Several studies have been carried out in the recent past regarding the effects of global alteration, more so global warming, on the preferred environment for optimal growth of land and water species. It has been found that agricultural ecologies have been directly affected by the increasing levels of greenhouse gases. For the rice grown in America, rising CO2 levels have proven to be a booster in the reproductive abilities of the weedy natural type of rice which is mostly referred to as red rice. The name stems from the color of the seed covering.
Scientists in the agriculture industry conducted their experiments in the lab in a carefully controlled environment. Some rice was grown in very low CO2 levels as was the case decades ago. The CO2 concentration was increased gradually for the different plots of rice plants to gauge their reaction. Some rice was even grown in very high CO2 levels depicting what will be the case in the future. The result was that with rising CO2, the weedy rice progressively crossbred with the crop rice, incorporating native genes that had previously given growers a hard time to eliminate or amend.
According to Lewis Ziska from the USDA Agriculture Research Service located in Beltsville Md, the worth and quality of the rice decreased, practically turning it into a weed. He referred to the transformation as science fiction, equating it to the Invasion of the Body Snatchers. The good plant now produces bad seed.
This scientific concept suggests that the genes can also be transferred in the other direction, to the weedy rice from the crop plant. Even though, the experiments did not demonstrate any of that. The trials consistently transferred genes from the weedy rice to the crop plants. This is according to the PloS ONE report of 23rd May. Since 50% of the rice grown in America is resistant to the most common weed killers, any crossbreed also possesses similar qualities.
Ziska and his colleagues divided the rice crops into 3 plots. Every plot contained 7 crop plants and 1 weedy rice plant, matching the ratio in most rice fields in Southern U.S. The first plot was provided with conservative levels of CO2, 300 parts in a million depicting the situation about 1 century ago. The second plot had 400ppm, which is approximately the CO2 level today. The third plot had 600ppmCO2 depicting the possible levels in the years to come.
It was noted that rising CO2 levels favored the weedy rice, as opposed to the crop rice. The feral rice flowered and produced pollen much earlier, so much so that it could now pollinate the cultivated rice. It also grew more flowers and longer stems. These factors allowed for cross pollination due to the increased pollen and taller stems which aided in its distribution.
The capability of the weedy rice to pollinate the crop rice increased threefold as the CO2 levels were raised to the maximum. The resultant seeds were more delicate with covers disintegrating easily. The grains decreased in quality as well as the market value. Ziska suggests that these events have been occurring in several rice fields in the past 5 decades, without the knowledge of the farmers. This is because of the steadily rising CO2 levels.
The crossbreeds also maintained the resistance of the crop rice to weed killers. This aspect according to Ziska sheds some light on the decreasing effectiveness of herbicide sprays on rice in the recent times.
Commercial American fields have experienced immunity to the common herbicide, imidazolinone, used for eliminating weedy rice. These findings were reported 1 year ago by Elena Sanchez Olguin and Carol Mallory-Smith from the Oregon State University in Corvallis. In addition, the weedy rice seeds are able to lie dormant in the soil for a longer time compared to the rice crop, posing the danger of attacking crops in the following season.
Ziska vows to put all effort into producing something positive from these findings. He reasons that it is possible to track the traits that make weedy rice do exceptionally well in high CO2 environments, and incorporate them into cultivated rice. If his current venture succeeds, farmers could be working with a new rice breed in the next decade or so.