Tolerance to excess moisture in maize (Zea mays L.): susceptible crop stages and identification of tolerant genotypes

Excess moisture (water-logging) during the summer–rainy season is one of the major production constraints for maize (Zea mays L.) in a large area of Southeast Asia. Identification and development of genotypes capable of withstanding the stress conditions could be an ideal and affordable approach suitable for resource poor maize-growing farmers of such areas. We attempted to identify the most susceptible/critical crop stage(s) of maize for excess moisture stress, and to develop a screening technique and selection strategies for identification of germplasm tolerant to excess moisture stress. Among the four crop stages, i.e. early seedling (V2), knee-high (V7), tasseling (VT) and milk stage (R1), V2 was found to be highly susceptible, followed by the V7 stage. A screening technique (cup method) was developed/standardized, and was found to be an efficient technique for large-scale screening of maize genotypes against excess soil moisture stress. Germplasm was screened using this technique followed by field evaluation at the V7 growth stage (seventh leaf visible). Excess soil moisture stress severely affected various growth and biochemical parameters, impaired anthesis and silking, and eventually resulted in poor kernel development and yield. However, remarkable variability was found among the genotypes studied. Genotypes with good carbohydrate accumulation in stem tissues, moderate stomatal conductance, <5 days ASI, high root porosity, and early brace root development ability have been found to have good tolerance against the hypoxia/anoxia caused by excess soil moisture conditions.     

Impact of Bran Addition on Water Properties and Gluten Secondary Structure in Wheat Flour Doughs Studied by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

The aim of this work was to elucidate the underlying physical mechanism(s) by which bran influences whole grain dough properties by monitoring the state of water and gluten secondary structure in wheat flour and bran doughs containing 35–50% moisture and 0–10% added bran. The system was studied with attenuated total reflectance (ATR) FTIR spectroscopy. Comparison of the OH stretch band of water in flour dough with that in H₂O‐D₂O mixtures having the same water content revealed the formation of two distinct water populations in flour dough corresponding to IR absorption frequencies at 3,600 and 3,200 cm^–1. The band intensity at 3,200 cm^–1, which is related to water bound to the dough matrix, decreased and shifted to lower frequencies with increasing moisture content of the dough. Addition of bran to the dough caused redistribution of water in the flour and bran dough system, as evidenced by shifts in OH stretch frequency in the 3,200 cm^–1 region to higher frequencies and a reduction in monomeric water (free water). This water redistribution affected the secondary structure of gluten in the dough, as evidenced by changes in the second‐derivative ATR‐FTIR difference spectra in the amide I region. Bran addition caused an increase in β‐sheet content and a decrease in β‐turn (β‐spiral) content. However, this bran‐induced transconformational change in gluten was more significant in the 2137 flour dough than in Overley flour dough. This study revealed that when bran is added to flour dough, water redistribution among dough components promotes partial dehydration of gluten and collapse of β‐spirals into β‐sheet structures. This transconformational change may be the physical basis for the poor quality of bread containing added bran.     

Potentiation of Hypolipidemic and Weight-Reducing Influence of Dietary Tender Cluster Bean ( Cyamopsis tetragonoloba ) When Combined with Capsaicin in High-Fat-Fed Rats

Soluble fiber-rich tender cluster bean pod ( Cyamopsis tetragonoloba ) (CB) and a combination of CB and capsaicin, a thermogenic spice compound, were evaluated for weight-reducing effect in high-fat-fed Wistar rats. Freeze-dried CB and capsaicin were included at 15 and 0.015%, respectively, in the high-fat (30%) diet for 8 weeks. Excretion of dietary fat, fat deposition in adipose, and activities of enzymes involved in lipolysis and lipogenesis were examined. CB and capsaicin additively decreased weight gain in high-fat-fed rats, without affecting feed intake. The antiobesity potential of CB was through impeding fat accumulation in adipose and enhancing fat excretion. Decrease in adipose triglyceride by the combination was higher than their individual effects and was accompanied by enhanced activity of hormone-sensitive lipase-facilitating mobilization of depot fat. Increased fecal excretion of triglycerides by the combination of CB and capsaicin was additive. Whereas the hypolipidemic effect of the combination was higher than their individual effects, the decrease in hepatic cholesterol and triglycerides produced by the combination was additve. Thus, dietary CB significantly checked weight gain and adverse changes in lipid profile in high-fat-fed condition amounting to a cardioprotective effect. These beneficial effects were potentiated by coadministration of capsaicin.     

Additional wet milling step for fractionation of barley flour after hull separation

Fuel ethanol production from barley is increasing and there is a need to develop more efficient production processes. In the conventional ethanol production process, the hulls (fiber) in barley do not get fermented. The objective of this study is to evaluate a wet fractionation method, similar to the one used in corn wet milling in the endosperm fiber separation step, on the flour remaining after hull separation from barley in order to increase the starch content of barley flour. Hulls were separated from hammer milled barley flour using a combination of sieving and air classification. The remaining flour was soaked in water and the slurry was ground using an attrition mill. The cell wall material was screened out from the fine slurry. The fermentation material produced by hull separation followed by wet fractionation comprised 80.9% by weight of the original flour and contained 10.1% higher starch and 7.9% lower fiber (neutral detergent fiber; NDF) contents than the original flour. The cell wall coproduct has potential as a functional food ingredient because it has high fiber (NDF of 42.7%), high beta-glucan (4.5%) and high protein (20.2%) contents. The increase in starch content may be beneficial in fuel ethanol production.     

Spatial distribution of soil physical properties of alluvial soils: a geostatistical approach

Knowledge of spatial variation of soil is important in site-specific farming and environmental modeling. Soil particles size and water distribution are most important soil physical properties that governing nearly all of the other attributes of soils. The objectives of this study were to determine the degree of spatial variability of sand, silt and clay contents, and water content at field capacity (FC), permanent wilting point (PWP), and available water content (AWC) of alluvial floodplain soils. Data were analyzed both statistically and geostatistically to describe the spatial distribution of soil physical properties. Soil physical properties showed large variability with greatest variation was observed in sand content (68%). Exponential and spherical models were fit well for the soil physical properties. The nugget/sill ratio indicates except clay all other soil physical properties were moderate spatially dependent (37–70%). Cross-validation of the kriged map shows that prediction of the soil physical properties using semivariogram parameters is better than assuming mean of observed value for any unsampled location. The spatial distribution of water retention properties closely followed the distribution pattern of sand and clay contents. These maps will help to planner to develop the variable rate of irrigation (VRI) for the study area.     

Contacts between domestic livestock and wildlife at the Kruger National Park Interface of the Republic of South Africa

One of the most important transboundary animal diseases (TADs) in the southern African region is foot-and-mouth disease (FMD). In this region, a pathway for spread of FMD virus is contacts between cattle and certain species of wildlife. The objective of this study was to evaluate contacts between cattle and wildlife in the Kruger National Park (KNP) and the adjacent Limpopo province for the time periods October 2006 to March 2007 and April to September 2007. In this study, 87 livestock owners and 57 KNP field rangers were interviewed. Fifteen (17%) livestock owners reported contacts between wildlife and cattle. More livestock owners reported observing contacts between cattle and all wildlife species during October-March than April-September (p = 0.012). However, no difference was found between these periods for contacts between cattle and individual wildlife species. A total of 18 (32%) field rangers reported contacts between cattle and wildlife. The most common species-specific contacts were between cattle and buffalo (63/year), cattle and impala (17/year) and cattle and lion (10/year). There were no significant differences in rangers reporting observed contacts between cattle and wildlife during October-March versus April-September or between rangers reporting observed contacts outside versus within the KNP. Overall, there was no evidence of higher contact rates between cattle and wildlife in the study area during October-March compared to April-September. Contact data collected in this study can be used to better understand the transmission of FMD virus in this region.     

Screening for resistance against major lepidopteran and stem weevil pests of amaranth in Tanzania

Insect pests pose major challenges to optimum productivity of amaranth in Africa and Asia. The use of insecticides is the main control strategy, but is expensive and may pose health and environmental concerns, especially if proper care is not taken. Host plant resistance offers a cheap and sustainable pest management alternative. Open field experiments were conducted during two cropping seasons in 2016 and 2017 to screen 35 amaranth accessions and lines for resistance to leaf-webbers and stem weevils. The diversity (H) of lepidopteran defoliators and their parasitoids on each accession ranged from 0.00 to 1.57 and 0.00 to 1.65, respectively during the long rainy season and from 0.00 to 1.58 and 0.00 to 1.01 in the short rainy season. Accessions VI036227, RVI00027, VI054569, VI033487, VI044432, VI048076, VI049639, VI049530 and VI049698 had high levels of pest resistance with significantly lower infestations (≤?11.11?±?2.14%) and damage (≤?68.06?±?3.90%) by leaf-webbers and leaf-worms. Stem weevil infestations ranged from 68.70?±?2.0% to 90.42?±?1.0% during the long and short rainy seasons, respectively. Accessions VI047517-B, VI036227 and VI056563 had the least stem weevil infestations (<?62.5%) but differences among accessions for damage incidences were non-significant. Parasitism was observed in all the accessions except seven of them. Amaranth accessions exhibiting pest resistance or at least non-preference traits are important for success of breeding programs. The importance of deploying such accessions to breed for improvement of susceptible lines (by introgression) or their release to farmers, if they have desirable horticultural traits that are required by vegetable producers and consumers, for effective management of amaranth pests is also discussed.     

Effect of FMD vaccine antigen payload on protection, sub-clinical infection and persistence following needle challenge in sheep

The relationship of Foot-and-Mouth Disease (FMD) virus antigen payload and single and double vaccinations in conferring protection against virus challenge in sheep was studied. Sheep vaccinated with half the cattle dose (1 ml) containing 15 and 3.75 μg of FMDV antigen with or without booster resisted virulent challenge on 21 days post vaccination or 7 days post booster. FMDV RNA could be detected in nasal secretions in 26% of vaccinated sheep (10^3.12 to 10^3.82 viral RNA copies) on day 35 post challenge. No live virus could be isolated after 5 days post challenge indicating that the risk of transmission of disease was probably very low. The finding showed that vaccines containing antigen payload of 1.88 μg may prevent or reduce the local virus replication at the oropharynx and shedding of virus from nasal secretions and thereby reduce the amount of virus released into the environment subsequent to exposure to live virus. Sheep with no vaccination or with poor sero conversion to vaccination can be infected without overt clinical signs and became carriers.     

Detection of intercellular adhesion genes and biofilm production in <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> isolated from bovine subclinical mastitis

Biofilm production by Staphylococcus aureus, an important virulence factor was investigated employing phenotypic and genotypic methods. A total of 102 S. aureus isolates from bovine subclinical mastitis cases were included in the study. Maximum number of biofilm producing strains were detected by Congo red agar (CRA) method (48.03%) followed by tube method (36.27%). Tissue culture plate method (TCP) without and with destaining identified 19.60 and 29.41% of S. aureus as biofilm producers, respectively. A polymerase chain reaction for detection of intercellular adhesion genes, icaA and icaD, responsible for biofilm formation was standardized. Of the 102 S. aureus isolates investigated, 36 (35.29%) strains revealed presence of both the genes. Considering polymerase chain reaction as a standard test, CRA and TCP without destaining were the most sensitive and specific, respectively. PCR technique standardized for detection of the icaA and icaD genes is reliable for identifying biofilm producing potential of S. aureus which may help in rapid detection of biofilm-producer Staphylococci. This would allow the early application of control measures.     

Current control methods for diamondback moth and other brassica insect pests and the prospects for improved management with lepidopteran-resistant Bt vegetable brassicas in Asia and Africa

The diamondback moth (DBM), Plutella xylostella (L.), remains a major pest of brassica crops worldwide. DBM has been estimated globally to cost US$ 1 billion in direct losses and control costs. Chemical control of this pest remains difficult due to the rapid development of resistance to insecticides and to their effect on natural enemies. These problems are especially severe in South Asia and Africa where lack of knowledge, limited access to newer and safer insecticides, and a favourable climate result in DBM remaining a serious year-round pest which substantially increases the cost and uncertainty of crop production. Despite these problems, application of synthetic insecticides remains overwhelmingly the most common control strategy. Biologically-based efforts to control DBM in Africa and Asia have focused strongly on parasitoid introductions. However, despite the identification and deployment of promising parasitoids in many regions, these efforts have had limited impact, often because farmers continue early-season spraying of broad-spectrum insecticides that are lethal to parasitoids and thus exacerbate DBM outbreaks. A significant driver for this pattern of insecticide use is the presence of aphids and other pests whose appearance initiates inappropriate spraying. Despite often extensive training of producers in farmer field schools, many growers seem loath to discard calendar or prophylactic spraying of insecticides. The introduction of an IPM technology that could replace the use of broad-spectrum insecticides for DBM and other key Lepidoptera is crucial if the benefits of parasitoid introduction are to be fully realised. The deployment of DBM-resistant brassicas expressing proteins from Bacillus thuringiensis could help to break this cycle of insecticide misuse and crop loss, but their deployment should be part of an integrated pest management (IPM) package, which recognises the constraints of farmers while addressing the requirement to control other Lepidoptera, aphids and other secondary pests.