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Rattalino Edreira J.I.,University of Buenos Aires | Budakli Carpici E.,FAUBA | Budakli Carpici E.,Uludag University | Sammarro D.,FAUBA | Otegui M.E.,University of Buenos Aires
Field Crops Research | Year: 2011

Final kernel number in the uppermost ear of temperate maize (Zea mays L.) hybrids is smaller than the potential represented by the number of florets differentiated in this ear, and than the number of silks exposed from it (i.e., kernel set <1). This trend increases when stressful conditions affect plant growth immediately before (GS1) or during (GS2) silking, but the magnitude of change has not been documented for heat stress effects and hybrids of tropical background. In this work we evaluated mentioned traits in field experiments (Exp1 and Exp2), including (i) two temperature regimes, control and heated during daytime hours (ca. 33-40°C at ear level), (ii) two 15-d periods during GS1 and GS2, and (iii) three hybrids (Te: temperate; Tr: tropical; TeTr: Te×Tr). We also measured crop anthesis and silking dynamics, silk exposure of individual plants, and the anthesis-silking interval (ASI). Three sources of kernel loss were identified: decreased floret differentiation, pollination failure, and kernel abortion. Heating affected all surveyed traits, but negative effects on flowering dynamics were larger (i) for anthesis than for silking with the concomitant decrease in ASI, and (ii) for GS1 than for GS2. Heat also caused a decrease in the number of (i) florets only when performed during GS1 (-15.5% in Exp1 and -9.1% in Exp2), and only among Te and TeTr hybrids, (ii) exposed silks of all GS×Hybrid combinations, and (iii) harvestable kernels (mean of -51.8% in GS1 and -74.5% in GS2). Kernel abortion explained 95% of the variation in final kernel numbers (P<0.001), and negative heat effects were larger on this loss (38.6%) than on other losses (≤11.3%). The tropical genetic background conferred an enhanced capacity for enduring most negative effects of heating. © 2011 Elsevier B.V.

Carfagno P.F.,Instituto Nacional de Tecnologia Agropecuaria | Eiza M.J.,Instituto Nacional de Tecnologia Agropecuaria | Quiroga A.,EEA Guillermo Covas | Babinec F.,EEA Guillermo Covas | And 2 more authors.
Ciencia del Suelo | Year: 2013

In subhumid and semiarid environments, the main factor affecting water loss from the soil surface is evaporation. This process can be reduced by using cover crops (CC) that increase transpiration and potentially reallocate evaporated water to plant transpiration. The aim of this work was to study the water dynamics under cropping systems (SC) with continuous soybean in two soil great groups, four CC and three fallow lengths. We studied four CC and three drying times under two soils, a Haplustol and a Hapludol, evaluating the available water depth (LAD) for two years. For the Hapludol, in general, the LAD at soybean planting rotated with CC was greater than or equal to the SC under continuous soybean. In the Haplustol, the LAD at soybean planting was greater only in the SC with the late-dried CC rye when compared to the continuous soybeans SC. We conclude that the water dynamics under continuous soybean is affected by the inclusion of CC, where rye is the best species adapted to these environments.

Mercado Cardenas G.E.,Instituto Nacional de Tecnologia Agropecuaria | Galvan M.Z.,Instituto Nacional de Tecnologia Agropecuaria | Galvan M.Z.,CONICET | Barrera V.A.,Instituto Nacional de Tecnologia Agropecuaria | And 5 more authors.
Tropical Plant Pathology | Year: 2015

In Argentina, more than 60 % of the tobacco crops are grown in the northwestern part of the country and where Rhizoctonia solani leads to a reduction in crop yield and quality. In this study, 35 isolates of Rhizoctonia were obtained from 32 tobacco fields in northwestern Argentina and characterized by both morphological and molecular approaches. Based on the variability in the ITS region, isolates were identified as R. solani (80 %), Waitea circinata var. zeae (Rhizoctonia zeae) (8 %) and binucleate Rhizoctonia (8 %). Most isolates of R. solani belonged to the anastomosis groups (AGs) AG 4 HG-I (44 %), AG 2-1 (41 %) and AG 4 HG-III (13 %). Isolates of binucleate Rhizoctonia belonged to AG-F and AG-P of Ceratobasidium sp. Morphological variability was higher within isolates of AG 2-1 and AG 4 HG-III than within those of AG 4 HG-I. Aggressiveness of the isolates towards tobacco seedlings was assessed in the greenhouse. Isolates of AG 2-1 were the most aggressive on leaves, causing target spot, whereas isolates of AG 4 HG-I were the most aggressive on stems and roots, causing damping-off. © 2015, Sociedade Brasileira de Fitopatologia.

Otero M.L.,Instituto Nacional de Tecnologia Agropecuaria | Roca M.,SENASA | Zapata R.,FAUBA | Ladux J.L.,Instituto Nacional de Tecnologia Agropecuaria | And 4 more authors.
Acta Horticulturae | Year: 2014

In October 2005, two trials were conducted at two locations of La Rioja province (Argentina), to assess the effect of soil solarization, application of organic matter and inoculation with Thichoderma harziarum on diseased olive plants. The trials included 25 'Manzanilla' and 12 'Arauco' trees, with less than 50% of affected branches, at Aimogasta and El Tala. Treatments were: solarization (SOL), solarization + Trichoderma (SOL+TRI), solarization + organic matter (SOL + OM) and control (C). Disease severities were recorded during 2.5 and 1.5 years, respectively. For soil solarization, a transparent polyethylene of 100 μm was placed around each tree for 3 months. Before placing the plastic and one year later, soil samples were taken to determine the initial amount of microsclerotia per gram of soil (ID). Solarized plots reached maximum 51°C and control plots 40°C. Initial ID values were 2.52 to 1.84 and 1.23 to 2.13 after one year. The major decreases were obtained for SOL+TRI (0.08) and SOL. Controls did not increase ID at El Tala but it decreased at Aimogasta. All treatments decreased disease severities but there were no differences among treatments. Overall, disease severities decreased from 19 to 8% and 34 to 5% at both places. There were significant differences among plants (replicates) within each treatment. Results may have been influenced by fungus pathogenecity, inoculum distribution and density, edaphic factors, soil solarization efficiency and natural recovery phenomenon. © 2014, International Society for Horticultural Science. All rights reserved.

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