Infection on plant caused by Aspergillus niger leads to the destruction of quantity and quality of crop yields. Normally, this disease is solved by the chemical fungicides. Therefore, this study was carried out to seek a potential natural fungicide from fruit waste which is safer and economical to inhibit Aspergillus niger. Cucurbita maxima (pumpkin) seeds and Punica granatum (pomegaranate) peels were extracted using maceration method with 80% ethanol. Brine Shrimp Lethality Assay (BLSA) was used to test the presence of bioactive components in the extracts at concentration of 10 µg/mL, 100 µg/mL and 1000 µg/mL and they are expressed in terms of LC50 (Median Lethal Concentration) respectively. The study revealed that Cucurbita maxima extract was inactive, while Punica granatum extract and the mixture of both extracts at ratio 1:1 were active at 1000 µg/mL. Furthermore, the antifungal activity of Cucurbita maxima extract, Punica granatum extract, and mixture of both extracts were further tested using well-diffusion method against A. niger at 25 mg/ml, 50 mg/mL, 75 mg/ml and 100 mg/mL respectively. The findings revealed the mixture of both extracts were exerted effectively against A. niger at the lowest concentration with 20.67±2.52 mm and this gave significant zone of inhibition. The result of the study indicates that the mixture extraction of pomegranate peels and pumpkin seeds at 25 mg/mL has a great potential to be formulated as commercial bio-fungicide.
ABSTRACT
This research is conducted to assess the accuracy of spline interpolation methods to predict and
model the surface water pH of Pulau Tuba, Langkawi, Kedah, Malaysia. In-situ sampling
activities using pH-meter and Geographic Positioning Systems (GPS) were carried out during
high tides and at noon in November 2018. The development of spatial models was constructed
using Regularized and Tension spline methods. Then, validation of models was carried out to
compare the observed and predicted values of pH using correlation analysis, regression analysis,
and error analysis. The accuracy of the developed map was calculated using the overall accuracy
equation. This research found that the regularized spline method had more accuracy in estimating
surface water pH variability than the tension spline method. Pearson correlation coefficient (r),
Coefficient of determination (R2
), Mean Absolute Error (MAE) and Root Mean Square Error
(RMSE) were reported at 0.896, 0.803, 0.0265 and 0.0344 for the regularized spline method,
respectively. The developed spatial model was then transformed into a map by adding map
elements such as legend, title, north arrow, and scales for effective visualization. The developed
map has an accuracy of 87.50%. The surface water pH was found at the range of 7-8. Low
reading of pH is expected due to the addition of rainwater to the coastal water of Pulau Tuba,
Langkawi, Kedah. The research outcomes would benefit government and non-government
agencies to monitor the coastal and ocean acidification and the development of strategic policies
and rules to reduce the impact of anthropogenic activities and climate changes for this area.