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| List of Problems (2014) |
| Problem 3 : Development of early warning system for rice blast and brown planthopper (BPH), pest and disease of rice |
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Pests and diseases are major factors affecting rice production in Malaysia as well as in other rice growing countries.
Brown plant hopper (BPH, Nilaparvata lugens) and rice blast disease (Pyricularia oryzae) are considered as a major constraint in Southeast Asia.
In Malaysia alone, the estimated yield loss caused by the disease was about 90 000t/ season which is valued at about RM 72 million.
Although P. oryzae may infect at any parts of the aboveground parts of the plant, but infection on the panicles are the most damaging.
It has been shown to significantly reduce yield, grain weight and milling quality. In the off-season 2007,
total acreage affected by BPH in Muda area reached more than 4,497 ha or about 4.7% of the total planted area in the region.
At the moment, the defense strategies against the blast disease is still mainly based on variatal resistance with the support of chemical control. However, the issue is when is the appropriate time and situation that require chemical treatment intervention to ensure its effectiveness in controlling the disease. Usually disease incidence and severity need to be above a certain level (the threshold level) to cause significant yield loss. Therefore investigation involving predicting when the disease is likely to exceed this threshold level need to be conducted. Generally, high relative humidity and long periods of leaf wetness under tropical climate, dew periods, plant density, fertilizer rate, optimum temperature, water stress, with the support of the presence of virulent isolates and susceptible varieties are among the main factors that contribute towards the infection, colonization and sporulation of spore on plants. The rate of BPH population build-up in the rice field is depended upon several factors including the intensity of migrant population, the susceptibility levels of the planted host varieties, the nutritional qualities of the host, the abundance of other biotic components including natural enemies and competitor organisms, and conducive physical environments as above. The main aim of this study is to determine in advance the biological and other environmental parameters that are conducive and may trigger rice blast and BPH outbreak in the field so that the most effective preventive and control measures can be taken to prevent potential large scale outbreak to occurs. The gathered information may lead to ability to develop an effective technique to forecast rice blast and BPH occurence in the fields. Optimization of the parameters and multiple regression analysis used to analyzed the relationships between the parameters with the in-field blast incidence and in-field generation of BPH population were known as the main constraint in developing both forecasting models. |
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