be utilized as a donor in disease resistance breeding programme for generating MYMV resistant progenies in future.

Screening of rice bean genotypes against major insect pests and avoidable yield losses

Screening of rice bean genotypes against major insect pests and avoidable yield losses

QTL analysis of domestication syndrome in zombi pea (Vigna vexillata), an underutilized legume crop.

Zombi pea (Vigna vexillata (L.) A. Rich) is an underutilized crop belonging to the genus Vigna. Two domesticated forms of zombi pea are cultivated as crop plants; seed and tuber forms. The cultivated seed form is present in Africa, while the cultivated tuber form is present in a very limited part of Asia. Genetics of domestication have been investigated in most of cultivated Vigna crops by means of quantitative trait locus (QTL) mapping. In this study, we investigated genetics of domestication in zombi pea by QTL analysis using an F2 population of 139 plants derived from a cross between cultivated tuber form of V. vexillata (JP235863) and wild V. vexillata (AusTRCF66514). A linkage map with 11 linkage groups (LGs) was constructed from this F2 population using 145 SSR, 117 RAD-seq and 2 morphological markers. Many highly segregation distorted markers were found on LGs 5, 6, 7, 8, 10 and 11. Most of the distorted markers were clustered together and all the markers on LG8 were highly distorted markers. Comparing this V. vexillata linkage map with linkage maps of other four Vigna species demonstrated several genome rearrangements in V. vexillata. QTL analysis for 22 domestication-related traits was investigated by inclusive composite interval mapping in which 37 QTLs were identified for 18 traits; no QTL was detected for 4 traits. Number of QTLs detected in each trait ranged from 1 to 5 with an average of only 2.3. Five QTLs for tuber width and three QTLs for tuber weight. Interestingly, 2 QTLs each for tuber width and tuber weight detected on LG2 and LG4 were located at similar position and wild allele increased tuber width and weight. This indicated wild germplasm having small tuber have potential to increase yield of large tuber cultivated type. Large-effect QTLs (PVE > 20%) were on LG4 (pod length), LG5 (leaf size and seed thickness), and LG7 (for seed-related traits). Comparison of domestication-related QTLs of the zombi pea with those of cowpea (Vigna unguiculata), azuki bean (Vigna angularis), mungbean (Vigna radiata) and rice bean (Vigna umbellata) revealed that there was conservation of some QTLs for seed size, pod size and leaf size between zombi pea and cowpea and that QTLs associated with seed size (weight, length, width and thickness) in each species were clustered on same linkage.

Confirmation of Fusarium oxysporum as a causal agent of mung bean wilt in China

Fusarium wilt is becoming an increasingly severe disease affecting mung bean in China. However, the pathogen has not thoroughly been identified. We therefore carried out a multi-year disease investigation and gathered an extensive collection of diseased mung bean plants, aiming to confirm the causal agent through morphological characterization, pathogenicity tests, molecular detection, and phylogenetic analysis. Field surveys were conducted for five consecutive years, covering the main mung bean-growing areas and spanning seven provinces of China. In total, 170 isolates with Fusarium oxysporum-like colonies were isolated from the collected samples, which were subsequently confirmed as F. oxysporum by morphological observation and PCR-based molecular detection. Then, 70 isolates (10/province) were subjected to pathogenicity tests and molecular detection of pathogenicity-related secreted in xylem (SIX) genes. Sixty-eight of the 70 isolates were pathogenic to mung bean and were verified to carry the pathogenicity-related genes SIX6 and SIX11, while the remaining two nonpathogenic isolates did not contain any SIX genes. Additionally, in a host range test of seven representative pathogenic isolates (1/province) on eight other crops, only two isolates caused mild symptoms on one of two adzuki bean cultivars, and no visual symptoms were observed on chickpea, common bean, cowpea, pea, rice bean, soybean, or cotton, indicating the isolates were host-specific to mung bean. Finally, phylogenetic analysis using multiple genes, TEF1-ɑ, IGS, mtSSU, SIX6 and SIX11, revealed that the seven mung bean isolates formed a unique clade distinct from other formae speciales of F. oxysporum. Here, the F. oxysporum isolates causing mung bean wilt were confirmed as an independent forma specialis distinguished from those affecting other crops.

Alleviation by abscisic acid of Al toxicity in rice bean is not associated with citrate efflux but depends on ABI5‐mediated signal transduction pathways

Under conditions of aluminum (Al) toxicity, which severely inhibits root growth in acidic soils, plants rapidly alter their gene expression to optimize physiological fitness for survival. Abscisic acid (ABA) has been suggested as a mediator between Al stress and gene expression, but the underlying mechanisms remain largely unknown. Here, we investigated ABA-mediated Al-stress responses, using integrated physiological and molecular biology approaches. We demonstrate that Al stress caused ABA accumulation in the root apex of rice bean (Vigna umbellata [Thunb.] Ohwi & Ohashi), which positively regulated Al tolerance. However, this was not associated with known Al-tolerance mechanisms. Transcriptomic analysis revealed that nearly one-third of the responsive genes were shared between the Al-stress and ABA treatments. We further identified a transcription factor, ABI5, as being positively involved in Al tolerance. Arabidopsis abi5 mutants displayed increased sensitivity to Al, which was not related to the regulation of AtALMT1 and AtMATE expression. Functional categorization of ABI5-mediated genes revealed the importance of cell wall modification and osmoregulation in Al tolerance, a finding supported by osmotic stress treatment on Al tolerance. Our results suggest that ABA signal transduction pathways provide an additional layer of regulatory control over Al tolerance in plants.

Diversity analysis of rice bean (Vigna umbellata (Thunb.) Ohwi and Ohashi) collections from North Eastern India using morpho-agronomic traits

Abstract Ricebean (Vigna umbellata (Thunb.) Ohwi and Ohashi), believed to be domesticated in Myanmar–Thailand region, is grown in the North-Eastern hills of India as a pulse, vegetable, and fodder crop. Depending on the farming system where it is grown, plant types vary. Sixty-five accessions collected from across the North-Eastern hills of India were characterized for ten quantitative and ten qualitative morpho-agronomic traits using a minimal descriptor. Different data transformation and dissimilarity calculation methods were used to assess diversity. Mean dissimilarity using the average taxonomic distance was 14.05 (0.141) and using Gower’s general coefficient was 0.249. Both methods identified four clusters where one of the clusters contained more than 70% of the accessions. One of the accessions, BKSB-40, was identified as a unique accession. Quantitative traits were further grouped into qualitative factors, which gave an idea of farmer's preference for plant type and indicated wide difference between accessions collected from areas bordering Myanmar and East Nepal.

Genetic divergence, path coefficient and cluster analysis of ricebean (Vigna umbellata) genotypes in the mid-altitudes of Meghalaya

One hundred and twenty germplasm of ricebean [Vigna umbellata (Thunb) Ohwi and Ohashi] were evaluated during 2015-16 and 2016-17 to study the yield related traits in ricebean in the mid-altitudes of Meghalaya. Luxuriant ricebean growth with a wide spectrum of variability for plant height, number of branches per plant, days to flowering, number of pods per plant and 100 seed weight was observed. The genotypic variance was moderate to high for the said characters which resulted in moderate to high heritability and genetic advance values. Grain yield/plant was positively and significantly correlated with number of clusters per plant, number of pods per plant and 100 seed weight. Moderateto high heritability and the genetic advance of these plant characters vis-a-vis their positive association and direct positive effect on grain yield/plant suggested for their consideration during selection of high yielding genotypes. All the tested ricebean genotypes could be grouped into seven distinct clusters. An analysis of the percentage contributionof individual characters towards genetic diversity revealed that 100-seed weight and days to 80% maturity, days to 50% flowering were the major characters contributing to genetic diversity in ricebean. Based on the results we found genotype CHAK HAWAI-2 may be used as parent for developing long pod with bold seed cultivar. Genotype ChakHawai-31 may be used as parent for developing high yielding genotypes. Genotype BKSB-23 had less bold seed but, high yield and may be used as parent for developing small seed and high yielding variety.

Studies on cross compatibility in interspecific crosses of Vigna radiata × Vigna umbellata species

The present study was undertaken to study the crossability barriers in interspecific crosses of Vigna radiata × Vigna umbellata. The basic materials of this experiment comprising of five mungbean MYMV Susceptible genotypes and five rice bean MYMV resistant genotypes. Interspecific crosses were attempted by utilizing rice bean genotypes as male parents and mungbean genotypes as female parents. The successful pod set was observed on 12 crosses out of 25 interspecific crosses of Vigna radiata and Vigna umbellata. The results revealed that highest crossability per cent was recorded in the crosses Yellowmung × KBR-1 (17.30 %), DGGV-2× RBL-35 (16.0%), Selection-4×KBR-1 (11.80%), Chinamung × KBR-1 (11.0%) and BGS-9× RBL-35 (10.20%) which were considered as successful crosses. This suggests that the parents of these four interspecific cross combinations may be ideal for transfer of useful genes across the two divergent species and to broaden the genetic base of interspecific hybrid and further, the existence of moderate hybrid pollen fertility (78.24%) coupled with moderate seed germination percentage (36.84%), lower hybrid lethality (21.43%) and lower hybrid breakdown (7.14%) was observed in Chinamung × KBR-1 followed by cross Selection-4 ×KBR-1. In the present investigation prominent observation noticed are strong pre-fertilization as well as post fertilization barriers were present in the cross between V. radiata and V. umbellata, while, growth and lethality of interspecific hybrid seedlings were influenced by the genotypes of both the parental species.

Yield attributes, yields and nutrient uptake of Basmati rice (Oryza sativa) as influenced by in-situ and ex-situ green manuring crops and zinc fertilization

A field experiment was conducted in a split plot design at the research farm of ICAR-Indian Agricultural ResearchInstitute (IARI), New Delhi during summer and kharif seasons of 2015 and 2016 to study the influence of in-situ and ex-situ green manuring and zinc fertilization on nutrient uptake, yield attributes, correlation between yield and yield attributes, and yield of Basmati rice (Oryza sativa L.). Results of this study revealed that the incorporation of Sesbania aculeata green manure @ 33.8 and 35.6 t/ha prior to transplanting of Basmati rice during 2015 and 2016, respectively resulted in higher yield attributes and yield of Basmati rice compared with Vigna umbellata, Leucaena leucocephala and summer fallow during both the years. Foliar application of 0.5% solution of chelated Zn-EDTA at 20, 40, 60 and 80 days after transplanting (DAT) was better than soil application of Zn with regard to yield attributes and yield of Basmati rice and uptake of nutrients by the crop. In general, there was significant and positive correlation of grain yield with yield attributes. The uptake of nutrients by the crop was highest with incorporation of Sesbania aculeata and lowest in summer fallow.

Rice bean: A healthy and cost-effective alternative for crop and food diversity

Rice bean (Vigna umbellata), an underutilized grain legume or pulse, is often considered a minor crop in Nepal and Northern India. Rice bean is attracting attention worldwide owing to its high yielding ability, resistance to viral, fungal and bacterial diseases, adaptability to grow in less-fertile lands, simple domestic processing and good nutritional potential, which help to make it an affordable substitute for conventional pulses. However, the presence of some anti-nutritional factors such as phenols, saponins, phytic acid, and enzyme inhibitors limit its usage, but simple domestic processing methods such as sprouting, pressure cooking and fermentation can alleviate these problems and enhance its nutritional adequacy. Rice bean can be cultivated in a range of soils to produce high quality grain as well as highly nutritious fodder for livestock, and thus a synergistic effect can be achieved for both human and animal nutrition. Although a multipurpose crop, little has been done to assess its field diversity, to develop high yielding varieties, or to tap its potential in terms of commercial importance and market value. Further research and promotion of rice bean could play a significant role in a diversified sustainable approach to alleviate the global problem of protein and energy malnutrition.

Efek Model Tumpangsari dan Pengaturan Barisan Jagung terhadap Evaluasi Keuntungan Hasil Jagung dan Kacang Nasi Kultivar Lokal Timor dalam Tumpangsari

Menurunnya produksi hasil pertanian saat ini menjadi salah satu tantangan bagi peneliti-peneliti pertanian karena lahan pertanian semakin sempit serta tingginya luas lahan tidur. Salah satu cara tepat meningkatkan produksi lahan dan tanaman adalah dengan memanfaatkan ruang antara tanaman baik pada tanaman semusim maupun tanaman umur panjang. Salah satu ruang yang memungkinkan untuk membudidayakan tanaman kacang nasi adalah sela antar tanaman jagung. Penelitian ini bertujuan untuk mengetahui efek model tumpangsari dan pengaturan barisan tanam jagung terhadap hasil dan evaluasi keuntungan hasil jagung dan kacang nasi kultivar lokal Timor dalam sistem tumpangsari. Perlakuan dirancang dengan menggunakan Rancangan Acak Kelompok (RAK) Faktorial 3×2+kontrol dan diulang 3 kali, faktor pertama adalah model tumpang sari yang terdiri dari tiga aras yaitu tumpangsari sela; dan tumpangsari Salome (model Timor ); tumpangsari gabungan dan faktor kedua adalah pengaturan barisan tanam jagung: Single Row; Doblerow. Parameter yang diamati adalah berat biji jagung per petak (t/ha), berat biji kacang nasi per petak (t/ha), total LER, total ATER, Agresivitas tanaman, Rasio Kompetisi tanaman. Data yang dikumpulkan dianalisis menggunakan Analisis Anova Rancangan Acak Kelompok Faktorial kemudian dilanjutkan dengan uji Duncan pada taraf α 0,05. Hasil penelitian menunjukkan bahwa terjadi interaksi terhadap berat kering biji jagung per petak, total LER, total ATER, dan rasio kompetisi jagung. Tumpangsari memberikan hasil ≥1, yang berarti menguntungkan pada perlakuan model tumpangsari maupun pada pengaturan barisan tanaman.. ©2018 dipublikasikan oleh Savana Cendana.

Pengaruh Model Tumpangsari dan Pengaturan Jarak Tanam Kacang Nasi (Vigna angularis L.) Kultivar Lokal terhadap Pertumbuhan dan Hasil Tanaman Jagung (Zea mays L.)

Tanaman jagung dan kacang nasi adalah dua jenis tanaman yang cocok diterapkan pada pola tumpangsari. Penelitian ini bertujuan untuk mengetahui 1) pertumbuhan dan hasil jagung dalam pola tanam tumpangsari; 2) model tumpangsari terbaik dalam meningkatkan pertumbuhan dan hasil jagung; dan 3) pengaturan jarak tanam yang baik dalam pola tanam tumpangsari jagung dan kacang nasi. Penelitian dilaksanakan di kebun percobaan Fakultas Pertanian Universitas Timor, pada bulan Desember 2016 sampai Maret 2017, menggunakan Rancangan Acak Kelompok (RAK) faktorial yang diulang tiga kali. Faktor pertama adalah model tumpangsari yang terdiri dari tiga aras yaitu tumpangsari standar nasional (sistem sela), tumpangsari salome (model timor) dan gabungan. Faktor kedua adalah pengaturan Jarak tanam yang terdiri dari dua aras yaitu single row dan doble row. Hasil penelitian menunjukkan interaksi antara model tumpangsari dan pengaturan jarak tanam terhadap parameter pengamatan berat kering biji per petak, berat kering biji per hektar. Tanaman jagung yang ditumpangsarikan dengan kacang nasi pada perlakuan model tumpangsari salome dengan pengaturan jarak tanam doble row menghasilkan berat kering biji per petak paling tinggi yaitu sebesar 269,31 g dan 0,89 t/ha.

Pengaruh Model Defoliasi Daun Jagung dan Jumlah Benih terhadap Hasil Jagung dan Kacang Nasi pada Sistem Tumpangsari Salome (Kearifan Lokal Timor)

Sistem tumpangsari yang dilakukan di pulau Timor khususnya Kabupaten Timor Tengah Utara (TTU) masih sangat tradisional yaitu dengan menanam beberapa jenis tanaman yang berbeda spesies dalam lubang tanam yang sama. Sistem ini biasanya disebut dengan Salome atau satu lubang rame-rame. Sistem tumpangsari salome tentunya memiliki kelemahan yaitu terjadi persaingan secara vertikal maupun secara horizontal. Penelitian ini bertujuan untuk mengetahui pengaruh model defoliasi dan jumlah benih terhadap hasil jagung dan kacang nasi serta untuk mengetahui Land Equivalend Racio (LER) dalam sistem tumpangsari salome. Rancangan yang digunakan dalam penelitian ini adalah Rancangan Acak Kelompok (RAK) factorial 6 x 4 + monokultur yang diulang 3 kali. Faktor pertama adalah model defoliasi daun jagung, Tanpa defoliasi, defoliasi batang atas 50% dari tongkol, defoliasi batang atas 100% dari tongkol, defoliasi daun jagung dengan hanya meninggalkan tulang daun 100% dari pangkal hingga daun bendera, defoliasi daun jagung dengan hanya meninggalkan tulang daun dari daun bendera hingga tongkol, defoliasi daun jagung dengan hanya meninggalkan tulang daun dari daun pangkal hingga tongkol. Faktor kedua adalah perbandingan jumlah benih jagung umur genjah kultivar lokal timor dan benih kacang nasi tipe tegak, satu jagung satu kacang, satu jagung dua kacang, dua jagung satu kacang, dua jagung dua kacang. Hasil penelitian menunjukkan bahwa model defoliasi daun jagung dan jumlah benih mempengaruhi hasil jagung secara signifikan tetapi tidak berpengaruh terhadap hasil kacang nasi dan tumpangsari salome menghasilkan nilai total LER>1. ©2018 dipublikasikan oleh Savana Cendana.

Two citrate transporters coordinately regulate citrate secretion from rice bean root tip under aluminum stress.

Aluminum (Al)-induced organic acid secretion from the root apex is an important Al resistance mechanism. However, it remains unclear how plants fine-tune root organic acid secretion which can contribute significantly to the loss of fixed carbon from the plant. Here, we demonstrate that Al-induced citrate secretion from the rice bean root apex is biphasic, consisting of an early phase with low secretion and a later phase of large citrate secretion. We isolated and characterized VuMATE2 as a possible second citrate transporter in rice bean functioning in tandem with VuMATE1, which we previously identified. The time-dependent kinetics of VuMATE2 expression correlates well with the kinetics of early phase root citrate secretion. Ectopic expression of VuMATE2 in Arabidopsis resulted in increased root citrate secretion and Al resistance. Electrophysiological analysis of Xenopus oocytes expressing VuMATE2 indicated VuMATE2 mediates anion efflux. However, the expression regulation of VuMATE2 differs from VuMATE1. While a protein translation inhibitor suppressed Al-induced VuMATE1 expression, it releases VuMATE2 expression. Yeast one-hybrid assays demonstrated that a previously identified transcription factor, VuSTOP1, interacts with the VuMATE2 promoter at a GGGAGG cis-acting motif. Thus, we demonstrate that plants adapt to Al toxicity by fine-tuning root citrate secretion with two separate root citrate transport systems.

Direct and Residual Effect of Organic Manure on Buckwheat (Fagopyrum Esculentum Moench) – Fodder Ricebean (Vigna Umbellata) Cropping System

The research programme was carried out during early summer seasons of 2012 and 2013 at the experimental farm of Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar to study the direct and left over effect of organics on Buckwheat (Fagopyrum esculentum Moench) – fodder Rice bean (Vigna umbellata) cropping system. The trial was carried out in Randomized block design with 14 treatments and replicated thrice. Results demonstrate that combined application of vermicompost, poultry manures, mustard cake and farmyard manure improved seed yield of buck wheat by 0.51 and 0.53 t ha-1 over 100 % RDF in 2012 and 2013, respectively. Among the sole application of organic manures, application of poultry manure at 5 t ha-1 proved its superiority in terms of stem and seed yield of buck wheat. Collective application of vermicompost at 2.5 t ha-1 + mustard Cake at 2.5 t ha-1 + poultry manure at 2.5 t ha-1 + Farmyard manure at 4 t ha-1 to the preceding buckwheat crop produced 18.67 and 17.20% more fodder yield of ricebean than 100 % chemically treated plot during both the years. Application of vermicompost at 2.5 t ha-1 + mustard Cake at 2.5 t ha-1 + poultry manure at 2.5 t ha-1 + Farmyard manure at 4 t ha-1 also leave highest amount of available N, P and K in the soil. Economic analysis revelaed that treatment producing highest yield of buck wheat and ricebean fetched lower B: C ratio (0.63 and 0.74 during 2012 and 2013, respectively) as compared to other treatemnts.

Intercropping Maize With Legumes for Sustainable Highland Maize Production

Residue burning to prepare soil for maize growing deprives the soil of both protective cover and organic matter, and it exacerbates environmental issues such as Southeast Asia's haze problem. This paper reports on a study that evaluated the effectiveness of maize/legume intercropping as an alternative to maize cultivation with residue burning. Cowpea (Vigna unguiculata), mung bean (V. radiata), rice bean (V. umbellata), and lablab (Lablab purpureus) were sown into a standing maize crop 30 days before harvest, and the results were compared with a maize crop grown using residue burning as the method for land preparation at Pang Da Agricultural Station in Chiang Mai, Thailand, in a replicated trial conducted over 3 growing seasons from 2012 to 2014. Intercropping increased maize grain yield by 31–53% and left 70–170% more residue containing 113–230% more nitrogen than the maize sown after residue burning, depending on the legume, and decreased weed dry weight by two-thirds after 2 seasons. Soil biodiversity was enriched by the intercrops, with a doubling in the spore density of arbuscular mycorrhizal fungi in the root-zone soil and increased abundance, diversity (Shannon index), and richness of the soil macrofauna. The abundance of soil animals increased with crop residue dry weight (r = 0.90, P < 0.05) and nitrogen content (r = 0.98, P < 0.01). The effect of intercropping on maize grain yield and accumulation of residue and nitrogen were then confirmed in a participatory experiment involving farmers in 2 highland villages in the Phrao and Chiang Dao districts of Chiang Mai Province with maize and rice bean in 2015. The effects of maize/legume intercropping—increased nitrogen accumulation and crop residue, enhanced soil biodiversity, suppression of weeds, and protection of the soil surface, which enabled the maize to be sown without land clearing with fire—should all contribute to sustainable highland maize production.

Evaluation and molecular characterization of advanced interspecific lines for genetic improvement in mungbean [Vigna radiata (L.) Wilczek

The present study was undertaken to evaluate advanced interspecific lines of mungbean [Vigna radiata (L.) Wilczek] for yield and its components and to understand genetic diversity among these lines using microsatellite markers (SSRs). The experimental material consisted of 51 advanced interspecific lines developed from mungbean [Vigna radiata (L.) Wilczek] ×urdbean [Vigna mungo L. Hepper] and mungbean [Vigna radiata (L.) Wilczek] ×ricebean [Vigna umbellata Thumb.] crosses and 13 parental lines (mungbean, urdbean and ricebean). A wide range of variability was observed for eleven yield and its component characters and many superior lines were identified. SSR markers synthesised from different Vigna species were used to assess genetic diversity in advanced interspecific lines along with their parents. The interspecific lines were converged into three main clusters while the parental lines were converged into three main and four sub clusters, depicting genetic diversity among them.

Combined effects of cover crops, mulch, zero-tillage and resistant varieties on Striga asiatica (L.) Kuntze in rice-maize rotation systems

In low-input rice-maize rotation systems in the hills of central Madagascar, farmers deal with erratic rainfall, poor soils, high soil erosion risks and infestation by the parasitic weed Striga asiatica (L.) Kuntze. Practices combining zero-tillage with permanent soil cover by intercropped legumes and crop residue mulches — known as Conservation Agriculture (CA)— are proposed as remedy against soil and climatic constraints. Implications of these practices for S. asiatica are unknown. A 4-season factorial experiment compared the current farmer practice of rice − maize rotation, involving seasonal tillage and crop residue removal (CONV), with three rice − maize rotation systems following CA with different cover crops, i.e. Vigna unguiculata (cowpea) and Mucuna pruriens (CACM), Vigna umbellata (ricebean) (CARB), and Stylosanthes guianensis (CAST). Performance of two rice varieties, NERICA-4 and −9, with partial S. asiatica resistance, were compared with the locally popular B22. Parasite emergence time, numbers, and seed bank sizes were recorded.In all CA practices S. asiatica infection was significantly reduced. Best results were obtained with Stylosanthes guianensis (CAST). This species also suppressed ordinary weeds much better than other cover crops. With CAST, average parasite emergence was delayed by 7.5 days (in rice) and 6.3 days (in maize) and infection levels were reduced by 79% (in rice) and 92% (in maize) compared to the conventional farmer practice (CONV). NERICA varieties delayed S. asiatica emergence by 5.7 days (NERICA-9) and 9.7 days (NERICA-4) and reduced infection levels by 57% (NERICA-9) and 91% (NERICA-4) compared to B22. In maize the residual effect of resistance of NERICA-4 resulted in a delay of 7.5 days in S. asiatica emergence and a reduction of 60% in parasite numbers. The best combinations delay S. asiatica emergence by 17.8 days (CAST + NERICA-9) and 19.1 days (CARB + NERICA-4) and reduce the parasite infection levels by 96% (CAST + NERICA-9 or −4) to 98% (CARB + NERICA-4) in rice, compared to CONV + B22. After two full rice-maize rotation cycles S. asiatica seed numbers in the soil (0–10 cm) were 76% (CACM), 78% (CAST) and 86% (CARB) lower than under CONV. Even the combination of zero-tillage, crop residue mulching, cover crops and resistant rice varieties does not entirely prevent S. asiatica parasitism and seed bank increase. Additional measures, targeted to escaping weeds, would be required for fully effective and long-term control.

Biological relationship of Bean common mosaic virus (BCMV) infecting cowpea with leguminous plant species

Bean common mosaic virus (BCMV) associated with cowpea mechanically inoculated to different legumi-nous plants. Out of nineteen including cowpea Var.C-152, the virus was easily transferred to ten different legumi-nous hosts. All other hosts assessed for the presence of BCMV were found to be uninfected. The number of days taken for symptom expression and symptoms were varied within plant species. Pole bean expressed mosaic symp-tom after long incubation period (15-18 days) whereas, shorter incubation period was observed in common bean and rice bean (7- 10 days). BCMV produced chlorosis, mosaic, leaf distortion, puckering, vein banding, vein clearing and vein netting on cowpea(C-152). A typical virus symptom, mosaic was observed in green gram, common bean, lime bean, rice bean and yard long bean, whereas, leaf rolling and leaf distortion was observed in black gram, pole bean and snap bean. The virus-host relationship was confirmed by back inoculation test to C. amaranticolor. Further symptomatic plants were subjected for Reverse Transcriptase polymerase chain reaction (RT-PCR) for molecular confirmation using BCMV coat protein (CP) specific primer pair. A PCR fragment size of 439bp was amplified for the symptomatic plants. The results generated indicated the ability of a plant to support virus expression and host speci-ficity of BMCV within the leguminous plant species.

Optimization of rice bean cooking parameters for the production of instant/convenience foods using response surface methodology

An optimized cooking protocol (OCP) for rice bean (Vigna umbellata) was developed to improve the efficiency of the conventional process (CP) which limits the exploration of rice bean for commercial applications. The cooking process was studied to achieve optimum processing time, least grain breakage, minimum solid loss (SL), and best overall acceptability (OAA). A central composite rotatable design was used to evaluate the effect of process variables, namely soaking time (STi: 3–12 hr), soaking temperature (STe: 30–60 °C), and cooking time (CT: 12–32 min) on process responses. The optimized process conditions were: STi of 7 hr, STe of 42 °C, and CT of 22 min that reduce the STi (12 hr), CT (35 min) and SL (22.5%) of the CP by 42, 37, and 52%, respectively. The grains from OCP had significantly (p < .05) better physico-nutritional (grain surface area: 159.52 ± 12 mm2, calcium: 156 ± 3.11 mg/100 g, antioxidant activity: 335 ± 43 μM butylated hydroxyanisole/100 g) properties and similar OAA (8.55). The OCP is highly suitable for rice bean intended for developing instant foods. Practical applications The cooked grains can easily be obtained from conventional process but certain constraints associated with it which limits its applicability for commercial production of rice bean based instant/convenience foods products. These constraints include susceptibility of cooked grains to breakage, necessity of immediate downstream processing to prevent germination or spoilage, and long processing time (soaking time: 12 hr, cooking time: 30–35 min) as well as high leaching loss of solid (22–28.55%). The optimized process conditions are able to reduce the soaking time (12 hr), cooking time (35 min), and solid loss (22.5%) of conventional process by 42, 37, and 52%, respectively. The information of this article will be useful for the industrialists associated with commercial production of ready-to-eat (RTE) bean products, baked bean, and instant bean products.