Adam Famoso, Zaunbrecher, Rick, Harrell, Dustin L., Angira, Brijesh
Adam Famoso, Dustin Harrell, Brijesh Angira and Rick Zaunbrecher
The aim of the LSU AgCenter rice breeding program is to improve the sustainability and profitability of the rice industry. The program focuses on all the market classes of rice grown in Louisiana — long-grain, medium-grain and specialty aromatic varieties. In addition to market classes defined by grain type, there are three different herbicide-resistant classes: conventional, Clearfield and Provisia.
Herbicide-resistant varieties are a crucial tool for rice growers to control weeds, allowing for more sustainable agronomic practices, such as no-till and reduced water needs. All of the herbicide-resistant rice varieties grown in the United States are non-GMO and have been developed with conventional breeding approaches. The first herbicide-resistant rice, the Clearfield production system, developed at the H. Rouse Caffey Rice Research Station, was released in the early 2000s, and still widely used. The Provisia rice production system, the second herbicide-resistant rice, was developed by BASF. The LSU AgCenter has released the first three Provisia varieties, starting in the mid-2010s. These systems help prolong the utility of these technologies and provide growers options for their specific operations.
The key traits the breeding program focuses on improving include: yield, milling quality, grain quality, disease resistance, early maturity and standability/lodging resistance. The development of new rice varieties is a continuous process and typically takes seven to eight years. The first step is the selection of rice lines to use as parents for crossing to develop a new breeding population. The goal is to select the best parents with the most desirable attributes to combine and then select progeny that are better than either parent.
Each spring, the breeding program crosses 70-80 lines and makes 400-500 new crosses in the greenhouse. These resulting populations are immediately planted into the greenhouse, where every plant has its leaf sampled to be tested with DNA markers to ensure the cross was successful. This first generation after the cross is called the F1 generation. Once the population and cross are confirmed, the plants are hand-transplanted into the field for self-pollination. The self-pollination of these F1 plants gives rise to the F2 generation, for which some populations are sent to the winter breeding nursery in Lajas, Puerto Rico, and some are advanced over the winter in the greenhouse. Populations that are advanced in the greenhouse are often selected via DNA marker-assisted selection, in which each individual plant can be tested for the presence of desirable genes for disease resistance, grain quality or herbicide tolerance.
In the second year of the breeding process, the F3 generation of each population is grown in the field at the Rice Research Station as 100-200 unique rows and evaluated visually for maturity, plant height/appearance and grain size/shape. At this stage, some populations are completely discarded, but most are advanced with 50-100 individual plants being selected and hand-harvested to be advanced to the F4 generation. The F4 generation is typically grown during the third year of the breeding process, and individual lines are selected and hand-harvested to be evaluated for grain quality.
In an average year, the breeding program selects, hand-harvests and evaluates 5,000 individual rows for grain appearance and shape. Based on the grain length, width and chalk values, approximately 2,500 new experimental lines are advanced into the preliminary yield trial.
The preliminary yield trial consists of replicated plots and is conducted in year four, which is the first year data is collected for yield, disease resistance and grain quality. Each entry is also genotyped for genes controlling key traits. The top performing lines from the preliminary yield trial are advanced to the regional yield test in year five, which is a replicated plot trial consisting of 165 entries tested at five locations across Louisiana. The most promising lines from each of the market classes are advanced to the commercial advanced yield test and the Uniform Rice Regional Nursery for two years of testing before release. The advanced stage yield trials are done with collaborators from the Rice Research Station, the AgCenter Macon Ridge Research Station in Winnsboro, and university breeders from neighboring states. A critical component to conducting these trials is the cooperation of rice farmers who allow us to use their land and help in the management of the trials.
When an advanced experimental line is being considered for release, the process of seed purification and increase begins at the end of year five or six at the winter nursery in Puerto Rico, where individual rows are grown and evaluated for uniformity. The selected rows are bulk harvested, shipped to the Rice Research Station, and used to plant a foundation seed field. This is the beginning of the variety release process, in which the foundation seed program begins to manage the seed increase and purity of the line. During the initial foundation seed increase, the breeding program and Foundation Seed program work closely together to finalize the purification and selection of the line. In recent years, this process has begun to use DNA markers to generate genetic profiles of each line. This has proved useful to identify potential off-types still present, which can be discarded.
The foundation seed program plays a critical role in the rice industry as the link between the newly bred and existing varieties and the rice producers. It is a central component to the seed certification process, which is critical to preserve genetic purity, variety identity and seed quality. The seed certification process is overseen by the Louisiana Department of Agriculture and Forestry.
Foundation seed is one of the largest field components of the Rice Research Station, with approximately 100 acres of land dedicated to foundation seed production. Foundation seed fields are grown on a three-year rotation, with one year of production, followed by two years fallow to ensure no plants are present that may have germinated from the previous year’s crop. Each year, six to 14 different varieties are grown in separate fields. Each variety is harvested separately, then the harvesting combine is taken apart and cleaned, a two-day process, before the next variety is harvested, to ensure no seed is carried over between varieties.
The foundation seed program is supported by seed companies and producers who purchase the seed for $70 per hundredweight. Each year, the program produces and sells between 1,000-4,000 hundredweights. Seed companies typically purchase foundation seed to plant for seed production to produce the “Registered Seed” class. Registered seed is typically planted by seed companies to produce the “Certified Seed” class, which is the class of seed most typically grown by rice farmers to be brought to the rice mill.
The LSU AgCenter H. Rouse Caffey Rice Research Station is not only involved in the development of new rice varieties, but the station also plays a critical role in maintaining the varieties and providing seed to the rice industry, long after a variety is released. When you pass a Louisiana rice field, know that approximately two-thirds of the rice grown are varieties developed by the Rice Research Station.
And, whether the variety was released two years ago or 20 years ago, the seed being grown in the farmers’ fields all derived from foundation seed produced within the past two to three years at the Rice Research Station.
Adam Famoso, associate professor; Dustin Harrell, professor and resident coordinator; Brijesh Angira, assistant professor; and Rick Zaunbrecher, research associate, all at the H. Rouse Caffey Rice Research Station, Crowley, Louisiana.
(This article appears in the spring 2021 issue of Louisiana Agriculture.)
Three AgCenter employees are picking panicles from rice plants in a field at the winter breeding nursery in Lajas, Puerto Rico. Left to right are Paola Mosquera, a Ph.D. student working with Jim Oard, professor in the School of Plant, Environmental and Soil Sciences; Brijesh Angira, assistant professor; and Brady Williams, research farm assistant. Photo by Adam Famoso
Rick Zaunbrecher, research associate at the H. Rouse Caffey Rice Research Station, is “rouging” a foundation seed field. Rouging is a critical component of foundation seed production and involves scouting fields to identify and physically remove off-type plants. Photo by Valerie Dartez