Rice is much more sensitive to salinity than previous guidelines suggest but proper water management can limit impacts on yield, according to peer-reviewed research published in the November-December issue of the University of California’s California Agriculture journal.
An important California field crop, rice was grown on about 470,000 acres in 2001, with a production value of $138 million. Cultivated under flooded conditions, it is one of the state’s most salt-sensitive crops.
To reduce pesticide contamination from their fields into natural waterways, rice growers — in concert with water regulatory agencies — began restricting drainage water discharges in the late 1980s and early 1990s. However, within several years some rice growers began noticing yield reductions.
In a series of unique field and greenhouse studies, scientists with UC and the U.S. Department of Agriculture determined that the salinity threshold for rice is 1.9 deciSiemens/meter (dS/m), substantially lower than the current guideline of 3.0 dS/m. They also found that water and soil salinity tend to increase as water flows through the series of basins typical of California rice growing. However, by altering water management practices — such as adding water during the plant’s most salt-sensitive growth stages — growers can reduce yield impacts while protecting the environment. Contact: Steve Grattan, (530) 752-1130 or srgrattan@ucdavis.edu.
Additional peer-reviewed articles in the current issue:
Mealybugs spread grapevine disease:
After several years of careful laboratory and field tests, UC scientists confirmed that four California species of mealybug could serve as vectors for grapevine leafroll disease, which is caused by a series of viruses. Found in grape-growing regions worldwide, the disease reduces the productivity and quality of wine and table grapes. The scientists found the first experimental evidence of grapevine virus transmission by several mealybug species. Contact: Deborah Golino, (530) 754-8102 or dagolino@ucdavis.edu.
Harvest timing improves alfalfa hay profits:
Harvest timing has a profound effect on the returns that growers obtain for alfalfa hay. Hay harvested early is of higher forage quality and fetches a better price, while later harvests result in lower quality grades but greatly improved yields. A decision model developed by UC scientists — based on 2 years of field data — helps alfalfa farmers in the intermountain region to calculate the optimal harvest timing and maximize crop returns. Contact: Steve Orloff, (530) 842-2711 or sborloff@ucdavis.edu.
News highlights:>
The front section of the November-December California Agriculture includes news articles on the discovery of sudden oak death in redwood and Douglas fir, the simultaneous mapping of genomes for the mosquito and malarial parasite, the first online course for grape pest advisors, and a new program that brings international environmental professionals to UC Berkeley for training and collaboration with UC faculty.
In an editorial, W.R. Gomes, UC Vice President for Agriculture and Natural Resources, discusses the impacts that the 10% state budget cut is having on the University’s research programs. “We are willing to share our part of the economic downturn, but if we are to survive and rebuild, we must keep basic capabilities intact,� Gomes writes.