Contribution of contrasting plant hierarchies to the response to N fertilizer in maize

The typical size structuring process that occurs as a consequence of intra-specific competition in maize promotes the appearance of contrasting plant hierarchies (i.e. dominated and dominant individuals). This process may become more intense under low nitrogen (N) availability. The alleviation of plant competition by N addition may reduce plant yield variability through a differential response to N in individuals of contrasting hierarchies. In this work, the response to N of dominated and dominant plants from stands with contrasting N supply (0 to 140-200kgNha-1) was examined on 11 experiments carried out in Paraná, Argentina (31°50'S; 60°31'W) in a broad range of growing conditions that included the variation of the year, genotype, plant population and sowing date. Our objectives were: (i) to evaluate the response to N in contrasting plant hierarchies of maize, (ii) to quantify the contribution of dominated and dominant plants to the response to N of the overall stand, and (iii) to study the effect of N on relationships between plant hierarchies and stand variability. Response to N of yield per plant was associated with biomass per plant in non-fertilized controls, tending to be higher in plants with low biomass. The response to N of yield per unit area (i.e., considering all individuals of the stand) was related to the response to N of dominant and dominated plants (P50-60%), dominant plants had a considerable lower response than dominated plants, whereas at a lower level of response (<30%), the contribution of contrasting plant hierarchies was similar. In stands with similar plant biomass between hierarchies, the differences in the response to N between plant types tended to be negligible. The coefficient of variation of yield per plant was reduced (P<0.05) by effect of N in 4 out of 11 experiments, although it tended to be consistently lower in fertilized treatments. When the differences between the biomass of dominated and dominant plants were ample we found the highest response to N at the stand level, as a result of the higher increase in grain yield per plant in dominated plants than in dominant ones. The response to N in each plant hierarchy was differentially associated with increases in shoot biomass, harvest index, kernel number per plant and kernel weight.Fil: Caviglia, Octavio Pedro. Universidad Nacional de Entre Ríos; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Melchiori, Ricardo José Miguel. Instituto Nacional de Tecnología Agropecuaria; Argentin

¿Cómo decidir la fertilización nitrogenada en maíz en escenarios de incertidumbre?

La producción de maíz en Entre Ríos, se ha incrementado en los últimos años, impulsada, en parte, por cambios en las políticas económicas que permitieron que mejore su competitividad respecto al cultivo de soja. El incremento del área de siembra del cultivo de maíz es un aspecto clave que contribuye con la sustentabilidad de los agro ecosistemas, respondiendo además a satisfacer la creciente demanda local impulsada por las cadenas de producción animal. Sin embargo, la diferencia nutricional de los suelos condiciona los rendimientos alcanzables, y para trabajar bajo escenarios climáticos inciertos, como los pronosticados para el ciclo agrícola 2022/2023, resulta indispensable el uso de herramientas sólidas de análisis para el soporte de decisiones en la fertilización.Fil: Melchiori, Ricardo José Miguel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: Maltese, Nicolás Elías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; ArgentinaFil: Correndo, A.A.. Kansas State University; Estados UnidosFil: Novelli, Leonardo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; ArgentinaFil: Caviglia, Octavio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentin

¿Cómo decidir la fertilización nitrogenada en maíz en escenarios de incertidumbre?

La producción de maíz en Entre Ríos, se ha incrementado en los últimos años, impulsada, en parte, por cambios en las políticas económicas que permitieron que mejore su competitividad respecto al cultivo de soja. El incremento del área de siembra del cultivo de maíz es un aspecto clave que contribuye con la sustentabilidad de los agro ecosistemas, respondiendo además a satisfacer la creciente demanda local impulsada por las cadenas de producción animal. Sin embargo, la diferencia nutricional de los suelos condiciona los rendimientos alcanzables, y para trabajar bajo escenarios climáticos inciertos, como los pronosticados para el ciclo agrícola 2022/2023, resulta indispensable el uso de herramientas sólidas de análisis para el soporte de decisiones en la fertilización.Fil: Melchiori, Ricardo José Miguel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: Maltese, Nicolás Elías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; ArgentinaFil: Correndo, A.A.. Kansas State University; Estados UnidosFil: Novelli, Leonardo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; ArgentinaFil: Caviglia, Octavio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentin

Aplicación de fotografías aéreas de alta resolución en la planificación de cosecha de caña de azúcar

The tolerable losses in the mechanical harvest of sugar cane are proposed around 2.5%. It increased from an initial value of 20% fallen sugar cane, depending on the harvester experience. The objective of the present work, was to evaluate the use of high resolution airborne multispectral imaging to estimate the area of fallen sugar cane in productive fields, as an index to planning harvest process. Several flights were accomplished with a Sky Arrow 650 TCNS ERA aircraft over advanced sugar cane crop fields in Salta and Tucuman in Argentina. Multispectral images were acquired (G-R-NIR). Mosaics were made and the management units were extracted. Entropy images were generated evaluating different types and sizes of filtering moving windows. Threshold values were used to discriminate between stand and fallen cane. These procedures were adapted in response to the presence of internal irrigation. The total area of both stand and fallen sugar cane was determined generating a ranking of the management units as a decision tool for the harvest process. The obtained results were satisfactory demonstrating the feasibility of use entropy analysis with high spatial resolution airborne imaging for a rapid and effective mapping of the distribution of fallen sugar cane in production fields.Pages: 1-

Plant nitrogen status at flowering and kernel set efficiency in early- and late-sown maize crops

In maize (Zea mays, L.) genotypic variability in the relationship between total kernel number per plant (KNP) and plant growth rate (PGR) during the period bracketing silking (R1 ± 15 d), and in kernel set efficiency (KNP PGR−1, KSE) have been widely documented. Nitrogen supply (Ns) affects PGR and hence KNP (i.e. indirect effect on KNP), but reports on a direct N effect on KNP PGR−1 are still contradictories. Moreover, recent studies have documented that prolificacy (the number of ears per plant) was cancelled out in N-limited plants despite of their high PGR. Additionally, PGR can be differentially affected by environmental conditions (e.g. sowing dates) through indirect effects on plant size or directly, which could determine changes on KSE. Field experiments were carried-out in Paraná (31° 48' S, 60° 32' W), Argentina, during two growing seasons (2014−15 and 2015−16). Two single cross hybrids were sown in two sowing dates (early: September and late: December), with three N fertilizer rates (0, 90, and 270 kg N ha−1) at three plant densities (5, 7 and 9 pl m−2). The effects of plant N status and plant size on KNP, KSE and prolificacy were study for a wide range of PGR and relative PGR (rPGR). Plant N status was estimated by using SPAD measurements on the ear-leaf blade at R1. Ranges of lower, mid and higher PGR (absolute and relative values) and SPAD units were established using 33rd and 66th percentiles. Curvilinear functions were fitted to kernel number at the apical ear (KNE1) vs. PGR and KNP vs. PGR and boundary functions were also fitted to calculate the unexplained variance (i.e. residuals) of these functions, indicative of direct plant N status effects on KSE. Residuals of KNE1 vs. PGR relationship decreased with increases in plant N status up to a threshold value of 46.8 SPAD units (R2 = 0.75, P < 0.001). Prolificacy was expressed for plants with SPAD units greater than 50 and residuals of KNP vs. PGR relationship decreased with increases in SPAD units only in prolific plants of early-sown crops (R2 = 0.55, P < 0.10). The analysis of KNP vs. PGR and KNP vs. rPGR allowed us to elucidate the direct effect of plant N status on KSE under a wide range of environmental conditions, especially those promoting by sowing date x plant density x N rate.Fil: Maltese, Nicolás Elías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Maddonni, Gustavo Angel. 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; ArgentinaFil: Melchiori, Ricardo José Miguel. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Caviglia, Octavio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos; Argentin

Crop sequence and P fertilization effects on soil P fractions under no-tillage

Increasing cropping intensity may affect phosphorus (P) recycling through crop residue inputs, which maydiffer in soils with different productivity, P adsorption capacity, and P fertilization level. In three crop sequences: Soybean (Glycine max L. Merr.) monoculture (S–S), Maize (Zea mays L.) monoculture (M-M), and Wheat (Triticum aestivum L.)/Soybean as a double crop (W/S) in a Vertisol and a Mollisol; we assessed the long-term effect of the crop sequences on soil inorganic P (Pi) and organic P (Po) fractions, and the short-term effect of P fertilization on soil Pi and Po fractions, P uptake, and grain yield. Two P fertilization levels (50 kg P ha-1, and control) were established in 2016 on long-term experiments that included S–S, W/S, and M-M. Bray1-P, as well as total P, Po, and Pi in both the coarse soil ([53 lm)fraction (CF) and the NaHCO3 extract, and accumulated yield and P uptake were measured. In the long-term, the crop sequences did not change soil P fractions, but Po-CF and Pi-CF showed similar values in both soils, suggesting less soil-type dependence than in other labile P fractions. In the short-term, the P fertilization only increased the extractable Pi fractions (16% in the Mollisol and 25% in the Vertisol), suggesting that P in the CF was not a sink of P fertilizer. Our study showed that P fertilization in different crop sequences may increase labile P fractions and P recycling depending on soil type, a useful tool to develop P fertilization strategies at the crop sequence level.Fil: Appelhans, Stefania Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: Novelli, Leonardo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: Melchiori, Ricardo José Miguel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: 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; ArgentinaFil: Caviglia, Octavio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentin

Crop sequence and P fertilization effects on soil P fractions under no-tillage

Increasing cropping intensity may affect phosphorus (P) recycling through crop residue inputs, which maydiffer in soils with different productivity, P adsorption capacity, and P fertilization level. In three crop sequences: Soybean (Glycine max L. Merr.) monoculture (S–S), Maize (Zea mays L.) monoculture (M-M), and Wheat (Triticum aestivum L.)/Soybean as a double crop (W/S) in a Vertisol and a Mollisol; we assessed the long-term effect of the crop sequences on soil inorganic P (Pi) and organic P (Po) fractions, and the short-term effect of P fertilization on soil Pi and Po fractions, P uptake, and grain yield. Two P fertilization levels (50 kg P ha-1, and control) were established in 2016 on long-term experiments that included S–S, W/S, and M-M. Bray1-P, as well as total P, Po, and Pi in both the coarse soil ([53 lm)fraction (CF) and the NaHCO3 extract, and accumulated yield and P uptake were measured. In the long-term, the crop sequences did not change soil P fractions, but Po-CF and Pi-CF showed similar values in both soils, suggesting less soil-type dependence than in other labile P fractions. In the short-term, the P fertilization only increased the extractable Pi fractions (16% in the Mollisol and 25% in the Vertisol), suggesting that P in the CF was not a sink of P fertilizer. Our study showed that P fertilization in different crop sequences may increase labile P fractions and P recycling depending on soil type, a useful tool to develop P fertilization strategies at the crop sequence level.Fil: Appelhans, Stefania Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: Novelli, Leonardo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: Melchiori, Ricardo José Miguel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: 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; ArgentinaFil: Caviglia, Octavio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentin