DEVELOPING NEW ALFALFA CULTIVARS FOR CALIFORNIA. Francisco Maciel, Desert Research and Education Center

Transcription

1 A. COVER PAGE PROJECT TITLE DEVELOPING NEW ALFALFA CULTIVARS FOR CALIFORNIA PRINCIPAL INVESTIGATOR E. Charles Brummer, Professor 1234 PES, UC Davis OTHER INVESTIGATORS Tami Leathers, Staff Research Associate II, UC Davis Francisco Maciel, Desert Research and Education Center Dan Putnam, Extension Agronomist and Forage Specialist BUDGET TOTALS 7/1/16-6/30/17 $32,559 SUMMARY (200 words or less): This project represents the second year of our long-term project in alfalfa improvement at UC, Davis. Through the past year, I have tried to clarify my objectives and the project this year hopefully reflects a better focus than last year. We remain focused primarily on the Imperial Valley, with the goal of developing publicly released cultivars that are high yielding, persistent, productive under limited water, and free of major pests and diseases.

2 B. OBJECTIVES The long-term objective is to develop alfalfa cultivars and germplasm that offer consistent production, high yield, and multi-year persistence to California alfalfa growers. The cultivars will be adapted to the southern part of the state and will be particularly suited to the Imperial Valley and desert production regions. For this project, our objectives are: 1. Plant selection nurseries at DREC and Davis under subsurface drip irrigation, 2. Evaluate additional germplasm for productivity and persistence under subsurface drip irrigation and in saline conditions. C. PROCEDURES Objective 1: Source germplasm: (a) In 2015, we selected desirable plants from selection nurseries that Dr. Teuber had planted at DREC and Davis, and we developed two populations. We are increasing seed of these populations this summer. (b) We will be selecting desirable plants from a large germplasm evaluation at DREC and Davis in April 2016 (Objective 4 last year). We will intercross these plants from both locations in one polycross during the summer 2016 in the greenhouse or in a bee cage outside. (c) Elite UC Davis germplasm, including two recent experimentals from Dr. Teuber s program as well as five UC germplasms previously selected for blue alfalfa aphid resistance, stem nematode resistance, and/or salinity tolerance. This represents ten populations for inclusion in the breeding nursery. Experiment: We will transplant spaced plants into selection nurseries at both DREC and Davis in autumn The plot areas will be set up with subsurface drip irrigation and will not be bedded. At each location, we will plant two nurseries, one which will be fully watered throughout the year and one for which water will be terminated on July 1. The date of termination may change depending on results Dan Putnam obtains in his on-going deficit irrigation trials that are planted at both locations. In each nursery, we will plant ~250 plants from each population, or ~5000 at each location. Plants will be spaced 1 apart within rows, with rows spaced 2.5 apart. A subsurface drip line will be placed in the middle of each pair of rows. Data to be collected: We will visually score plant vigor, record insect prevalence or absence, incidence of disease, and autumn plant height on each plant. We will plant to select ~5% of the population after two years in the field, although depending on mortality, we could select sooner than that. Selection will be based on vigor at the time of digging, informed by scores taken previously. Future plan: The selected plants will be intercrossed to generate half-sib families to be grown in multi-location yield trials. Our goal will be to generate two sets of selected populations those selected from fully watered nurseries and those from deficit irrigated nurseries. These populations can be compared in subsequent years to determine if selection under deficit irrigation is necessary to develop the best cultivars for those 2

3 conditions. All populations will be potential new cultivars. The populations developed in this objective represent the core breeding program. Objective 2: Source germplasm: In 2015, we planted 200 (putatively) non-dormant germplasm accessions from the National Plant Germplasm System to synthesize populations for long-term improvement. Some of these accessions were actually quite dormant and many accessions died due to disease or other issues. We identified several accessions that were excellent, and we have selected plants to form a new population (see Objective 1). We plan to screen another ~200 accessions that derive from regions geographically close to the best accessions in the initial set in order to develop additional new breeding populations. Experiment: We will transplant these 200 accessions together with the populations included in Objective 1 at DREC and at the Westside Field Station in autumn We will include the fall dormancy standard check cultivars in the trial for reference. Each entry will be replicated twice in an alpha-lattice design. Ten seedlings will constitute a plot, so that each accession will be represented by 40 plants across the two locations. At DREC, we will plant trials as specified in Objective 1, using SDI. In 2017, we will fully irrigate the plots. In 2018, we will stop watering on July 1, and allow plots to dry out so that we can assess survival under deficits. At Westside, plots will be planted as part of Dan Putnam s salinity trials. These plots will be established using non-saline water, but as soon as transplants are fully established, we will irrigate with saline water with an EC value of ~8.5. The comparison in survival between DREC and Westside will enable us to identify accessions well suited to desert systems. We will select vigorous plants under both conditions. Data to be collected: We will collect data on fall dormancy (height in autumn), winter activity (vigor in January), spring regrowth, recovery after harvest, disease presence, and insect damage. Data will be analyzed by standard analysis of variance procedures, and a scientific publication describing the germplasm evaluation will be written. Future plans: We will select desirable plants from these nurseries at the end of the experiment and also return to the best germplasm (and geographic regions) to plant additional nurseries for further selection. D. JUSTIFICATION Alfalfa is an economically important crop in California, adapted to conditions throughout the state. As with other crops, alfalfa faces production constraints due to limited water, increasing salinity, evolving disease and pest problems, and a general lack of yield improvement over the past decade or more. While private alfalfa breeding companies offer numerous cultivars for production throughout the state, publicly available cultivars provide alternatives to alfalfa hay and seed producers and at least anecdotally, some growers would welcome new public alfalfa cultivars. Further, the UC Davis breeding program can develop germplasm useful for commercial breeding programs. 3

4 Over the past year, I have thought a lot about the direction I wanted to take the breeding program what selection environment to use, what traits to target, and what germplasm to evaluate. One of the experiments I proposed to plant in fall 2015 was an evaluation of older UC germplasm. That collection both at Davis and in DREC includes literally hundreds of experimentals, some with known traits or pedigrees and others with no information. As I thought about evaluating that material, I came to the conclusion that I had not fully thought through the first two elements of that list namely, under what conditions I wanted to evaluate the material and what traits to prioritize. (Ironically, in my PLS222 Advanced Plant Breeding class, my first day lecture is about setting goals and priorities and suggesting to the students that planting germplasm without those clear objectives in hand is not a good use of time or resources.) Consequently, I held off planting that trial last fall. The traits of most importance remain high yield, high nutritive value, and persistence. However, the question is really defining the production environment under which those traits need to be expressed. As I ve thought about the likely production scenarios in the future during the past year, two developments seem increasingly clear. We will have less water and salinity problems will increase. Thus, production and survival under these conditions is the environment we need to target, and our traditional selection environments that I had initially planned to use for a germplasm evaluation do not reflect this reality. Irrigation water is likely to become more limited, and consequently, production of higher yield per unit water is an imperative. However, in addition to productivity, survival of a stand under deficit irrigation is necessary. Future production environments will include an increased use of subsurface drip irrigation (SDI) and an increase in limited or no irrigation for part of the season, typically later in summer. These changes will provide a very different selection environment than current flood or furrow irrigation, particularly using fullseason water. The current and past breeding programs in California have used those methods, and therefore, moving to SDI as the irrigation method in our selection nurseries seems to be a good idea. For breeding, a uniform selection environment is essential to differentiating good from poor plants, particularly in spaced-planted nurseries of non-replicated plants. Our current use of bedded nurseries and furrow irrigation is not uniform, with water pooling in places, difficulty in cultivation, and difficulty in uniform harvest, especially if some stems lodge into the furrow. Therefore, moving to SDI will also allow us to more precisely control water applied to plots, will enable us to easily turn off water for periods of stress, will improve our ability to cultivate, and will facilitate uniform harvest. For all these reasons, I feel that setting up future trials on SDI will result in better selection results. Second, irrigation water is likely to become increasingly saline and/or the switch to SDI will result in a greater salinity problem in the rhizosphere than was seen previously with flood irrigation. Consequently, screening germplasm under saline conditions seems sensible, so that anything released from the program will at least have some salinity tolerance built into it. 4

5 Much of Dr. Teuber s breeding program in recent years had focused on whitefly resistance in the Imperial Valley. Possibly because cotton production has declined in the region, whitefly populations have not been present in the past several years. Consequently, further selection for whitefly resistance at this point does not seem to be necessary. However, other diseases and pests continue to be problematic, such as the blue alfalfa aphid and stem nematode. Whether new blue alfalfa aphid biotypes are developing is unclear, but their presence has increased in the past several years in desert locations. Resistance can be improved in existing germplasm and if a new biotype has arisen, then resistance to that biotype is needed. The research projects proposed here are all straightforward alfalfa breeding program activities that do not pose any particular problems for completion. Dr. Brummer has over 25 years of experience breeding alfalfa, and now a full production year in California; Tami Leathers has experience with alfalfa and numerous other field and vegetable crops in California; and Francisco Maciel has worked for several decades with alfalfa in the Imperial Valley. Collectively, the research team should have no problem conducting the work. Of course, weather, disease, and insect problems could arise to destroy experiments, so we will scout nurseries to avoid the latter two; not much we can do about the former. In all cases, we could replant the experiment if needed. 5

6 E. BUDGET I am requesting funds for one year in this proposal, with the understanding that the research outlined here is by necessity an on-going activity and subsequent year funding will be necessary. Expenditure Category Requested Funds General Assistance Staff Research Associate II (Tami Leathers) 30% $14,861 Benefits 7,698 Part-time Assistance (field labor) 5,000 Supplies and expenses Field and greenhouse supplies 3,000 Travel to DREC and Westside for PI and SRA II 2,000 TOTAL $32,559 Related projects While none of these projects is funded by other sources (that it, I m using start-up funding to get them going), S&W Seed Company is funding an M.S. graduate student with Dr. Brummer since Fall The student, Scott Newell, will spend part of his time collecting data for Objective 2. F. APPROVALS E. Charles Brummer, Principal Investigator Chris Van Kessel, Department Chair 6