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Context Sulfur deficiency is a limiting factor of cereal crops, causing significant crop losses associated with a decrease in the number of grains. In barley (Hordeum vulgare L.) crops, grain number (and grain yield) is associated with spike biomass at anthesis, which is related to crop growth rate during the period preceding anthesis (i.e. the ‘critical period’) when spike growth occurs. These relationships have been established for various cultivars under varying radiation intensity and in different locations, and have been confirmed in crops grown under nitrogen and phosphorus deficiencies. Aims The objective of this study was to determine, for malting barley, whether the effects of sulfur, nitrogen and their interaction on the number of grains per unit area could be explained by changes in crop growth rate or photothermal quotient (ratio of intercepted photosynthetically active radiation to temperature) during the critical period. Methods Three field experiments were conducted in the Pampean region of Argentina to evaluate the effects of sulfur fertilisation under three levels of nitrogen availability on the number of grains per unit area. Key results Changes in grain number were associated with crop growth rate or photothermal quotient during the critical period. This association was maintained when sulfur fertilisation changed grain number. Crop growth rate during the critical period varied mainly as a result of changes in accumulated intercepted radiation. Conclusions Sulfur fertilisation increases grain number and grain yield by increasing radiation interception during the critical period, probably as a consequence of increased leaf area. Implications The determination of grain number under sulfur deficiency is similar to that observed under deficiencies of other nutrients.

The objectives were to calibrate the Soil Plant Analysis Development (SPAD) and Green Seeker (GS) as tools to determine the differential of the economic optimum nitrogen rate (dEONR) at different growth stages of barley and to evaluate if a single SPAD or GS calibration model can be used for two cereal crops: barley and spring wheat. Fourteen field experiments were conducted (2016–2018) evaluating five N rates. Relative canopy indices were determined using a SPAD-502 (rSPAD) and a GS sensor (rNDVI) at Z24, Z31, and Z39 growth stages. The relationship between sensor indices and dEONR was evaluated by fitting quadratic-plateau (QP) regression models. Data from a previous study was used to evaluate if a unique QP model could predict dEONR from canopy indices for barley and wheat. Statistically significant QP models were determined for rSPAD and rNDVI at all evaluated growth stages. The sensitivity of these models was greater for rSPAD (0.0006 on average) than for rNDVI (0.0004 on average). A single QP model was developed to predict dEONR from rSPAD at Z31 and Z39 barley growth stages (R2 = 0.68). Also, a unique model was developed to predict dEONR from rSPAD at Z31 and Z39, but not only for barley but also for wheat (R2 = 0.64). A single model could be used to determine variable in-season N rates for barley and wheat, increasing the N use efficiency and limiting possible negative economic and environmental impacts of fertilization over the agroecosystems.

Fil: Prystupa, Pablo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agricolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones en Biociencias Agricolas y Ambientales; Argentina

Nutrient uptake per unit grain yield (i.e. the ratio between nutrient uptake and grain yield) is an index of the amount of nutrient available for partitioning to the grain. It can be divided into two components: grain nutrient concentration and nutrient harvest index. The aim of the present study was to analyze and compare the relationships between nutrient uptake per unit grain yield and its components for N and S in malting barley (Hordeum vulgare L.). Fifty field experiments were conducted with treatments that included farmer fertilization rate, +S, +N and + NS. Grain nutrient concentration was positively related to nutrient uptake per unit grain yield for N and S in a curvilinear fashion. However, grain N concentration tended to increase threefold while S concentration doubled as nutrient uptake per unit grain yield increased. Nutrient harvest index showed a constant phase and, after exceeding a certain threshold, a negative association with nutrient uptake per unit grain yield was observed. However, the decrease in S harvest index was far steeper than in N harvest index. Therefore, contrary to what was observed for N, grain S concentration would be hard to modify through sulfur addition, since a high proportion of the absorbed S would be partitioned to the straw.

Twenty-five single-year field experiments were established in order to assess the effects of nitrogen fertilization on grain yield, size, and protein concentration, and to explain its response to fertilization with soil, climate, and crop management variables easy to collect. While grain yield in control treatments was positively related to rainfall during the full crop cycle and negatively related to temperature during the critical period previous to heading, grain yield response to nitrogen was positively related with the product of fertilizer nitrogen rate by rainfall. Grain protein concentration response to nitrogen fertilization was positively related to fertilizer nitrogen rate and negatively related soil nitrate. It is worth noting that the effect of N fertilization on grain protein concentration was not conditioned by rainfall. We could establish that grain protein concentration was determined by the ratio between nitrogen availability (soil nitrogen-nitrate at sowing plus nitrogen added as fertilizer) and grain yield. Fil: Prystupa, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina Fil: Ferraris, G.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina Fil: Ventimiglia, Leandro Nicolas. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Loewy, T.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Bordenave; Argentina Fil: Couretot, L.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina Fil: Bergh, R.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Barrow; Argentina Fil: Gómez, Federico Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina Fil: Gutiérrez Boem, Flavio Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina

The commercial quality of malting barley is dependent on the content and composition of grain proteins which are subjected to nitrogen (N) and sulfur (S) control. In nutrient deficient soils, grain protein content is mainly a consequence of the remobilization efficiency. In order to evaluate the effect of N and S soil availability on phloem amino acid and sugar export rates and B- and C-hordein gene expression during grain filling, a factorial combination of N and S fertilization assay was carried out under field conditions. Besides, several carbon (C) and N metabolites were analyzed in leaves and spikes. We observed that, even under soil N and S availabilities that do not limit yield, N and S fertilization induced significant changes in N and C metabolism. N phloem remobilization was promoted by S fertilization independently of N fertilization and C remobilization was also promoted by S fertilization but only in N fertilized plants. The B- and C-hordein gene expression correlated positively with sugar and amino acid exudation rate, respectively. Our results suggest an important role of the export rate of sugars and amino acids in the regulation of grain prolamine expression. Fil: Veliz, Cintia Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales; Argentina Fil: Criado, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales; Argentina Fil: Roberts, Irma. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales; Argentina Fil: Echeverria, Mariela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales; Argentina Fil: Prystupa, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales; Argentina Fil: Prieto, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales; Argentina Fil: Gutiérrez Boem, Flavio Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales; Argentina Fil: Caputo Suarez, Carla Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomia. Instituto de Investigaciones En Biociencias Agrícolas y Ambientales; Argentina

Balanced nutrition is necessary to reduce yield gaps in maize. Simultaneous phosphorus (P) and sulfur (S) deficiencies may be present in soils, so a P × S interaction is expected. In maize, yield is closely related to grain number (GN); thus, nutrient deficiencies impacting crop growth during GN formation can consequently impact yields. Grain nutrient concentration may reflect soil supplying capacity, and nutrient stoichiometry in grains can be used as an indirect indicator of nutrient deficiency for a retrospective diagnosis of sites responsive to P or S fertilization. The objectives of this study were to: i) determine maize response to increasing S fertilizer rates and to P addition; ii) analyze the effects of P, S, and their interaction on mechanisms involved in yield determination of maize; and iii) evaluate the effects of P and S shortage on stoichiometric relationships among N, P, and S content in maize grains. Two fertilization experiments were conducted on-farming conditions in 19 sites-year (SY) for analyzing grain yield response to increasing S fertilizer rates (E1), and studying the interaction between P and S fertilization on grain yield and physiological attributes associated with grain yield determination (E2), i.e. CGRCP, IPARCP, RUECP and biomass at R6. Also N (%N), S (%S) and P (%P) concentration in grains were determined. Stoichiometric relationships among N, P and S in both P or S fertilized and unfertilized treatments in all SY were analyzed. Average grain yield response due to S and P addition was ca. 13 and 20%, respectively. Grain yield increased up to S fertilizer rates around 10 kg S ha−1. P addition increased CGRCP by 15–60% in 8 SY while S addition 12–16% in 2 SY. Both, RUECP and IPARCP were positively associated with biomass production. P fertilization increased IPARCP by 4%, but no S effect was observed. Before silking, P addition boosted cumulated radiation by 7%, but after silking no P or S effects were observed. A significant P × S interaction was observed for RUECP, since S fertilization increased RUECP by 14% only when P was not added. Independently of P or S shortage, grain N content scaled almost isometrically with grain S content, while N:P and P:S showed allometric relationships. Phosphorus deficiency did not modify N:S, N:P nor P:S stoichiometry. Likewise, S addition did not modify the N:P or N:S stoichiometry. A significant change in the intercept of the P:S relationship was observed in response to fertilization and may be used as a tool for identifying S responsive sites using grain nutrient analysis. Fil: Salvagiotti, Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Oliveros; Argentina Fil: Prystupa, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Cátedra de Fertilidad y Fertilizantes; Argentina Fil: Ferraris, Gustavo Nestor. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina Fil: Couretot, Lucrecia. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina Fil: Magnano, Luciana Ines. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Oliveros; Argentina Fil: Dignani, Damián. No especifica; Fil: Gutiérrez Boem, Flavio Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina

Sulfur (S) fertilization has increasingly become an important issue in crop management. In Argentina S deficiencies have been reported, but there has been no success in finding soil tests for predicting soybean response to S fertilization. The objectives of this study were to: (i) evaluate seed S and N:S ratio as a tool for identifying S deficient soybean crops in field conditions and (ii) determine shifts in stoichiometric relationships among nitrogen (N), phosphorus (P) and S in soybean seeds which can be used for identifying S responsive sites under field conditions. Seed samples from 20 field experiments designed to explore response to S fertilization in soybean were collected in a large area in the Argentinean Pampas region. Seed yield (SY) and P (%P), S (%S) and N (%N) concentration in seeds were determined. Different data analyses were tested in order to find an S deficiency index. Moderate SY responses to S fertilization were observed in the present study (i.e. relative SY was never below 75%). seed S concentration increased in response to S fertilization in most responsive sites, and N:S ratio was governed by variations in seed S concentration. Stoichiometric relationships were more accurate for identifying S responsive sites than using single variables (e.g. seed S concentration or N:S). The isometric variations among N, P and S suggest that the accumulation of these nutrients is proportional in seed tissue. A significant increase in the intercept of the stoichiometric relationship between N and S in S deficient crops was observed. An S deficient index (SDI) was calculated based on this difference that can be used as a diagnostic tool for identifying S responsive sites in soybean. The present study shows a novel approach for using stoichiometric concepts in fertilizer management in soybean. Fil: Salvagiotti, Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Oliveros; Argentina Fil: Ferraris, Gustavo Nestor. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina Fil: Quiroga, Alberto Raul. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis. Estación Experimental Agropecuaria Anguil; Argentina Fil: Barraco, Mirian Raquel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires. Estación Experimental General Villegas; Argentina Fil: Vivas, Hugo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina Fil: Prystupa, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina Fil: Echeverria, Hernan Eduardo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina Fil: Gutiérrez Boem, Flavio Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina

Improved topsoil structural quality is expected under no-till farming, but soil physical constraints can develop under continuous no-till. Our objectives were: to evaluate the properties of loam, silty loam, and silty clay loam soils under various management practices on a regional scale; to clarify the relationship between soil organic matter pools and soil physical properties; and to find a minimum set of topsoil properties to characterize trends established by tillage. Thirty-nine loam, silty loam, and silry clay loam soils were sampled from cropped fields managed using conventional tillage (CT) and no-till (NT) as well as six undisturbed soils (uncropped). The A horizon thickness did not differ among soil textural groups and was 4 cm thicker in uncropped soils. Total and particulate organic C were significantly affected by management (uncropped > CT = NT, P < 0.001). Soil structural instability of uncropped soils (0.317 mm) differed from CT soils (0.723 mm) but not from NT soils (0.573 mm). Soil structural instability was negatively related to total and particulate organic C, and no relation was found with the resistant organic C pool. Water infiltration rate was the only topsoil properry affected by a significant texture x management interaction. Lower infiltration rates in NT silry soils were caused by plary structural forms with horizontal pores. Soil penetration resistance (0-5 cm) was 0.77 MPa higher in NT than in CT soils. A minimum set of topsoil properties to evaluate tillage management includes structural instability, total or particulate organic C, infiltration rate, and penetration resistance.

Decreasing P buffer capacity of the soil surface in no-tilled soils has been attributed to enrichment of both P and OM (OM). As soil surface enrichment with P and OM usually occurs simultaneously in no-tilled soils, it is not clearly established whether the increase of soil OM affects the capacity of soils to retain P. A study was conducted to assess whether the variations in soil OM (total and particulate) at soil surface affects P retention capacity. Thirty five soils from the Rolling Pampa (17 tilled and 18 no-tilled) were selected. All soils had medium to low levels of available P (P Bray1 53 μm), particle size distribution, and pH. Tilled and no-tilled soils did not differ in soil texture, pH, total and available P content. On the contrary, no-tilled soils had more OM (+14%) and POM (+56%) than tilled soils. The capacity of soils to retain added P was not different in both groups of soils. Phosphorus sorption index was not related to soil content of total OM or POM. Variation in P sorption index was only related to soil clay content (r 2 = 0.44). This study provides evidence contradicting the long held assumption that the reported decrease in P sorption at the surface of no-tilled soils was caused in part by OM enrichment.

The knowledge of nitrogen (N) losses in direct‐drilling agrosystems is essential to develop strategies to increase fertilizer efficiency and to minimize environmental damage. The objectives were i) to quantify the magnitude of N volatilization and leaching simultaneously as affected by different urea fertilization rates and ii) to evaluate the capacity of these specific plant–soil systems to act as a buffer to prevent nitrate leaching. Two experiments were conducted during 2001/02 and 2002/03 growing seasons in Alberti, Argentina. The crop was direct‐drilled maize and the soil a Typic Argiudoll. Ammonia losses, N uptake by crop at flowering and harvest, grain yield, N in previous crop residues, and soil nitrate content up to 2‐m depths were determined. Nitrogen availability, soil nitrate (NO3)‐N up to 1 m plus fertilizer N, was linearly and highly associated with crop N uptake at flowering (R2=0.93, P

In soybean, seed number and yield is largely determined by the environmental conditions between initial bloom and the beginning of seed filling. Four field experiments were conducted to determine the effects of two sources of sulfur (S) on crop growth during the critical period of seed number determination and yield. Ammonium sulfate and gypsum were applied at a rate of 15 kg S ha− 1. Seed yield was closely related to the number of seeds per m2 (R2 = 0.93), but seed number was not related to crop growth between bloom and the beginning of seed filling. There was no effect of fertilization on aboveground biomass accumulation until the seed filling period began. The results from this study suggest that a moderate S deficiency reduced seed yield by affecting crop growth during the seed filling period. This late effect of a moderate S deficiency could be a consequence of the known high sulfate mobility in soils and low S remobilization in plants.

Nous avons etudie les reponses a un preconditionnement par la secheresse des semis de trois provenances d'Eucalyptus globulus subsp. biscotata (Maiden, Blakely et J. Simm) J.B. Kirkp. et nous avons evalue leurs effets apres transplantation. Apres un mois de conditionnement par une secheresse moderee, les semis ont montre un ajustement osmotique et une reduction de taille, de surface foliaire, de rapport partie aerienne/partie racinaire et de conductance stomatique. Nous avons trouve des differences de capacite d'ajustement osmotique entre les provenances. Au cours des premiers jours suivant la transplantation et pendant les premieres etapes de cette periode, le preconditionnement par la secheresse a permis aux semis traites d'avoir une amelioration de leur etat hydrique et de leurs echanges gazeux. Ensuite leur superiorite initiale a disparu. Les semis non conditionnes ont aussi developpe des changements morphologiques et physiologiques qui ont augmente leur tolerance a la secheresse et qui ont permis une performance similaire a celle des plants conditionnes. Cependant leurs rapports partie aerienne/partie racinaire ont ete encore plus eleves. Bien que le preconditionnement n'ait pas favorise la croissance des plants traites, il a ete particulierement efficace pour ce qui concerne la survie des plants, un attribut correle au rapport partie aerienne/partie racinaire et a la teneur relative en eau. Nous avons trouve des differences dans les reponses physiologiques et morphologiques entre provenances, mais il n'a pas ete possible de trouver une relation entre ces differences et la secheresse du site d'origine des graines. Ces resultats nous permettent de confirmer l'avantage du preconditionnement par la secheresse, pour Eucalyptus globulus subsp. biscotata, qui a pour effet un meilleur comportement pendant les premiers jours apres la transplantation et une survie superieure, facteurs etroitement associes au succes de l'installation des plants.

The aim of this work was to study the effects of nitrogen (N) and phosphorus (P) deficiencies and their interaction on spike N, P and biomass around flowering in barley ( Hordeum vulgare spp. distichum L.) and its relationship with grain number and grain yield. Two experiments were carried out with microcrops grown in 200 l containers using malting barley (cv. Quilmes Palomar). Treatments were a factorial combination of two levels of N and two or three levels of P fertilization. Dry matter partitioning to spikes was not or only slightly affected by nutrient deficiencies. Then, the effects on spike biomass were similar to those on total aboveground dry matter. Although partitioning of N to the spike in N fertilized treatments was lower than in N stressed ones, spike N content was higher in the N fertilized. Number of grains was positively associated with spike N and P content as well as spike dry matter at heading in both experiments. Number of grains per unit of spike dry matter at heading in N fertilized microcrops tended to be higher than in N stressed ones, though this effect was not associated with N fertilization effects on N concentration in spikes. Combining these results with others from the literature from wheat crops, we found a strong relationship between number of grains and spike N content at flowering, but this relationship does not seem to be better than that with spike biomass, judged by the regression coefficients. This indicates that the early application of N may induce a higher number of grains than that predicted by increased spike dry weight at flowering, but this additional effect is not universally related to differences in spike N concentration.

Shoot water relations and morphological responses to drought preconditioning were studied by subjecting 5-month-old seedlings of three provenances of Eucalyptus globulus to different water regimes for 36 days in a greenhouse pot study. Moderately stressed plants were watered every 6 days and severely stressed plants were watered every 9 days. Control plants were watered daily. Drought cycles induced significant changes in morphological and physiological characteristics. Preconditioned seedlings were smaller in size, root collar diameter, height, and leaf area than control seedlings. Shoot/root ratio was not affected by drought. Osmotic potential at full turgor (ψπFT) and osmotic potential at turgor loss point (ψπTLP) were significantly lower and the magnitude of osmotic adjustment was significantly higher under the severe than under the moderate stress treatment. In severely stressed plants a decrease of turgid mass/dry mass contributed to osmotic adjustment. In a subsequent acclimation test, preconditioned seedlings showed higher values of stomatal conductance, predawn relative water content and water potential and lower mortality than control plants. These variables were significantly related to ψπFT. We assume that the reduced leaf area and osmotic adjustment observed in preconditioned seedlings contributed to drought acclimation in the selected E. globulus provenances leading to better rates of gas exchange and improved water status than non-conditioned plants. Provenances exhibited differences in their responses to drought, albeit mainly morphological differences. E. globulus subsp. bicostata from Tumbarumba grew more quickly (larger diameter and height relative growth rate) than the other provenances, implying a greater ability to tolerate water stress. It can be expected that preconditioned seedlings will display greater tolerance of water stress than non-conditioned plants and perform better during early establishment (higher survival and early growth).

The aim of this work was to study the effects of nitrogen (N) and phosphorus (P) deficiencies and their interaction on the appearance of leaves and tillers of barley (Hordeum vulgare spp. distichum L.) by analyzing the rate and duration of the appearance period. Three microcrops experiments were carried out in 200 L containers using malting barley cv. Quilmes Palomar. Treatments were a factorial combination of two levels on N and two or three levels of P fertilization. Both N and P deficiencies delayed leaf and tiller appearance rates but leaf appearance was less susceptible to nutrient deficiencies than tiller appearance. P deficiency effects on leaf emergence differed from N effects. While N deficiency diminished the rate of leaf appearance (RLA), it has no significant effect on the duration of leaf appearance or on the duration of the period from emergence to flowering. On the other hand, P deficiency diminished RLA, and increased both the duration of leaf appearance and the duration of the period from emergence to flowering.

The negative relationship between grain size (percentage >2.5mm) and protein content usually observed in barley grain samples is attributed to the presence of thin grains. The objective of this study was to determine whether, in grain samples from a given environment, thin grains had a different protein content than plump grains. Grain samples from field experiments were analysed for grain yield, size and protein content of the whole sample and of four size fractions within each sample. Grain yield ranged from 1.5 to 6.5mgha 1 and grain protein (whole sample) ranged from 6.8 to 13.4 %. Most of the variation observed in protein content was explained by the ratio of nitrogen availability to grain yield. Within a grain sample, thin grains had more protein than plump grains (>2.5mm) only when the protein content of the whole sample was high, that is, when the grain sample came from an environment with a high relative abundance of nitrogen. The fact that grain samples with low grain size tend to have high protein content is not due to the presence of a high proportion of thin grains, because thin grains do not always have more protein than plump grains. Copyright © 2014 The Institute of Brewing & Distilling

The Rolling Pampa is the most important cropping region of Argentina, and its soils are subjected to degradation. No-tillage has been proposed to replace the use of the moldboard plow to reduce soil C losses. The effects of no-tillage and plow tillage with and without N fertilization (0 or 90 kg N ha -1 ) on C inputs and outputs of a Typic Argiudoll and on organic C level and density fractions were studied in a field experiment at the end of 15 yr under a corn (Zea mays L.)-wheat (Triticum aestivum L.)-soybean [Glycine max (L.) Merr.] rotation. Microbial biomass and the rate of organic C mineralization during laboratory incubations were also determined. Nitrogen fertilization had no significant influence on C emission in the field, soil organic matter level or microbial biomass and activity. The annual C budget was negative under both tillage systems, but no-tillage lost about 0.7 to 1.5 Mg ha -1 yr -1 more C than did plow tillage. Carbon in the medium-density fraction (density = 1.6-2.0 g mL -1 ) of the 0-to 20-cm soil layer was 30% higher (P ≤ 0.05) under no-tillage. Light (density 2.0 g mL -1 ) organic fractions, total C, and microbial biomass and activity in the 0- to 20-cm layer were not different in no-tilled and plowed soils, despite different patterns of distribution with depth. The rates of organic C mineralization during laboratory incubations were the same for both tillage systems. We propose that, after an accumulation phase, soil under no-tillage loses higher amounts of CO 2 -C than under plowing. The use of no-tillage would not significantly affect soil organic matter pools of the region in situations with low erosion losses.

Sulfur (S) deficiencies in grain and forage crops have been detected in many agricultural regions of the world, but soil tests are not commonly used as the basis for S fertilizer recommendation programs. Errors of measurements of soil sulfate were determined to assess whether the variation among and within soil-testing laboratories could be a factor that prevent the adoption of soil testing to assess soil sulfate availability. Subsamples of 10 selected soils (Mollisols) from the Pampas (Argentina) were sent in two batches to five soil-testing laboratories. Laboratories were unaware of the existence of subsamples and performed routine sulfate analysis as if these soils came from 60 different fields. Soil sulfate ranged from 3.3 to 20.6 mg kg-1. One laboratory reported sulfate values greater than the other ones, having a mean bias of 4.1 mg kg-1 S sulfate (SO4). The other four laboratories reported similar sulfate values when soils had low sulfate availability (less than 10 mg S kg-1), even when they used different extractants. Considering only these four laboratories, average interlaboratory coefficients of variations ranged from 6 to 24% for the 10 soils. Within-laboratory mean coefficients of variation (CVs) ranged from 12 to 22%. However, mean absolute errors of all laboratories were less than 1.2 mg kg-1 S-SO4. Two laboratories reported different sulfate values for the two batches of shipment (an average difference of 4.7 and 3.8 mg kg-1 of S-SO4). Laboratories using different extractants obtained similar results, suggesting that using the same extractant is not a prerequisite to standardize laboratory results in these soils. Differences between laboratories in our study were smaller than in other interlaboratory comparisons for soil sulfate. These differences could be easily detected and corrected if laboratories participate in an interlaboratory control system. The observed low mean absolute errors suggested that, in general, all laboratories achieve acceptable precision when evaluating within the same batch of determinations. Differences between batches of shipment (within laboratory error) stressed the importance of using reference material for internal quality control. © 2012 Copyright Taylor and Francis Group, LLC. Fil: Russi, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Cátedra de Fertilidad y Fertilizantes; Argentina Fil: Gutiérrez Boem, Flavio Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Cátedra de Fertilidad y Fertilizantes; Argentina Fil: Prystupa, Pablo. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Cátedra de Fertilidad y Fertilizantes; Argentina Fil: Rubio, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Cátedra de Fertilidad y Fertilizantes; Argentina

En diversas regiones del mundo se han observado incrementos en el rendimiento de cereales de invierno por efectos de la fertilización con cobre (Cu), pero son raros los reportes de efectos sobre el contenido proteico de los granos. En cultivos extensivos de la Región Pampeana no existen antecedentes de deficiencias de este micronutriente. El objetivo de este trabajo fue evaluar los efectos de la fertilizaciones foliares con Cu durante floración o principios de llenado sobre el rendimiento y el contenido proteico en cultivos de cebada cervecera en el partido de Junín. A modo exploratorio, durante los años 2007 y 2008 se condujeron sendos ensayos en franjas apareadas sin repeticiones. En el año 2007 la fertilización con Cu incrementó significativamente el contenido proteico de los granos en casi 1% mientras que en 2008 los efectos no fueron significativos. Durante el 2009 se realizó un experimento en un suelo alcalino donde se evaluó el efecto de la fertilización con quelatos de Cu en dos dosis (62 y 125 g Cu ha-1) aplicado en dos momentos (espigazón y llenado). Se alcanzaron rendimientos aceptables (3780 kg ha-1) que no fueron afectados por la fertilización. La fertilización con Cu incrementó 1% el contenido proteico siendo mayores los efectos con la dosis mayor. No se observaron diferencias entre momentos de aplicación. En el año 2010 se realizó un ensayo donde se evaluó el efecto de la interacción entre la fertilización con Cu y la nitrogenada. No se observaron efectos del Cu sobre el rendimiento y el contenido proteico de los granos. Los efectos significativos del Cu sobre las proteínas fueron observados en los dos ambientes con mayores rendimientos. Lo observado en estos ensayos constituye un llamado de atención sobre las posibles deficiencias de este micronutriente en los agrosistemas pampeanos.