Abstract:

In the Pampean region of Argentina, farming systems are based on intensive land use, wheat/soybean double cropping being a key component of these agricultural systems. However, during the last years farmers have been replacing wheat for barley due to its earlier maturity date, reducing yield penalization in soybean as a consequence of delays in its sowing date, and improving the economic profits of the double cropping system. To maximize the benefits of barley/soybean double cropping system, the proper timing of key barley ontogenic stages should be easily identifiable by farmers. The objectives of the present study were to (i) characterize crop phenology through thermo-photoperiod models in response to different sowing dates, (ii) use the algorithms calculated in point (i) to generate a simple model for predicting phenology, using historical climatic series, and (iii) validate the model with independent data. Barley cultivars used in the present study did not show vernalization requirements. Variations in phenology, measured in thermal time, were mainly associated with variations in photoperiod sensitivity during the emergence-heading phase. Significant differences in photoperiodic sensitivity, from −65 °Cd h−1 (Scarlett) to −344 °Cd h−1 (Q. Ayelen), were observed among cultivars. However, cultivars did not show significant differences in critical photoperiod or intrinsic earliness. The slope of the relationship between heading time and date of emergence, calculated from the algorithms used to build the model, based on thermo-photoperiodic response, varied between locations and cultivars. When the model was tested with an independent data set, predictions for the sowing-flowering phase showed a root mean square error lower than 4% (similar to that observed using more complex models). The algorithms used in the model were masked into a friendly frame and outputs were shown in a simple and attractive manner for users. The model was uploaded to the web site of the University of Buenos Aires to be used by students, advisors, professionals and farmers barley.

Author affiliation: Alzueta, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina

Author affiliation: Arisnabarreta Dupuy, Sebastián. Monsanto Company. Production Research; Argentina

Author affiliation: Abeledo, Leonor Gabriela. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Miralles, Daniel Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina

Abstract:

It is traditionally assumed that barley has a higher tillering capacity than wheat whatever the environmental condition; however, this supposition has not been formally tested under experimental conditions nor analyzed its relationship with leaf appearance. In the present work, leaf appearance and tillering dynamics were studied in wheat and barley genotypes grown under contrasting nitrogen and sulfur levels at sowing. There was no difference in phenology (seedling emergence, first visible node and flowering) between wheat and barley or due to different nutrients. Phyllochron in barley tended to be higher than (or at least equal to) that observed in wheat, without effect of the N or S levels on this trait. Differences in final leaf number were negligible. Tillering dynamics was analyzed considering the tillering appearance rate (TAR), the maximum number of tillers appeared (MTN), the tillering mortality rate (TMR), and the final number of tillers per plant (FTN). TAR was significantly greater in barley than in wheat genotypes in all experiments. In both species, TAR was enhanced as N supply was increased while S promoted TAR only under high N conditions. The MTN was positively and significantly associated with TAR. Although cessation of tillering was similar between both species, the maximum number of tillers was superior in barley than in wheat, due to the differences between species in tiller appearance rate. A high MTN was related to a high tiller mortality rate. In spite of that counterbalance, FTN was closely related to MTN; as a consequence, FTN was pre-defined during the early phase of the tillering process. Barley showed higher values of tiller initiated per leaf appeared (synchrony) than wheat, while N and S deficiencies decreased that synchrony.

Author affiliation: Alzueta, Ignacio. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Abeledo, Leonor Gabriela. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Mignone, César M.. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina

Author affiliation: Miralles, Daniel Julio. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina

Abstract:

Aims: Wheat and barley plants exposed to waterlogging reduced their growth, but the final impact on grain yield depends on the capacity of the plant to recover after stress. The aim of this study was to evaluate shoot and root biomass accumulation in wheat and barley plants during waterlogging events applied at different stages during preflowering and after stress removal. Methods: Wheat and barley plants were waterlogged for 15–20 days at four consecutive periods during phenological cycle from emergence to flowering. Results: Waterlogging produced a delayed effect on shoot biomass, as biomass reductions were detected 20 days after waterlogging was released. The highest relative reductions of shoot biomass (60% in wheat and 68–74% in barley regarding control) occurred when waterlogging was applied early in the cycle (from emergence to tillering). Waterlogged plants showed a remarkable capacity to recover from early waterlogging (reaching similar shoot biomass as control plants at flowering), but recovery capacity decreased when waterlogging occurred later in the phenological cycle. For both species green leaf area and photosynthetic rate were reduced and water soluble carbohydrates increased when waterlogging ended, however the general trend showed values at flowering similar to the control plants. The impact of waterlogging on roots was generally higher than the one on shoots and the effect was detected immediately after treatment. The root system capacity to recover after waterlogging was lower than the one for shoots, and was higher in barley than in wheat. Conclusions: Waterlogging first damaged root biomass while effects on shoots were delayed. Shoot recovery at flowering was possible for waterlogging events previous to stem elongation, but root recovery was lower, especially for wheat.

Author affiliation: de San Celedonio, Romina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina

Author affiliation: Abeledo, Leonor Gabriela. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Mantese, Anita Ida. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Botánica General; Argentina

Author affiliation: Miralles, Daniel Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina

Abstract:

Background and aims Crop tolerance to waterlogging depends on factors such as species sensitivity and the stage of development that waterlogging occurs. The aim of this study was to identify the critical period for waterlogging on grain yield and its components, when applied during different stages of crop development in wheat and barley. Methods Two experiments were carried out (E1: early sowing date, under greenhouse; E2: late sowing date, under natural conditions). Waterlogging was imposed during 15-20 days in 5 consecutive periods during the crop cycle (from Leaf 1 emergence to maturity). Results The greatest yield penalties occurred when waterlogging was applied from Leaf 7 appearance on the main stem to anthesis (from 34 to 92% of losses in wheat, and from 40 to 79% in barley for E1 and E2 respectively). Waterlogging during grain filling reduced yield to a lesser degree. In wheat, reductions in grain number were mostly explained by reduced grain number per spike while in barley, by variations in the number of spikes per plant. Conclusions The time around anthesis was identified as the most susceptible period to waterlogging in wheat and barley. Exposing the crop to more stressful conditions, e.g. delaying sowing date, magnified the negative responses to waterlogging, although the most sensitive stage (around anthesis) remained unchanged.

Author affiliation: de San Celedonio, Romina Paola. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina

Author affiliation: Abeledo, Leonor Gabriela. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Miralles, Daniel Julio. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina

Abstract:

Barley is one of the most popular crops in dryland agricultural systems of Mediterranean areas, where it is assumed that barley, or traditional wheat cultivars, performs better than modern wheat under low-yielding conditions. It was tested whether variations in net leaf photosynthetic rate (PN) during grain filling provide any basis for the potential better performance of barley and traditional wheat compared to modern wheats in Mediterranean areas. Two groups of field experiments were conducted in Agramunt (NE Spain) during 2005/06 (06) and 2006/07 (07) growing seasons combining low and high nitrogen (N) availabilities under rain-fed and irrigated conditions. Cultivars used in the first group of experiments were a traditional (Anza) and a modern (Soissons) wheat, whilst in a second group of experiments, a wheat (Soissons) and a barley (Sunrise) modern cultivars were used. Both wheat cultivars showed a similar PN during grain filling but higher than that of the modern barley cultivar. Differences between species in PN were maximized under high-yielding conditions. There were no differences between cultivars in instantaneous water-use efficiency. The barley cultivar showed a higher specific leaf area, but lower N content per unit of leaf area, than wheat. Photosynthetic nitrogen-use efficiency was similar between the traditional and the modern cultivar but lower than barley. Decreases in PN after anthesis were not exactly observable in SPAD measurements. In conclusion, we found no consistent differences between cultivars in terms of post-anthesis photosynthetic activity to support the assumption of better performance under Mediterranean farm conditions of traditional wheat or barley against modern wheat.

Author affiliation: Abeledo, Leonor Gabriela. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Savin, Roxana. Universidad de Lleida; España. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Slafer, Gustavo Ariel. Institució Catalana de Recerca i Estudis Avancats; España. Universidad de Lleida; España. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Abstract:

The importance of yield improvement at farm conditions is highly dependent on the interaction between genotype and environment. The aim of the present work was to assess the attainable yield of a traditional and a modern malting barley cultivar growing under a wide range of soil nitrogen (N) availabilities and different water scenarios (low, intermediate and high rainfall conditions during the fallow period and throughout the crop cycle) considering a 25-year climate dataset for two sites (a shallow and a deep soil) in the Pampas, Argentina. For that purpose, a barley model was first calibrated and validated and then used to expand field research information to a range of conditions that are not only much wider but also more realistic than experiments on experimental farms. Yield of the modern cultivar was at least equal to (under the lowest yielding conditions) or significantly higher (under most growing conditions) than that of the traditional cultivar. Averaged across all the scenarios, yield was ~20% higher in the modern than in the traditional cultivar. The average attainable yield represented 42% of the yield potential in the shallow and 79% in the deep soil profiles. Yield advantage of the high yielding cultivar was based on using N more efficiently, which not only determined higher attainable yields but also reduced the requirements of soil N to achieve a particular yield level. Farmers would face little risk in adopting higher yielding cultivars in both high and low yielding environments and even in the latter ones N fertilisation could be beneficial in most years.

Author affiliation: Abeledo, Leonor Gabriela. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina

Author affiliation: Calderini, Daniel F.. Universidad Austral de Chile; Chile

Author affiliation: Slafer, Gustavo A.. Universitat de Leida; España

Abstract:

En Argentina, la producción de trigo es afectada ocasionalmente por eventos de anegamiento, cuya frecuencia depende del clima, tipo de suelo y relieve de cada zona en particular. Sin embargo, es muy escasa la información sobre el nivel de riesgo de ocurrencia de dichos anegamientos en las distintas zonas productivas de Argentina. El objetivo del presente trabajo fue cuantificar la probabilidad de ocurrencia de anegamiento durante el ciclo ontogénico de trigo en diversas localidades de la región triguera argentina, utilizando un modelo de simulación de cultivos. Para ello, se realizaron simulaciones de 33 campañas de trigo, utilizando el modelo CERES-Wheat v. 3.5, para una combinación de localidades (Bordenave, Capitán Sarmiento, Gualeguaychú, Junín y Tandil), fechas de siembra (temprana y tardía) y contenidos contrastantes de agua útil en el perfil del suelo a la siembra (valor esperado alto, medio y bajo). La probabilidad de anegamiento promedio durante el ciclo del cultivo varió entre el 7 y el 24%, dependiendo de la localidad, para una condición hídrica inicial media y fecha de siembra temprana. Dicha probabilidad se incrementó durante el período de mayor sensibilidad del cultivo al anegamiento (i.e. espiguilla terminal (ET)-floración (Fl)). Para una fecha de siembra temprana y partiendo de un suelo con contenido hídrico medio, en 1 de cada 2 años se espera que ocurran entre 2 y 7 días de anegamiento durante la etapa ET-Fl, dependiendo de la localidad. Dicho valor fue levemente mayor o menor si el contenido hídrico del suelo a la siembra era alto o bajo, respectivamente. La fecha de siembra no modificó significativamente la probabilidad de anegamiento; sin embargo, el daño que puede producir sobre el cultivo la misma cantidad de días de anegamiento en una fecha tardía sería mayor que en una fecha temprana, como consecuencia de un aumento de la demanda ambiental a la que está expuesto el cultivo. De la misma manera, en las distintas localidades, el mismo número de días de anegamiento produciría distintas magnitudes de pérdidas de rendimiento como consecuencia de diferencias en la demanda ambiental entre sitios.

Author affiliation: de San Celedonio, Romina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina

Author affiliation: Micheloud, José Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina

Author affiliation: Abeledo, Leonor Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina

Author affiliation: Miralles, Daniel Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina

Author affiliation: Slafer, Gustavo Ariel. Institució Catalana de Recerca i Estudis Avancats; España

Abstract:

The aim of this study was to analyse (i) the crop attributes that determine floweringtime (i.e. final leaf number, FLN; and phyllochron, Phy), (ii) the dynamics oftiller appearance and (iii) the synchrony between leaf and tiller appearance inwheat and barley plants exposed to waterlogging. Two experiments were carriedout in pots, in which wheat and barley cultivars were exposed to five waterloggingtreatments, during different periods throughout the crop cycle, from emergenceto maturity. The appearance of leaves and tillers on the main stem was measuredtwice a week in labelled plants. Waterlogging from emergence to flag leaf appearancesignificantly delayed time to flowering. The delay was greater when waterloggingoccurred at the beginning of tillering, lengthening the period fromemergence to flowering 24 % (13?15 days) in barley and 10?15 % (6?10 days)in wheat, as compared to control. Phy was the main attribute explaining the delayin flowering, as FLN was not altered. Waterlogging during the early stages ofdevelopment reduced tiller appearance rate (TAR) in both species, but this effectwas partially counterbalanced by a lengthening of the tillering phase, so the effecton final tiller number at maturity was limited. In conclusion, the exposure ofwheat and barley to waterlogging during early stages of development delayed timeto flowering and reduce TAR in both species. Waterlogging during moreadvanced crop stages produced slight effects on tillering dynamics, which wouldindicate that waterlogging affected structure generation more than mortality

Author affiliation: de San Celedonio, Romina Paola. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina

Author affiliation: Abeledo, Leonor Gabriela. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Brihet, J. M.. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina

Author affiliation: Miralles, Daniel Julio. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina