Daniel H. Putnam

Some compositional properties of camelina (camelina sativa L. Crantz) seeds and oils

Fatty acid profiles (FAP), tocopherol (T), and tocotrienol (T3) contents, total lipid contents, and trypsin inhibitor activity were quantitated from thirteen accessions of camelina (Camelina sativa L. Crantz), a little-known oilseed. Camelina seeds of ten accessions were also assayed for ß-glucans. FAP (%) of camelina oils were: oleic (14.1 to 19.5), linoleic (18.8 to 24.0), linolenic (27.0 to 34.7), eicosenoic (12.0 to 14.9), erucic (0.0 to 4.0), all others (11.8 to 17.4). Camelina oil T and T3 contents (mg/100 g) were: αT (0.66 to 2.38), ßT (0.38 to 1.45), γT/ßt3 (4.37 to 18.68), δT (0.00 to 0.48), γT3 (0.00 to 0.79), γT3 (0.00), γT3 (0.00). Total tocols were higher in camelina than in canola, crambe, flax, soybean, and sunflower, with γT/ßT3 constituting 82% of total tocols. The oil content of camelina seeds ranged from 29.9 to 38.3%. Camelina seeds did not contain ß-glucans. Trypsin units inhibited ranged from 12 to 28 compared to 111 for raw soybean.

Some compositional properties of seeds and oils of eightAmaranthus species

Grain of 21Amaranthus accessions (eight species) was analyzed for crude fat, fatty acid profiles (FAP), and vitamin E (tocopherols and tocotrienols). Contents of (1→3), (1→4) β-glucan were determined in 12 accessions (four species), and trypsin inhibitor activity (TIA) in 20 accessions (six species). FAP and vitamin E profiles were compared to those of barley, buckwheat, corn, lupin, oat, and wheat oils. Crude fat content ranged from 5.2 to 7.7%, and of the oils examined, amaranth oil was most similar in FAP to corn and buckwheat oils. Amaranth was higher than all but wheat and lupin in tocopherol content but was virtually devoid of tocotrienols, which have been shown to have hypocholesterolemic activity. Amaranth grain did not contain (1→3), (1→4) β-glucans and was low in trypsin inhibitor activity (≤4.3 trypsin units inhibited/mg). Any hypocholesterolemic effects of dietary amaranth are apparently due to substances other than (1→3), (1→4) β-glucans or tocotrienols.

Vitamin E isomers in grain amaranths (Amaranthus spp.)

Vitamin E isomers are important antioxidants, but their variation is poorly documented in pseduocereal grains such as amaranths. Using normal-phase, high-performance liquid chromatography with fluorescence detection, seeds of thirteen amaranth (Amaranthus cruentus L.,A. hypochondriacus L.) accessions were surveyed for the composition of tocols. The most common tocols found were α-tocopherol (2.97 to 15.65 mg/kg seed) and β-tocotrienol (5.92 to 11.47 mg/kg seed) and γ-tocotrienol (0.95 to 8.69 mg/kg seed), while someA. cruentus accessions contained δ-tocotrienol (0.01 to 0.42 mg/kg seed). This is the first report of tocotrienols in amaranths.Amaranthus cruentus grain-types of Mesoamerican origin had significantly (P≤0.01) greater levels of four tocols than didA. cruentus African vegetable-types. Unlike many cereal grains, amaranths have significant amounts of both β- and γ-tocotrienols; however, β-tocopherol was not detected in any of the amaranths. Using multiple linear regressions, α-tocopherol variation of both species and types was consistently explained by variation in tocols other than α-tocopherol. On the whole, fresh amaranth samples of both species tended to have higher levels of tocotrienols than samples stored for two years. Storage effects on amaranth tocol composition are suspected.

Simulating switchgrass biomass production across ecoregions using the DAYCENT model

The production potential of switchgrass (Panicum virgatum L.) has not been estimated in a Mediterranean climate on a regional basis and its economic and environmental contribution as a biofuel crop remains unknown. The objectives of the study were to calibrate and validate a biogeochemical model, DAYCENT, and to predict the biomass yield potential of switchgrass across the Central Valley of California. Six common cultivars were calibrated using published data across the US and validated with data generated from four field trials in California (2007–2009). After calibration, the modeled range of yields across the cultivars and various management practices in the US (excluding California) was 2.4–41.2 Mg ha−1 yr−1, generally compatible with the observed yield range of 1.3–33.7 Mg ha−1 yr−1. Overall, the model was successfully validated in California; the model explained 66–90% of observed yield variation in 2007–2009. The range of modeled yields was 2.0–41.4 Mg ha−1 yr−1, which corresponded to the observed range of 1.3–41.1 Mg ha−1 yr−1. The response to N fertilizer and harvest frequency on yields were also reasonably validated. The model estimated that Alamo (21–23 Mg ha−1 yr−1) and Kanlow (22–24 Mg ha−1 yr−1) had greatest yield potential during the years after establishment. The effects of soil texture on modeled yields tended to be consistent for all cultivars, but there were distinct climatic (e.g., annual mean maximum temperature) controls among the cultivars. Our modeled results suggest that early stand maintenance of irrigated switchgrass is strongly dependent on available soil N; estimated yields increased by 1.6–5.5 Mg ha−1 yr−1 when residual soil mineral N was sufficient for optimal re‐growth. Therefore, management options of switchgrass for regional biomass production should be ecotype‐specific and ensure available soil N maintenance.

Productivity, 15N dynamics and water use efficiency in low‐ and high‐input switchgrass systems

Sustainable and environmentally benign switchgrass production systems need to be developed for switchgrass to become a large‐scale dedicated energy crop. An experiment was conducted in California from 2009 to 2011 to determine the sustainability of low‐ and high‐input irrigated switchgrass systems as a function of yield, irrigation requirement, crop N removal, N translocation from aboveground (AG) to belowground (BG) biomass during senescence, and fertilizer 15N recovery (FNR) in the AG and BG biomass (0–300 cm), and soil (0–300 cm). The low‐input system consisted of a single‐harvest (mid‐fall) irrigated until flowering (early summer), while the high‐input system consisted of a two‐harvest system (early summer and mid‐fall) irrigated throughout the growing season. Three N fertilization rates (0, 100, and 200 kg N ha−1 yr−1) were applied as subtreatments in a single application in the spring of each year. A single pulse of 15N enriched fertilizer was applied in the first year of the study to micro‐plots within the 100 kg N ha−1 subplots. Average yields across years under optimal N rates (100 and 200 kg ha−1 yr−1 for low‐ and high‐input systems, respectively) were 20.7 and 24.8 Mg ha−1. However, the low input (372 ha mm) required 47% less irrigation than the high‐input system (705 ha mm) and achieved higher irrigation use efficiency. In addition, the low‐input system had 46% lower crop N removal, 53% higher N stored in BG biomass, and a positive N balance, presumably due to 49% of 15N translocation from AG to BG biomass during senescence. Furthermore, at the end of 3 years, the low‐input system had lower fertilizer 15N removed by harvest (26%) and higher FNR remaining in the system in BG biomass plus soil (31%) than the high‐input system (45% and 21%, respectively). Based on these findings, low‐input systems are more sustainable than high‐input systems in irrigated Mediterranean climates.

Influence of tannic acid application on alfalfa hay: in vitro rumen fermentation, serum metabolites and nitrogen balance in sheep

Alfalfa protein is poorly utilised by ruminants due to its rapid degradation in rumen. The objective of the study was to assess the influence of spraying tannic acid (TA) on chopped alfalfa hay on in vitro rumen fermentation and nitrogen (N) retention by sheep. Alfalfa hay with and without TA was fed to sheep to determine nutrient digestibility and N balance. TA was sprayed on chopped alfalfa at three concentrations to determine its effect on in vitro fermentation of dry matter (DM) and N balance in sheep. Final TA concentrations were 0, 30, 60 and 90 g TA per kg DM. The control was sprayed with the same amount of water but without TA. In vitro DM degradation and the production of gas, ammonium-N (NH4-N) and short-chain fatty acid (SCFA) were measured. TA-sprayed alfalfa and the control were fed to sheep to determine nutrient digestibility and N retention. Addition of TA had no influence on the extent and rate of gas production but significantly decreased NH4-N concentration at 30 (P < 0.05), 60 and 90 (P < 0.0001) g/kg DM. Addition of polyethylene glycol (PEG) to TA-sprayed alfalfa increased NH4-N to a level comparable to non-TA-sprayed alfalfa. Spraying of alfalfa with TA significantly decreased (P < 0.05) isovalerate but did not affect the total and individual SCFA acid production. Tannic acid significantly (P < 0.05) reduced in vitro true degradability of DM (IVTD) after 24 h incubation at levels of 60 and 90 g TA per kg DM. Neutral-detergent fibre digestibility (dNDF) after 24 h (P < 0.01), 60 and 90 (P < 0.0001) g TA per kg DM. The effect of TA on either IVTD or dNDF was not significant (P > 0.05) after 48 h of incubation. There was a strong linear relationship between percentage increase in gas production due to PEG and protein precipitation capacity (R2 = 0.94). N digestibility was significantly reduced with all three levels of TA additions. However, the proportion of urine-N to total N output was reduced by adding 60 g (P < 0.05) and 90 g (P < 0.01) TA per kg DM. Serum metabolites and liver enzymes were not affected by TA (P > 0.05). Higher faecal N as the TA level increased indicates incomplete dissociation of tannin-protein complexes post ruminally. Factors affecting dissociation of tannin-protein complexes need further study.

Protein accumulation and rumen stability of wheat γ-gliadin fusion proteins in tobacco and alfalfa

The nutritional value of various crops can be improved by engineering plants to produce high levels of proteins. For example, because methionine deficiency limits the protein quality of Medicago Sativa (alfalfa) forage, producing alfalfa plants that accumulate high levels of a methionine-rich protein could increase the nutritional value of that crop. We used three strategies in designing methionine-rich recombinant proteins that could accumulate to high levels in plants and thereby serve as candidates for improving the protein quality of alfalfa forage. In tobacco, two fusion proteins, γ-gliadin-δ-zein and γ-δ-zein, as well as δ-zein co-expressed with β-zein, all formed protein bodies. However, the γ-gliadin-δ-zein fusion protein accumulated to the highest level, representing up to 1.5% of total soluble protein (TSP) in one transformant. In alfalfa, γ-gliadin-δ-zein accumulated to 0.2% of TSP, and in an in vitro rumen digestion assay, γ-gliadin-δ-zein was more resistant to microbial degradation than Rubisco. Additionally, although it did not form protein bodies, a γ-gliadin-GFP fusion protein accumulated to much higher levels, 7% of TSP, than a recombinant protein comprised of an ER localization signal fused to GFP in tobacco. Based on our results, we conclude that γ-gliadin-δ-zein is a potential candidate protein to use for enhancing methionine levels in plants and for improving rumen stability of forage protein. γ-gliadin fusion proteins may provide a general platform for increasing the accumulation of recombinant proteins in transgenic plants.

Estimating Evapotranspiration of Fully-and Deficit-irrigated Alfalfa in Commercial Fields with the Eddy Covariance and Surface Renewal Methods

Evapotranspiration (ET) of fully irrigated and deficit irrigated (no irrigation in July, August, and September) was measured in four commercial alfalfa fields with the eddy covariance (EC) and surface renewal (SR) energy balance methods. Both EC and SR methods were used in the fully irrigated part of the fields, while the SR method only was used in the deficit irrigated part. Deficit irrigation reduced ET, but the amount of reduction was highly site specific. Good agreement was found between the EC and SR methods. However, patterns of the daily differences between the EC and SR methods differed between the four fields.

The impact of lignin downregulation on alfalfa yield, chemical composition, and in vitro gas production: The impact of lignin downregulation on alfalfa yield, chemical composition

BACKGROUND Lignin is a complex, phenolic polymer found in plant cell walls that is essential for mechanical support, water and mineral transport, and defense in vascular plants. Over ten different enzymes play a role in the synthesis of lignin in plants. Suppression of any one enzyme or combinations of these enzymes may change the concentration and composition of lignin in the genetically transformed plants. Two lines of alfalfa that were downregulated for caffeoyl coenzyme A O-methyltransferase were used to assess the impact of lignin downregulation on chemical composition and fermentation rate and extent using an in vitro gas production technique. A total of 64 samples consisting of two reduced lignin (RL) and two controls (CL), four field replicates, two cutting intervals (CIs; 28 and 35 days), and two cuts (Cut-1 and Cut-3) were used. RESULTS No differences were detected in yield, crude protein, neutral detergent fiber (aNDF), and acid detergent fiber between the lines when harvested at the 28-day CI. The acid detergent lignin (ADL) concentration in RL alfalfa lines was significantly (P < 0.001) lower than in the CL. In alfalfa harvested at the 35-day CI, the RL alfalfa resulted in lower (P < 0.001) yield than CL. RL alfalfa lines had 24% and 22% lower (P < 0.001) ADL in Cut-1 and Cut-3 respectively than CL lines. The in vitro dry matter digestibility and aNDF digestibility (both as determined by the near-infrared reflectance method) were greater (P < 0.001) in RL than in CL lines harvested at the 35-day CI. In alfalfa harvested at the 35-day CI, extent of in vitro gas production and metabolizable energy content were greater in RL than in CL alfalfa. RL lines had 3.8% indigestible aNDF per unit ADL, whereas CL had 3.4% (P < 0.01). The positive effect of lignin downregulation was more pronounced when intervals between harvests were longer (35-day CI compared with the 28-day CI). CONCLUSION Lignin downregulation in alfalfa offers an opportunity to extend harvesting time (CI) for higher yield without compromising the nutritional quality of the alfalfa forage for dairy and livestock feeding. However, the in vitro results reported here warrant further study using in vivo methods.

Mid-Summer Deficit Irrigation of Alfalfa as a Strategy for Saving Water

Alfalfa is California’s single largest agricultural water user due to its large acreage and long growing season, using 4 to 5.5 million acre feet of water each year. Because of this water use, the California Department of Water Resources is interested in deficit irrigation of alfalfa for providing water for transfer elsewhere. One strategy is to terminate irrigation during July and August when alfalfa yields are relatively small and use the “saved” water for nonagricultural uses. The amount of transferable water would be the difference in the evapotranspiration (ETc) of a fully-irrigated field and that of a deficit-irrigated field; however, no information exists on the potential ETc differences. Evapotranspiration was determined in a commercial field using the eddy covariance and surface renewal energy balance methods in a fully irrigated part of the field, and the surface renewal method in the deficit irrigated part of the field. In addition, alfalfa yield, applied water, canopy coverage and plant height measurements were made in both parts of the field. Deficit irrigation greatly reduce alfalfa yield in 2003, 2004, and 2005. Yield reductions due to deficit irrigation generally ranged from 41 to 88% of the fullyirrigated treatments. Cumulative ETc in 2005 was 48.1 inches for the fullyirrigated treatment. Deficit irrigation (no irrigation) started on July 25. Cumulative ETc between July 25 and December 6 (end of measurement period) was 20.8 inches for the fully irrigated treatment and 11.4 inches for the deficit irrigated treatment for a difference of 9.4 inches. INTRODUCTION Water transfers from the water-rich agricultural areas of northern California are ______________________ 1 Extension Irrigation and Drainage Specialist, Dept. of Land, Air and Water Resources, University of California, Davis, CA; brhanson@ucdavis.edu 2 Extension Forage Specialist, Dept. of Plant and Environmental Sciences, University of California. Davis, CA; dhputnam@ucdavis.edu. 3 Extension Biometeorology Specialist, Dept. of Land, Air and Water Resources, University of California, Davis, CA; rlsnyder@ucdavis.edu