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A greenhouse experiment was conducted to study the effectiveness of Dwell, a nitrification inhibitor, on the efficiency of two fertilizers applied to three Arizona soils, Anthony sandy loam, Laveen loam, and Vinton loamy sand. Tomato plants Lycopersicum esculentum cultivar Row Pak were used as an index plant. These plants were grown in soil columns of 10 cm internal diameter and 50 cm in length, containing 4,500 g of soil. Two fertilizers, urea and ammonium sulfate (AS), were applied at two rates: 112 and 224 kg N/ha. The nitrification inhibitor Dwell was applied also at two rates: 0 and 1.27 kg/ha⁻¹ of active ingredient. The active ingredient in the chemical is 5- ethoxy -3- (trichloromethyl)-1, 2,4- thiadizole. Both fertilizers and Dwell were added to the soils using two methods: (1) uniform mixtures, in which the fertilizer and Dwell were mixed with the top 500 cm³ soil volume in the columns, and (2) banded fertilizers and Dwell, in which a soil paste, made by mixing 10 ml of 0.02% Dwell solution with the volume of 50 cm³ soil, was added to the required amount of the fertilizer to soil column about 7cm below the soil surface. This factorial designed experiment was arranged in a randomized complete block with three replications of each treatment. Plants were allowed to grow for 67 days after transplanting to the soil columns. At the end of the experiment, samples from two depths (0 to 18 cm and 18 5o 40 cm) were analyzed for NH₄, NO₃, and organic N. Dry matter yield and N content of plants were also determined. Results showed that Dwell was effective in improving N efficiency, as determined by yield and N content of plants, with all three soils and with both fertilizers. Higher yields were obtained when AS was used in all soils. Higher response to Dwell, but lower yields, were observed in urea treatments as compared to AS treatments. Dwell resulted in yield increase of 139 and 60% with urea in Vinton and Laveen soils, respectively, while with AS, the increases were 74 and 11%. The lowest response to Dwell occurred with the Anthony soil. Generally, higher yield was obtained when AS was thoroughly mixed and when urea was banded. Yield and N content in plants grown in these soils were in the following order: Laveen > Anthony > Vinton. Dwell was effective with both N rates, particularly with the high N rate of urea. Incubation studies showed that Dwell was effective in retarding nitrification for about 10 days. Accordingly, Dwell seems to have had no residual effect on soil nitrogen.

The influence of variable amounts of irrigation water and nitrogen fertilizer and their interaction on the development, growth, grain yield and nitrogen uptake of grain sorghum were studied under monocrop (May 21 planting) and simulated double crop (July 1 planting) in the 1985 growing season and under monocrop in the 1986 growing season. Six grain sorghum hybrids, three of which had a higher grain yielding ability and the other three with a lower grain in yielding ability, were used in this study conducted at the University of Arizona, Marana Agricultural Center. All six hybrids were grown under two planting dates (May 21, July 1), two levels of irrigation water (dry, wet), and two levels of nitrogen fertilizer (0, 112 kg N/ha) in the 1985 growing season. In the 1986 growing season, two hybrids were grown under three levels of irrigation water (dry, medium, and wet) and three levels of nitrogen fertilizer (0, 84, 168 kg N/ha). Planting on May 21 (monocrop) had more days to 50% bloom, leaf area, heads number, grain yield and total dry weight than the July 1 planting (double crop). However, planting on July 1 produced a longer head exsertion (peduncle length) compared to May 21 planting. Head length, plant height, 500 seed weight, and grain volume-weight were not affected by planting date. Water stress reduced head exsertion, head length, plant height, head number, 500 seed weight, grain yield and total dry matter. However, numbers of days to 50% bloom were increased by dry treatment. Leaf area and grain volume-weight were not significantly affected by water levels. Under the conditions of this study, nitrogen fertilizer rates did not produce an effect on most of the agronomic characteristics of grain sorghum hybrids studied in this experiment. However, increased nitrogen fertilizer rates increased the uptake and nitrogen concentration in all growth stages of hybrids in the 1986 growing season.

The yield, fruiting habits, plant nitrogen uptake, dry matter production, and boll and fiber properties were studied in relation to nitrogen fertilizer and water application rate interactions in trickle-irrigated cotton. Nitrogen applications did not significantly increase yields because of high initial soil nitrogen and nitrogen added with the irrigation water. Significant yield differences did exist between the 60% consumption use (CU) irrigation level and the 90% and 120% CU irrigation levels. The 60% CU level resulted in appreciable plant water stress and appreciably lower yields. Nitrogen additions significantly increased seasonal plant petiole NO₃-N values as well as the number of flowers produced during the growing season. Increased water application rate lengthened the periods of peak flowering and peak boll production but had no effect on petiole NO₃-N. Increased water application rate did not significantly increase boll production, but an increasing trend of increased boll production with increasing water application rates was evident. Nitrogen applications did not significantly increase boll production, but percent boll set for the control treatment was higher. Both nitrogen additions and increased water application rates increased plant nitrogen uptake, which ranged from 163 kg N/ha to 242 kg N/ha for the water levels and 188 kg N/ha to 220 kg N/ha for the nitrogen treatments. Increased water application rates significantly increased dry matter production during the growing season. Nitrogen and water application rates affected only a few boll and fiber properties. Average boll size was increased significantly with increasing water application rates. This partially accounted for the higher yield observed at the higher irrigation levels.

Nitric oxide (NO) has been shown to both suppress and promote tumor growth, depending in part on concentration. Exogenous delivery of NO may lead to tumor suppression. Recent studies have proposed ruthenium nitrosyl complexes as catalytic donors of NO in reductive environments. Catalytic donation can provide a long-term, elevated NO flux compared to single use donors. Site-specific delivery is desirable to reduce systemic side effects, such as lowering of blood pressure. Three new ruthenium nitrosyl complexes were synthesized to impart site-specificity through amide coupling to polymers, silica nanoparticles, iron oxide nanoparticles and antibodies. The catalytic activity of new and existing compounds was then assessed. However, upon one-electron reduction of ruthenium nitrosyl complexes, insignificant amounts of NO were detected, suggesting an alternative mechanism than that proposed in prior reports. The mechanism of [Ru(EDTA)NO]²⁻ decay was more thoroughly analyzed. Spectrophotometric decay of [Ru(EDTA)NO]²⁻ indicates that one or multiple nitrogen oxide species are released. Previous studies have suggested a disproportionation mechanism leading to the generation of more highly reduced species such as N₂ and NH₄⁺. Experiments were designed to analyze possible decomposition products such as [Ru(EDTA)NO]⁻ and [Ru(EDTA)H₂O]²⁻. A disproportionation mechanism was determined likely. Decomposition of [Ru(EDTA)NO]²⁻ was also observable following reductive nitrosylation of [Ru(EDTA)H₂O]⁻ in the presence of HNO. The decomposition product, [Ru(EDTA)H₂O]²⁻, was observed through the binding of pyrazine (pz) or dipyridine (bipy) and formation of [Ru(EDTA)pz]²⁻ or [Ru(EDTA)bipy]³⁻. Formation of [Ru(EDTA)bipy]³⁻ or [Ru(EDTA)pz]²⁻ via reductive nitrosylation of [Ru(EDTA)H₂O]⁻ also provides an indirect method of HNO detection that is selective from NO.

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One low salt tolerant alfalfa (Medicago sativa L.) cultivar and two germination salt tolerant alfalfa selections were compared for growth and N fixation at four salinity levels (0, -0.3, -0.6 and -1.2 Mpa). In the first experiment a Hoagland's solution at 5 ppm-N was used; in the second experiment the solution had a 1 ppm-N concentration and supplemental light was used. No significant differences were found among the cultivars. This provides additional support that germination salt tolerance is not necessarily related to salt tolerance for growth. Nitrogen fixed to the first harvest was 61, 48, 49, and 27% of the total shoot N for plants in the control, -0.3, -0.6, and -1.2 Mpa solutions, respectively. At the second harvest, N fixation percentages were 94, 89, 80, and 57% for the corresponding salinity levels which showed significant reduction in N fixation at -0.3 Mpa. The evaluation of N fixation was by 15N techniques.

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