By Melody M. Aguiba, Manila Bulletin via SEAMEO SEARCA Biotechnology Information Center

A hybrid rice that is close to 100 percent resistant to the destructive bacterial leaf blight (BLB) may be released in 2007 by Germany-based Bayer to give farmers more yield edge specially in the infesting wet season.

"We're incorporating genetic resistance (against BLB) in hybrid rice through conventional means. Bigante already has field tolerance against BLB which helps reduce epidemia in the field and raise yield, but this one is really disease-resistant," said Christian Carensac, Bayer CropScience (BCS) global supply chain manager.

The BCS hybrid rice itself has proven in multilocation trials in the Philippines over the last four years to have higher yield by 1.7 metric tons (MT) per hectare over the best inbred variety called a "check" variety during the dry season. This gives Bigante about 8.3 MT per hectare yield in an average of 22 trials.

In the wet season when BLB is widely-infesting, the same average of 22 trials proved the hybrid rice variety's additional 1.1 MT per hectare yield or seven MT per hectare over the inbred check.

The BLB resistance will further enhance yield since BLB may damage about 50 percent of the crop depending on infestation. BLB is manifested through the wilting of seeds, yellowing of leaves, and eventually harvest loss.

It may be observed one to three weeks after transplanting. The development of the disease is worsened by the presence of weeds, rice stubbles and rations of infected plants, presence of bacteria in the rice paddy, overfertilization, mishandling of seedling at transplanting, and warm temperature with rain and deep water.

There are management practices recommended to fight BLB, but the use of resistant varieties is the most effective and the most common management practice by farmers in most growing countries in Asia, according to the International Rice Research Institute (IRRI).

This is because common practices to fight BLB are laborious and labor-costly. Some of the practices include field sanitation such as removing weed hosts, rice straws, ratoons, and volunteer seedlings.

"Maintaining shallow water in nursery beds, providing good drainage during severe flooding, plowing under rice stubble and straw following harvest are also management practices that can be followed. Proper application of fertilizer, especially nitrogen, and proper plant spacing are recommended for the management of bacterial leaf blight," according to IRRI.