Papers by Dr. D.M.D. M . M . S H A N T H I Dissanayake
Tropical agricultural research, Mar 30, 2022
Tropical Agricultural Research, 2021
The dynamics of organic and inorganic nutrient sources in diverse input systems can affect physio... more The dynamics of organic and inorganic nutrient sources in diverse input systems can affect physiological processes of rice. Understanding these nutrient dynamics and their relation to final yields are important to devise optimum nutrient management strategies. This experiment was conducted to evaluate the relationships between nutrient availability from different sources, and growth physiology and crop yield of rice during 2019 Yala and 2019/20 Maha seasons. The Department of Agriculture (DOA) recommended inorganic fertilizer application (conventional system), 50% of DOA recommended inorganic fertilizer with organic manure mixture (integrated system), and 100% organic manure mixture application (organic system) were used as three treatments. Organic manure mixture was added to equalize the nitrogen supply through DOA rate. The systems were arranged in a randomized complete block design with six replicates and Bg 300 rice variety was used. The conventional and integrated systems were similar, while the organic system was weak in canopy light interception, photosynthetic rate, and leaf chlorophyll content at panicle initiation and heading stages. The treatment effect was significant (P<0.05) in 2019 Yala (dry season) but not in 2019/20 Maha (wet season). The correlations between leaf nitrogen concentration and yield were observed with respect to input systems. Most physiological parameters showed no robust correlation to biomass and crop yield. Crop yields were higher in the conventional and integrated systems compared to the organic system. However, the differences are expected to be narrowed down with the development of long-term nutrient status in the organic system as this study was conducted during the first year of the transition.
International Journal of Agronomy
The future of food crop production is uncertain due to the negative effects of global warming. Co... more The future of food crop production is uncertain due to the negative effects of global warming. Cowpea is grown in warm environments including in Sri Lanka, where less is known about the potential acclimation of ecophysiological and agronomic traits to increasing temperatures. We evaluated the acclimation potential of yield components and ecophysiological traits of three recommended cowpea genotypes to the seasonal variation in growth temperature in Anuradhapura, Sri Lanka. This study was conducted at the Faculty of Agriculture, Rajarata University of Sri Lanka, in two consecutive seasons with average daytime temperatures of 30.4°C and 33.2°C. Three genotypes, Dhawala, Waruni, and MI-35, were tested in this study, and their rates of leaf photosynthesis and respiration at the 50% flowering stage and final yield parameters were measured at their respective average growth temperatures in both seasons. The total yield per hectare showed an average decrease of 16%, 17%, and 22% in the Dha...
Sri Lanka Journal of Food and Agriculture, 2018
Late flowering-affected spikelet sterility was found in dry zone of Sri Lanka. It was defined as ... more Late flowering-affected spikelet sterility was found in dry zone of Sri Lanka. It was defined as a combination effect of air temperature and relative humidity at anthesis. It is considered important to develop mitigation options to avoid temperature stress. Therefore, the impact of some phenotypic markers on pollen sterility was studied. This paper highlights flag leaf characteristics regulate the direct sunlight penetration and augment the spikelet surface temperature. A field trial was conducted at the Field Crops Research and Development Institute, Mahailluppallama, Sri Lanka during 2013/14 and 2014/15 Maha seasons (main cultivating season; October to February). Due to water shortage, this experiment was not conducted in the Yala season (March to September). A split plot design was adopted with early and late planting as a main factor and two rice (Oryza sativa L) varieties (Bg358 and Bg366) and two rice lines (Bg3171 and Bw03-1198) as a sub factor, in a two factor factorial arra...
Tropical Agricultural Research and Extension, 2010
The protein toxins produced by Bacillus thuringiensis are the most widely used natural insecticid... more The protein toxins produced by Bacillus thuringiensis are the most widely used natural insecticides in vector and pest control in agriculture. B. thuringiensis strains present in surface and sub-surface soil samples collected from Nochchiyagama were isolated by 0.25M sodium acetate selection method. Isolated B. thuringiensis was grown on Luria Bertani agar medium and stained by Gram staining procedures. Sixty isolates of B. thuringiensis were identified by Coomassie Blue staining procedure and characterized based on colony morphology, crystal shape, plasmid profile and bioassay. Results revealed that sub-surface samples had more B. thuringiensis counts than surface soils. This study also indicated that B. thuringiensis was abundant in soils contaminated with animal wastes. All the isolates formed 'pan cake' shape circular colonies with smooth or serrate margins with varying diameter. Fifty five isolates were found to have rod shape crystals, 4 were spherical shape and only one isolate had rhomboidal shape crystal. Thirty six isolates were toxic to the third instar larvae of Aedes aegypti including the isolate which contained rhomboidal shape crystal. All the other isolates found toxic to the mosquito larvae consisted with rod shape crystal inclusion bodies. There were eight different B. thuringiensis strains among the isolates and 55% of these were B. thuringiensis israelensis.
International Symposium on Soilless Cultivation, 2013
Tropical Agricultural Research, 2015
The impact of integration of inorganic fertilizer and organic manures on yield of rice (Oryza sat... more The impact of integration of inorganic fertilizer and organic manures on yield of rice (Oryza sativa L.) was evaluated under field conditions over two seasons. The experiment was laid out in a split-plot design with three replicates. The main plots were two rice varieties namely, Kaluheenati and Bg 352, and the sub-plots consisted of five fertilizer/manure combinations viz. T1-control (without fertilizer and organic manure), T2-100% of fertilizer recommendation of the Department of Agriculture (DOA), T3-50% of fertilizer recommendation of the DOA, T4-organic manure alone, T5-50% of fertilizer recommendation of the DOA + T4. The variety effect, fertilizer/manure combination effect and interaction effect of variety and fertilizer/manure combination on yield were significant (p<0.05). In Kaluheenati, organic manure (T4) was the most suitable for higher yield. The variety Bg 352 responded positively to organic manures in combination with inorganic fertilizers, which illustrates the possibility of substituting a part of inorganic fertilizers with organic manures (T5) saving 130, 43 and 37 kg urea, Triple Super Phosphate and Muriate of Potash/ha, respectively.
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Papers by Dr. D.M.D. M . M . S H A N T H I Dissanayake