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Post harvest requirements of HYV

The modern higher yielding varieties revolutionized farm production and post-production practices. Traditional varieties were harvested during the dry months. The mature crop was reaped and left in windrows to dry. Dry straw and panicle were later carried home to the village where stacks were built. These stacks at as a form of paddy storage. When grain was needed for consumption or sale, it was threshed by beating or trampling the rice. This practice was used in Thailand and the Philippines as late as the 1960's and still continues in Bangladesh, a major rice producer.

HYV with irrigation can be planted all year round. With these varieties, a second crop is normally harvested in the monsoon months from June to November. Clearly the practice of sun drying in windrows cannot be done anymore. The mature crop must be harvested without delay, threshed and dried. The summer harvest has grain moisture of 18% to 21% wet basis (wb) and is relatively stable. The rainy season harvest measures from 24 to 28% wb, and deteriorates rapidly. New technologies for harvesting and drying HYV had to be developed.

It is unfortunate that rice is rarely tested for their processing characteristics; instead only cooking and eating qualities, and acceptability in the markets is evaluated. Even IRRI has not undertaken studies to establish the thermophysical properties of their recommendations, which are essential to design drying and storage systems. Justin Tumambing at NAPHIRE found out that their data differ significantly from the published data of the ASAE, which is used by many engineers. Rusty Bautista whose work in Japan with Dr Bekki also established that the different varieties dry differently according to their test results.

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