10. Weather and rice.
Proc. of the Int. Workshop on the Impact of Weather Parameters on Growth and Yield of Rice; IRRI, Philippines, 1987, 320 pp. + annexes
Rice is the staple food of about half of mankind. At least 1.125 billion people, comprising 225 million rural families, depend on rice as their major crop; the majority of them are subsistence farmers.
Rice is cultivated under diverse climatic, hydrological, and edaphic conditions.
Its wide adaptability is illustrated by rice cultivation at latitudes from 40 S to 53 N at elevations ranging from below sea level to more than 2,000 m; under upland conditions with no accumulated surface water and lowland conditions with no accumulated surface water and lowland conditions with 5 m deep water. Temperatures and humidity also vary widely. The importance of studies to determine the impact of weather variables on rice crop performance is apparent.
The World Meteorological Organization has implemented a number of programs, including the World Climate Impact Studies (WCIP), to which the undertaking of this workshop is relevant.
In the Philippines, specifically in the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), a system to assess climate impact for agriculture started in January 1985. Its objective is to provide a reliable and timely, yet inexpensive, weather-based information system that will continuously monitor and assess the impact of weather (such as drought, floods, typhoons, etc.) on rainfed agriculture.
Summarizing the main recommendations of the workshop are:
- Weather and biological stresses:
The extent to which information on the prevalence of rice pests under different cultural types and climatic conditions is quantitative or qualitative needs to be reviewed.
Information on the current status of major pests in different rice-growing environments should be collected in a central data bank.
Pest monitoring should be incorporated into studies on rice- weather relationships, including data on both research plots and adjacent farmers' fields.
Provision for measuring or calculating leaf wetness, an important parameter in disease epidemiology, should be added to the basic data set. Continuous temperature and humidity records are desirable.
- Weather and rainfed rice:
The constraints to upland rice production can be grouped as environmental, environment-dependent, and site-specific.
The constraints to rainfed rice production include:
- Climate: rainfall amount and variability, solar radiation, and temperature.
Most of these constraints can be related directly or indirectly to climatic factors or site characteristics.
Water balance is the best tool for determining soil water availability or deficiency throughout the crop season.
Because of the socioeconomic problems in rainfed rice regions and the complexities of environmental constraints on rainfed rice, international collaboration is the only avenue with the potential to contribute significantly to increased and stabilized production.
- Rice modeling:
Several recommendations to rice modeling were made.
Because of the importance of the impact of weather on the rice crop, the major importance of the crop, and the success of the UNDP-funded Rice-Weather Project in initiating the collection of essential basic information on weather and rice crop yields, and noting that the project has already established a basis for prediction models for rice yield and shows potential for developing forecasting models for pest outbreaks, the workshop recommends that appropriate donor agencies make funds available to IRRI to continue the rice-weather project, encompassing as far as possible the recommendations of the working groups.
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