Written by the Web Team
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, a plant breeder based in the Philippine Rice Research Institute (PhilRice) said.
Thelma F. Padolina, head of PhilRice`s Plant Breeding and Biotechnology Division, said that breeding is continuously pursued 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.
“Not all outstanding traits such as high-yielding, resistant to pests, excellent grain and eating quality are in just one rice variety. Breeders keep on improving varieties to help the farmers keep pace with the evolving pests and diseases, changing climatic conditions resulting in various abiotic stresses such as low and high temperature, submergence, salinity that reduces yield, and changing preferences of farmers, millers and consumers,” she said.
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 5 months as rice is grown for 6-7 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 that are being incorporated in the development of new and modern rice varieties. She explained that they have survived ages even in adverse environment as they also undergo proper seed selection by the communities. This is the reason why some traditional varieties are being put back into commercial cultivation in adverse environments.
“Maintaining good quality seeds is one of the key elements in the breeding process as varieties with improved adaptation to the environment are selected”, she said.
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 include occurrence of pests and diseases while abiotic stress include drought, salinity, high and low temperatures, and other environmental conditions that cause harm to the plant and reduces its yield.
However, she explained that resistance of rice plants decreases owing to intensive cropping and 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,” she said.