Variety mixtures may lessen competition among plants and reduce effects of stress particularly in environments where resources are limiting. Mixtures of four barley varieties were grown under low input conditions at the Maricopa Agricultural Center. The barley varieties seeded were Barcott, Solum, Solar, and an experimental low input line designated Entry 9. The highest yields were not obtained with mixtures in this experiment, but rather when the varieties were grown alone. Barcott and Entry 9 decreased yield when part of the mixture more than Solum or Solar. When Solum was grown in a mixture rather than alone, test weight and lodging were improved, but yield was decreased.

CSM-Cropsim-CERES -Wheat is a crop growth model that predicts crop development stages, among other things, using genetic coefficients for vernalization and photoperiod. We used this model to predict flowering date for 12 durum varieties seeded in trials at Maricopa and Yuma from 1998 to 2006. The difference between simulated and measured flowering date averaged 4 days without genetic coefficients and improved to 3.5 days if genetic coefficients for flowering and vernalization were included for each variety.

Crop coefficients are used to estimate water use from reference evapotranspiration values provided by weather stations. Two varieties of barley and durum were planted at the Maricopa Agricultural Center in late November and early January. Water use was estimated from neutron probe readings and crop coefficients were calculated by dividing water use by reference evapotranspiration. The crop coefficients calculated in this study peaked close to 1.2, similar to published values, except for the short season barley cultivar Barcott which had much lower values than the other cultivars.

Crop coefficients are used to estimate water use from reference evapotranspiration values provided by weather stations. Two varieties of barley and durum were planted at the Maricopa Agricultural Center in late November and early January. Water use was estimated from neutron probe readings and crop coefficients were calculated by dividing water use by reference evapotranspiration. The crop coefficients calculated in this study peaked at 1.0 or less in contrast to published values which generally peak around 1.2. The crop coefficients were lower at the later planting, and there appear to be differences between barley and durum and among barley varieties.

Crop coefficients are used to estimate water use from reference evapotranspiration values provided by weather stations. Four varieties of barley and durum were planted at the Maricopa Agricultural Center early December and early January and one durum variety was planted at the Yuma Valley Agricultural Center in late December and mid-February. Water use was estimated from neutron probe readings and crop coefficients were calculated by dividing water use by reference evapotranspiration. The crop coefficients calculated in this study peaked from 1.0 to 1.3, and the peak averaged about 1.16. Some differences were detected among planting dates and varieties, but it has yet to be determined if these differences are of practical significance.

Durum growers were surveyed in cooperation with the USDA’s National Agricultural Statistics Service to determine production practices and their effects on yield and protein in the 2004 growing season. The survey was conducted in two regions: West (Yuma and La Paz counties) and Central (Maricopa, Pinal, and Pima counties). These two regions represent about 96% of the durum acreage. We obtained responses from 91 out of an estimated 195 durum growers (47%) representing about 38,000 out of 95,500 acres (40%). Durum was grown following cotton (48%), vegetables (43%), or other crops. The predominant soil texture was a sandy loam (36%), followed by clay loam (26%) and sandy clay loam (26%). Herbicide was applied on 67% of the acreage. The major varieties were Kronos (20%), WestBred 881 (18%), Kofa (14%), and Duraking (11%). Border flood irrigation accounted for 77% of the acreage, followed by furrow (11%), and level basin (10%). The crop was typically irrigated 6 to 7 times. The average planting date (irrigation applied) was December 19 in the Central region and January 7 in the West region. The seed was planted at an average rate of 163 lbs/acre. Phosphorus was applied to only a third of the acreage, but when it was applied, the rate averaged 67 lbs P2O5/acre. Nitrogen rate averaged 210 lbs N/acre. Grain yield tended to be higher following crops other than cotton grown on clay loam to sandy clay loam soils. Increased yield was associated with early planting, certain varieties, high N rate, and irrigation frequency. Higher protein content was associated with previous crops other than cotton, border irrigation, early planting, and N rate. This survey documents associations, not cause-and-effect relationships, among durum production practices, yield, and protein.

This work represents the first year of a 3-year testing program to identify low input wheat and barley entries with higher test weight and less lodging than Solum barley. Twenty lines each of barley and wheat were grown at the Maricopa Agricultural Center with one, two, or seven irrigations. Several barley entries yielded similar to Solum but had much higher test weight and less lodging. None of the wheat entries were as productive as Solum with one or two irrigations this year, but several exhibited good yield potential and lodging resistance with seven irrigations.

Small grain varieties are evaluated each year by University of Arizona personnel. The purpose of these tests is to characterize varieties in terms of yield and other attributes. Variety performance varies greatly from year to year and several site-years are necessary to adequately characterize the yield potential of a variety. A summary of small grain variety trials conducted by the University of Arizona can be found online at http://ag.arizona.edu/pubs/crops/az1265.pdf.

Durum growers were surveyed in cooperation with the USDA’s National Agricultural Statistics Service to determine production practices and their effects on yield and protein in the 2005 growing season. The survey was conducted in two regions: West (Yuma and La Paz counties) and Central (Maricopa, Pinal, and Pima counties). These two regions represent about 95% of the durum acreage. We obtained responses from 97 out of an estimated 195 durum growers (50%) representing 42,920 out of 75,400 acres (57%). Durum was grown following cotton (38%), lettuce (24%), vegetables (21%), or other crops. The predominant soil texture was a sandy loam (42%), followed by sandy clay loam (31%) and clay loam (21%). Herbicide was applied on 57% of the acreage. The major varieties were Kronos (21%), Alamo (16%), and Orita (16%). Level basin irrigation accounted for 52% of the acreage, followed by border flood (36%), and furrow (12%). The crop was typically irrigated 6 to 7 times. The average planting date (irrigation applied) was December 28 in the Central region and January 14 in the West region. The seed was planted at an average rate of 167 lbs/acre. Phosphorus was applied to only a third of the acreage, but when it was applied, the rate averaged 71 lbs P2O5/acre. Nitrogen rate averaged 213 lbs N/acre. Increased yield was associated with previous crops other than cotton, certain varieties, level basin irrigation, early planting in the Central region, a seeding rate between 140 and 160 lbs N per acre, N rate between 100 and 200 lbs N per acre, and an irrigation number of less than six in the West and seven in the Central Region. Grain protein was associated with varieties. This survey documents associations, not cause-and-effect relationships, among durum production practices, yield, and protein.

Lower stem nitrate concentration is used as a guide for fertilization of small grains in Arizona. The objective of this study is to determine if the timing of stem sampling has an appreciable effect on stem nitrate and corresponding fertilizer recommendations. Durum and barley were grown at the Maricopa Agricultural Center and lower stems were analyzed for nitrate from 3-leaf to maturity. Stem nitrate concentration varied considerably between the 3-leaf and preboot stages, but thereafter was relatively constant and low (averaged 736 ppm). In this study, the timing of the stem sampling could have affected fertilizer recommendations before the pre-boot stage, but afterwards fluctuations in stem nitrate would have resulted in relatively minor differences in fertilizer recommendations.