Nitrogen is one of the main inputs of the winter wheat crop (Triticum aestivum L.) in southern Chile. Nitrogen efficient management is basic to optimizing its utilization while decreasing pollution risks and operational costs. Crop response and N use efficiency (NUE, defined as the ratio of yield to mineral N supply, regardless of source) are important for evaluating N requirements of winter wheat, and reaching maximum and economic yields. The objective of this study was to determine the effect of N rate on grain yield, calculate the N rate that maximizes yield, and estimate the optimal grain yield rate and quality of high-yielding winter wheat cv. Kumpa-INIA. Five annual N rates were evaluated in a randomized complete block design during two successive winter wheat cropping seasons on a Vilcún series soil of the Pachic Melanudands family (Andisol) in La Araucania Region, Chile, and subjected to intensive annual crop rotation. Significant effects (P ≤ 0.01) of N rate on grain yield and quality were found. The optimal physical N rate (OPR) in both seasons ranged from 290 to 339 kg ha-1 , whereas optimal economic N rate (OER) ranged from 248 to 274 kg ha-1 , with yields between 10.2 and 10.1 t ha-1. Nitrogen use efficiency associated to OER was high in both seasons (36.9 and 41.2 kg grain kg-1 N) and fluctuated in similar ranges. Nitrogen rate increased hectoliter weight and grain protein, but decreased NUE.
O. Andrade, R. Campillo, A. Peyrelongue, and L. Barrientos. 2011. Soils suppressive against Gaeumannomyces graminis var. tritici identified under wheat crop monoculture in southern Chile. Cien. Inv. Agr. 38(3):345-356. Improved knowledge of the biological phenomenon of soil suppressiveness is critical for the management and biological control of soilborne pathogens. Andisols, which are located in southern Chile, show very high conduciveness to the take-all disease of wheat caused by the fungal soil-borne pathogen Gaeumannomyces graminis var. tritici. However, no previous reports have investigated suppressive soils in this important wheat-producing area. The first part of this study was conducted to identify soils suppressive to the take-all disease, and will be followed by a characterization of its microflora to identify potential bio-control agents against the fungal pathogen. Based on the transferability of suppressiveness into the same sterile soil background, 20 soils were collected from different wheat-growing areas in southern Chile and were classified as either suppressive or conducive to the take-all disease under artificial inoculation in a greenhouse environment. Five soils were found to have highly suppressive properties to the take-all disease of wheat, and suppressiveness was observed in soils with a long history of wheat monoculture. Suppressive and conducive soils were found to have overlapping physicochemical characteristics. This is the first report of soils suppressive to take-all of wheat in Chile.
Pastures in southern Chile are composed of forage grasses and associated legumes. Apart from native grass species, in many areas perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) have been introduced. It is thought that most of the N in these pastures is derived from the symbiosis between rhizobium bacteria and the clover. However, various factors can limit the biological nitrogen fixation (BNF) potential. Soils of Chiloe´(southern Chile) are derived from volcanic ash (Andisols), and show high acidity and phosphorus (P) retention capacity and there is often a low availability of exchangeable cations and, sometimes, micronutrients, which together with high aluminium (Al) concentrations can inhibit BNF potential by nodulated legumes. An experiment was carried out on an Andisol of Chiloe´, on a permanent pasture, to evaluate the influence of these fertility factors grass and legume productivity and on the BNF contribution to white clover. Treatments included two rates of lime (0 and 4 Mg ha )1 ) and eight fertilisation treatments: 1. Complete (macronutrients in kg ha )1 : N-50, P 2 O 5 -180, K 2 O-100, MgO-70, S-50, and micronutrients); six other treatments with complete fertilisation but, respectively, without N, P, K, Mg, S and micronutrients, and a control without fertiliser application. The experiment was conducted over 2 years and soil fertility parameters, grass and clover biomass production were evaluated and the BNF contribution to the clover was estimated using 15 N isotope dilution technique. Potassium was found to be the most limiting element for dry matter production, especially for the clover. Liming increased soil pH values and Ca and Mg contents, strongly reduced Al saturation and increased dry matter production. The proportional contribution of BNF to the white clover was high, reaching 80% of total N accumulated by the plants and not significantly affected by addition of lime or fertiliser. However, the accumulation of dry matter and total N, and the total N derived from BNF by the clover were over three times higher in the complete fertilisation treatments than in the control in both years and in the limed and unlimed treatments. The results of this study indicate that pasture productivity can be improved by liming and fertilisation which favour growth of the legume and ryegrass to the detriment of the native grasses. The increase in the proportion of ryegrass and clover should result in improved quality of the available forage, and in the case of the clover, stimulates an increase in the N contribution from BNF thus dispensing with the need for N fertiliser.
Maxwell es un cultivar de trigo (Triticum aestivum L.) de invierno, introducido a Chile en el año 2004 por el Instituto de Investigaciones Agropecuarias (INIA) en colaboración con la Empresa Saaten Union Research de Francia, y liberado comercialmente el año 2012. Maxwell fue evaluado por el Programa de Mejoramiento de Trigo del INIA de Chile. Esta investigación se realizó con el fin de evaluar su comportamiento agronómico en el área nacional más importante de producción de trigo, bajo diferentes condiciones de suelo y clima. En base a los resultados obtenidos se pudo establecer que para el hábito de crecimiento, altura de la planta, precocidad, sanidad, rendimiento y calidad industrial, el cultivar Maxwell se destacó por sobre los testigos comerciales y mostró gran adaptabilidad para siembras tempranas, en zonas de inviernos largos y primaveras húmedas. La planta alcanza una altura promedio de 90 cm, siendo clasificado como un trigo enano a semienano. Su rendimiento promedio, en diferentes localidades y varios años de evaluación, fue 1,06 t ha -1 , superior al testigo, siendo clasificado desde el punto de vista industrial como un trigo de calidad intermedia.
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