The interactive effects of biochar and cow manure on rice growth and selected properties of salt-affected soil

Salt-affected soil induces detrimental influences on paddy rice (Oryza sativa L.) growth and ameliorating the influences could be done with organic amendments, such as animal manure and biochar. The aims of the current study are: (1) to examine the interactive effects of biochar and cow manure on rice growth and on selected properties of salt-affected soil, and (2) to identify potential mechanisms related to the amendments. Saline-sodic soil was used for a net house experiment with two experimental factors: biochar (no-biochar, rice-husk, and -straw biochar) and cow manure (with and without cow manure). Without the manure, addition of both rice-hush and – straw biochar significantly increased rice growth, whereas a combination of individual biochar with manure did not show a positive synergistic effect. The interactive effect of two factors was not significant on available P and exchangeable K concentrations, but the main effects of the two factors were significant. Biochar addition resulted in higher soil cation exchange capacity (CEC) (28.8 to 29.0 cmol_c kg^?1) than the control (25.6 cmol_c kg^?1), but manure addition did not. Improved nutrient availabilities such as P and K, as well as CEC are among the potential mechanisms accounting for the enhanced rice growth with biochar.     

Marker-Assisted Selection of Xa21 Conferring Resistance to Bacterial Leaf Blight in indica Rice Cultivar LT2

Bacterial leaf blight of rice (BLB), caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases in Asian rice fields. A high-quality rice variety, LT2, was used as the recipient parent. IRBB21, which carries the Xa21 gene, was used as the donor parent. The resistance gene Xa21 was introduced into LT2 by marker-assisted backcrossing. Three Xoo races were used to inoculate the improved lines following the clipping method. Eleven BC₃F₃ lines carrying Xa21 were obtained based on molecular markers and agronomic performance. The 11 lines were then inoculated with the three Xoo races. All the 11 improved lines showed better resistance to BLB than the recipient parent LT2. Based on the level of resistance to BLB and their agronomic performance, five lines (BC₃F₃ 5.1.5.1, BC₃F₃ 5.1.5.12, BC₃F₃ 8.5.6.44, BC₃F₃ 9.5.4.1 and BC₃F₃ 9.5.4.23) were selected as the most promising for commercial release. These improved lines could contribute to rice production in terms of food security.     

Downregulation of Kinesin Spindle Protein Inhibits Proliferation,Induces Apoptosis and Increases Chemosensitivity in Hepatocellular Carcinoma Cells

Background: Kinesin spindle protein (KSP) plays a critical role in mitosis. Inhibition of KSP function leads to cell cycle arrest at mitosis and ultimately to cell death. The aim of this study was to suppress KSP expression by specific small-interfering RNA (siRNA) in Hep3B cells and evaluate its anti-tumor activity. Methods: Three siRNA targeting KSP (KSP-siRNA #1-3) and one mismatched-siRNA (Cont-siRNA) were transfected into cells. Subsequently, KSP mRNA and protein levels, cell proliferation, and apoptosis were examined in both Hep3B cells and THLE-3 cells. In addition, the chemosensitivity of KSP-siRNA-treated Hep3B cells with doxorubicin was also investigated using cell proliferation and clonogenic survival assays. Results: The expression of endogenous KSP at both mRNA and protein levels in Hep3B cells was higher than in THLE-3 cells. In Hep3B cells, KSP-siRNA #2 showed a further downregulation of KSP as compared to KSP-siRNA #1 or KSP-siRNA #3. It also exhibited greater suppression of cell proliferation and induction of apoptosis than KSP-siRNA #1 or KSP-siRNA #3; this could be explained by the significant downregulation of cyclin D1, Bcl-2, and survivin. In contrast, KSP-siRNAs had no or lower effects on KSP expression, cell proliferation and apoptosis in THLE-3 cells. We also noticed that KSP-siRNA transfection could increase chemosensitivity to doxorubicin in Hep3B cells, even at low doses compared to control. Conclusion: Reducing the expression level of KSP, combined with drug treatment, yields promising results for eradicating hepatocellular carcinoma (HCC) cells in vitro. This study opens a new direction for liver cancer treatment. Key Words: Apoptosis, Chemosensitivity, Doxorubicin, Hepatocellular carcinoma (HCC) cells, Kinesin spindle protein (KSP)     

Rural income generation through improving crop-based pig production systems in Vietnam: Diagnostics,interventions, and dissemination

Sweetpotato-pig production is an important system that generates income, utilizes unmarketable crops, and provides manure for soil fertility maintenance. This system is widely practiced from Asia to Africa, with many local variations. Within this system, pigs are generally fed a low nutrient-dense diet, yielding low growth rates and low economic efficiency. Our project in Vietnam went through a process of situation analysis, participatory technology development (PTD), and scaling up over a seven-year period to improve sweetpotato-pig production and to disseminate developed technologies. The situation analysis included a series of pig production assessments in several provinces in northern and southern Vietnam, and pig supply-market chain identification was conducted in 13 provinces. The analysis of these studies informed the project of the following: (1) appropriate locations for our activities; (2) seasonal available feedstuff and farmers feeding practices; (3) market fluctuation and requirements; and (4) feeding and management improvement needs based on which the subsequent phase of PTD was designed. The PTD involved a limited number of farmers participating in sweetpotato varietal selection, sweetpotato root and vine silage processing, seasonal feeding combination, and pig feeding with balanced crop-feed diet and silage. Six years of multi-location and multi-season sweetpotato selection resulted in a few promising varieties that yielded up to 75% more dry matter and have since been formally released. The most significant results of silage processing and feeding trials include improved growth, higher feeding efficiency, increased year-round local feedstuff, and considerable labor reduction from eliminated cooking and vine cutting. Once these technologies were developed, a farmer-to-farmer training model was designed for scaling up the adoption and impact. Farmer trainers from seven communes in seven provinces received training in these technologies. In turn, they undertook the responsibility of training other farmers on sweetpotato selection, processing, and feeding. An impact study was also administered to monitor and evaluate (M&E) the dissemination process and to document the impact of the new technologies and farmer-to-farmer training model on pig growth and farmer income generation. The results showed that both participating and non-participating farmers have taken up the technologies, although the former demonstrates higher rates of adoption than the latter. The participants also generated more income and saved more labor from the adoption of the technologies. While the scaling up and M&E activities are on-going, the project has since broadened from a sweetpotato-pig system perspective to a pig-cropfeed system perspective based on farmers needs. It has included other crop feeds such as cassava and peanut stems in the research portfolio. New technologies based on on-going PTD will continuously be incorporated into the future training curriculum.Dai Peters is currently a senior scientist with the International Center for Tropical Agriculture (CIAT) based in Hanoi, Vietnam. This publication is based on research conducted while she was a research scientist with the International Potato Center (CIP). She holds a PhD from North Carolina State University. Her research interests include on-farm participatory research methodologies, agroenterprise development, and sweetpotato-pig farming systems in Vietnam and Papua, Indonesia. Her recent publications include a manual on crop-based pig feed systems, post-harvest fermentation of sweetpotato roots and vines, and agroenterprise development.Nguyen Thi Tinh is currently a coordinator of the sweetpotato-pig improvement project at the International Potato Center in Vietnam. Ms. Tinh holds a Masters degree in animal nutrition from Wageningen University, Netherlands. She participated in the project on pig feeding trials for five years.Mai Thach Hoanh is a sweetpotato breeder with the Root Crop Research Center of Vietnam Agricultural Science Institute (VASI). He holds a PhD in sweetpotato breeding from the same institute. He participated in the project for seven years on sweetpotato selection. Nguyen The Yen is a crop scientist in the Food Crop Research Institute of Vietnam. He holds a PhD in sweetpotato breeding from VASI. He participated in the project for five years on sweetpotato selection.Pham Ngoc Thach is a lecturer with the Hanoi Agricultural University. He holds a PhD in veterinarian science from the same university. He participated in the project for five years in controlling pig diseases during the feeding trials.Keith Fuglie is a regional coordinator and research scientist in the International Potato Center based at Bogor, Indonesia. He holds a PhD in agriculture economics from the University of Wisconsin. He designed the impact study for the project.     

Genetic diversity in two threatened species in Vietnam: <Emphasis Type="Italic">Taxus chinensis</Emphasis> and <Emphasis Type="Italic">Taxus wallichiana</Emphasis>

Taxus chinensis and T. wallichiana in have been threatened in their distribution areas in recent decades because of their over-exploitation and reduction and destruction of native habitats. Determining the genetic diversity in populations of the two species will provide guidelines for their protection and preservation. Two hundred and fifteen trees from six populations of T. chinensis and 150 sampled trees of T. wallichiana were sampled. Six microsatellite primer pairs selected from 16 primer pairs were used to investigate genetic variation at the population and species levels. Five yielded polymorphic alleles, and among the 13 putative alleles amplified, 11 were polymorphic (accounting for 76.33 %).Shannon’s information index (I) and percentage of polymorphic bands (PPB) (I = 0.202 and PPB = 67.22 % for T. chinensis; I = 0.217 and PPB = 65.03 % for T. wallichiana). Both species had low levels of genetic diversity (mean H _o = 0.107, H _e = 0.121 for T. chinensis; H _o = 0.095, H _e = 0.109 for T. wallichiana). Genetic differentiation among populations was higher (F _ST = 0.189) for T. chinensis and lower (0.156) for T. wallichiana, indicating limited gene flow (Nm) among populations for T. chinensis (0.68) and T. wallichiana (0.65). Variation among individuals of T. chinensis was 63.59 and 73.12 % for T. wallichiana. Thus, the threatened status of the two conifers is related to a lack of genetic diversity. All populations are isolated in small forest remnants. An ex situ conservation site should be established with a new population for these species that comprises all the genetic groups for the best chance to improve their fitness under environmental stresses.     

Changes in fineroot growth dynamics in response to phosphorus application in an Acacia mangium plantation in Vietnam

Fineroots (≤ 2 mm diameter) are dynamic components of the forest ecosystems and play important role in water and nutrient acquisition in forests. These roots are sensitive to forest fertilization and therefore, the response of fineroots to nutrient application would provide better understanding of the forest carbon and nutrient dynamics that will be helpful in sustainable forest management plans. Two fertilization treatments, including (1) F400: 400 g P₂O₅ (16.5%)/tree and (2) F600: 600 g P₂O₅ /tree, and F0: control (without fertilization), were applied in an Acacia mangium plantation with a planting density of 1100 trees/ha (3 m?×?3 m). The evaluation of fineroot growth across seasons showed that fertilization significantly increased production and subsequent mortality and decomposition. The total decomposition associated with F600 application was 7.95 tons ha^?1 year^?1, equaling 121% of F400 and 160% of the control. Mortality in F600 was 8.75 tons ha^?1 year^?1, equaling 111% of F400 and 198% of F0, while production in F600 was 10.40 tons ha^?1 year^?1, equaling 127% of F400 and 143% of F0. Fineroot production, mortality, and decomposition are seasonally dependent, with higher values measured in the rainy season than in the dry season. Stand basal area increment was significantly correlated with fineroot production (R²?=?0.75), mortality (R²?=?0.44), and decomposition (R²?=?0.48). This study showed that fertilization could facilitate fineroot production, which can then lead to a higher turnover of carbon and nutrients through the decomposition of the greater mass of the fineroots.

     

Effect of fishmeal replacement with Artemia biomass as a protein source in practical diets for the giant freshwater prawn Macrobrachium rosenbergii

A 30-day feeding experiment was conducted in 160-L plastic tanks to evaluate the potential use of Artemia biomass as a protein source in practical diets for postlarval Macrobrachium rosenbergii (initial mean weight of 12.12–12.29 mg). Nine isoenergetic and isonitrogenous experimental diets (approximately 40% crude protein) were formulated by replacing levels of the fishmeal (FM) protein difference either with dried or frozen Artemia (0, 25, 50, 75 and 100%). The 0% Artemia treatment, in which Peruvian FM was the only main protein source, was considered to be the control diet. The results showed that prawn postlarvae (PLs) fed the FM control diet had a lower survival (46%) compared with all Artemia diets. Significant differences ( P <0.05) were, however, only found at 75% and 100% Artemia protein inclusion levels (survival of 68–77%). A gradual increase in growth performance (live weight gain, specific growth rate and total length) of the prawns was achieved on increasing dietary inclusion of Artemia protein. Additionally, the size distribution exhibited the same response as growth performance. However, prawns fed the frozen Artemia diets showed a better performance than the ones fed the dried Artemia diets. It can be suggested that Artemia biomass may totally replace FM in practical diets for PLs of the freshwater prawn M. rosenbergii .     

Incorporation of rice straw mitigates CH4 and N2O emissions in water saving paddy fields of Central Vietnam

This study evaluated the effects of rice straw and water regimes on CH₄ and N₂O emissions from paddy fields for two rice growing seasons (summer 2014 and spring 2015). Water regimes included alternating wet–dry irrigation (AWD) maintained at three levels (–5 cm, – 10 cm and –15 cm) in comparison to continuous flooding irrigation (CF). Rice straw (5 t ha^–1) was incorporated into the top soil (0 – 15 cm), distributed and burned in situ. Results showed that using burned in situ rice straw was found to reduce seasonal cumulative CH₄ emission (24–34% in summer; 18–28% in spring), N₂O emission (21–32% in summer; 22–29% in spring) and lower rice yield (8–9%) than rice straw incorporation into top soil. AWD methods reduced the amount of CH₄ production (22.6–41.5%) and increased N₂O emission (25–26%) without any decrease in rice yield. Rice straw incorporation into the top soil with AWD had higher water productivity (23–37%) than rice straw when burned in situ with CF. The results conclude that AWD and rice straw management can be employed as mitigation strategy for CH₄ and N₂O emissions from paddy fields in Central Vietnam.     

Combined effects of a simulated marine heatwave and an algal toxin on a tropical marine aquaculture fish cobia (Rachycentron canadum)

Ongoing global warming is one of the major challenges for the development of aquaculture in the tropical regions where species are already cultured in the water temperature close to their upper physiological thresholds. Furthermore, warming can trigger blooms of toxic algae, yet we do not know how extreme warming such as a marine heatwave (MHW) and algal toxins may affect marine aquaculture species. To address this issue, we investigated the effects of a simulated MHW in combination with exposure to trans‐4‐trans‐decadienal (PUA), a diatom‐derived toxin, on survival, growth, development and biochemical composition of cobia larvae and juveniles. Cobia larvae were exposed for 48 hr to one of two temperatures (29 vs. 34°C) and two PUA treatments (0 vs. 0.5 µM). Surviving larvae from each treatment were divided into two subsets: three replicates were used for the feeding test and five replicates were used for the recovery test in a non‐contaminated environment at the respective temperatures of 29 or 34°C. Survival of cobia larvae was reduced by 16% in either MHW or PUA, but it dropped by 60% when both stressors were present, indicating a synergistic effect. MHW, but not PUA, reduced the feeding of cobia larvae. PUA had no delayed effects on growth rate and biochemical composition of the fish. MHW strongly reduced specific growth rate, body protein and lipid contents in cobia. Our results provide the first empirical evidence of how MHW and toxic algae may interact and challenge cobia and marine aquaculture production in tropical countries.