K. H. B. H. Delgoda, S. Sugathas, N. A. S. A. Neththasinghe, E. D. C. T. Chandrasekara, D. M. S. B. Dissanayaka, M. Ariyarathne, B. Marambe, D. N. Sirisena, U. Rathnayake, H. K. Kadupitiya, L. D. B. Suriyagoda
Soil pH and electrical conductivity (EC) are two major chemical properties affecting nutrient availability and rice grain yield. Therefore, this study was conducted to investigate the variation of pH and EC in the topsoil layer (0-15 cm) of rice fields as affected by major water source used for rice cultivation, rice-based cropping system adopted and rice growing soil orders in different agro-climatic zones (ACZs) in Sri Lanka. A total of 998 soil samples were collected from lowland rice fields. Both pH and EC were measured in 1:5 soil: water extracts. The pH of soil samples was in the range of 3.0-7.7 with a mean value of 5.0. Moreover, 75% of the soil samples had pH values below the optimum range for rice cultivation (5.5-7.0). Values of pH observed in Dry Zone soils were higher (5.2) than those in Wet Zone (4.4). Soil EC values ranged between 1.0 - 3,100 μScm−1 with a mean value of 148.5 μScm−1. Soil EC was similar among climatic zones (P>0.05). Upcountry Intermediate zone recorded the highest soil EC than that in other ACZs (P<0.05). Moreover, 73%, 22%, 3%, 2% and 0.1% of soil samples recorded EC values in the ranges of less than 150 (non-saline), 150-400 (slightly saline), 400-800 (moderately saline), 800-2000 (highly saline) and more than 2000 (very highly saline) μScm−1, respectively. Considering micro (e.g. paddy track) and macro (e.g. ACZ) scale spatial heterogeneity in soil pH and EC, appropriate site-specific strategies need to be adopted to improve soil pH and EC to suit sustainable rice crop production.
{"title":"Variability of pH and EC of Selected Rice Cultivated Soils of Sri Lanka","authors":"K. H. B. H. Delgoda, S. Sugathas, N. A. S. A. Neththasinghe, E. D. C. T. Chandrasekara, D. M. S. B. Dissanayaka, M. Ariyarathne, B. Marambe, D. N. Sirisena, U. Rathnayake, H. K. Kadupitiya, L. D. B. Suriyagoda","doi":"10.4038/tar.v34i4.8676","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8676","url":null,"abstract":"Soil pH and electrical conductivity (EC) are two major chemical properties affecting nutrient availability and rice grain yield. Therefore, this study was conducted to investigate the variation of pH and EC in the topsoil layer (0-15 cm) of rice fields as affected by major water source used for rice cultivation, rice-based cropping system adopted and rice growing soil orders in different agro-climatic zones (ACZs) in Sri Lanka. A total of 998 soil samples were collected from lowland rice fields. Both pH and EC were measured in 1:5 soil: water extracts. The pH of soil samples was in the range of 3.0-7.7 with a mean value of 5.0. Moreover, 75% of the soil samples had pH values below the optimum range for rice cultivation (5.5-7.0). Values of pH observed in Dry Zone soils were higher (5.2) than those in Wet Zone (4.4). Soil EC values ranged between 1.0 - 3,100 μScm−1 with a mean value of 148.5 μScm−1. Soil EC was similar among climatic zones (P>0.05). Upcountry Intermediate zone recorded the highest soil EC than that in other ACZs (P<0.05). Moreover, 73%, 22%, 3%, 2% and 0.1% of soil samples recorded EC values in the ranges of less than 150 (non-saline), 150-400 (slightly saline), 400-800 (moderately saline), 800-2000 (highly saline) and more than 2000 (very highly saline) μScm−1, respectively. Considering micro (e.g. paddy track) and macro (e.g. ACZ) scale spatial heterogeneity in soil pH and EC, appropriate site-specific strategies need to be adopted to improve soil pH and EC to suit sustainable rice crop production.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. G. J. P. Mahindapala, M. W. A. P. Jayatilaka, L. N. A. C. Jayawardana, M. Wijerathna
Farmers Organizations (FO) have evolved to address the major constraints faced by smallholder farmers. They need to address the diverse concerns of members. Tea Smallholding Development Societies (TSDS) were established through a legislative act and are expected to serve tea smallholders on resource and market-related issues. However, currently, the tea smallholding sub-sector seems stagnant as indicated by some of the key indicators that question the interventions made by TSDS to uplift the lives of tea growers. This study sought to explore the efficacy of TSDS and investigate its relationship with CA status. Data were collected from 120 TSDSs in major tea-growing areas using structured questionnaires. Results revealed that only 25% of TSDS offer multipurpose services at varying rates. The majority of TSDS acts only as an intermediary agency linking tea smallholders with government agencies for various forms of assistance. Market-oriented activities were minimal. Policy dialogue was found to be often lacking within organizations, which can block opportunities to develop a collective consciousness among the membership. Overall observations can be classified into four clusters based on the level of multitasking service provision. A significant correlation was e revealed between the efficacy of TSDSs and the status of collective action. The above correlation was stronger when collective action took place voluntarily than when a third party intervened, raising the question of dependency. The results, supported by the literature, revealed that collective action and efficacy function as interdependent variables. Thus, these two factors have the potential to behave in a vicious circle.
{"title":"Influence of Collective Action on the Efficacy of Tea Smallholding Development Societies in Sri Lanka","authors":"K. G. J. P. Mahindapala, M. W. A. P. Jayatilaka, L. N. A. C. Jayawardana, M. Wijerathna","doi":"10.4038/tar.v34i4.8674","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8674","url":null,"abstract":"Farmers Organizations (FO) have evolved to address the major constraints faced by smallholder farmers. They need to address the diverse concerns of members. Tea Smallholding Development Societies (TSDS) were established through a legislative act and are expected to serve tea smallholders on resource and market-related issues. However, currently, the tea smallholding sub-sector seems stagnant as indicated by some of the key indicators that question the interventions made by TSDS to uplift the lives of tea growers. This study sought to explore the efficacy of TSDS and investigate its relationship with CA status. Data were collected from 120 TSDSs in major tea-growing areas using structured questionnaires. Results revealed that only 25% of TSDS offer multipurpose services at varying rates. The majority of TSDS acts only as an intermediary agency linking tea smallholders with government agencies for various forms of assistance. Market-oriented activities were minimal. Policy dialogue was found to be often lacking within organizations, which can block opportunities to develop a collective consciousness among the membership. Overall observations can be classified into four clusters based on the level of multitasking service provision. A significant correlation was e revealed between the efficacy of TSDSs and the status of collective action. The above correlation was stronger when collective action took place voluntarily than when a third party intervened, raising the question of dependency. The results, supported by the literature, revealed that collective action and efficacy function as interdependent variables. Thus, these two factors have the potential to behave in a vicious circle.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. M. D. M. Wickramasinghe, T. D. C. Priyadarshani, W. C. P. Egodawatta, D. I. D. S. Beneragama, G. D. N. Menike, P. A. Weerasinghe, D. A. U. D. Devasinghe
Weather factors are key determinants in ecological disease management in sustainable agriculture, while judicious crop management systems deliver better control over rice diseases in tropical conditions. This study was designed to explore the effect of weather factors under different crop management systems and seasons on Rice Brown Leaf Spot (RBLS) disease incidences caused by Bipolaris oryzae in the tropical dry zone of Sri Lanka. The incidence of RBLS was measured under Conventional, Reduced, and Organic crop management systems commencing from the first occurrence of disease symptoms, at three-day sampling intervals in the tropical dry zone during wet (Maha) 2018/19 and 2019/20, and dry (Yala) 2019 and 2020 seasons. Secondary data on weather parameters were collected from the regional weather station. The RBLS incidences were highest in the wet season and were most abundant at the reproductive stage. The disease incidence dynamics over time were found to be similar among all the crop management systems in three seasons. The cumulative amount of rainfall seven days before the disease observation (RF7), the day-RH (DRH), and the maximum (TMAX48) and average temperature (TAVG48) that were recorded 48 h before the disease observations were found to be significantly correlated with the disease incidence of crop management systems in the wet season. DRH and minimum temperature (TMIN72) of 72 h before the disease observed in the wet season resulted in higher disease incidences. The RBLS disease can be managed concerning the crop management systems under high DRH and TMIN (20-25 ℃) in the wet season.
{"title":"Dynamics of Rice Brown Leaf Spot Disease (<em>Bipolaris oryzae</em>) Incidences Due to Seasonal Weather Differences in the Dry Zone of Sri Lanka","authors":"W. M. D. M. Wickramasinghe, T. D. C. Priyadarshani, W. C. P. Egodawatta, D. I. D. S. Beneragama, G. D. N. Menike, P. A. Weerasinghe, D. A. U. D. Devasinghe","doi":"10.4038/tar.v34i4.8675","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8675","url":null,"abstract":"Weather factors are key determinants in ecological disease management in sustainable agriculture, while judicious crop management systems deliver better control over rice diseases in tropical conditions. This study was designed to explore the effect of weather factors under different crop management systems and seasons on Rice Brown Leaf Spot (RBLS) disease incidences caused by Bipolaris oryzae in the tropical dry zone of Sri Lanka. The incidence of RBLS was measured under Conventional, Reduced, and Organic crop management systems commencing from the first occurrence of disease symptoms, at three-day sampling intervals in the tropical dry zone during wet (Maha) 2018/19 and 2019/20, and dry (Yala) 2019 and 2020 seasons. Secondary data on weather parameters were collected from the regional weather station. The RBLS incidences were highest in the wet season and were most abundant at the reproductive stage. The disease incidence dynamics over time were found to be similar among all the crop management systems in three seasons. The cumulative amount of rainfall seven days before the disease observation (RF7), the day-RH (DRH), and the maximum (TMAX48) and average temperature (TAVG48) that were recorded 48 h before the disease observations were found to be significantly correlated with the disease incidence of crop management systems in the wet season. DRH and minimum temperature (TMIN72) of 72 h before the disease observed in the wet season resulted in higher disease incidences. The RBLS disease can be managed concerning the crop management systems under high DRH and TMIN (20-25 ℃) in the wet season.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. M. P. S. Kumari, C. K. Weebadde, M. A. Pastor-Corrales, R. G. A. S. Rajapakshe, P. C. G. Bandaranayake
Bean rust is one of the major diseases of the common bean (Phaseolus vulgaris) reported in Sri Lanka and at the global level. This study aimed to develop rust-resistant snap bean breeding lines via gene pyramiding assisted by molecular markers. Resistant sources; PI 181996, BelMiNeb-RMR-8, and BelDakMi-RMR-19, enriched with the rust-resistant genes Ur-3 and Ur-11, were selected as donor parents to obtain a wide range of resistance to the rust pathogen. Resistant genotypes were crossed with popular local varieties Kappetipola nil and Galpalama Kalu (Capri) to introgress Ur-3 and Ur-11 resistant genes. Successive F1, F2, and BC (backcross) generations were obtained with the self-pollination and backcrossing processes. Standard phenotypic disease screening methods were applied to identify resistant lines. Phenotypically resistant plants obtained from these crosses were tested with sequence-characterized amplified region (SCAR) markers linked to two rust-resistant genes: SK 14 (linked to Ur-3) and SI 19 (linked to Ur-11). Molecular marker SI-19 showed higher reproducibility (50% to 80%) with the availability of relevant banding patterns for phenotypically resistant F1, F2, and BC1 progenies. However, SK 14 showed lower reproducibility (30–60%) for the same progenies. Approximately 450 genotypes introgressed with rust-resistant genes (Ur-3 and Ur-11)were produced. Among them, four advanced resistant lines obtained from the different cross combinations (Kappetipola nil x BelDakMi-RMR-19, Galpalama Kalu x BelMiNeb RMR-8, Kappetipola nil x PI 181996, and Kappetipola nil x BelMiNeb RMR-8) with preferred agronomic characters were selected for further variety development. All new genotypes will be important for future bean-resistant breeding programs in Sri Lanka.
{"title":"Development of Local Breeding Lines for Rust Resistance in the Common Bean (<em>Phaseolus vulgaris</em>) through the Incorporation of Rust-Resistant Genes","authors":"H. M. P. S. Kumari, C. K. Weebadde, M. A. Pastor-Corrales, R. G. A. S. Rajapakshe, P. C. G. Bandaranayake","doi":"10.4038/tar.v34i4.8677","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8677","url":null,"abstract":"Bean rust is one of the major diseases of the common bean (Phaseolus vulgaris) reported in Sri Lanka and at the global level. This study aimed to develop rust-resistant snap bean breeding lines via gene pyramiding assisted by molecular markers. Resistant sources; PI 181996, BelMiNeb-RMR-8, and BelDakMi-RMR-19, enriched with the rust-resistant genes Ur-3 and Ur-11, were selected as donor parents to obtain a wide range of resistance to the rust pathogen. Resistant genotypes were crossed with popular local varieties Kappetipola nil and Galpalama Kalu (Capri) to introgress Ur-3 and Ur-11 resistant genes. Successive F1, F2, and BC (backcross) generations were obtained with the self-pollination and backcrossing processes. Standard phenotypic disease screening methods were applied to identify resistant lines. Phenotypically resistant plants obtained from these crosses were tested with sequence-characterized amplified region (SCAR) markers linked to two rust-resistant genes: SK 14 (linked to Ur-3) and SI 19 (linked to Ur-11). Molecular marker SI-19 showed higher reproducibility (50% to 80%) with the availability of relevant banding patterns for phenotypically resistant F1, F2, and BC1 progenies. However, SK 14 showed lower reproducibility (30–60%) for the same progenies. Approximately 450 genotypes introgressed with rust-resistant genes (Ur-3 and Ur-11)were produced. Among them, four advanced resistant lines obtained from the different cross combinations (Kappetipola nil x BelDakMi-RMR-19, Galpalama Kalu x BelMiNeb RMR-8, Kappetipola nil x PI 181996, and Kappetipola nil x BelMiNeb RMR-8) with preferred agronomic characters were selected for further variety development. All new genotypes will be important for future bean-resistant breeding programs in Sri Lanka.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135509144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tank Cascade Systems (TCS) in the dry zone of Sri Lanka is threatened by soil erosion and high levels of sedimentation. Despite these challenges, the nation lacks studies exploring spatial soil loss variations within TCS contexts. Consequently, this research aimed to assess the sedimentation levels of five tanks and to analyze the spatial distribution of potential soil erosion rates across six selected sub-catchments within the Palugaswewa TCS. By utilizing sediment depth contour maps, the current sedimentation volume for each tank was computed. The study employed the revised universal soil loss equation (RUSLE) and geographic information system techniques to evaluate the potential average annual soil erosion rate, considering both existing land use scenarios and conservation interventions. The potential annual sediment yield was calculated using the sediment delivery ratio and potential average annual soil erosion rate. At present, 40 to 50 % of the tank storage capacity has been filled with sediments under existing land use. The potential average annual erosion rates of the sub-catchments of Palugaswewa TCS ranged from 19 t/ha/yr to 44 t/ha/yr. Notably, Sri Lanka's acceptable erosion rate stands below 12 t/ha/yr, rendering the erosion rates within Palugaswewa TCS unsuitable and destructive to sustained land productivity. The sediment delivery ratio varied from 0.18 to 0.9. This study suggests that adapting appropriate conservation measures such as cover cropping and soil contour bunding reduces the potential average annual erosion rate by 8.9 t/ha/yr to 14.5 t/ha/yr in the Palugaswewa sub-catchments.
{"title":"Tank Sedimentation, Soil Erosion Simulations and Conservation Interventions of the Sub-catchments in Palugaswewa Tank Cascade System, Sri Lanka","authors":"P. Kowshayini, H. B. Nayakekorala, S. Pathmarajah","doi":"10.4038/tar.v34i4.8671","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8671","url":null,"abstract":"Tank Cascade Systems (TCS) in the dry zone of Sri Lanka is threatened by soil erosion and high levels of sedimentation. Despite these challenges, the nation lacks studies exploring spatial soil loss variations within TCS contexts. Consequently, this research aimed to assess the sedimentation levels of five tanks and to analyze the spatial distribution of potential soil erosion rates across six selected sub-catchments within the Palugaswewa TCS. By utilizing sediment depth contour maps, the current sedimentation volume for each tank was computed. The study employed the revised universal soil loss equation (RUSLE) and geographic information system techniques to evaluate the potential average annual soil erosion rate, considering both existing land use scenarios and conservation interventions. The potential annual sediment yield was calculated using the sediment delivery ratio and potential average annual soil erosion rate. At present, 40 to 50 % of the tank storage capacity has been filled with sediments under existing land use. The potential average annual erosion rates of the sub-catchments of Palugaswewa TCS ranged from 19 t/ha/yr to 44 t/ha/yr. Notably, Sri Lanka's acceptable erosion rate stands below 12 t/ha/yr, rendering the erosion rates within Palugaswewa TCS unsuitable and destructive to sustained land productivity. The sediment delivery ratio varied from 0.18 to 0.9. This study suggests that adapting appropriate conservation measures such as cover cropping and soil contour bunding reduces the potential average annual erosion rate by 8.9 t/ha/yr to 14.5 t/ha/yr in the Palugaswewa sub-catchments.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Wijayaraja, M. Piyarathne, L. K. Weerasinghe, M. A. P. W. K. Malaviarachchi, D. P. Kumarathunge, U. Devasinghe, S. Rathnayake, N. Geekiyanage
Cowpea [Vigna unguiculata (L.) Walp.] is an important legume growing in tropical regions. Cowpea is grown in the Dry Zone of Sri Lanka as an inter-season crop. Rising temperatures and unpredictable precipitation patterns are major factors contributing to soil moisture stress in tropical agriculture. Despite the short life cycle, it is highly likely that cowpea experiences mild soil moisture stress (around 70% of field capacity) conditions at flowering stage due to enhanced evapotranspiration in response to increasing air temperature. In this study, five cowpea varieties were subjected to two soil moisture conditions; field capacity and mild water stress, at the onset of flowering under a split-plot design for two consecutive inter-seasons with the objectives to determine the leaf gas exchange and hydraulic traits of cowpea exposed to soil moisture stress and the underlying relationships between yield reduction and leaf gas exchange, hydraulic, and agronomic traits. The yield reduction (p<0.05) in the five varieties tested was associated with a reduction in leaf net assimilation rate, number of pods/plant, and number of seeds/pod. Variety-dependent reductions in leaf functional traits in many varieties leading to a reduction in yield parameters (p<0.05) were obvious under mild water stress conditions. Despite the water stress variety, Waruni performed well in both moisture conditions. As conclusion, cowpea varieties for inter-season cultivation should be selected based on ability to maintain yield under mild water stress conditions. A special emphasis should be placed on commencing cultivation as soon as the main crop is harvested to better utilize the residual moisture.
{"title":"Impact of Mild Water Stress During the Flowering Stage on Leaf Functional Traits and Yield of Selected Cowpea Varieties Grown in The Low Country Dry Zone of Sri Lanka","authors":"I. Wijayaraja, M. Piyarathne, L. K. Weerasinghe, M. A. P. W. K. Malaviarachchi, D. P. Kumarathunge, U. Devasinghe, S. Rathnayake, N. Geekiyanage","doi":"10.4038/tar.v34i4.8673","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8673","url":null,"abstract":"Cowpea [Vigna unguiculata (L.) Walp.] is an important legume growing in tropical regions. Cowpea is grown in the Dry Zone of Sri Lanka as an inter-season crop. Rising temperatures and unpredictable precipitation patterns are major factors contributing to soil moisture stress in tropical agriculture. Despite the short life cycle, it is highly likely that cowpea experiences mild soil moisture stress (around 70% of field capacity) conditions at flowering stage due to enhanced evapotranspiration in response to increasing air temperature. In this study, five cowpea varieties were subjected to two soil moisture conditions; field capacity and mild water stress, at the onset of flowering under a split-plot design for two consecutive inter-seasons with the objectives to determine the leaf gas exchange and hydraulic traits of cowpea exposed to soil moisture stress and the underlying relationships between yield reduction and leaf gas exchange, hydraulic, and agronomic traits. The yield reduction (p<0.05) in the five varieties tested was associated with a reduction in leaf net assimilation rate, number of pods/plant, and number of seeds/pod. Variety-dependent reductions in leaf functional traits in many varieties leading to a reduction in yield parameters (p<0.05) were obvious under mild water stress conditions. Despite the water stress variety, Waruni performed well in both moisture conditions. As conclusion, cowpea varieties for inter-season cultivation should be selected based on ability to maintain yield under mild water stress conditions. A special emphasis should be placed on commencing cultivation as soon as the main crop is harvested to better utilize the residual moisture.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. R. W. Pathiranage, M. A. Wijeratne, W. A. J. M. De Costa
Motorized tea harvesters vary in shoot cutting & collecting mechanisms and reported considerable yield decline in Sri Lanka. In this study, three non-selective harvesters were used to evaluate the impacts of different cutting & collecting mechanisms on tea yield-determining parameters compared to manual harvesting (control). The machines used were battery-operated Forbes & Walker harvester with helically arranged picking arms (BatFW), battery-operated Kawasaki harvester with reciprocating blades (BatKW), and petrol-driven Kawasaki harvester with reciprocating blades (PetKW). Tea yield, coarse leaf content, operational time, shoot compositions, branch girthing, and root starch content were recorded for one year. The motorized harvesters reduced tea yield by nearly 50% compared to the control. The number of machines required (units/ha/day) were 6, 4 and 2 for BatFW, BatKW and PetKW, respectively, as compared to eight manual pluckers and the corresponding land extents covered were 0.17, 0.25 and 0.47 (ha/unit/day), as against 0.13 in manual. Manual harvesting and BatFW consumed comparable higher worker requirements than the others. The average shoot weight and shoot density were the least affected by BatFW. The highest immature (arimbu) shoot removal was by PetKW. The highest dormant shoot accumulation in the plucking table was by BatFW. Reciprocating blades harvested more productively (700 g/cm/day) than picking arms (500 g/cm/day). All machines affected branch girthing and root starch reserves compared to manual harvesting. The mechanical impacts on yield determining parameters viz., immature shoot removal, accumulated dormant shoots, affected yield components, poor branch development, and depleted root starch reserves collectively resulted the tea yield reduction.
{"title":"Impact of Motorized Tea Harvesters on Tea Yield and Yield Determining Parameters","authors":"S. R. W. Pathiranage, M. A. Wijeratne, W. A. J. M. De Costa","doi":"10.4038/tar.v34i4.8672","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8672","url":null,"abstract":"Motorized tea harvesters vary in shoot cutting & collecting mechanisms and reported considerable yield decline in Sri Lanka. In this study, three non-selective harvesters were used to evaluate the impacts of different cutting & collecting mechanisms on tea yield-determining parameters compared to manual harvesting (control). The machines used were battery-operated Forbes & Walker harvester with helically arranged picking arms (BatFW), battery-operated Kawasaki harvester with reciprocating blades (BatKW), and petrol-driven Kawasaki harvester with reciprocating blades (PetKW). Tea yield, coarse leaf content, operational time, shoot compositions, branch girthing, and root starch content were recorded for one year. The motorized harvesters reduced tea yield by nearly 50% compared to the control. The number of machines required (units/ha/day) were 6, 4 and 2 for BatFW, BatKW and PetKW, respectively, as compared to eight manual pluckers and the corresponding land extents covered were 0.17, 0.25 and 0.47 (ha/unit/day), as against 0.13 in manual. Manual harvesting and BatFW consumed comparable higher worker requirements than the others. The average shoot weight and shoot density were the least affected by BatFW. The highest immature (arimbu) shoot removal was by PetKW. The highest dormant shoot accumulation in the plucking table was by BatFW. Reciprocating blades harvested more productively (700 g/cm/day) than picking arms (500 g/cm/day). All machines affected branch girthing and root starch reserves compared to manual harvesting. The mechanical impacts on yield determining parameters viz., immature shoot removal, accumulated dormant shoots, affected yield components, poor branch development, and depleted root starch reserves collectively resulted the tea yield reduction.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There is a growing interest in controlling nitrification by using botanical nitrification inhibitors to enhance the nitrogen (N) fertilizer use efficiency. The main objective of this study was to develop a botanical formulation (BF) with Cinnamomum verum (cinnamon) and Pongamia pinnata (karanda) leaves to suppress the nitrification rate of two soils (Red Yellow Podzolic (RYP) and Reddish-Brown Earth (RBE)) commonly used for vegetable cultivation in Sri Lanka. A BF was prepared using dried and powdered leaves of cinnamon and karanda, biochar and corn flour. The two soils were treated with BF at three rates (0, 5 and 10%, w/w) and the potential nitrification rate (PNR) was determined using the shaken slurry method in a laboratory incubation. The obtained data were analysed by Statistical Analysis Software (SAS) adopting a two factor factorial design. The BF application significantly delayed (P<0.05) nitrate formation in both soils. The RBE soil had significantly lesser (P<0.05) PNR compared to RYP soil. Application of 5 and 10% BF, significantly reduced PNR in both soils at 4 h of incubation. However, only a 10% BF application rate remained effective in suppressing PNR at 21 h of incubation. Results indicate the possibility of using dried, powdered leaves of cinnamon and karanda for suppressing nitrification in soil. Further studies are required to investigate the effect of developed BF on soil biological properties.
{"title":"Development of a Botanical Formulation Using <em>Cinnamomum verum</em> and <em>Pongamia pinnata</em> Leaves for Suppression of Nitrification in Soil","authors":"A. M. Dias, W. S. Dandeniya","doi":"10.4038/tar.v34i4.8678","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8678","url":null,"abstract":"There is a growing interest in controlling nitrification by using botanical nitrification inhibitors to enhance the nitrogen (N) fertilizer use efficiency. The main objective of this study was to develop a botanical formulation (BF) with Cinnamomum verum (cinnamon) and Pongamia pinnata (karanda) leaves to suppress the nitrification rate of two soils (Red Yellow Podzolic (RYP) and Reddish-Brown Earth (RBE)) commonly used for vegetable cultivation in Sri Lanka. A BF was prepared using dried and powdered leaves of cinnamon and karanda, biochar and corn flour. The two soils were treated with BF at three rates (0, 5 and 10%, w/w) and the potential nitrification rate (PNR) was determined using the shaken slurry method in a laboratory incubation. The obtained data were analysed by Statistical Analysis Software (SAS) adopting a two factor factorial design. The BF application significantly delayed (P<0.05) nitrate formation in both soils. The RBE soil had significantly lesser (P<0.05) PNR compared to RYP soil. Application of 5 and 10% BF, significantly reduced PNR in both soils at 4 h of incubation. However, only a 10% BF application rate remained effective in suppressing PNR at 21 h of incubation. Results indicate the possibility of using dried, powdered leaves of cinnamon and karanda for suppressing nitrification in soil. Further studies are required to investigate the effect of developed BF on soil biological properties.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fallowed uplands dominated by Chromolaena odorata, Hyptis suaveolens, Tithonia diversifolia, Imperata cylindrica and other grasses were selected and their effects on the emergence of associated weed species, the nutrient status of the soil and subsequent maize yield were examined. A survey was conducted to estimate the floristic composition in each field in 2017 and 2018. Five fallowed fields and one arable field were used during the 2018 and 2019 seasons. The trial was laid on each field in a Randomized Complete Block Design with 3 replicates. Zero tillage was adopted for the fallow land while the arable field was ploughed, harrowed, and ridged. Weed, soil, and grain yield data were collected and subjected to analysis of variance at P=0.05. The results showed that weed composition and emergence pattern differed marginally among the five fallowed fields. Tridax procumbens, Brachiaria lata and Cyperus rotundus were the most associated weed species. Soils under T. diversifolia and C. odorata were rich in organic carbon and total porosity and low in bulk density with an average return biomass to the soil amounting to 23.18 - 27.18g/m2. The continuously managed arable field showed maize grain yield of 2.72 t/ha compared with fallowed fields dominated by T. diversifolia (2.64 t/ha) and C. odorata (2.38 t/ha). Tithonia diversifolia and C. odorata contributed positively to reducing weed emergence and improving soil nutrients. Small-holder farmers can re-incorporate the tested weed species into the cropping system to reduce herbicide usage and improve maize grain yield in the Nigerian southern Guinea savannah.
{"title":"Impact of Fallowing on the Emergence of Weed Species, Soil Nutrient Dynamics and Yield of Maize (<em>Zea mays</em> L.)","authors":"F. O. Takim, K. O. Affinnih, J. O. Adeyemi","doi":"10.4038/tar.v34i4.8580","DOIUrl":"https://doi.org/10.4038/tar.v34i4.8580","url":null,"abstract":"Fallowed uplands dominated by Chromolaena odorata, Hyptis suaveolens, Tithonia diversifolia, Imperata cylindrica and other grasses were selected and their effects on the emergence of associated weed species, the nutrient status of the soil and subsequent maize yield were examined. A survey was conducted to estimate the floristic composition in each field in 2017 and 2018. Five fallowed fields and one arable field were used during the 2018 and 2019 seasons. The trial was laid on each field in a Randomized Complete Block Design with 3 replicates. Zero tillage was adopted for the fallow land while the arable field was ploughed, harrowed, and ridged. Weed, soil, and grain yield data were collected and subjected to analysis of variance at P=0.05. The results showed that weed composition and emergence pattern differed marginally among the five fallowed fields. Tridax procumbens, Brachiaria lata and Cyperus rotundus were the most associated weed species. Soils under T. diversifolia and C. odorata were rich in organic carbon and total porosity and low in bulk density with an average return biomass to the soil amounting to 23.18 - 27.18g/m2. The continuously managed arable field showed maize grain yield of 2.72 t/ha compared with fallowed fields dominated by T. diversifolia (2.64 t/ha) and C. odorata (2.38 t/ha). Tithonia diversifolia and C. odorata contributed positively to reducing weed emergence and improving soil nutrients. Small-holder farmers can re-incorporate the tested weed species into the cropping system to reduce herbicide usage and improve maize grain yield in the Nigerian southern Guinea savannah.","PeriodicalId":23313,"journal":{"name":"Tropical agricultural research","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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