Decision Support Tool(DST)enables farmers to make site-specific crop management decisions;however,comprehensive calibration can be both costly and time-consuming.This study assessed the production and economic benefit...Decision Support Tool(DST)enables farmers to make site-specific crop management decisions;however,comprehensive calibration can be both costly and time-consuming.This study assessed the production and economic benefits of two calibrations of the Nutrient Expert(NE)tool for rice in Sri Lanka’s Alfisols:the basic calibration(Nutrient Expert Sri Lanka 1,NESL1)and the comprehensive calibration(Nutrient Expert Sri Lanka 2,NESL2).NESL1 was developed by adapting the South Indian version of NE to local conditions,while NESL2 was an updated version,using three years of data from 71 farmer fields.展开更多
Phosphorus(P) deficiency in soil is a major constrain for rice production. An important set of rice genotypes(landraces, old improved and new improved varieties) were screened for P deficiency tolerance in two major c...Phosphorus(P) deficiency in soil is a major constrain for rice production. An important set of rice genotypes(landraces, old improved and new improved varieties) were screened for P deficiency tolerance in two major cropping seasons of Sri Lanka, in 2012. The Ultisol soil, which was collected from a plot cultivated with rice without fertilizer application for past 40 years(P_0) at the Rice Research and Development Institute(RRDI), Bathalagoda, Sri Lanka, was used as the potting medium for greenhouse trials. Two field trials were conducted in the same plots at RRDI. Both P_0 and P_(30)(30 mg/kg P_2O_5) conditions were used in the two greenhouse trials. At the early vegetative(three weeks after transplanting), late vegetative(six weeks after transplanting) and flowering stages, plant height and number of tillers per plant were recorded. At the flowering stage, shoots were harvested and shoot dry weight, shoot P concentration, shoot P uptake and P utilization efficiency were measured. All data were statistically analyzed using analysis of variance, regression and cluster procedures. The measured parameters were significantly different between P_0 and P_(30) conditions(P < 0.05). Higher shoot dry weight was reported by the rice genotypes H4 and Marss under P_0 conditions. The regression analysis between shoot dry weight and P utilization efficiency revealed that the studied rice genotypes could be categorized to three P deficiency tolerance classes. A total of 13 genotypes could be considered as highly tolerant and 4 genotypes as sensitive for P deficiency. These results could be used to select parental genotypes for breeding and genetic studies and also to select interesting varieties or landraces for organic rice production.展开更多
Copper(Cu)is an essential micronutrient for rice.However,the current status of Cu in Sri Lankan paddy soils is not known.Therefore,the current study was conducted to determine the distribution of exchangeable Cu conce...Copper(Cu)is an essential micronutrient for rice.However,the current status of Cu in Sri Lankan paddy soils is not known.Therefore,the current study was conducted to determine the distribution of exchangeable Cu concentration and examine the interactive effects of the agro-climatic zone(ACZ),soil order,and water source in determining the exchangeable Cu concentration in lowland paddy fields in Sri Lanka.A total of 7,544 soil samples representing six ACZs,six soil orders,and three water sources were collected using a stratified random sampling approach.Soil exchangeable Cu fraction was extracted in 0.01 M CaCl_(2)and measured using Inductively Coupled Plasma Mass Spectrophotometry.Exchangeable Cu concentration was in the range of 0.04−728μg·kg^(−1)with a mean value of 62.4μg·kg^(−1).Only 5%of the soil samples tested had Cu concentration greater than 200μg·kg^(−1)indicating a widespread Cu deficiency in Sri Lankan paddy fields(i.e.critical level causing Cu deficiency;200-300μg·kg^(−1)).Among the climatic zones Wet zone had higher and the Dry zone had lower Cu concentrations.Among the soil orders,histosols had higher and alfisols had lower Cu concentrations.Water sources used for rice cultivation did not determine Cu concentration.Moreover,Cu concentration was positively correlated with soil pH.As most of the soil samples were deficient in soil exchangeable Cu,spatial maps generated in the current work could be used to develop ACZ and soil order-specific agronomic and management strategies to improve soil Cu fertility status.展开更多
Rice is largely self-fertilized and accordingly a field population of rice is completely composed of near homozygotes. Due to the emergence of off-types, homozygosity will be affected. With the time, this will cause t...Rice is largely self-fertilized and accordingly a field population of rice is completely composed of near homozygotes. Due to the emergence of off-types, homozygosity will be affected. With the time, this will cause the reduction of genetic purity in some rice varieties. One of the reasons has been suspected to be the high out-crossing frequencies of such varieties. Studies were conducted at the Rice Research and Development Institute, Batalagoda, Sri Lanka to estimate the out-crossing rate of Bg 379-2, a variety having the problem of maintaining genetic purity. Bg 379-2 was allowed to out-cross with Bg 450 and the number of out- crossed plants were counted using dominant morphological markers such as short-round grain and purple culm of pollen donor. A molecular confirmation of out-crossing was also performed using sequence tagged site （STS） molecular marker pTA248. The variety Bg 379-2 showed a potential out-crossing rate of 3.41% and an average out-crossing rate of 1.29% using dominant morphological markers. Polymorphism was cleady detected between parents and out-crossed plants as well as selfed plants of Bg 379-2 using their banding patterns. A similar study can be performed to determine the out-crossing rates of other varieties which show high percentage of off-types in the population for the better understanding of the breeding behavior of the varieties.展开更多
Conventional, grid-based sampling location tracking approach with GPS or topographic maps is time-consuming and inconvenient. Therefore, this study combined the freely available virtual/digital globe with recent advan...Conventional, grid-based sampling location tracking approach with GPS or topographic maps is time-consuming and inconvenient. Therefore, this study combined the freely available virtual/digital globe with recent advancements of smartphone geo-browsers to develop a new sampling location tracking approach. The sampling frame was developed with pre-uploaded point map formulated in GIS environment by combining land-use map and one-kilometer grid with center coordinates. The sampling location grid was uploaded to smartphone and each point was tracked with Google Map path finder using point ID (coded grid coordinate) when searching each sampling location. The suitability of the new approach was tested for soil sample collection from paddy lands distributed in 0.9 million hectares in Sri Lanka. The sampling locations could be reached conveniently with the help of Google path-finder voice direction guide and optional routes. The efficiency of new approach was found to be remarkably high, <em>i.e</em>., over 99% of the 9000 sampling points, which were spread across Sri Lanka having an area of 65,610 km<sup>2</sup>. All sampling points in the country could be covered with twelve member field investigation crew who were guided through smartphones uploaded with sampling point grid on six motorbikes within 60 days. The new sampling location tracking approach is effective in terms of cost, time, human resource requirements, thus can be adopted in large-scale soil/plant sampling frames with high accuracy.展开更多
Objective: To evaluate the physicochemical and nutritional properties of selected traditional rice varieties of Sri Lanka. Methods: Twenty three rice varieties were selected. All the varieties were studied for grain c...Objective: To evaluate the physicochemical and nutritional properties of selected traditional rice varieties of Sri Lanka. Methods: Twenty three rice varieties were selected. All the varieties were studied for grain colour, grain size and shape as physicochemical properties, while for nutritional properties, moisture, crude ash, crude protein, crude fat and total carbohydrate contents were studied. Only selected set of varieties were studied for total, soluble and insoluble dietary fiber. These properties were studied using internationally accepted standard techniques. Results: The results showed significant (P < 0.05) difference in the physicochemical and nutritional properties of the studied varieties. Out of 23 varieties tested, 20 varieties were red rices, while the rest were white rices. The grain size and shape were mostly medium bold (30%) and short bold (56%). The mean moisture, crude ash, crude protein, crude fat and total carbohydrate contents of selected varieties varied from (10.42 ± 0.25)% to (12.33 ± 0.02)%, (1.30 ± 0.14)% to (1.92 ± 0.05)%, (10.59 ± 0.12)% to (13.27 ± 0.32)%, (2.18 ± 0.10)% to (4.12 ± 0.28)% and (81.42 ± 0.25)% to (85.66 ± 0.24)%, respectively. The selected varieties had total, soluble and insoluble dietary fiber contents in the range of 4.2%–6.9%, 0.8%–2.1%and 3.1%–4.8%, respectively. The varieties Pachchaperumal, Suduru samba, Wanni Dahanala, Gonabaru and Sudu Heeneti had the highest crude protein, crude fat, crude ash, total carbohydrate and dietary fiber contents, respectively. Conclusions: Selected traditional rice varieties of Sri Lanka had physicochemical properties preferred by consumers and nutritional properties with dietary importance.展开更多
基金supported by the National Research Council of Sri Lanka(Grant No.NRC TO 16-07).
文摘Decision Support Tool(DST)enables farmers to make site-specific crop management decisions;however,comprehensive calibration can be both costly and time-consuming.This study assessed the production and economic benefits of two calibrations of the Nutrient Expert(NE)tool for rice in Sri Lanka’s Alfisols:the basic calibration(Nutrient Expert Sri Lanka 1,NESL1)and the comprehensive calibration(Nutrient Expert Sri Lanka 2,NESL2).NESL1 was developed by adapting the South Indian version of NE to local conditions,while NESL2 was an updated version,using three years of data from 71 farmer fields.
基金supported by the National Research Council (NRC), Sri Lanka (Grant No. 11-087)
文摘Phosphorus(P) deficiency in soil is a major constrain for rice production. An important set of rice genotypes(landraces, old improved and new improved varieties) were screened for P deficiency tolerance in two major cropping seasons of Sri Lanka, in 2012. The Ultisol soil, which was collected from a plot cultivated with rice without fertilizer application for past 40 years(P_0) at the Rice Research and Development Institute(RRDI), Bathalagoda, Sri Lanka, was used as the potting medium for greenhouse trials. Two field trials were conducted in the same plots at RRDI. Both P_0 and P_(30)(30 mg/kg P_2O_5) conditions were used in the two greenhouse trials. At the early vegetative(three weeks after transplanting), late vegetative(six weeks after transplanting) and flowering stages, plant height and number of tillers per plant were recorded. At the flowering stage, shoots were harvested and shoot dry weight, shoot P concentration, shoot P uptake and P utilization efficiency were measured. All data were statistically analyzed using analysis of variance, regression and cluster procedures. The measured parameters were significantly different between P_0 and P_(30) conditions(P < 0.05). Higher shoot dry weight was reported by the rice genotypes H4 and Marss under P_0 conditions. The regression analysis between shoot dry weight and P utilization efficiency revealed that the studied rice genotypes could be categorized to three P deficiency tolerance classes. A total of 13 genotypes could be considered as highly tolerant and 4 genotypes as sensitive for P deficiency. These results could be used to select parental genotypes for breeding and genetic studies and also to select interesting varieties or landraces for organic rice production.
基金supported by the World Bank under the Accelerating Higher Education Expansion and Development Grant(AHEAD)(Grant No.AHEAD/RA3/DOR/AGRI/PERA-No16).
文摘Copper(Cu)is an essential micronutrient for rice.However,the current status of Cu in Sri Lankan paddy soils is not known.Therefore,the current study was conducted to determine the distribution of exchangeable Cu concentration and examine the interactive effects of the agro-climatic zone(ACZ),soil order,and water source in determining the exchangeable Cu concentration in lowland paddy fields in Sri Lanka.A total of 7,544 soil samples representing six ACZs,six soil orders,and three water sources were collected using a stratified random sampling approach.Soil exchangeable Cu fraction was extracted in 0.01 M CaCl_(2)and measured using Inductively Coupled Plasma Mass Spectrophotometry.Exchangeable Cu concentration was in the range of 0.04−728μg·kg^(−1)with a mean value of 62.4μg·kg^(−1).Only 5%of the soil samples tested had Cu concentration greater than 200μg·kg^(−1)indicating a widespread Cu deficiency in Sri Lankan paddy fields(i.e.critical level causing Cu deficiency;200-300μg·kg^(−1)).Among the climatic zones Wet zone had higher and the Dry zone had lower Cu concentrations.Among the soil orders,histosols had higher and alfisols had lower Cu concentrations.Water sources used for rice cultivation did not determine Cu concentration.Moreover,Cu concentration was positively correlated with soil pH.As most of the soil samples were deficient in soil exchangeable Cu,spatial maps generated in the current work could be used to develop ACZ and soil order-specific agronomic and management strategies to improve soil Cu fertility status.
文摘Rice is largely self-fertilized and accordingly a field population of rice is completely composed of near homozygotes. Due to the emergence of off-types, homozygosity will be affected. With the time, this will cause the reduction of genetic purity in some rice varieties. One of the reasons has been suspected to be the high out-crossing frequencies of such varieties. Studies were conducted at the Rice Research and Development Institute, Batalagoda, Sri Lanka to estimate the out-crossing rate of Bg 379-2, a variety having the problem of maintaining genetic purity. Bg 379-2 was allowed to out-cross with Bg 450 and the number of out- crossed plants were counted using dominant morphological markers such as short-round grain and purple culm of pollen donor. A molecular confirmation of out-crossing was also performed using sequence tagged site （STS） molecular marker pTA248. The variety Bg 379-2 showed a potential out-crossing rate of 3.41% and an average out-crossing rate of 1.29% using dominant morphological markers. Polymorphism was cleady detected between parents and out-crossed plants as well as selfed plants of Bg 379-2 using their banding patterns. A similar study can be performed to determine the out-crossing rates of other varieties which show high percentage of off-types in the population for the better understanding of the breeding behavior of the varieties.
文摘Conventional, grid-based sampling location tracking approach with GPS or topographic maps is time-consuming and inconvenient. Therefore, this study combined the freely available virtual/digital globe with recent advancements of smartphone geo-browsers to develop a new sampling location tracking approach. The sampling frame was developed with pre-uploaded point map formulated in GIS environment by combining land-use map and one-kilometer grid with center coordinates. The sampling location grid was uploaded to smartphone and each point was tracked with Google Map path finder using point ID (coded grid coordinate) when searching each sampling location. The suitability of the new approach was tested for soil sample collection from paddy lands distributed in 0.9 million hectares in Sri Lanka. The sampling locations could be reached conveniently with the help of Google path-finder voice direction guide and optional routes. The efficiency of new approach was found to be remarkably high, <em>i.e</em>., over 99% of the 9000 sampling points, which were spread across Sri Lanka having an area of 65,610 km<sup>2</sup>. All sampling points in the country could be covered with twelve member field investigation crew who were guided through smartphones uploaded with sampling point grid on six motorbikes within 60 days. The new sampling location tracking approach is effective in terms of cost, time, human resource requirements, thus can be adopted in large-scale soil/plant sampling frames with high accuracy.
文摘Objective: To evaluate the physicochemical and nutritional properties of selected traditional rice varieties of Sri Lanka. Methods: Twenty three rice varieties were selected. All the varieties were studied for grain colour, grain size and shape as physicochemical properties, while for nutritional properties, moisture, crude ash, crude protein, crude fat and total carbohydrate contents were studied. Only selected set of varieties were studied for total, soluble and insoluble dietary fiber. These properties were studied using internationally accepted standard techniques. Results: The results showed significant (P < 0.05) difference in the physicochemical and nutritional properties of the studied varieties. Out of 23 varieties tested, 20 varieties were red rices, while the rest were white rices. The grain size and shape were mostly medium bold (30%) and short bold (56%). The mean moisture, crude ash, crude protein, crude fat and total carbohydrate contents of selected varieties varied from (10.42 ± 0.25)% to (12.33 ± 0.02)%, (1.30 ± 0.14)% to (1.92 ± 0.05)%, (10.59 ± 0.12)% to (13.27 ± 0.32)%, (2.18 ± 0.10)% to (4.12 ± 0.28)% and (81.42 ± 0.25)% to (85.66 ± 0.24)%, respectively. The selected varieties had total, soluble and insoluble dietary fiber contents in the range of 4.2%–6.9%, 0.8%–2.1%and 3.1%–4.8%, respectively. The varieties Pachchaperumal, Suduru samba, Wanni Dahanala, Gonabaru and Sudu Heeneti had the highest crude protein, crude fat, crude ash, total carbohydrate and dietary fiber contents, respectively. Conclusions: Selected traditional rice varieties of Sri Lanka had physicochemical properties preferred by consumers and nutritional properties with dietary importance.
