2020 - Volume 15 Issue 3

Effect of UV-C Hormesis in Regulating Anthracnose Disease and Postharvest Quality of Tomato

Tue, 01 Sep 2020 00:00:00 GMT

Effect of UV-C Hormesis in Regulating Anthracnose Disease and Postharvest Quality of Tomato Wanasinghe, W. U. T; Damunupola, J. W Purpose : Anthracnose disease caused by Colletotrichum coccodes is a significant postharvest disease in tomatoes. Although there are negative impacts of fungicides usage on fresh produce, at present, it is the most common method of eliminating diseases. UV-C hormesis was used in this study as a trending non-chemical postharvest treatment. Research Method : Tomato varieties ‘Thilina’ and ‘Roma’ were used to check the efficacy of UV-C treatments. Five different UV-C dosages (0, 1, 2, 3, 4, 5 kJ/m2 ) were applied to pure cultures of C. coccodes (254 nm at a distance of 15 cm). The selected dosages (3.0 and 4.0 kJ/m2 ) were tested on the effect of anthracnose disease development in vivo and the change in postharvest quality parameters (weight loss, firmness, shelf life, antioxidant and total phenolic content). Antifungal activity of the peel was investigated using Cladosporium bioassay. Findings : Weight loss of treated ‘Thilina’ variety has significantly increased (P < 0.05). The antioxidant activity and the total phenolic content of both treated varieties have increased. The firmness has significantly retained in treated ‘Thilina’ variety. Further, the shelf life has significantly extended in both treated varieties by approx. 2 folds compared to the non-treated control. All tested tomato samples indicated the presence of antifungal compounds in their peels. Therefore, to suppress anthracnose disease 4.0 kJ/m2 , and 3.0 and 4.0 kJ/m2 are the most suitable UV-C dosage for ‘Thilina’ and ‘Roma’ respectively. Research Limitations : This research is based on the available tomato cultivars in the market. Originality / Value : This is a non-chemical treatment which could be utilized by farmers in future, to control postharvest anthracnose in tomatoes.

Mapping of the Cadmium Lead and Mercury in Rice of Paddy Fields Within a CKDu Hotspot in Sri Lanka

Tue, 01 Sep 2020 00:00:00 GMT

Mapping of the Cadmium Lead and Mercury in Rice of Paddy Fields Within a CKDu Hotspot in Sri Lanka Ananda Jayalal, T. B Purpose : Evidence of substantial levels of chronic exposure to heavy metals from food has emerged in a number of studies carried out in the recent past. The contamination of rice, the main dietary staple, is attributed in the main source to this chronic toxicity. Determining of source and magnitude of such contamination will assist to propose suitable public health interventions. Research Method : The area with the second highest prevalence of Chronic Kidney Disease of uncertain aetiology (CKDu) in Sri Lanka; Padaviya Divisional Secretariat area paddy fields were selected for the study. Paddy samples were collected from cross-section of locations with GPS locations, intended to represent the entire field. Paddy was processed for rice by routine methods. The fields were rain fed or irrigation fed, this being duly noted. Findings : Analytical results were expressed on a wet matter basis. Mercury was not detected in any of the 196 samples. Out of 196 rice samples, 21 (11%) had no detectable levels of lead or cadmium. Seventeen (9%) samples contained cadmium exceeding 50 μg/kg and lead exceeding 100 μg/kg. The minimum, maximum and mean lead levels in rice were 50, 790, 118 μg/kg respectively. Minimum, maximum and mean cadmium levels in rice were 30, 280, 33 μg/kg respectively. Lead contamination appeared to be an equally widespread issue in the tested irrigation water fed paddy fields. However, determined lead concentrations are significantly lower in rain-fed fields. Cadmium contamination seems to be significantly greater in the rain-fed fields than in irrigation-fed fields. Originality / Value : The magnitude of contamination of potential nephrotoxic heavy metals and its geospatial distribution in rice which is the main staple diet of people living around the studied paddy field where second highest CKDu prevalence were reported, and have been revealed. The information generated can be utilized to reduce the contaminant levels by agronomic practices and diet based public health intervention to reduce the human exposure.

Phytoextraction of Nutrients and Heavy Metals by two Monocot Plants in Thaulla Area of Small Reservoir in Anuradhapura, Sri Lanka

Tue, 01 Sep 2020 00:00:00 GMT

Phytoextraction of Nutrients and Heavy Metals by two Monocot Plants in Thaulla Area of Small Reservoir in Anuradhapura, Sri Lanka Abeysingha, N. S; Maduranga, K. H. R. S; Singh, Suryendra; Duminda, D. M. S Purpose : Small tanks/ reservoirs are one of the major components of dry zone landscape and they were the basis of prosperity in ancient Sri Lanka. There are identified ecosystem components associated with the tanks such as upper peripheral area (thaulla). It is useful to understand the role of hydrophytes in thaulla area scientifically. This field study aimed to investigate the phytoextraction ability of two monocot plants, Paspalidium punctatum and Cyperus rotundus naturally grown in thaulla area of Ulankulama tank located in Anuradhapura. Research Method : The accumulation of total N, P, K, Ca, Mg, Cd, Pb and As were assessed by getting both plant and soil samples from 20 sampling points in thaulla area. Total K, Ca, Mg, As, Cd, and Pb contents were measured using the Inductivity Couple Plasma Optical Emission Spectrophotometer (ICP-OES) procedure. N, P, K were assessed following standard analytical procedures. Findings : Results showed that As and Cd were not observed in detected amount in soils of root zone of the plants. However, As and Cd were present in shoots and roots in both plant species. Both species could be considered as hyperaccumulator for K, Ca and Mg as they have biological concentration factor higher than one. Originality / Value : Paspalidium punctatum and Cyperus rotundus could be considered as hyperaccumulator for K, Ca and Mg and bio accumulation of heavy metals in thaulla area.

Utilization of SNP-based Highly Saturated Molecular Map of a RIL Population for the Detection of QTLs and Mining of Candidate Genes for Salinity Tolerance in Rice

Tue, 01 Sep 2020 00:00:00 GMT

Utilization of SNP-based Highly Saturated Molecular Map of a RIL Population for the Detection of QTLs and Mining of Candidate Genes for Salinity Tolerance in Rice Abhayawickrama, B.P; Gimhani, D.R; Kottearachchi, N.S; Herath, V Purpose : Previously, QTL hotspots were identified for salt tolerance from a RIL population of At354 x Bg352, under a temperature-controlled environment at the International Rice Research Institute, Philippine. However, as the rice-growing environment in Sri Lanka experiences salinity stress exaggerated with high temperature, the importance of revealing QTLs under such environment of a tropical region was realized. Therefore, the present study was focused to examine QTLs under such environment, deploying SNP-based molecular map, and retrieving potential candidate genes underlying the QTLs. Research Method : RIL population was assessed at 12 dSm-1 electrical conductivity coupled with average temperature ranged from 38 to 32 °C, day and night, respectively. QTLs were mapped using SNP markers. Potential candidate genes were identified using NGS-based high-throughput QTL-seq strategy employing whole-genome re-sequencing data of At354 and Bg352 and Gene Ontology approach. Findings : The results revealed a broad spectrum of phenotypic variation and a significant coefficient of correlation among the morpho-physiological traits in the RIL population. Four QTLs were revealed on chromosome 7, 9, and 11 for shoot Na+ concentration (qSNC7), shoot K+ concentration (qSKC9), shoot Na+/ K+ ratio (qSNK9) and root length (qRL11). Five genes, Os07g0635900, Os07g0637300, Os09g0330000, Os11g0514500, and Os11g0523800 within novel QTLs with polymorphic variants between At354 and Bg352, were recognized as potential candidate genes regulating salinity stress. Originality / Value : The putative candidate genes have been reported to be involved in cellular transmembrane and growth modulating functions under stress, indicating their usefulness to be further researched.