J. L. Stroehlein

Effect of salt stress on dry matter production and nitrogen uptake by tomatoes.

Abstract Dry matter yield and nitrogen (total and 15N) uptake of tomato plants (Lycopersicum esculentum Mill., cv. Columbia) subjected to saline stress by NaCl were studied in a greenhouse. The treatments consisted of low (control), medium (4 bars), and high (8 bars) salinity. The saline treatments were prepared by adding NaCl to culture solutions. The plants were 80 days old at the start of the 15N treatments and each was in a pot containing 1.8 kg of quartz sand. The 15N was provided to plants by adding K15NO3 to the pots and the 15N treatment period continued for 30 days. The plants were harvested at each 5‐day interval during the 15N treatment period. Dry matter production and nitrogen (total and 15N) uptake were significantly lower for the saline treatments as compared with the control. The significant difference in the above factors (dry matter production, total‐N, and 15N content of plants) was first noted on day 15 of the 15N treatment, and this difference continued to the end of the study period....

Effects of nitrogen and phosphorus on yields and tissue analyses of chili peppers

Abstract Nitrogen applications affected plant growth characteristics, color, nutrient content of leaves and yield of chili peppers as shown by results in this two‐year study. Moderate rates of N (100–150 kg/ha) tended to produce a more desirable type of plant and highest yields. Phosphorus treatments did not affect yields under these conditions. Analysis of stem‐petiole samples for nitrate appeared to be a good indicator of the N status of the plant. A heavy fruit set in August accompanied with NO3‐N values below 8,000 to 10,000 ppm resulted in harvest time N deficiencies and lower yields.

Subsurface drip irrigation and urea phosphate fertigation for vegetables on calcareous soils

Abstract Drip irrigation lines installed at 5 cm (shallow) or 15 cm (deep) below the soil surface and furrow irrigation were compared for vegetables grown on calcareous desert soils. Urea phosphate (UP) fertilizer (17–44–0) was injected twice in the drip irrigation lines during the growing season. Yields were compared to preplant fertilized and unfertilized furrows. Fall cabbage (Brassica oleracea var. capitata L.) gave comparable yields under the different irrigation treatments with the drip treatments using half the water used by the furrow treatment. Cabbage yield increased in all fertilized treatments as compared to the unfertilized furrow. Petiole P and NO3‐N concentrations were higher from the drip than from the furrow treatments. Zucchini squash (Cucurbita pepo L.) had the highest yields under deep drip and fertilized furrow treatments, with the deep drip using half the water and P rate used by the furrow treatment. The deep drip increased squash yield by 34% over the shallow drip. The unfertilized...

Cotton response to zinc fertilizer

Abstract The purpose of this investigation was to evaluate cotton (Gossypium hirsutum L.) response to zinc (Zn) fertilization in terms of plant growth and development and yield components. Therefore, the effects of Zn fertilizer (ZnSO4) on cotton plants were investigated in both field experiments and pot trials. Application of zinc sulfate promoted nutrient (N, P, and K) uptake, utilization, and metabolism, slightly increased root and shoot growth, bloom, dry matter production, and improved cotton quality.

Net fluxes of mineral nutrients, water, and carbohydrate influenced by manganese in root and shoot of Cucumis sativus L. 1

Abstract An experiment was conducted with cucumber (Cueumis sativus L., cv. Sumter) plants in the vegetative phase of growth to determine effects of manganese deficiency (0.2 μM Mn) and toxicity (182 μM Mn) on fluxes of several mineral nutrients, water, and carbohydrate in the root and shoot, beginning 43 d after germination. Plants were sampled every three days from 34 to 58 d after germination. First and second derivatives of regression equations were used to estimate fluxes and study source/sink phenomena of dry weight (DW), fresh weight (FW), H2O, Cu, Fe, Mn, Zn, N, P, and K in root and shoot tissues. With Mn sufficiency (1.8 μM Mn), both root and shoot acted as sinks for of each of the 10 dependent variables through 58 d. In contrast, Mn deficiency caused net loss of K and N from the root beginning at 53 and 56 d, respectively, and net loss of P and Fe from the shoot beginning at 57 and 58 d, respectively. With Mn toxicity, net loss of Cu, N, and K from the root began at 46, 46, and 51 d, respectivel...

Response of grape cultivars to nitrogen and phosphorus grown with water harvesting.

Abstract Two fertilizer studies were conducted on mature vineyards established with a water harvesting system on a White House sandy loam (fine, mixed, thermic, Ustollic Haplargid) soil at the University of Arizona Oracle Agricultural Center. In one study, two grape (Vitis vinifera L.) cultivars, ‘Cabernet Sauvignon’ and ‘Sauvignon blanc’, were treated with different levels of 15N and P fertilizer and tested for tissue NO3‐N and total‐P content. In second study, eleven grape varieties were treated with three levels of N. Tissue samples were analysed for total P and NO3‐N content, and the ratio of petiole‐P to leaf blade‐P was determined. When sufficient quantities of both nutrients were provided, N and P interacted positively resulting in increased grape yields. The petiole‐P to leaf blade‐P ratio correctly monitored the P status of the vines.

Evaluation of dwell as a nitrification inhibitor and its interaction with nitrogen source and soil properties

Abstract Incubation studies were conducted to evaluate the effectiveness of Dwell (5‐ethoxy‐3‐trichloromethy 1–1–2–4‐thiadiazole), as a nitrification inhibitor of urea and ammonium sulfate (AS) in three Arizona surface soils. In the first experiment, 50 g soil samples were treated with urea to provide ? equivalent to 224 kg/ha. Half of these samples were treated with Dwell solution equivalent to 1.27 kg/ha active ingredient. These samples were incubated at 33 ± 2C and the pH was measured at intervals of 0, 1, 2, 3, 4, 6, 8 and 16 days. In the second experiment one set of 25 g soil was treated with 39 ppm ? as urea solution, and another set received an equal amount amount of ? as AS solution. Half of the urea and AS treated soils received 0.55 mL of 9.68 mg active ingredient Dwell solution which is equivalent to 1.27 kg/ha. Moisture was adjusted to 3/4 field capacity in each soil sample. The samples were incubated at a constant 30C temperature for 0, 5, 10, 15, 20 and 25 days. Total inorganic ? (NO2 ‐, NO3...

Reactions of urea phosphate in calcareous and alkaline soils: II. effects on soil sodium and salinity

Abstract Large areas of agricultural land, containing alkalinity and salinity problems, are potentially suitable for crop production with little alteration of their chemical properties. This study was conducted to determine and compare the effectiveness of urea phosphate (UP) in reducing soil salinity and alkalinity with sulfur foam (SF), phosphoric solution (PHP), and a mixture of SF and UP (Mix) on leaching soil sodium (Na) and salinity on two saline sodic soils (Pima L and Crot CL) in columns. Each of these amendments was applied at rates of one and two equivalent amounts of the exchangeable sodium (Naex). Urea phosphate was as effective as PHP or Mix treatments in reducing soil salinity and alkalinity in Pima and Crot soils. No difference was found between rates of application (1 and 2 equivalent amount of Naex) except for soil pH. The decrease in soil salinity was similar to the decrease in pH levels; both decreases followed this order: PHP, UP, Mix, SF, and control treatments. No significant differe...

Response of tomato to rates and methods of placement of urea and ammonium sulfate as affected by Dwell, a nitrification inhibitor.

Abstract The effectiveness of Dwell, a nitrification inhibitor, was tested in a greenhouse with two fertilizers and three Arizona soils. Tomato plants (Lycopersicum esculentum Mill., cv. Row Pak) were grown in ABS plastic columns 10 cm diameter and 50 cm long containing 4500 g soil. Urea and ammonium sulfate (AS) were applied at 112 and 224 kg N/ha and Dwell (5‐ethoxy‐3‐trichloromethyl‐l,2,4‐thiadiazole) was applied at rates of 0 and 1.27 kg/ha of active ingredient. Both fertilizers and Dwell were added by mixing uniformly or in a band. Dwell increased ? uptake by 41%. The highest ? uptake was with Dwell with the highest urea rate, but Dwell was effective with both fertilizers in all soils. The lowest response to Dwell was with AS‐Laveen loam treatment, whereas the highest response, but the lowest ? uptake, was with urea ‐ Vinton loamy sand treatment. Dwell did not affect the inorganic‐N contents of the soils.

Determining higher fatty acid levels in plant materials 1

Abstract The higher fatty acids (HFA) are important plant constituents that are implicated in the grass tetany hazard in livestock. A method is given whereby a technician can analyze 12 forage samples daily for HFA content. The method consists of saponifying the plant material in ethanol and KOH and extracting the subsequently acidified HFA with petroleum ether. The petroleum ether phase is evaporated and the HFA residue is dissolved in ethanol and then titrated with standardized isobutanolic KOH in the absence of O2 by using a N2 atmosphere. A standard plant sample, analyzed over a 37‐day period, had a mean of 136 mmol H+ /kg ±4.5, where a 0.1 mmol H+ / l palmitic standard was determined with an accuracy of 99 ± 1.9%.