Kalu Ganga basin is one of the most important river basins in Sri Lanka which receives very high rainfalls and has higher discharges. Due to its hydrological and topographical characteristics, the lower flood plain suffers from frequent floods and it affects socioeconomic profile greatly. During the past several years, many researchers have investigated climatic changes of main river basins of the country, but no studies have been done on climatic changes in Kalu Ganga basin. Therefore, the objective of this study was to investigate precipitation trends in Kalu Ganga basin. Annual and monthly precipitation trends were detected with Mann-Kendall statistical test. Negative trends of annual precipitation were found in all the analyzed rainfall gauging stations. As an average,-0.98 trend with the annual rainfall reduction of 12.03 mm/year was found. April and August were observed to have strong decreasing trends. July and November displayed strong increasing trends. In conclusion, whole the Kalu Ganga basin has a decreasing trend of annual precipitation and it is clear that slight climatic changes may have affected the magnitude and timing of the precipitation within the study area
Aims: The effects of exogenously applied salicylic acid (SA) on gas exchange characteristics, photosynthetic pigments and chloroplast ultrastructure were investigated in gerbera at their reproductive stage under salt-stressed conditions. Methodology: A pot experiment was conducted under glasshouse conditions at the Zhejiang University, Hangzhou, China, (30° N/120° E) between February 2008 and March 2009.Plants, pretreated with foliar applications of 0, 0.5, and 1.0 mmoldm-3 SA at the onset of flower initiation were irrigated with 100 mmoldm-3NaCl(aq) for two weeks, starting after three days from the SA pretreatment. Control did not receive either NaCl or SA.Photosynthetic rate, gas exchange, photosynthetic pigments content and chloroplast ultrastructure were investigated against treatments. All data were subjected to analysis of variance (ANOVA) and Generalized Linear Model (GLM) using SAS statistical software. Pearson’s correlation test was carried out to study the relationships among the parameters. The means were compared using Duncan’s multiple range test (DMRT). For all the tests, P< .05 was considered statistically significant. Results: Salt stress adversely affected the gas exchange characteristics, photosynthetic pigment contents and chloroplast ultrastructure. SA application significantly increased the net photosynthesis, stomatal conductivity, intra-cellular CO2 content and transpiration rate but decreased the stomatal limitation, compared to those of untreated salt-stressed plants. Further, the enhanced photosynthetic pigment contents and notably undamaged chloroplast ultrastructure were evident of the ameliorative effects of SA on photosynthetic system under salt stress. Of the two concentrations tested, 0.5 mmoldm-3 SA concentration seemed to have greater effect throughout the experiment showing no significant variation from control in some attributes (chlorophyll contents and chloroplast ultrastructure). Conclusion: Responses of plants pretreated with SA spraying and significant correlation among them plausibly suggest SA-induced enhancement of photosynthetic system as another target for conferring salt tolerance in crop plants.
Ocean atmospheric phenomenon such as El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (DMI) have an impact on global level climatic patterns and agriculture. The climate and agricultural activities of Sri Lanka, which is a tropical island in the Indian Ocean, mainly depends on the amount and the distribution of rainfall. The objective of this study was to assess the impact of ENSO and DMI on growing seasonal characteristics of Batalagoda, Sri Lanka. The growing seasonal characteristics such as the onset, retreat, length of the season, seasonal rainfall and rainy days were initially assessed using Instat Statistical Programme. Pearson correlation analysis was then performed to check their relationship with oceanic indices. The Multivariate ENSO Index and DMI did not show a significant correlation (p > 0.05) between onset, retreat and length of the season. However, the retreat of the season showed a significant (p < 0.05) relationship with Southern Oscillation Index (SOI). Both SOI and MEI showed significant (p < 0.05) correlation with the growing seasonal rainfall. Due to some signals of the impact of oceanic indices on the growing seasonal characteristics of Batalagoda, further studies are needed to be carried out throughout the county using the similar approach.
Though water is the most abundant natural resource on the earth, in most occasions, it is limited to agriculture especially in dry spells and dry regions. This is aggravated by higher losses from evaporation as well as percolation. If a method adopts to trap percolating water that would be one of the appropriate alternatives which helps to survive plants during dry climates and increase the water use efficiency. Therefore, the present study aims to identify the possibility of reducing percolation by using moisture absorbing substrate beneath the root zone. Three moisture absorbing substrates i.e sponge, biochar and sawdust were used as treatments and a control experiment was conducted without any water absorbing material. Treatmentswere arranged as Complete Randomized Design with three replicates. Treatments were buried at 20 cm depth as 5 cm layer separated by high gauge polythene. In a 90cm×180cm plot, 12 chilli (Capsicum annuum) plants were planted as two plants per hole.All recommended agronomic practices were carried out.Soil moisture content was maintained above 50 % allowable depletion level by measuring it dailythroughout the experiment, supplying the deficiency. Days to 50% flowering, plant height at 50% flowering, first harvesting yield, plant biomass and root biomass were measured.There were no significant differences in plant height, days to 50% flowering, plant biomass or root biomass between treatments. It indicates that there was no any moisture stress among treatments. However, there was a significant difference among the treatments in water usage by the crop throughout the duration. The water usage was significantly lower in sponge compare to other treatments. It means sponge material can conserve water at the rate of 992.59 m 3 /ha without any effect on the yield. Therefore, a substrate can be used to effectively conserve soil moisture by reducing the percolation and sponge is the best among tested treatments.
Historical and predicted rainfall records and spatial interpolation of temporal trends were analyzed to identify its impact on major climatic zones of Sri Lanka. Data from GHCN version 2.0 of monthly precipitation from 1930-2000 of 15 gauging stations in Sri Lanka were used in this study. Annual and four temporal seasons: Southwest monsoon (SWM), Northeast monsoon (NEM), First Inter-monsoon (FIM) and Second Inter-monsoon (SIM) were used for the analysis. Regression models and the Mann-Kendall test were employed to build the linear and nonlinear long term annual and seasonal models. From 2001 to 2100, monthly rainfall values were simulated from GCMs predictions by using LS-SVM. Then the annual and seasonal spatial distributions of trend statistics were mapped by using the inverse distance weighted interpolation method (IDW). The results suggest that the current boundaries of the wet zone of Sri Lanka have to be broadened and current intermediate zone could be expanded further in the next century. A semi-arid region can be developed around Batticaloa and the eastern coastal belt of the country. Current semi-arid regions may remain unchanged.
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