Use of same rice variety results in lower yields - PhilRice

SCIENCE CITY OF MUÑOZ, Nueva Ecija, Philippines  – Here’s one tip for the country’s rice farmers: Don’t use one and the same rice variety over and over again. That is if you want to increase your yields.

This advice was offered by a biotech expert of the Philippine Rice Research Institute who explained that pests become immune when exposed to one and the same rice variety for a long time.

Thelma Padolina, chief of the Philippine Rice Research Institute’s plant breeding and biotechnology division, said resistance of rice plants to pests decreases principally due to two reasons: Intensive cropping and the use of the same variety every season.

“If pests are continuously exposed to the same variety, these might evolve into more powerful types that would overcome the resistance of the varieties,” Padolina said.

Padolina said not all outstanding traits are present in one rice variety such as high-yielding, resistant to pests, excellent grain and eating quality among others. She said PhilRice breeders keep on improving varieties to help the farmers keep pace with the evolving pests and diseases, changing climatic conditions resulting in various stresses such as low and high temperature, submergence, salinity that reduces yield, and changing preferences of farmers, millers and consumers.

She said modern rice varieties yield higher than traditional ones as they are more efficient in absorbing nutrients and more effective in photosynthetic activities owing to plant physical traits such as short upright leaves and more tillers.

Many modern varieties, she added, are resistant to “biotic” and “abiotic” stresses. Biotic stress refers to occurrence of pests and diseases while abiotic stress includes drought, salinity, high and low temperatures, and other environmental conditions that cause harm to the plant and reduces its yield.

Padolina said while there are rice varieties that have evolved by natural and farmer selection, rice varietal development remains a priority in a country with a fast-growing population and with a rice self-sufficiency goal.

She added that PhilRice is actively pursuing breeding to provide the farmer more choices and allow him to cope with rapid changes in the biophysical and socio-economic environments as evolution by natural and farmer selection in rice is simply too slow for the needs of modern humans.  

Padolina said traditional varieties, mostly planted in the highlands, are low-yielding and late-maturing. Based on studies, the rice produced by highland farmers is only sufficient to meet their rice consumption for five months as rice is grown between six to seven months and yield per hectare is very low.

Furthermore, she said that an intensive cropping using traditional variety is not possible in the terraces or in the highland farms because of the varieties’ long maturity.

Although traditional varieties mature within 150-180 days, they are good sources of resistance and grain quality traits which are being replicated in the development of new and modern rice varieties.