Sulfur affects root growth and improves nitrogen recovery and internal efficiency in wheat

Wheat plants were cultivated in pots with the objective of evaluating the effect of two sulfur (S) rates (+S and ?S) on (i) shoot growth, S and nitrogen (N) uptake and nitrogen use efficiency (NUE) and (ii) root growth and architecture and its relations with S and N uptake. Plant samplings were at Z39, Z51 and Z92 stages. Shoot mass and NUE were greater in +S treatment at the three stages. ?S treatment increased root growth at Z39 (14% more length and 16% more tips) in comparison with +S, but the opposite occurred at Z51 (31% less area and 42% less mass). S uptake per unit root mass, area and length were greater in +S treatment at Z39 and Z51. A similar pattern was determined for nitrogen uptake (Nu) at Z39, but the opposite occurred at Z51. This indicates that Nu is mainly controlled by shoot growth and not by root growth.     

Growth and ion accumulation responses of four grass species to salinity

Ion inclusion or ion exclusion are the two main strategies developed by plants to tolerate saline environments. Shoot sodium (Na⁺), potassium (K⁺), and calcium (Ca²⁺) in four perennial grass species (tall wheatgrass, Nuttall's alkaligrass, creeping foxtail, and switchgrass) treated with nutrient solution salinity levels ranging from 2 to 32 dS m^?1 were measured. As the nutrient solution salinity was increased from 2 to 10 dS m^?1, tall wheatgrass, creeping foxtail and Nuttall's alkali grass had increased shoot Na⁺ and decreased Ca²⁺ concentration while maintaining growth suggesting that these species tolerated these changes in shoot ion concentration. In contrast, switchgrass excluded Na⁺ from the shoot and maintained K⁺ and Ca²⁺ concentrations but suffered dramatic shoot dry weight reduction. Thus, the Na⁺ exclusion mechanisms present in switchgrass were less efficient in maintaining growth under the 10 dS m^?1 nutrient solution treatment than the Na⁺ inclusion mechanisms used by the other three species.     

Mineral‐nutrient synergism and dilution responses to nitrogen fertilizer in field‐grown maize

Nitrogen (N)‐fertilizer applications to field‐grown maize may result in a dilution response whereby essential mineral‐element concentrations in shoots would decrease as shoot‐dry‐matter accumulation increased. To investigate this, the effect of N‐fertilizer treatments (no N or fertilizer rate based upon 5.3 or 8.5 t ha^–1 yield goal) on maize (Zea mays L.) shoot dry weight and shoot mineral concentrations (N, P, K, S, Mg, Ca, and Mn) at the sixth leaf (V6), twelfth leaf (V12), and tassel (VT) development stages were investigated in a 2‐year study conducted at Brookings, South Dakota (USA). With increasing N‐fertilizer application rates, shoot dry weight was greater and shoot P and K concentrations decreased. A possible explanation of this dilution response is that planting‐time P and K fertilizers, which were applied in a band near the seed furrow, may have enhanced the uptake of P and K in a manner that was independent of N‐fertilizer treatments. Increased shoot‐dry‐weight production due to the application of N fertilizers, if P and K uptake were similar across N‐fertilizer treatments, would lead to decreased shoot P and K concentrations in N‐sufficient compared with N‐deficient plants. Conversely, N‐fertilizer‐induced increases in shoot dry weight were accompanied by increased shoot concentrations of N, Ca, and Mn. This synergistic response between dry‐weight accumulation and shoot N concentration was present at all leaf developmental stages studied, while that for Ca was present only at VT. Thus, N fertilizer applications that increase shoot dry weight can affect the dilution and synergistic responses of specific mineral nutrients in maize shoots. Crop developmental stage as well as the location of these specific mineral nutrients in the soil profile might play important roles in mediating these responses.     

Biochemical characterization of amandin,the major storage protein in almond (Prunus dulcis L.)

The almond major storage protein, amandin, was prepared by column chromatography (amandin-1), cryoprecipitation (amandin-2), and isoelectric precipitation (amandin-3) methods. Amandin is a legumin type protein characterized by a sedimentation value of 14S. Amandin is composed of two major types of polypeptides with estimated molecular weights of 42-46 and 20-22 kDa linked via disulfide bonds. Several additional minor polypeptides were also present in amandin. Amandin is a storage protein with an estimated molecular weight of 427,300 +/- 47,600 Da (n = 7) and a Stokes radius of 65.88 +/- 3.21 A (n = 7). Amandin is not a glycoprotein. Amandin-1, amandin-2, and amandin-3 are antigenically related and have similar biochemical properties. Amandin-3 is more negatively charged than either amandin-1 or amandin-2. Methionine is the first essential limiting amino acid in amandin followed by lysine and threonine.     

Grain yield increases in wheat and barley to nitrogen applied after transient waterlogging in the high rainfall cropping zone of western Australia

Nitrogen (N) is a major factor limiting grain production in the high rainfall zone (HRZ, 450–700 mm annual average rainfall of southwestern Australia (SWA). Transient waterlogging and leaching of applied N fertilizer are hazards faced in most years by crop producers. The major crops are wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), canola (Brassica napus L.) and lupin (Lupinus angustifiolius L.) grown in rotation. Two series of experiments involving, levels and timing of N fertilizer application and levels of plant population were done. The first series, in 2003–2004, consisted of 3 experiments in 3 growing seasons (early May to late-October) to measure the grain yield (GY) increase (response) of wheat and barley to various methods of N fertilizer application (methods of split N application were compared to N applied at sowing). The aim of the experiments was to determine the optimal N fertilizer application strategy for maximum GY and quality in situations where transient waterlogging was a frequent occurrence. The second series of four experiments, from 2007–2009, measured the GY of wheat sown at three levels of plant population to 4 levels of N applied after transient waterlogging (taken to be rainfall events in which >25 mm of rain was recorded in 24 to 48 hours).

Applying the N fertilizer after high rainfall and transient waterlogging (tactical N application) increased GY and protein percentage of grain compared to applying all of the N fertilizer at sowing. Where transient waterlogging was not frequent, applying the N after waterlogging was not always better than applying part of the N according to growth stage of the crop or according to fixed times after sowing. When the crop was water-logged three or more times, N uptake by the crop at anthesis and apparent fertilizer N recovery in the crop was substantially increased by applying the N after waterlogging compared to applying the entire N at sowing. This study found that a tactical N management strategy for the HRZ of SWA is to apply some N at sowing with subsequent applications made after heavy rainfall that leads to transient waterlogging. Split N fertilizer applied either according to time after sowing or to growth stage of the crop was equally effective for increasing GY in situations where waterlogging was less frequent.

The observation from these experiments, that grain yield increases due to splitting the N dose were associated with increases in ear numbers, lead to a further set of experiments where plant population was increased in conjunction with N applied after waterlogging events. The combined strategy of increased plant population with strategic N application decreased the amount of N required for maximum GY where more than 3 heavy rainfall events occurred in a growing season.

One practical outcome of this research is to indicate that farmers can withhold applications of N fertilizer after sowing in seasons when transient waterlogging does not occur.     

Concentration and deposition of trace metals in Ontario-1982

Results of trace metal concentrations in air and precipitation and the corresponding wet and dry deposition in Ontario in 1982 arc reported. In terms of the spatial patterns, in general, there was a decreasing gradient from south-to-north in both concentration and deposition. Patterns differed with each parameter although certain groups of metals (e.g., Fe and Al; Pb, Zn, and Mn) displayed similar patterns. In general, wet deposition was greater than dry deposition at all sites. Geographically, the variability in the wet to dry deposition ratio for coarse particles (MMD > 2.5 μm) was small. However, it increased from the south to the north for fine particles (MMD < 2.5 μm), being higher away from the source areas. Scavenging ratios (W) have been derived from the precipitation and air concentrations of trace metals. The scatter in W is quite large for all trace metals, up to 2 orders of magnitude. There was little seasonal variability in W for fine particles (Pb, Mn, Zn, and Cd). However, coarse particles (Fe, Al, and Cu) were more efficiently scavenged by snow than by rain.     

Nitrogen and phosphorus requirements of different wheat plant types under dryland and irrigated conditions 1

The wheat (Triticum aestivum L.) plant type in major producing areas of the U.S. is changing rapidly from tall cultivars to high‐yielding semidwarf cultivars. Objectives of experiments were to determine if nitrogen and phosphorus nutritional requirements differ between traditional tall cultivars and modern semidwarf cultivars under dryland and irrigated conditions. ‘Larned’, a tall cultivar; ‘Newton’, a semidwarf cultivar; and ‘Plainsman V, a high‐protein semidwarf cultivar, were grown with all combinations of three nitrogen fertilizer levels (0, 84, and 168 kg N/ha) and two phosphorus fertilizer levels (0 and 90 kg P₂O₅/ha) at Colby, Kansas for two years. Three levels of irrigation—dryland, limited irrigation, and full irrigation—were applied. Grain yields were highest with 84 kg N/ha under dryland and with 168 kg N/ha under irrigation. Phosphorus increased grain yield under dryland conditions one year, but had no effect under irrigated conditions. Cultivar X nutrition interactions from differential yield responses to fertility levels occurred under the dryland and limited irrigation regimes one year. Grain protein content was increased by nitrogen fertilization under all regimes both years and was decreased only by phosphorus fertilization under dryland conditions one year. Cultivar X nitrogen interactions for grain protein occurred under all irrigation regimes. We concluded that nutrient requirements do not differ between tall and semi dwarf wheat culti‐vars under any irrigation regime. Raising the recommended level of nutrients, particularly nitrogen, should be considered for all cultivars, both tall and semidwarf.     

Nitrogen Fixation,Ureide, and Nitrate Accumulation Responses to Soybean Aphid Injury in Glycine max

There is little information available about soybean aphid (Aphis glycines Matsumura) effects on the physiology and mineral nutrition of soybean (Glycine max [L.] merr.). Controlled-environment studies were conducted to measure soybean aphid infestation effects on dry weight, nitrogen (N) fixation, ureide-N, and nitrate-N concentration and accumulation. Plants grown in perlite using –N nutrient solution culture were infested at the 3rd trifoliolate (V3) stage and measured for N fixation, nodule characteristics, and ureide-N concentration at the full pod (R4) stage. When compared to uninfested control plants, aphid infestation reduced total nodule volume per plant by 34%, nodule leghemoglobin per plant by 31%, plant N fixation rate by 80% and shoot ureide-N concentration by 20%. Soil-grown plants were infested at the first trifoliolate (V1) stage and shoots were measured for dry weight, nitrate-N, and ureide-N at the full bloom (R2) stage. Infestation reduced shoot dry weight by 63%, increased nitrate-N concentration by 75%, but did not significantly affect ureide-N concentration. Because nutrient concentration is a single-point measurement that results from the integration of two dynamic processes, nutrient accumulation and dry matter production, we conclude that aphid-induced reductions in N fixation, coupled with decreased dry weight accumulation, caused shoot ureide-N concentration to remain unchanged in aphid-injured plants when compared to uninfested plants. Because nitrate-N concentration was greater in aphid-damaged shoot tissue, we further conclude that nitrate-N accumulation was less sensitive to aphid injury than dry weight accumulation.