Field Application Strategies for the Inoculant Biofertilizer Biogro Supplementing Fertilizer Nitrogen Application in Rice Production

Biofertilizer research for rice in Vietnam has focused on the isolation and selection of strains that can fix nitrogen, solubilize inorganic phosphates, stimulate plant growth, and breakdown soil organic matter. This paper assesses the consistent positive effect of BioGro on grain yield and agronomic parameters, including the rates and times for its application, the need for continued inoculation of crops grown in the same site, varietal differences, and nitrogen (N), phosphorus (P), and potassium (K) combinations on the effectiveness of BioGro. The commercial biofertilizer, BioGro, consists of four strains, one formerly considered as nitrogen fixing, Pseudomonas fluorescens, a soil yeast strain, Candida tropicalis is P-solubilizing, and two other bacilli, Bacillus amyloliquefaciens and Bacillus subtilis, potentially breaking down cellulose, protein, and starch. All four strains contribute to plant growth promoting rhizobacteria (PGPR) effect as shown by enhanced root growth. BioGro can be produced in local factories providing there is technical backup in the supply of starter culture and quality control of the final product.     

Effects of heat tolerance on expression of resistance toPresudomonas solanacearum E. F. Smith in potato

Summary Twelve potato clones with different genetic background for resistance to bacterial wilt and adaptation were tested for resistance to a race 1 and a race 3 isolate of the pathogen at three locations in the Philippines representing different ranges of ambient temperature. The results showed that the genes for heat tolerance are crucial for resistance. Stability analysis indicated that clones with both resistance and heat tolerance genes displayed higher and more stable resistance to the race 1 isolate than those clones having only resistance genes. The latter group tended to have higher values of both regression of disease index on environmental index and deviation from the regression in the stability analysis. Host — pathogen interaction effects were found to be statistically significant but small compared to main effects of isolates and clones. The involvement of genes with different effects on wilt resistance is discussed. Introduction     

Evaluation of the management practice for controlling herbicide runoff from paddy fields using intermittent and spillover-irrigation schemes

Two water management practices, an intermittent irrigation scheme using automatic irrigation system (AI) and a spillover-irrigation scheme (SI), were compared for the fate and transport of commonly used herbicides, mefenacet (MF) and bensulfuron-methyl (BSM) in experimental paddy plots. Maximum mefenacet concentrations in paddy water were 660 and 540 μg L⁻¹ for AI and SI plot, respectively. The corresponding values for bensulfuron-methyl were 46.0 and 42.0 μg L⁻¹. Dissipation of the herbicides in paddy water appeared to follow the first-order kinetics with half-lives (DT₅₀) of 1.9–4.5 days and DT₉₀ (90% mass dissipation) of 7.8–11.3 days. The AI plot had no surface drainage, hence no herbicide was lost through paddy-water discharge. However, SI plot lost about 38 and 49% of applied mefenacet and bensulfuron-methyl, respectively. The intermittent irrigation scheme using automatic irrigation system with a high drainage gate was recommended to be a best management practice for controlling the herbicide losses from paddy fields. The paddy field managed by spillover-irrigation scheme may cause significant water and herbicide losses depending on the volume of irrigation and precipitation. The water holding period after herbicide application was suggested to be at least 10 days according to the DT₉₀ index.     

Factors impacting yields in rain-fed paddies of the lower Mekong River Basin

The Mekong River Basin (MRB) is the biggest basin in Monsoon Asia. About 80% of the agricultural lands, which occupy about 40% of the basin are rain-fed paddy rice area. Therefore, it is assumed that changes in rain-fed paddy rice production affect the total agricultural production to a great degree in the Mekong River Basin. While there are many factors affecting the productivity of rain-fed paddies, such as climate, water use, rice varieties, applications of manure, fertilizer and agro-chemicals, sowing date and other agronomic practices, this paper focuses on the relation between rainfall and yields of rain-fed paddies. Agricultural statistics and rainfall data were collected and analyzed for all 24 provinces in Cambodia for the years 2001 and 2002. Factors such as soil fertility and other natural conditions were removed by comparing the yield and rainfall in one province for different years. Special attention was given to the relation between yields of paddy in the wet season and rainfall, considering factors such as rice varieties, soil fertility, irrigation ratio and the ratio of area damaged by flood, drought, and insect. Although it is not easy to assess those impact factors on yields because they are organically interactive, the following results were obtained: (1) The ratio of high yielding varieties (HYV), soil fertility, and irrigation ratio among many factors that affect yields individually, especially if they are combined, (2) Total rainfall did not have a significant influence on rice yields even for the rain-fed paddies if it was over 700 mm in wet season, and one of the reasons for this would be that there exist supplementary water uses through small ponds and water ponding in local land depressions in and around paddies.     

Assessment of biochemical and antioxidant diversities in a shallot germplasm collection from Vietnam and its surrounding countries

The shallot is considered an important genetic resource for Allium breeding programs because, compared to the bulb onion, the shallot contains higher levels of several functional chemical compounds. However, there may be differences in content, composition and beneficial activity among shallot landraces. This study was carried out to characterize the differences in phenolic, quercetin, sugar, S-alk(en)yl-l-cystein sulfoxide (ACSO), and saponin contents and antioxidant capacities of a shallot germplasm including 31 strains derived from different regions of Vietnam and six other countries. A wide variation was observed in the quantitative analyses of the chemical contents. Shallots with high contents of polyphenols, saponins, and quercetins were found in the south of Vietnam and other low-latitude countries. Meanwhile, those possessing fairly high ACSO and sugar contents were observed in the north of Vietnam. Qualitative analysis of saponins via thin layer chromatography did not show clear variation among shallot strains, but polymorphism was observed between the shallot and other Allium species, such as A. roylei. The principal component analysis could clearly discriminate shallot strains by their geographical origins. All shallot strains showed potent antioxidant activities in a DPPH assay. The highest antioxidant capacity was in the strains possessing relatively high contents of polyphenol, quercetin, and saponin. Significant correlations were found between antioxidant capacity (IC ₅₀ ^?1 ) and four groups of chemical compounds (polyphenols, quercetins, saponins, and ACSOs) (r = 0.40–0.59). A strong correlation was observed between IC ₅₀ ^?1 and quercetin contents (r = 0.59, p < 0.01). The six Fusarium-inoculated shallot strains seemed to be adequately resistant against disease, and the levels of resistance may be related to the saponin content in the bulb tissues.     

Effects of salt stress on plant growth characteristics and mineral content in diverse rice genotypes

ABSTRACT

When rice is grown under moderate salinity (6?dS m^?1), yields are reduced by up to 50%. The development of salt-tolerant varieties is a key strategy for increasing yields. We conducted an experiment using a hydroponic system with ion components similar to seawater to determine useful parameters for assessing salt tolerance. Two-week-old seedlings were grown for 7 days on Yoshida hydroponic solution. The treatment group then additionally received an artificial seawater solution (electrical conductivity, 12 dS m^?1). After a 2-week period of salt stress, standard evaluation scores (SES) of visual salt injuries were assessed. The K, Na, Mg, and Ca contents were then determined in the roots, sheaths, and leaves of each plant. Following the SES results, we divided the 37 genotypes into four groups: salt-tolerant groups (STGs), moderately salt-tolerant groups, salt-sensitive groups (HSSGs), and highly salt-sensitive groups (HSSGs). In the control, STGs had the highest sheath K content (30.1 mg g^?1 dried weight [DW]), whereas HSSGs had the lowest (21.4 mg g^?1 DW). Sheath K was also highly and negatively correlated with SES. This suggests that sheath K may be useful for identifying salt-tolerant varieties under non-saline conditions. Plant growth was significantly affected under salt stress, but STGs had the smallest decrease in sheath DW. SES was significantly correlated with sheath and leaf Na, sheath K and Mg, and sheath and leaf Na/K and Na/Mg ratios. The results suggested that sheath K, Na/K, and Na/Mg may be useful indicators for genetic analyses of salt-tolerant varieties under salt-stress conditions. The salt-tolerant cultivars, KCR20, KCR124, and KCR136, are possible candidates for such studies because they had high sheath K content (31.19, 31.21, 29.44 mg g^?1 DW, respectively) under non-saline conditions and low SES (3.3, 3.6, 3.9, respectively), and low sheath Na/K (0.64, 0.52, 0.92, respectively) and Na/Mg ratios (2.96, 2.27, 3.03, respectively) under salt-stress conditions.     

Characterizing morphological traits and estimating genetic relationship for intermediate soybean collected from South Korea

Twenty‐two wild, 16 intermediate and 20 cultivated soybean varieties were used to analyse relationships among the species of subgenus Soja, genus Glycine using 11 morphological traits and simple sequence repeat (SSR) markers. These genotypes using eleven agronomic characteristics were divided into three clusters: cluster I included 20 G. max, cluster II included 12 intermediate, and cluster III included 22 G. soja and four intermediate lines. Genetic relationships among the species of subgenus Soja showed three distinct clusters. Cluster I consisted of 20 G. max cultivars and two intermediate type lines, and cluster II consisted of 13 intermediate type and two G. soja lines; however, cluster III consisted of 20 G. soja and one intermediate type lines. These phenotypic and genetic data suggest that the intermediate type lines could be distinguished between G. max and G. soja lines. However, the intermediate type could not be classified as a new species.     

Assessment of genetic diversity and population structure of Vietnamese indigenous cattle populations by microsatellites

Cattle play a very important role in agriculture and food security in Vietnam. A high level of cattle diversity exists and serves different needs of Vietnamese cattle keepers but has not yet been molecularly characterized. This study evaluates the genetic diversity and structure of Vietnamese indigenous cattle populations, using microsatellite markers. A total of 410 individuals from six indigenous cattle populations and an exotic breed was characterized using 27 microsatellite markers A total of 362 alleles was detected and the number of alleles per locus ranged from 8 (INRA005 and ILSTS005) to 17 (ETH185). The level of gene diversity was high indicated by a mean expected heterozygosity (He) across populations and loci of 0.73. Level of inbreeding (mean F_IS=0.05) and genetic differentiation (mean F_ST=0.04) was moderate. The phylogenetic tree based on Reynolds genetic distance reflected geographic distances. Structure analysis indicated five homogeneous clusters. The Brahman, Lang Son, Ha Giang and U Dau Riu cattle were assigned to independent clusters while Nghe An, Thanh Hoa and Phu Yen cattle were grouped in a single cluster. We conclude that Vietnamese indigenous cattle have high levels of genetic diversity and distinct genetic structures. Based on these results, we recommend that for conservation homogenous populations (Nghe An, Thanh Hoa and Phu Yen) can be grouped to reduce costs and U Dau Riu, Lang Son and Ha Giang populations should be conserved separately to avoid loss of genetic diversity.     

Structural Characteristics and Anticancer Activity of Fucoidan from the Brown Alga Sargassum mcclurei

Three different fucoidan fractions were isolated and purified from the brown alga, Sargassum mcclurei. The SmF1 and SmF2 fucoidans are sulfated heteropolysaccharides that contain fucose, galactose, mannose, xylose and glucose. The SmF3 fucoidan is highly sulfated (35%) galactofucan, and the main chain of the polysaccharide contains a →3)-α-l-Fucp(2,4SO₃⁻)-(1→3)-α-l-Fucp(2,4SO₃⁻)-(1→ motif with 1,4-linked 3-sulfated α-l-Fucp inserts and 6-linked galactose on reducing end. Possible branching points include the 1,2,6- or 1,3,6-linked galactose and/or 1,3,4-linked fucose residues that could be glycosylated with terminal β-d-Galp residues or chains of alternating sulfated 1,3-linked α-l-Fucp and 1,4-linked β-d-Galp residues, which have been identified in galactofucans for the first time. Both α-l-Fucp and β-d-Galp residues are sulfated at C-2 and/or C-4 (and some C-6 of β-d-Galp) and potentially the C-3 of terminal β-d-Galp, 1,4-linked β-d-Galp and 1,4-linked α-l-Fucp residues. All fucoidans fractions were less cytotoxic and displayed colony formation inhibition in colon cancer DLD-1 cells. Therefore, these fucoidan fractions are potential antitumor agents.     

Predictors of the distribution of street and backyard vegetation in Montreal,Canada

Urban vegetation is shown to be unevenly distributed across cities and there is evidence of disparities in benefits provided by vegetation and of public health problems induced by urban heat islands. In order to improve vegetation cover, it remains crucial to understand the underpinning of such unevenness. In this paper, we investigate in Montreal (Canada) how the built environment, sociodemographic factors and administrative boroughs influence tree and lawn cover in public and residential land. The analysis was conducted at the dissemination area (DA) level, a Canadian census unit containing about 400–700 people. Six vegetation indicators were used as dependent variables: the proportion of a DA covered by trees/shrubs, lawn and total vegetation; the proportion of streets covered by trees/shrubs and the proportion of residential yards covered by trees/shrubs and total vegetation. Three sets of independent variables were studied: the built environment, sociodemographics and borough names. We used spatial autoregressive models to control for dependence and the spatial autoregressive term explained a large amount of variability in vegetation cover. The built-environment variables tend to have higher effects than the socio-demographic variables when predicting the three DA vegetation indicators, backyard vegetation, and to a lesser degree, street tree/shrub cover. In particular, population density is associated negatively to all indicators but positively to street tree cover. Socio-demographics are substantial in the explanation of the distribution of street trees, especially the presence of recent immigrants (negative effect) and of university degree holders (positive effect). These findings call for appropriate greening programs adapted to the local socio-demographic profile. The significance of boroughs also suggests the need for further research on the impact of within-city administrative hierarchies on the unevenness of urban vegetation.