Volume 66, Issue 2, 2012
Research and Review Articles
Reducing tillage and maintaining crop residues on the soil surface could improve the water use efficiency of California crop production. In two field studies comparing no-tillage with standard tillage operations (following wheat silage harvest and before corn seeding), we estimated that 0.89 and 0.97 inches more water was retained in the no-tillage soil than in the tilled soil. In three field studies on residue coverage, we recorded that about 0.56, 0.58 and 0.42 inches more water was retained in residue-covered soil than in bare soil following 6 to 7 days of overhead sprinkler irrigation. Assuming a seasonal crop evapotranspiration demand of 30 inches, coupling no-tillage with practices preserving high residues could reduce summer soil evaporative losses by about 4 inches (13%). However, practical factors, including the need for different equipment and management approaches, will need to be considered before adopting these practices.
California's fruit and nut tree crops represent one-third of the state's cash farm receipts and 70% of U.S. fruit and nut production. Advances in crop biotechnology and genetic engineering could help protect these valuable crops from pests and diseases and improve productivity. However, due to the difficulty of genetically engineering woody tree crops, as well as intellectual property concerns, regulatory hurdles and public perceptions about genetic engineering, biotechnology has not gained a foothold in this area of agriculture. Our survey of published genetic engineering research and issued field trial permits between 2000 and 2011 revealed that citrus and grape are the focus of most current work, and that walnut — not the more widely planted almond — is the focus among nut crops. Matching publicly funded genetic engineering research projects to a survey of the industry's top needs, we found that far less than half of the funded research has focused on the top-identified pest and disease threats. The most promising genetic engineering technology for fruit and nut tree crops may be transgrafting, which could address consumer concerns and benefit growers.
Researchers from various countries have proposed using dry matter at harvest as a worldwide quality index for Hayward kiwifruit, because it includes both soluble (sugars and acids) and insoluble (structural carbohydrates and starch) solids and doesn't change during post-harvest handling. Our consumer tests in 1999 and 2008 indicated that dry matter and ripe titratable acidity are related to in-store consumer acceptance of kiwifruit. In most California seasons, when ripe titratable acidity was less than 1.2%, only a dry matter greater than or equal to 15.1% was required for consumer acceptability. Our 6-year quality attribute survey of California kiwifruit at harvest and from cold storage demonstrated that dry matter and ripe soluble solids concentration were highly variable among vineyards and seasons, but ripe titratable acidity values varied more among seasons than between vineyards. Our results provide strong evidence that dry matter would be a reliable quality index candidate for California kiwifruit, especially if ripe titratable acidity were factored in.
The regulatory implications of using transgrafted plants are currently unknown. A plant's vascular system can selectively transport across graft junctions endogenous elements such as full-length RNAs, sRNAs, proteins, hormones, metabolites and vitamins, and even elicit epigenetic effects, heritably changing the way genes are expressed without changing the actual DNA sequence. However, not all of these elements are transported freely, and they either require specific molecular signals or cellular transporters to aid in their movement through a plant's vascular system.
Editorial, News, Letters and Science Briefs
In 1862, in a nation torn by secession and Civil War, President Abraham Lincoln signed a visionary law that laid the cornerstone of public higher education. The Morrill Land-Grant College Act gave federal public lands to states, allotting 30,000 acres for each Senator and Representative. The total endowment was $7.55 million, then the value of 17.4 million acres. Today, more than 100 land-grant universities serve the nation and the world, including what many believe is the greatest public university in the world, the University of California.
WHAT DO YOU THINK?
The editorial staff of California Agriculture welcomes your letters, comments and suggestions. Please write to us at: 1301 S. 46th St., Building 478-MC 3580, Richmond, CA 94804, or firstname.lastname@example.org. Include your full name and address. Letters may be edited for space and clarity.
Growing up in West Philadelphia, the son of an electrician, I never had much occasion to encounter farm life. Our meat and potatoes came from the grocery store and our vegetables from the frozen food aisle. So one of the great privileges I have enjoyed as president of the University of California is learning about my adopted state's diverse agriculture industry and the amazing bounty it produces.
This year marks the sesquicentennial, or 150th anniversary, of four events key to American agriculture. In 1862, the United States Department of Agriculture (USDA) was created. Three pieces of legislation were also passed that would forever change the face of the nation: the Pacific Railroad Act, the Homestead Act and the Morrill Land-Grant College Act, which created America's land-grant institutions, including the University of California.
UC land grants: A photo history
A new report by UC Davis researchers, commissioned by the California State Water Resources Control Board and released in mid-March, is the first comprehensive scientific investigation of nitrate contamination of drinking water in high-risk areas of California.
Fire has always been a part of California's Sierra Nevada ecosystem, but over the past 100 years, a national fire suppression policy has disrupted the natural order.
Between 2008 and 2010, Central Valley farmers switched to conservation tillage on more than 344,000 acres used to grow row crops such as corn and wheat silage; meanwhile, in their 11th year of field research, UC scientists studying no-tillage practices achieved record yields in cotton and tomato.