Shinya Oba

Indigenous utilization of termite mounds and their sustainability in a rice growing village of the central plain of Laos

BackgroundThe objective of this study was to investigate the indigenous utilization of termite mounds and termites in a rain-fed rice growing village in the central plain of Laos, where rice production is low and varies year-to-year, and to assess the possibility of sustainable termite mound utilization in the future. This research was carried out from 2007 to 2009.MethodsThe termites were collected from their mounds and surrounding areas and identified. Twenty villagers were interviewed on their use of termites and their mounds in the village. Sixty-three mounds were measured to determine their dimensions in early March, early July and middle to late November, 2009.ResultsEleven species of Termitidae were recorded during the survey period. It was found that the villagers use termite mounds as fertilizer for growing rice, vegetable beds and charcoal kilns. The villagers collected termites for food and as feed for breeding fish. Over the survey period, 81% of the mounds surveyed increased in volume; however, the volume was estimated to decrease by 0.114 m3 mound-1 year-1 on average due to several mounds being completely cut out.ConclusionIt was concluded that current mound utilization by villagers is not sustainable. To ensure sustainable termite utilization in the future, studies should be conducted to enhance factors that promote mound restoration by termites. Furthermore, it will be necessary to improve mound conservation methods used by the villagers after changes in the soil mass of mounds in paddy fields and forests has been measured accurately. The socio-economic factors that affect mound utilization should also be studied.

Evaluation of the SPAD Value in Faba Bean (Vicia faba L.) Leaves in Relation to Different Fertilizer Applications

Abstract The correlations of the reading of a portable chlorophyll meter (SPAD-502) with the chlorophyll and N contents of leaves of two faba bean (Vicia fabaL.) cultivars, Japanese (Ryousai-issun) and Egyptian (Cairo 241), were examined. The SPAD readings positively correlated (ρ<0.01) with the chlorophyll contents and the r2 values were 0.99 and 1.00 for Ryousai-issun and Cairo 241, respectively. A close linear relationship (ρ0.001) was observed between SPAD reading and total leaf N content at the pod development stage of faba bean plants with r2 = 0.88 and 0.99 for Ryousai-issun and Cairo 241, respectively. The SPAD reading was the highest in the 2nd to 4th leaves counted from the top (the youngest fully expanded leaves). The changes in leaf chlorophyll content of both cultivars from 3 weeks after transplanting to the ripening stage showed an incomplete “M” type curve. SPAD readings were significant¬ly higher in Ryousai-issun than in Cairo 241 throughout the growth season. Organic fertilizers application improved faba bean plant growth. These results suggest that the SPAD-502 chlorophyll meter can be used to measure chlorophyll and nitrogen contents of faba bean leaves for quick screening faba bean genotypes.

Foliar Application of Salicylic Acid Improved the Growth, Yield and Leaf's Bioactive Compounds in Red Amaranth (Amaranthus tricolor L.)

Foliar Application of Salicylic Acid Improved the Growth, Yield and Leafs Bioactive Compounds in Red Amaranth (Amaranthus tricolor L.) This study was conducted to determine the effect of foliar salicylic acid (SA) applications on growth, yield and bioactive compounds of red amaranth grown under greenhouse conditions in 2008 at Gifu University, Japan. SA was applied at three different concentrations (10-3, 10-4 and 10-5 M), three times during the vegetation at 7-day intervals one week after sowing. Growth parameters (plant height, stem length, number and size of leaves, root length) and yield (fresh and dry matter weight) were recorded from treated and control plants on 28 days after sowing. Among bioactive compounds, betacyanins, chlorophyll, total polyphenol and antioxidant activity were the determined from the leaves of treated and control plants. All of three doses SA application enhanced the plant growth, yield and leafs bioactive compounds compared to the control. The growth parameters and yield of red amaranth was significantly influenced by foliar SA applications. The highest yield, antioxidant activity, amount of betacyanins, chlorophyll and total polyphenol occurred in 10-5 M SA treatment. According to our results, applications SA at rate of 10-5 M should be recommended in order to improve yield and bioactive compounds in red amaranth. Dolistne Stosowanie Kwasu Aalicylowego Poprawia Wzrost, Plonowanie Oraz Związki Bioaktywne w Liściach Amarantu Czerwonego (Amaranthus tricolor L.) Niniejsze badania przeprowadzono w celu określenia wpływu dolistnego stosowania kwasu salicylowego na wzrost, plonowanie i związki bioaktywne roślin amarantu czerwonego uprawianego w warunkach szklarniowych w roku 2008 na Uniwersytecie Gifu w Japonii. Kwas salicylowy stosowano w trzech stężeniach (10-3, 10-4 i 10-5 M), trzy razy w okresie wegetacji w odstępach 7-dniowych po tygodniu od wysiewu nasion. Notowano parametry wzrostu (wysokość rośliny, długość łodygi, liczbę i wielkość liści, długość korzeni) oraz plonowania (świeżą i suchą masę) roślin traktowanych i kontrolnych 28 dni po siewie. Spośród związków bioaktywnych w liściach roślin traktowanych i kontrolnych określano betacyjaniny, chlorofil, polifenole ogółem i aktywność przeciwutleniającą. Wszystkie trzy zastosowane stężenia kwasu salicylowego zwiększały wzrost roślin, plonowanie oraz związki bioaktywne w liściach w porównaniu z kontrolą. Stosowanie kwasu salicylowego miało istotny wpływ na parametry wzrostu i plonowanie amarantu czerwonego. Najwyższy plon, aktywność przeciwutleniającą, ilość betacyjanów, chlorofilu i polifenoli ogółem uzyskano po traktowaniu roślin kwasem salicylowym w stężeniu 10-5 M. Na podstawie naszych wyników zalecane jest stosowanie kwasu salicylowego w stężeniu 10-5 M, w celu poprawy plonu i zawartości związków bioaktywnych w amarancie czerwonym.

Effect of Chinese Milk Vetch (Astragalus sinicus L.) as a Cover Crop on Weed Control, Growth and Yield of Wheat under Different Tillage Systems

Abstract Reduced tillage systems are gaining popularity but weed control is often a limiting factor in the adoption of such systems. Cover crops have become a viable option for sustainable agriculture because of its contribution to soil fertility and improved crop performance. However, the contribution of cover crops to weed management is not clearly defined. We compared minimum tillage (MT) and no-tillage (NT) with conventional tillage (CT) for their effects on wheat growth in an original paddy land clay soil in the presence of Chinese milk vetch as a cover crop. Cover crop biomass, weed emergence, main crop growth and yield and soil penetration resistance were examined. Chinese milk vetch was successfully established under MT and CT but not under NT, which retarded its growth resulting in a significantly large biomass of all weed species. Weed suppression was more effective when the cover crop was broadcasted than row seeded. The presence of milk vetch as a cover crop significantly suppressed weed growth under MT especially at the late stage of growth and resulted in a comparable grain yield to that under CT. Although soil penetration resistance under MT remained high throughout the period of wheat growth, milk vetch could be effectively utilized as a cover crop under MT and wheat grain yield under MT was comparable to that under CT without mulch treatment.

Influence of Cultivar and Growth Stage on Pigments and Processing Factors on Betacyanins in Red Amaranth (Amaranthus tricolor L.)

Seven cultivars of red amaranth (Amaranthus tricolor L.) with different leaf color were evaluated for their betacyanin and chlorophyll content at two stages of development. The effects of food processing factors such as thermal treatment, light, H2O 2, and prolonged storage on betacyanin extracts were also examined. Betacyanin concentrations were highly correlated with the leaf color index and the cultivars (Rocto joba, BARI-1, and Altopati) with better color index tended to be associated with high betacyanin. Within a shoot canopy, the apical leaves accumulated higher betacyanin than those of middle and basal leaves. While the highest concentrations of chlorophyll were found in BARI-1, however Red queen had the lowest concentrations. Color index of leaves and betacyanin concentrations were increased and chlorophyll concentrations were decreased with the plant age, which indicate that change of these colorant pigment concentrations with plant age enhance the red leaf formation in red amaranth. Low temperature, darkness, and free or low oxidants maintained the stability of betacyanin concentrations of red amaranth; prolonged storage degraded the betacyanin. Variable factors such as the cultivar of red amaranth, its degree of maturity, and the food processing factors have been shown to have a quantitatively important influence on betacyanin yields and preservation.

Response of nutrients, minerals, antioxidant leaf pigments, vitamins, polyphenol, flavonoid and antioxidant activity in selected vegetable amaranth under four soil water content

Four selected vegetable amaranths were grown under four soil water content to evaluate their response in nutrients, minerals, antioxidant leaf pigments, vitamins, polyphenol, flavonoid and total antioxidant activity (TAC). Vegetable amaranth was significantly affected by variety, soil water content and variety × soil water content interactions for all the traits studied. Increase in water stress, resulted in significant changes in proximate compositions, minerals (macro and micro), leaf pigments, vitamin, total polyphenol content (TPC), and total flavonoid content (TFC) of vegetable amaranth. Accessions VA14 and VA16 performed better for all the traits studied. Correlation study revealed a strong antioxidant scavenging activity of leaf pigments, ascorbic acid, TPC and TFC. Vegetable amaranth can tolerate soil water stress without compromising the high quality of the final product in terms of nutrients and antioxidant profiles. Therefore, it could be a promising alternative crop in semi-arid and dry areas and also during dry seasons.

Phenotypic divergence in vegetable amaranth for total antioxidant capacity, antioxidant profile, dietary fiber, nutritional and agronomic traits

ABSTRACT A lot of variations in vegetable amaranth germplasm have been observed in Bangladesh. It has been used as a cheap source of antioxidants, nutrients, protein, and dietary fiber. But no efforts had not been taken to know the status of antioxidant content, polyphenol, flavonoid, antioxidant vitamins and minerals, dietary fiber, nutritional and agronomic traits. In this study, Forty-three vegetable amaranth genotypes were evaluated to determine the status of total antioxidant content, polyphenol, flavonoid, antioxidant vitamins and minerals, dietary fiber, nutritional and agronomic traits and the magnitude of genetic diversity based on the contribution of those traits for meaningful grouping and proper utilization in future breeding program. The experiment was carried out in an open experimental field at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Bangladesh in a randomized complete block design with three replications. Multivariate (Principal component and cluster) analysis was done using numerical taxonomic techniques of Sneath, & Sokal. Four principal components contributed 98.61% of the variation. Biological yield and total antioxidant content was strongly associated with their related all agronomic traits. Total flavonoid content had a higher contribution to total antioxidant capacity compared to vitamin and mineral antioxidants. Contribution of antioxidant profile and agronomic traits was the highest in diversity of vegetable amaranth. Both high and low yielding genotypes had a high antioxidant profile. Therefore, high yielding genotypes (From cluster VI) could be used directly as high antioxidant profile varieties and low yielding genotypes as a source of donor parents in hybridization program. Cluster analysis grouped the genotypes into six clusters. The diverse genotypes in different clusters were identified. Genotypes with desirable genes of one cluster hybridized with promising genotypes of other diverge clusters could facilitate the accumulation of favorable genes in hybrids. Abbreviations: PCA: principal component analysis; PC: principal component; dw: dry weight; TFC: total flavonoid content; TAC: total antioxidant capacity; TPC: total polyphenol content; K: potassium; Ca: calcium; Mg: magnesium; Fe: iron; Mn: manganese; Cu: copper; Zn: zinc

Genotypic diversity in vegetable amaranth for antioxidant, nutrient and agronomic traits

In this investigation, magnitude of genetic divergence was studied in 25 vegetable amaranth using D2 statistics. The genotypes were grouped into 5 clusters with the highest number of genotypes (10) in cluster V. High inter-cluster distance indicated that genotypes of cluster III were far diverged from the genotypes in cluster I, II and IV, respectively. The PCA indicated prominent contribution of protein, foliage yield, leaf area and Zn content towards total divergence. Cluster I and Cluster III could be considered for excellent antioxidant and nutrients and high foliage yield. Cluster II for nutrients, cluster IV for antioxidant and nutrients and cluster V for antioxidant, nutrients, and foliage yield. Based on inter-cluster distance, intra-cluster and scatter diagram, the genotypes AA28, AA15, AA19, AA26, AA9 and AA17 would be potential genotypes for generating transgressive segregants.

Drought Stress Effects on Growth, ROS Markers, Compatible Solutes, Phenolics, Flavonoids, and Antioxidant Activity in Amaranthus tricolor

Four selected Amaranthus tricolor cultivars were grown under four irrigation regimes (25, 50, 80, and 100% field capacity) to evaluate the mechanisms of growth and physiological and biochemical responses against drought stress in randomized complete block design with three replications. Drought stress led to decrease in total biomass, specific leaf area, relative water content (RWC), photosynthetic pigments (chlorophyll a, chlorophyll b, chlorophyll ab), and soluble protein and increase in MDA, H2O2, EL, proline, total carotenoid, ascorbic acid, polyphenols, flavonoids, and antioxidant activity. However, responses of these parameters were differential in respect to cultivars and the degree of drought stresses. No significant difference was observed in control and LDS for most of the traits. The cultivars VA14 and VA16 were identified as more tolerant to drought and could be used for further evaluations in future breeding programs and new cultivar release programs. Positively significant correlations among MDA, H2O2, compatible solutes, and non-enzymatic antioxidant (proline, TPC, TFC, and TAC) suggested that compatible solutes and non-enzymatic antioxidant played vital role in detoxifying of ROS in A. tricolor cultivar. The increased content of ascorbic acid indicated the crucial role of the ASC–GSH cycle for scavenging ROS in A. tricolor.

Association of grain shedding habit with polyploidy in tartary buckwheat (Fagopyrum tataricum) strains

Abstract Sixty tartary buckwheat (Fagopyrum tataricum) strains were investigated for grain shedding habit, plant height, grain yield, dry weight of plant, weight of grain, days to flowering after sowing and DNA content of nuclei. The grain shedding habit was evaluated from the breaking strength of pedicel and the percentage of the grains dropped by threshing. DNA content of nuclei was detected by flow cytometry to classify the polyploidy level. The fluorescence intensity of the flow cytometry demonstrated no difference between common buckwheat (F. esculentum) and tartary buckwheat, but a clear difference was detected between the diploid and the autotetraploid strains. The survey of DNA content of the 60 tartary buckwheat strains revealed that most of the strains were diploids, but one strain was autotetraploid. The autotetraploid strain exhibited less grain shedding, and produced the largest grains among the strains tested. However, the other characters of the autotetraploid strain, such as plant height, grain yield, dry weight of a plant, and days to flowering, were similar to the mode of the traits of the diploid strains.