Bibliography: leaves 223-247. / xiii, 247 p. : ill, maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Effects of water availability during grain filling is examined in wheat (Triticum aestivum L.) and barley (Hordum vulgare L.) genotypes. The study tests the accumulation of dry matter (DM) and nitrogen (N) in the grain and also their remobilization from the shoot to the grain. Water stress during grain filling was found to reduce DM and N accumulation and also to increase N concentration in both wheat and barley grain. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1996

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.

The actual evapotranspiration rate for wheat at the Campus Agriculture Center (CAC) and alfalfa at the Maricopa Agricultural Center (MAC) were measured using the Bowen ratio technique for near real-time irrigation scheduling. The Bowen ratio method underestimated evapotranspiration when compared with AZMET and Penman data. There were problems with the hygrometer and the net radiometer which might have caused this underestimation. The height-fetch ratio requirement was not met, and this may have affected the data. Irrigation scheduling programs and the technique to schedule irrigation in a near real-time were developed. Irrigation programs were not field tested because of the problem with field data. Simulated data was successfully used to demonstrate its application. It was found that irrigation could be scheduled in a near real-time with the programs provided reliable data and proper data acquisition systems are used.

Bibliography: leaves 245-271 / xiv, 271 leaves, [47] leaves of plates : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Physiology, 1985

Durum grain quality is affected by many factors, but water and nitrogen are factors that the grower can control. The purpose of this research was to determine 1) the nitrogen application rate required at pollen shed to maintain adequate grain protein levels if irrigation is excessive or deficient during grain fill and 2) if nitrogen applications during grain fill can elevate grain protein. Field research was conducted at the Maricopa Agricultural Center using the durum varieties Duraking, Minos, and Turbo. The field was treated uniformly until pollen shed when nitrogen was applied at rates of 0, 30, and 60 lbs/acre. During grain fill, the plots were irrigated based on 30, 50, or 70% moisture depletion. In a separate experiment, nitrogen fertilizer was applied at a rate of 30 lbs N/acre at pollen shed only, pollen shed and the first irrigation after pollen shed, and pollen shed and the first and second irrigation after pollen shed. Irrigation had no effect on grain protein level, although increasing nitrogen rates at pollen shed from 0 to 30 and 30 to 60 lbs N/acre increased protein by 1 percentage point. Nitrogen fertilizer application at the first irrigation after pollen shed increased grain protein content from 10.4 to 11.4% and application at the first and second irrigation after pollen shed increased grain protein content further to 11.9% averaged over varieties. Irrigation management during grain fill may not play as large a role in controlling grain protein content as was originally thought except perhaps on heavy soils, and nitrogen fertilizer application during grain fill may not be too late to increase grain protein content.

No description available.

Application of nitrogen (N) fertilizer in conjunction with the irrigation event occurring closest to the flowering stage is effective in reducing the incidence of yellowberry and boosting grain protein levels of durum wheat. However, N applications at this time normally do not increase grain yield, except perhaps on very sandy soils. A field experiment was conducted to determine the profitability of applying 35 pounds of N per acre at flowering to durum wheat to avoid dockage for poor grain quality. Two treatments consisted of a check plot with no N applied at flowering and UAN 32 water run at a rate of 35 lbs. N /acre to basin irrigated durum wheat grown on a loamy sand soil. Maximum durum wheat grain yield (6157 lbs. /acre), protein concentration (13.7 %), and corrected income per acre ($480.31) was obtained with the N fertilizer application. In fact, N fertilization at flowering on this sandy soil increased durum wheat grain yield by 255 lbs. /acre compared to the unfertilized plot.

No description available.