Mariano M.J.,Philippine Rice Research Institute |
Villano R.,University of New England of Australia |
Fleming E.,University of New England of Australia
Agriculture, Ecosystems and Environment | Year: 2010
The variations in rice productivity in the irrigated and rainfed farming ecosystems in the Philippines from 1996/1997 to 2006/2007 are estimated using a stochastic metafrontier, which is a production function that envelops the production frontiers of the two farming ecosystems. The productivity levels are also compared across the two ecosystems through time. Results indicate that farms in the rainfed farming ecosystem achieve productivity levels only slightly different from those of farms in the irrigated farming ecosystem. Some farms in both ecosystems were able to achieve the highest possible output with respect to the metafrontier in all the seasons studied. The adoption and diffusion of appropriate technologies to the other farmers can narrow the technology gap that exists within and between the two farming ecosystems. As technical inefficiency is found on many farms within ecosystems, there is potential for most producers in both farming ecosystems to improve productivity with more efficient use of resources at the farm level. We find that technological progress is absent, confirming previous evidence of a lack of substantial productivity growth in the past decade. Research and development of improved rice technologies is needed to shift the metafrontier outwards. © 2010 Elsevier B.V.
Niones J.T.,Nagoya University |
Takemoto D.,Nagoya University |
Takemoto D.,Philippine Rice Research Institute
Eukaryotic Cell | Year: 2015
Symbiotic association of epichloae endophytes (Epichloë/Neotyphodium species) with cool-season grasses of the subfamily Pooideae confers bioprotective benefits to the host plants against abiotic and biotic stresses. While the production of fungal bioprotective metabolites is a well-studied mechanism of host protection from insect herbivory, little is known about the antibiosis mechanism against grass pathogens by the mutualistic endophyte. In this study, an Epichloë festucae mutant defective in antimicrobial substance production was isolated by a mutagenesis approach. In an isolated mutant that had lost antifungal activity, the exogenous DNA fragment was integrated into the promoter region of the vibA gene, encoding a homologue of the transcription factor VIB-1. VIB-1 in Neurospora crassa is a regulator of genes essential in vegetative incompatibility and promotion of cell death. Here we show that deletion of the vibA gene severely affected the antifungal activity of the mutant against the test pathogen Drechslera erythrospila. Further analyses showed that overexpressing vibA enhanced the antifungal activity of the wild-type isolate against test pathogens. Transformants overexpressing vibA showed an inhibitory activity on test pathogens that the wildtype isolate could not. Moreover, overexpressing vibA in a nonantifungal E. festucae wild-type Fl1 isolate enabled the transformant to inhibit the mycelial and spore germination of D. erythrospila. These results demonstrate that enhanced expression of vibA is sufficient for a nonantifungal isolate to obtain antifungal activity, implicating the critical role of VibA in antifungal compound production by epichloae endophytes. © 2015, American Society for Microbiology. All Rights Reserved.
Field evaluation on functional roles of root plastic responses on dry matter production and grain yield of rice under cycles of transient soil moisture stresses using chromosome segment substitution lines
Niones J.M.,Nagoya University |
Suralta R.R.,Philippine Rice Research Institute |
Inukai Y.,Nagoya University |
Yamauchi A.,Nagoya University
Plant and Soil | Year: 2012
Background: Fluctuating soil moisture resulting from the transient occurrences of waterlogging and drought are frequently reoccurring in the rice field, which adversely affects plant growth and yield. We previously established the significant contribution of plastic development and associated physiological responses of root to shoot dry matter production under soil moisture fluctuation stresses. Aim: To evaluated the functional roles of root plastic development on yield under field condition of continuous cycle of transient soil moisture stresses. Methods: Previously selected CSSL47 and the recurrent parent Nipponbare were exposed to two soil moisture conditions; cycles of alternating waterlogging and drought condition (CAW-D) and continuous waterlogging (CWL; control). Results: Under continuous waterlogging (CWL) conditions, the two genotypes showed no significant differences in most of the traits examined. In contrast, under continuous cycle of alternate waterlogging and drought (CAW-D) conditions, CSSL47 showed greater shoot dry matter production than Nipponbare, which was attributed to its higher stomatal conductance and photosynthetic rate, which then led to higher grain yield. The root system development of CSSL47 expressed as total root length was greater compared with Nipponbare. Before heading stage, plasticity was expressed as enhanced aerenchyma formation based on root porosity, which was associated with the promotion of lateral root production, elongation and branching and the eventual increase in total root length. Moreover, after heading, compared with Nipponbare, CSSL47 continued to produce more nodal roots from newly produced tillers, thus maintaining leaf photosynthesis and eventually resulting in heavier panicles. Conclusions: We provide evidences that root plasticity, which better expressed in CSSL47 than Nipponbare, under continuous cycle of transient soil moisture stresses contributed to increase in grain yield in fields. Genetic variation in plastic responses of roots could have substantial impact on yield in areas experiencing these kind of soil moisture stresses. © 2012 Springer Science+Business Media B.V.
Paz-Alberto A.M.,Central Luzon State University |
de Dios M.J.J.,Philippine Rice Research Institute |
Alberto R.T.,Central Luzon State University |
Sigua G.C.,Subtropical Agricultural Research Station
Journal of Soils and Sediments | Year: 2011
Purpose: Environmentally hazardous and health risk substances in animals and humans in the environment have increased as a result of continuing anthropogenic activities. Examples of these activities are food processing, laboratory, food production, industrial, and other relative activities that use various forms of acrylamide. All acrylamide in the environment are manmade. It is the building block for the polymer, polyacrylamide, which is considered to be a nontoxic additive. However, if the polymerization process is not perfect and complete, the polyacrylamide may still contain acrylamide which is toxic and may pose risks and hazards to the environment. Another form of acrylamide that may pose danger as well in the environment is the acrylamide monomer, which is also a very toxic organic substance that could affect the central nervous system of humans and is likely to be carcinogenic. Phytoremediation could be a tool to somehow absorb this neurotoxic agent and lessen the contamination in the soil. This technology could lessen the soil and water contamination by acrylamide thereby limiting the exposure of animals and humans. This study may also help solve the problem of disposing contaminated acrylamide waste materials. This study was conducted to achieve the following objectives: (1) to evaluate phytoremediation potentials of some selected tropical plants in acrylamide-contaminated soil, (2) to compare the performance of tropical plants in absorbing acrylamide through accumulation in their roots and shoots, and (3) to determine the outcome of acrylamide in the soil after treatment using the test plants with phytoremediation potentials. Materials and methods: Soil was collected from 40 sampling points (2,000 g of soil per sampling points) in a half-hectare rice field in the Philippine Rice Research Institute, Central Experiment Station, Science City of Muñoz, Nueva Ecija, Philippines. This study used Mustard (Brassica juncea L.), petchay (Brassica chinensis L.), vetiver grass (Vetiveria zizanioides L.), hog weeds (Portulaca oleracea L.), snake plant (Sanseviera trifasciata Prain), and common sword fern (Nephrolepsis cordifolia L.). These plants were selected to determine their capability of removing acrylamide residues from soil with unstable polyacrylamide gel. Analysis of acrylamide concentrations in soil and plant parts were done using a gas chromatograph equipped with flame ionization detector at the Training, Research and Development, Adamson University, Manila. This study was laid out using the completely randomized design with three replications. Data were analyzed with a one-way ANOVA using PROC GLM. Duncan's multiple range test (p≤0.05) was followed for the mean treatment separation and comparison. Results and discussion: Among the plants tested, the highest concentration of acrylamide was absorbed by the whole plant of mustard (6,512.8 mg kg-1) compared with pechay (3,482.7 mg kg-1), fern (2,015.4 mg kg-1), hogweeds (1,805.3 mg kg-1), vetiver grass (1,385.4 mg kg-1), and snake plants (887.5 mg kg-1). Results of the study regarding the acrylamide absorption of the whole plants of mustard and pechay conformed to previous findings of other studies. Two members of the Brassica family, B. juncea L. (mustard) and B. chinensis L. (pechay) were found to be effective in removing wide ranges of contaminants. Likewise, mustard obtained the highest acrylamide concentrations (mg kg-1) in the roots (2,372.9) and shoots (4,081.1) among the six test plants. Earlier studies showed the capability of mustard in absorbing metals. Mustard plant is known to remove large quantities of chromium, lead, copper, and nickel in soil and ethidium bromide in soil. This could be attributed to its well-developed root system. Plants with active growth of roots in soils bring more contact with the fresh areas of the soil and ions, thus, creating more likelihood of further absorption and uptake. Moreover, mustard, pechay, and fern plants had 60% survival rate while hogweeds had 80% survival rate. Snake plant and vetiver grass had 100% survival rate. All the test plants planted in soil without acrylamide had survival rate of 100%. The 100% survival rate of vetiver grass and snake plant was due to the tolerance of these plants to acrylamide. Among the six test plants, vetiver grass and snake plant had the greatest uptake of acrylamide from the soil (30.6 kg ha-1) and (29.4 kg ha-1), respectively. These plants exhibited great number and longer roots which are characteristics of excellent phytoremediator plants. Thus, vetiver grass can absorb more acrylamide due to its root's growth characteristics. These findings could be attributed to the extraordinary features of vetiver grass such as its massive and deep root system and heavy biomass including its high tolerance to extreme soil conditions like heavy metal toxicities and high metal concentration. Conclusions: Results of our study proved that all the test plants are potential phytoremediators of acrylamide. However, mustard and pechay were the most effective as they absorbed the highest acrylamide concentrations in their roots, shoots, and the whole plants. On the other hand, vetiver grass and snake plant had the highest uptake of acrylamide even though these plants did not absorb the highest acrylamide concentration. Therefore, these two plants can be considered as the best phytoremediator of acrylamide because they are perennial plants with heavier biomass with long, dense and extended root system. As such, these plants are capable of absorbing acrylamide in the soil for a long period of time. As preventive measures and for application purposes, vetiver grass and snake plants could be planted along and around the wastewater treatment ponds of laboratories using polyacrylamide gel. These plants can prevent further migration of pollutants to the environment aside from making the ponds more resistant to soil erosion. Further studies are suggested to evaluate acrylamide contaminations from laboratory washing, primary treatment pond, and seepage ponds that have earth dikes. Vetiver grass and snake plants are recommended for further phytoremediation studies for longer period of time to test the reduction of acrylamide in soil. Moreover, the outcome of acrylamide accumulation in the plants is also recommended for further study in conjunction with labeled-carbon tracer to determine its effects on the plants. © 2011 Springer-Verlag.
Juliano L.M.,Philippine Rice Research Institute |
Casimero M.C.,International Rice Research Institute |
International Journal of Pest Management | Year: 2010
Barnyardgrass (Echinochloa crus-galli [L.] Beauv.), a troublesome weed in rice production, has been confirmed for the first time to be resistant to both chloroacetamide (butachlor)- and acetanilide (propanil)-group herbicides commonly used in direct-seeded rice in the Philippines. Resistance screening showed that 17 of 18 sampled populations (94%) were resistant to butachlor + propanil. Dose-response assays using butachlor + propanil on the populations resulted in all but one not being controlled at twice the recommended rate for field application (1.4 kg ai or 2 l/ha) and seven populations not being controlled by 4 l/ha (2.8 kg ai). Dose-response assays using butachlor and propanil separately indicated that the latter populations were resistant to both of the herbicides. LD 50 values for butachlor + propanil populations ranged from 0.6 l/ha (0.42 kg ai) to 2.9 l/ha (2.03 kg ai) indicating 1.9 to 9.1 times less sensitivity than a known susceptible population. Thus, what was perceived by farmers to be reduced herbicide efficacy is actually herbicide resistance. Hence, this new development in major herbicides has become a threat in rice production and will alter weed management in direct-seeded rice. Concerted efforts in raising awareness on herbicide resistance and implementing an effective integrated weed management program are needed. © 2010 Taylor & Francis.