Potential,constraints and applications of in vitro methods in improving grain legumes

Grain legumes, the important constituents of sustainability‐based cropping systems and energy‐limited vegetarian diets have long been the subject of scientific research. Tremendous technological strides were made in the so‐called orphan crops, in terms of both varietal improvement and generation of basic information. Despite recalcitrancy and high genotype dependency, in vitro culture techniques such as organogenesis, in vitro mutagenesis, embryo rescue and in vitro gene transfer have been deployed for improvement of several grain legumes and these played an important role in introgression of desirable genes from related and distant species and creation of additional genetic variability. Stable and reproducible regeneration protocols resulted in the development of genetically modified chickpea, pigeon pea, cowpea, mungbean, etc., while embryo rescue was deployed successfully for recovery of interspecific recombinants, a few of them exploited for the development of commercial cultivars. Nevertheless, doubled haploidy witnessed limited success and protoplast regeneration and in vitro mutagenesis remained of academic interest. The present review focuses on the progress, achievements, constraints and perspectives of using in vitro technology in grain legume improvement.     

Understanding genetic diversity in blackgram [Vigna mungo (L.) Hepper] collections of Indian National Genebank

Genetic Resources and Crop Evolution - Blackgram [Vigna mungo (L.) Hepper] is a protein rich pulse crop of Indian origin. The crop is cultivated in diverse range of agro-ecological regions,...     

Nutrient losses from rain‐fed bench terraced cultivation systems in high rainfall areas of the mid‐hills of Nepal

Between the elevations of 1000 and 2000 m in the mid‐hills of Nepal, over 12 million people subsist on land‐holdings of less than 0·5 ha. These farmers have limited access to commercial inputs such as fertilisers and are reliant on organic manures for soil fertility maintenance. Participatory research was conducted with farmers on bari land (upper slope rain‐fed crop terraces) in the hill community of Landruk (bench terraces 0–5° slope, 3000–3500 mm annual rainfall, which aimed to develop soil and water management interventions that controlled erosion without resulting in high leaching, and so were effective in minimising total nutrient losses. Interventions tested were the control of water movement through diversion of run‐on and planting fodder grasses on terrace risers on bench terraces. The interventions were effective in reducing soil loss from the bari land in comparison with existing farmer practices, but no effect was observed on nutrient losses in solution form through runoff and leaching. Losses of NO₃‐N in leachate ranged from 17·3 to 99·7 kg ha⁻¹ yr⁻¹, but only 0·7 to 5·6 kg ha⁻¹ yr⁻¹ in runoff. The overall nutrient balance suggests that the system is not sustainable. Fertility is heavily dependent on livestock inputs and if the current trends of declining livestock numbers due to labour constraints continue, further losses in productivity can be expected. However, farmers are interested in interventions that tie ecosystem services with productivity enhancement and farmers' priorities should be used as entry points for promoting interventions that are system compatible and harness niche opportunities. Copyright © 2007 John Wiley & Sons, Ltd.     

Influence of tillage and crop residue on soil physical properties and yields of rice and wheat under shallow water table conditions

An experiment was conducted to evaluate the effects of tillage and residue incorporation on soil properties and yields of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) in rotation for 4 years on a silty clay loam of an Aquic Hapludoll with natural water table fluctuating between 0.05 and 0.97 m depth The rice experiment was laid out in split plot design with four levels of tillage, viz. conventional puddling (CP), puddling by four passes of rotavator (PR), reduced puddling by two passes of rotavator (ReP), and direct seeding without puddling (DSWP) and two levels of residue, viz. residue incorporation (RI) and residue removal (RR) in four replications. The treatments for wheat were zero tillage (ZT) and conventional tillage (CT) with RI and RR superimposed over the plots of rice. Tillage for rice increased puddling index and bulk density (BD) over the years. The increase was significantly higher in CP and PR than in ReP. In wheat season, BD was higher under ZT than under CT but the differences were not significant. Puddling decreased saturated hydraulic conductivity with time, which became significantly lower in CP and PR in the fourth year than in ReP in the first year. Infiltration rate (IR) also decreased with time and was lowest in CP and PR. In wheat season, IR was at par under ZT and CT. Rice yield in PR was maximum and at par with that in ReP. But wheat yield was lowest in PR and highest in DSWP, and was at par in DSWP and ReP. Thus, rice yields were optimum under ReP, in which changes in soil properties were least, and wheat yields were optimum both under ZT and CT in the DSWP and ReP plots of rice under shallow water table conditions of the silty clay loam.     

Hematologic reference intervals for koi (Cyprinus carpio), including blood cell morphology, cytochemistry, and ultrastructure

BACKGROUND: Hematologic data are used routinely in the health care of humans and domestic mammals. Similar data for fish are largely fragmentary or have not been collected. OBJECTIVES: The primary purpose of this study was to determine hematologic reference intervals for koi, an ornamental strain of the common carp (Cyprinus carpio). Secondarily, the morphology, cytochemical reactions, and ultrastructure of koi blood cells were characterized. METHODS: A CBC was performed manually on heparin-anticoagulated blood specimens using Natt and Herrick's diluent and a Neubauer-ruled hemacytometer. Leukocyte differential counts were done on Wright-Leishman- and Diff-Quik-stained blood smears. Cytochemical reactions of koi leukocytes were determined using commercial kits. Transmission electron microscopy was performed to characterize the ultrastructural features of koi blood cells. RESULTS: Hematologic reference intervals were established for healthy koi for PCV (30-34%), hemoglobin concentration (6.3-7.6 g/dL), RBC count (1.7-1.9 X 10(6)/ microL), WBC count (19.8-28.1 X 10(3)/ microL), RBC indices, and differential leukocyte counts. Lymphocytes were the predominant leukocyte (accounting for up to 80% of all leukocytes), whereas eosinophils were rare. Basophils were positive with PAS staining. Naphthol AS-D chloroacetate esterase activity was observed only in eosinophils. alpha-Naphthyl butyrate esterase and beta-glucuronidase activities were positive in monocytes. Some lymphocytes were reactive for alpha-naphthyl butyrate esterase and acid phosphatase activity. Ultrastructurally, leukocytes, erythrocytes, and thrombocytes were identified on the basis of cytoplasmic organelles and granule appearance. CONCLUSION: Hematologic reference intervals and knowledge of the cytochemical reactions and ultrastructural characteristics of koi leukocytes will help standardize hematologic studies in this species.     

Agro-morphological variation in “Jhinuwa” rice landraces (Oryza sativa L.) of Nepal

Jhinuwa is an aromatic rice (Oryza sativa L.) landrace from the Pokhara Valley of Nepal. A total of 210 accessions comprising seven types of Jhinuwa rice landraces were randomly collected from the rice fields to evaluate inter- and intra-population variability based on agro-morphological traits. The experiment was conducted in factorial randomized complete block design with three replicates in 2005. The first six principal components (PCs) accounted for 76.6 % variation for agro-morphological traits. Major traits that accounted for the variation by six PCs includes days to heading, days to maturity, total grain panicle^?1, fertile grain panicle^?1, culm length, panicle length, milling recovery, head rice recovery, aroma, 1,000 grain weight, sterile grain panicle^?1, grain sterility %, and leaf characteristics. Both principal coordinate analysis and cluster analyses revealed four phenotypic groups, two of which represent Bayarni, Jhinuwa, and Biramphul while the other two account for Tunde and Pakho Tunde. Tunde, Pakho Tunde, Kalo Bayarni, and Seto Bayarni showed higher intra- as well as inter-population variation compared to other populations. The phenotypic and genotypic coefficients of variation, broad sense heritability (h ²B) and genetic advance (GA) as a percent of the mean assessed for 210 accessions revealed high h ²B and GA estimates for leaf width, leaf length breadth ratio, ligule length, sterile grain panicle^?1, grain sterility % and 1,000 grain weight. The current study demonstrates that improvement in Jhinuwa rice landrace is possible by selecting superior accessions from existing natural populations while selection should be focussed to market traits with higher h ²B and GA estimates.     

Growth and reproduction of the vermicomposting earthwormPerionyx excavatus as influenced by food materials

An outdoor study was undertaken using polyethylene containers to assess the suitability of different organic residues, soybean straw (Glycine max L. Merril.), wheat straw (Triticum aestivum L.), maize stover (Zea mays L.), chickpea straw (citer arietinum L.) and city garbage, as food for the tropical epigeic earthwormPerionyx excavatus, and to assess the influence of this earthworm on the decomposition of these materials. Maize stover was found to be the most suitable of the food materials used. Population growth ofP. excavatus was enhanced by addition of these organic materials in the temperature range 24°-30°C, while the population was adversely affected above 30°C in a vermiculture system. Addition of earthworms accelerated the breakdown of residues, which ultimately resulted in a lowering of the C:N ratio, water-soluble carbon and carbohydrates, and increased ash percentage and cation exchange capacity compared with their respective controls.     

Allergenicity assessment of the papaya ringspot virus coat protein expressed in transgenic rainbow papaya

The virus-resistant, transgenic commercial papaya Rainbow and SunUp (Carica papaya L.) have been consumed locally in Hawaii and elsewhere in the mainland United States and Canada since their release to planters in Hawaii in 1998. These papaya are derived from transgenic papaya line 55-1 and carry the coat protein (CP) gene of papaya ringspot virus (PRSV). The PRSV CP was evaluated for potential allergenicity, an important component in assessing the safety of food derived from transgenic plants. The transgene PRSV CP sequence of Rainbow papaya did not exhibit greater than 35% amino acid sequence homology to known allergens, nor did it have a stretch of eight amino acids found in known allergens which are known common bioinformatic methods used for assessing similarity to allergen proteins. PRSV CP was also tested for stability in simulated gastric fluid and simulated intestinal fluid and under various heat treatments. The results showed that PRSV CP was degraded under conditions for which allergenic proteins relative to nonallergens are purported to be stable. The potential human intake of transgene-derived PRSV CP was assessed by measuring CP levels in Rainbow and SunUp along with estimating the fruit consumption rates and was compared to potential intake estimates of PRSV CP from naturally infected nontransgenic papaya. Following accepted allergenicity assessment criteria, our results show that the transgene-derived PRSV CP does not pose a risk of food allergy.