Papers by pongmanee thongbai
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2000
M ossbauer spectroscopy has been used to study iron uptake and translocation in rice plants. Spec... more M ossbauer spectroscopy has been used to study iron uptake and translocation in rice plants. Spectra were collected from intact root and leaf tissue of rice plants grown in anaerobic 57 Fe(II)-enriched nutrient solutions. The spectra obtained from root tissue of plants grown in nutrient solutions typical of paddy soils arise primarily from Fe(III)-oxide components precipitated on the root cell walls. In contrast, the spectra obtained from root tissue from plants exposed to lower, toxic, pH conditions show that, in addition to Fe(III), uncomplexed Fe(II) is taken up. No evidence of Fe(II) was seen in the leaf tissue of any of the plants, where the spectra are characteristic of Fe(III) in ferritin and other complexed forms.
... This result suggested that low ridges were not different from the high ridges under non-water... more ... This result suggested that low ridges were not different from the high ridges under non-waterlogged conditions, but caused a higher susceptibility to waterlogging; with yield and total number of bolls being significant ... Edited by Barry Rowe, Danny Donaghy and Neville ...
Watterlogging is an important cause of yield loss on the cracking grey clays. We conducted a fiel... more Watterlogging is an important cause of yield loss on the cracking grey clays. We conducted a field experiment to quantify its impact on growth and yield. In terms of management, the results demonstrates the importance of ensuring adequate bed height and allowing excess water to leave the field quickly, definitely not later than 48 hours after irrigation.
Zenodo (CERN European Organization for Nuclear Research), Sep 1, 1998
Field Crops Research, Aug 1, 2004
Cotton is known to be poorly adapted to waterlogged conditions. In Australia, cotton production i... more Cotton is known to be poorly adapted to waterlogged conditions. In Australia, cotton production is concentrated on soils with inherently low drainage rates, which, combined with the almost exclusive use of furrow irrigation and a summer dominant rainfall pattern, results in a significant risk of intermittent waterlogging. Three field experiments were conducted in which cotton was subjected to intermittent waterlogging by extending the duration of irrigation events. Timing of waterlogging, cultivar and landforming were also varied. Treatments required to generate significant impacts on crop growth and yield were more extreme than previously reported. Possible reasons for this are discussed. Consistent with the literature, yield loss was associated with reduced boll number (R 2 ¼ 0:82). The reduction in boll number was commensurate with the reduction in total plant dry matter: dry matter was reduced by up to 32% with the allometric ratio between boll number and glucose adjusted dry matter being unaltered by the treatments. The reduction in dry matter was due to lower radiation use efficiency (RUE g), which fell by up to 35%, rather than lower light interception. While leaf area was reduced, the resultant change in cumulative light interception was less than 5%. Thus, yield loss was caused by a reduction in the number of bolls. This reduction was commensurate with the reduced dry matter production from lower RUE g rather than light interception. A single waterlogging event during early squaring and five events throughout growth of the same cumulative duration gave the same impact on lint yield. However, when the single event was imposed at peak green bolls, it had no significant effect on yield. No impact of waterlogging on fibre quality was detected in any of the experiments.
Plant Nutrition — Molecular Biology and Genetics, 1999
... External efficiency, on the 2S3 C. Gissel-Nielsen and A. Jensen leds. ... Using soil-sandwich... more ... External efficiency, on the 2S3 C. Gissel-Nielsen and A. Jensen leds. ... Using soil-sandwich technique, Kirk & Bajita [12] showed that Zn efficient IR36 could acidify its rhizosphere by H* generated from the oxidation of Fe (II) by root-released Oj and, thereby, release Zn from highly ...
Field Crops Research, 2004
As cotton is an indeterminate species, the timing of crop maturity is largely determined by the c... more As cotton is an indeterminate species, the timing of crop maturity is largely determined by the capacity of the plant to continue the production of new fruiting sites. According to the nutritional hypothesis, the cessation of fruit production ('cutout') occurs when the demand on the resource supply by growing fruit increases to a point where no resource remains for the initiation and support of new fruiting sites. Thus dry matter production could impinge both on the timing of crop maturity and yield. The aim of this work was to determine the extent to which cotton genotypes of diverse genetic background varied in their growth determinants and dry matter partitioning and how this related to crop maturity. Two field experiments were conducted, each involving two sowing times to provide variation in effective season length and growing conditions. Growth analysis showed little difference in growth characteristics of eight genotypes that would affect timing of crop maturity. Allometric plots showed that partitioning to the fruit began earlier in early genotypes but there was little systematic difference in the rate of partitioning after the onset of reproductive growth. The timing of crop maturity (60% bolls open) was related to the time when the growth rate of the fruit per unit area was equal to the crop growth rate (CGR). Taken together, the results imply that the key trait driving maturity was the timing of the onset of reproductive growth and the subsequent development of the demand for dry matter.
Rice is the most important food security crop in Asia. Information on its seasonal extent forms p... more Rice is the most important food security crop in Asia. Information on its seasonal extent forms part of the national accounting of many Asian countries. Synthetic Aperture Radar (SAR) imagery is highly suitable for detecting lowland rice, especially in tropical and subtropical regions, where pervasive cloud cover in the rainy seasons precludes the use of optical imagery. Here, we present a simple, robust, rule-based classification for mapping rice area with regularly acquired, multi-temporal, X-band, HH-polarized SAR imagery and site-specific parameters for classification. The rules for rice detection are based on the well-studied temporal signature of rice from SAR backscatter and its relationship with crop stages. We also present a procedure for estimating the parameters based on "temporal feature descriptors" that concisely characterize the key information in the rice signatures in monitored field locations within each site. We demonstrate the robustness of the approach on a very large dataset. A total of 127 images across 13 footprints in six countries in Asia were obtained between October 2012, and April 2014, covering 4.78 m ha. More than 1900 in-season site visits were conducted across 228 monitoring locations in the footprints for classification purposes, and more than 1300 field observations were made for accuracy assessment. Some 1.6 m ha of rice were mapped with classification accuracies from 85% to 95% based on the parameters that were closely related to the observed temporal feature descriptors derived for Remote Sens. 2014, 6 10775 each site. The 13 sites capture much of the diversity in water management, crop establishment and maturity in South and Southeast Asia. The study demonstrates the feasibility of rice detection at the national scale using multi-temporal SAR imagery with robust classification methods and parameters that are based on the knowledge of the temporal dynamics of the rice crop. We highlight the need for the development of an open-access library of temporal signatures, further investigation into temporal feature descriptors and better ancillary data to reduce the risk of misclassification with surfaces that have temporal backscatter dynamics similar to those of rice. We conclude with observations on the need to define appropriate SAR acquisition plans to support policies and decisions related to food security.
Sub-global Scenarios Main Messages Scenarios involve thinking about a wide range of futures, incl... more Sub-global Scenarios Main Messages Scenarios involve thinking about a wide range of futures, including both well-known trends and uncertainties. Developing scenarios is a fundamental prerequisite of strategic thinking and planning. Scenarios facilitate strategy formulation and evaluation, improve understanding of the uncertainties inherent in ecosystems, and test the robustness of particular strategies against a set of plausible futures. Unlike other decision-making techniques such as prediction, forecasting, and other single future outlooks, scenario-building is a cognitive and imaginative mechanism for decision-making. It uses more holistic, integrated, and participatory approaches to aid understanding of the intrinsic heterogeneity and uncertainty of ecosystem management. It also extends prediction and forecasting methods to provide additional and relevant alternatives to help decision-makers think, talk, plan and act imaginatively in pursuit of a more sustainable society. Sub-global assessments used scenarios for multiple purposes, which often extended beyond the rationale for scenarios developed at the global level. Besides being used as a tool for decision-makers to plan for the future, many sub-global assessments, such as Southern Africa and the Northern Highland Lakes District of Wisconsin, also used scenarios as a means for communicating possible future changes and major uncertainties to stakeholders. In the assessments of San Pedro de Atacama, Chile, and Bajo Chirripó, Costa Rica, scenarios also have proved to be an important tool for acquiring data about stakeholder preferences, perceptions, and values. In a few cases, including Wisconsin, Caribbean Sea, and SAfMA, scenarios had a role in defining the boundaries within which discussions about management and policy options relevant to ecosystem services and human well-being could be held. Despite being based on the MA conceptual framework, scenarios in the sub-global assessments differed greatly from the MA global scenarios. Significant differences between global and sub-global assessments in terms of key uncertainties, stakeholders involved, and scales of analysis, resulted in sets of sub-global scenarios that were different from the global scenarios. Nonetheless, a substantive link was maintained between global and sub-global scenarios in the case of the SAfMA, Caribbean Sea, and Portugal assessments. Most sub-global assessments limited the discussions on which scenarios to develop around only one or two key uncertainties. Uncertainties were typically related to issues of technology, markets, and economic development; over half of the scenarios identified institutional arrangements/governance as a key uncertainty. Some unique examples of uncertainties included HIV/AIDS for Papua New Guinea, mining in San Pedro de Atacama, and the local legal system in India Local. Somewhat surprisingly, the Mae Chaem, Thailand, component of the Tropical Forest Margins assessment was the only assessment to explicitly address uncertainties surrounding ecosystem feedbacks. Qualitative rather than quantitative models were most often used to explore interactions between major processes and structures, in order to provide a framework within which scenario storylines were developed. There is little documented explanation of the methods by which narrative storylines were developed in most sub-global scenarios. Many sub-global assessments noted the desire to quantify storylines, but time constraints and the lack of available models or expertise prevented all but Western China, Tropical Forest Margins (Mae Chaem, Thailand component), and SAfMA Regional assessments from undertaking such analyses. Important scientific advances have been made in constructing nested scenarios at multiple scales. To meet the objectives of decision-makers and stakeholder groups with interests at different scales, the SAfMA assessment undertook five local-scale assessments that were nested within two basinscale assessments, which were in turn nested within a regional-scale assessment. The Portugal assessment was also undertaken at three scales-local, basin, and national-though the local case studies were not nested within the basins that were assessed. Scenario-building is an important method to involve stakeholders in policy formulation, and to encourage citizens to adopt policies aimed at environmental protection. The relevance, significance, and influence of the scenarios that are constructed will ultimately depend on who was involved in their development. Decision-makers will have difficulty introducing new policies designed to alter behaviors without the support of the general population. Participants in scenario building can provide essential input on the relevance of storylines being developed, and the nature of uncertainties that are important at sub-global scales. The scale and context of a sub-global assessment are primary considerations when selecting media for communicating the findings of scenarios. Specific contextual factors include the size of the audience, their level of literacy or formal education, their religious and cultural beliefs, and the cost of reaching the audience given available resources. Specific contexts have generated some unique and creative solutions including the use of theater in SAfMA Local Livelihoods and cartoon animation in Wisconsin. Identification of winners and losers in each scenario is an important step in guiding future responses. The inclusion of stakeholders in the scenario development and validation process helps make explicit the circumstances under which winners and losers emerge. Sub-global scenarios highlighted the importance of scale in determining winners and losers. In the Portugal assessment, one local scenario was characterized by the abandonment of agricultural fields and rural-urban migration, which is undesirable to local policy-makers. However, this scenario could be nested within the MA's Global Orchestration scenario (developed as a part of the MA's global assessment), which is characterized by economic growth and viewed by the policy-makers at higher levels as having the highest net benefits for human well-being. Future scenario activities need to pay even greater attention to ecosystem processes. Past and current scenario work has emphasized human activities as the main drivers of change in the availability of ecosystem goods and services, without much reflection on the implications of ecological feedbacks for ecosystems and human well-being. The large and growing number of sub-global assessment scenarios is a unique source of information within the multiscale assessment context of the MA. The sub-global scenarios, employing the common conceptual framework of the MA, allow for the critical evaluation of local variation. It seems likely that the incorporation of the findings from sub-global scenarios into the MA's global assessment would have been valuable. However, because of timing issues, the global MA scenarios did not have the opportunity to incorporate the findings of the sub-global assessments.
Bibliography: leaves 149-173.xiv, 173 leaves : ill. (some col.) ; 30 cm.Thesis (Ph.D.)--Universit... more Bibliography: leaves 149-173.xiv, 173 leaves : ill. (some col.) ; 30 cm.Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 199
Sub-global Scenarios Main Messages Scenarios involve thinking about a wide range of futures, incl... more Sub-global Scenarios Main Messages Scenarios involve thinking about a wide range of futures, including both well-known trends and uncertainties. Developing scenarios is a fundamental prerequisite of strategic thinking and planning. Scenarios facilitate strategy formulation and evaluation, improve understanding of the uncertainties inherent in ecosystems, and test the robustness of particular strategies against a set of plausible futures. Unlike other decision-making techniques such as prediction, forecasting, and other single future outlooks, scenario-building is a cognitive and imaginative mechanism for decision-making. It uses more holistic, integrated, and participatory approaches to aid understanding of the intrinsic heterogeneity and uncertainty of ecosystem management. It also extends prediction and forecasting methods to provide additional and relevant alternatives to help decision-makers think, talk, plan and act imaginatively in pursuit of a more sustainable society. Sub-global assessments used scenarios for multiple purposes, which often extended beyond the rationale for scenarios developed at the global level. Besides being used as a tool for decision-makers to plan for the future, many sub-global assessments, such as Southern Africa and the Northern Highland Lakes District of Wisconsin, also used scenarios as a means for communicating possible future changes and major uncertainties to stakeholders. In the assessments of San Pedro de Atacama, Chile, and Bajo Chirripó, Costa Rica, scenarios also have proved to be an important tool for acquiring data about stakeholder preferences, perceptions, and values. In a few cases, including Wisconsin, Caribbean Sea, and SAfMA, scenarios had a role in defining the boundaries within which discussions about management and policy options relevant to ecosystem services and human well-being could be held. Despite being based on the MA conceptual framework, scenarios in the sub-global assessments differed greatly from the MA global scenarios. Significant differences between global and sub-global assessments in terms of key uncertainties, stakeholders involved, and scales of analysis, resulted in sets of sub-global scenarios that were different from the global scenarios. Nonetheless, a substantive link was maintained between global and sub-global scenarios in the case of the SAfMA, Caribbean Sea, and Portugal assessments. Most sub-global assessments limited the discussions on which scenarios to develop around only one or two key uncertainties. Uncertainties were typically related to issues of technology, markets, and economic development; over half of the scenarios identified institutional arrangements/governance as a key uncertainty. Some unique examples of uncertainties included HIV/AIDS for Papua New Guinea, mining in San Pedro de Atacama, and the local legal system in India Local. Somewhat surprisingly, the Mae Chaem, Thailand, component of the Tropical Forest Margins assessment was the only assessment to explicitly address uncertainties surrounding ecosystem feedbacks. Qualitative rather than quantitative models were most often used to explore interactions between major processes and structures, in order to provide a framework within which scenario storylines were developed. There is little documented explanation of the methods by which narrative storylines were developed in most sub-global scenarios. Many sub-global assessments noted the desire to quantify storylines, but time constraints and the lack of available models or expertise prevented all but Western China, Tropical Forest Margins (Mae Chaem, Thailand component), and SAfMA Regional assessments from undertaking such analyses. Important scientific advances have been made in constructing nested scenarios at multiple scales. To meet the objectives of decision-makers and stakeholder groups with interests at different scales, the SAfMA assessment undertook five local-scale assessments that were nested within two basinscale assessments, which were in turn nested within a regional-scale assessment. The Portugal assessment was also undertaken at three scales-local, basin, and national-though the local case studies were not nested within the basins that were assessed. Scenario-building is an important method to involve stakeholders in policy formulation, and to encourage citizens to adopt policies aimed at environmental protection. The relevance, significance, and influence of the scenarios that are constructed will ultimately depend on who was involved in their development. Decision-makers will have difficulty introducing new policies designed to alter behaviors without the support of the general population. Participants in scenario building can provide essential input on the relevance of storylines being developed, and the nature of uncertainties that are important at sub-global scales. The scale and context of a sub-global assessment are primary considerations when selecting media for communicating the findings of scenarios. Specific contextual factors include the size of the audience, their level of literacy or formal education, their religious and cultural beliefs, and the cost of reaching the audience given available resources. Specific contexts have generated some unique and creative solutions including the use of theater in SAfMA Local Livelihoods and cartoon animation in Wisconsin. Identification of winners and losers in each scenario is an important step in guiding future responses. The inclusion of stakeholders in the scenario development and validation process helps make explicit the circumstances under which winners and losers emerge. Sub-global scenarios highlighted the importance of scale in determining winners and losers. In the Portugal assessment, one local scenario was characterized by the abandonment of agricultural fields and rural-urban migration, which is undesirable to local policy-makers. However, this scenario could be nested within the MA's Global Orchestration scenario (developed as a part of the MA's global assessment), which is characterized by economic growth and viewed by the policy-makers at higher levels as having the highest net benefits for human well-being. Future scenario activities need to pay even greater attention to ecosystem processes. Past and current scenario work has emphasized human activities as the main drivers of change in the availability of ecosystem goods and services, without much reflection on the implications of ecological feedbacks for ecosystems and human well-being. The large and growing number of sub-global assessment scenarios is a unique source of information within the multiscale assessment context of the MA. The sub-global scenarios, employing the common conceptual framework of the MA, allow for the critical evaluation of local variation. It seems likely that the incorporation of the findings from sub-global scenarios into the MA's global assessment would have been valuable. However, because of timing issues, the global MA scenarios did not have the opportunity to incorporate the findings of the sub-global assessments.
Jatropha curcas L. (Jatropha) is a perennial plant that has received attention as a source of bio... more Jatropha curcas L. (Jatropha) is a perennial plant that has received attention as a source of biodiesel production. However, the Jatropha plants exhibit unfavorable heights. Reducing the plant heights will improve seeds yield and easiness for harvesting. This study aimed to investigate the effect of paclobutrazol (PCB) on Jatropha seedlings (21 days after germination). The plant growth and mRNA accumulation of ent-kaurene oxidase (JcKO) and GA20-oxidase (JcGA20ox) genes were investigated. Height of the PCB treated plants was significantly shorter until the end of the experiment during 17-60 DAT (day after treated). The stem diameters of the treated plants were obviously and significantly thicker than those of the control during 7-19, 25-53 DAT. RT-PCR analysis was performed to determined mRNA accumulations of JcKO and JcGA20ox of the plant collected from 10, 17, and 22 DAT. The results showed that the mRNA accumulations of JcKO from the treated plants were not significantly different from those of the control at 17 and 22 DAT. The mRNA accumulations of JcGA20ox of the treated plant were not significantly different from those of the control at 10, 17 and 22 DAT.
Jatropha curcas L. is a monoecious perennial biofuel plant belonging to the family Euphorbiaceae.... more Jatropha curcas L. is a monoecious perennial biofuel plant belonging to the family Euphorbiaceae. This plant exhibits indeterminate flowering characteristics and has low number of female flowers resulting to its low yield. In this study, effect of paclobutrazol (PCB, 1,250 ppm) and 6-benzyladenine (BA, 125 ppm) on floral sex determination and fruit setting of J. curcas were determined. Although non-significantly different from control, ratio of female to male flowers and seed yield in PCB treated plant tended to be higher than the other treatments. This result is different from previously report by Pan and Xu (2010) on the higher female flowers in BA treated plants. Thus the effect of plant regulators on floral sex expression and seed yield in Thailand needs further investigation.
Remote Sensing, 2014
Rice is the most important food security crop in Asia. Information on its seasonal extent forms p... more Rice is the most important food security crop in Asia. Information on its seasonal extent forms part of the national accounting of many Asian countries. Synthetic Aperture Radar (SAR) imagery is highly suitable for detecting lowland rice, especially in tropical and subtropical regions, where pervasive cloud cover in the rainy seasons precludes the use of optical imagery. Here, we present a simple, robust, rule-based classification for mapping rice area with regularly acquired, multi-temporal, X-band, HH-polarized SAR imagery and site-specific parameters for classification. The rules for rice detection are based on the well-studied temporal signature of rice from SAR backscatter and its relationship with crop stages. We also present a procedure for estimating the parameters based on "temporal feature descriptors" that concisely characterize the key information in the rice signatures in monitored field locations within each site. We demonstrate the robustness of the approach on a very large dataset. A total of 127 images across 13 footprints in six countries in Asia were obtained between October 2012, and April 2014, covering 4.78 m ha. More than 1900 in-season site visits were conducted across 228 monitoring locations in the footprints for classification purposes, and more than 1300 field observations were made for accuracy assessment. Some 1.6 m ha of rice were mapped with classification accuracies from 85% to 95% based on the parameters that were closely related to the observed temporal feature descriptors derived for Remote Sens. 2014, 6 10775 each site. The 13 sites capture much of the diversity in water management, crop establishment and maturity in South and Southeast Asia. The study demonstrates the feasibility of rice detection at the national scale using multi-temporal SAR imagery with robust classification methods and parameters that are based on the knowledge of the temporal dynamics of the rice crop. We highlight the need for the development of an open-access library of temporal signatures, further investigation into temporal feature descriptors and better ancillary data to reduce the risk of misclassification with surfaces that have temporal backscatter dynamics similar to those of rice. We conclude with observations on the need to define appropriate SAR acquisition plans to support policies and decisions related to food security.
Plant and Soil, 1993
Page 1. Plant and Soil 153: 215-222, 1993. © 1993 Kluwer Academic Publishers. Printed in the Neth... more Page 1. Plant and Soil 153: 215-222, 1993. © 1993 Kluwer Academic Publishers. Printed in the Netherland.s. PLSO 9875 Interaction between zinc nutritional status of cereals and Rhizoctonia root rot severity II. Effect of Zn on disease severity of wheat under controlled conditions ...
Journal of Plant Nutrition, 2000
ABSTRACT
Field Crops Research, 1994
Surveys to determine the relation of uptake of nitrogen to yield of deepwater rice (DWR) in farme... more Surveys to determine the relation of uptake of nitrogen to yield of deepwater rice (DWR) in farmers' fields were conducted in the Central Plain of Thailand in 1988 and 1989. Farmers sowed their fields at the beginning of the wet season and the crops grew under rainfed dry land conditions until the flood arrived. Fields were sampled for soil pH, soil total N and available P, plant production and N content close to the arrival of the flood (pre-flood) and again at maturity. Start of flooding ranged from 22 to 122 days after emergence, with a mean of 66 days. Maximum water depths ranged from 0.30 to 2.10 m. Data from 32 fields in 1988 and 53 fields in 1989 were included in the analyses. Thirty seven DWR varieties were found. The mean farmer application of N for the 52 fields sampled in 1989 was 15.2 kg ha-~. Above-ground plant dry mass at maturity ranged from 2.7 to 20.5 t ha-~, with a mean of 10 t ha-~. Nitrogen content at maturity ranged from 23 to 115 kg ha-1, with a mean of 66 kg. Eighty percent of N was accumulated during the flood, but pre-flood plant production had a significant correlation with above-ground dry mass at maturity, indicating the importance of good early crop development for DWR. Yield ranged from 0.65 to 4.87 t ha-~, with a mean of 2.13 t ha-~. Factors closely correlated with yield were dry mass at maturity (r = 0.69"*), panicles m-2 (r = 0.59**) and rate of N uptake during flooding (r = 0.33**). Nitrogen content was most closely related to grain yield through total dry mass, but as most N was accumulated during the flood, a question still not answered is what proportions of this N came from the soil and from other sources, and how can the natural supply of N be sustained. These observations are also relevant to other rainfed lowland rice crops in Asia.
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Papers by pongmanee thongbai