ABSTRACT Legacy and Duke are the main blueberry (Vaccinium corymbosum L.) cultivars grown in Chile, with 32.8% of the total Chilean cultivated area with this fruit. The market demands fruit firmness, size, weight, and quality attributes, which are improved by some agronomic management practices such as winter pruning. The present study evaluated the effect on blueberry quality attributes and fruit yield of five fruit bud load levels, regulated by winter pruning during two consecutive seasons, on ʻLegacyʼ and ʻDukeʼ. The study was conducted in three commercial orchards under different soil conditions (Inceptisol, Andisol, and Entisol) in south-central Chile. Results indicated that there were differences in fruit load treatments between seasons, orchards, load levels, and week of harvest (first or second). Reducing the fruit bud load by winter pruning improved quality attributes of fruit firmness, size and weight, but negatively affected production per plant. We found in two seasons that pruning 60% of the fruit bud load level had the highest values for fruit firmness, size, and weight in both blueberry cultivars, but the production was 70% and 86% of the potential in ‘Duke’ and ‘Legacy’, respectively.

ABSTRACT Soilless blueberry (Vaccinium corymbosum L.) production is an alternative system that is increasing worldwide in surface area. There is little scientific information available as yet on the agronomic management of this cultivation system. The objective of the present study was to evaluate four N rates (0%, 100%, 200%, and 300% of the reference rate) and three water replacement level (70%, 100%, 130%) on leaf biomass production and leaf N concentration previous to winter fall (May and August 2021) in 10 pot-grown blueberry cultivars (Blue Ribbon, Duke, Camelia, Cargo, Last Call, Legacy, Ochlockonee, Suzie Blue, Ventura, and Victoria). An experiment was conducted in south-central Chile (36°55’ S) with first-year plants. During the first growing season, results showed interactions between cultivars, N rates, and water replacement levels; there was a synergistic effect between N rates and water replacement levels on leaf biomass production in ‘Duke’, ‘Camelia’, ‘Ochlockonee’ and ‘Suzie Blue’. Overall, the highest leaf biomass production in most cultivars was obtained with an N rate ranging from 33.2 to 53.1 g plant-1 season-1 (100% and 200% N rates, respectively) and 100% and 130% water replacement levels. Water consumption during the season fluctuated between 93.79 a 136.23 L season-1. The highest leaf N concentration in most of the blueberry cultivars was obtained with N rates ranging from 33.2 to 53.1 g plant-1 season-1 and 70% and 100% water replacement levels. Therefore, agronomic management recommendations for N fertilization and water replacement levels in blueberries produced with this growing system cannot be generalized.

ABSTRACT Soil acidity is one of the main factors that reduces productivity in agricultural crops, and it is corrected with materials that neutralize acidification. Among soils affected by acidity are those of volcanic origin. At least 30 % of agricultural soils in Chile are of volcanic origin, and acidity correction practices must be constantly performed. This study aimed to evaluate the effectively of two materials that may neutralize soil acidification and increase yield production in Chilean volcanic soils. An experiment was conducted during the 2019-2020 season, in which different acidity correction materials derived from the cellulose industry [Ash + Dregs (AD) and Ash + Dregs + Sludge (ADS)] were applied in three volcanic soils cultivated with wheat in southern Chile (Chillán, Temuco, and Osorno). Treatments were a control, CaCO3 at an adjusted rate to reach pH 6.0 and AD and ADS at the same rate as CaCO3 and twice the rate. Results indicated that the application of AD and ADS produced similar effects on pH(H2O), Ca2+, Mg2+, and Al3+ contents, cationic exchange capacity (CEC), and Al saturation compared with CaCO3 at the same rate; the effect was directly proportional to the rate used with each AD and ADS. Wheat production at each location was similar for AD, ADS, and CaCO3 at the same rate; however, it fluctuated between 10.1 and 10.4, 5.4 and 6.5, and 10.0 and 10.3 Mg ha-1 at Chillán, Temuco, and Osorno, respectively. Results indicate that these materials are an alternative to be used as a soil acidity correction amendment.

ABSTRACT Shade cloth is commonly used to reduce incident light in apple (Malus domestica [Suckow] Borkh.) orchards. Nevertheless, this technology can generate changes in plant physiology that affect tissue nutritional composition and cause fruit nutritional disorders. The effect of shade cloth on the nutritional concentration of six macroelements and six microelements on leaves, six macronutrients in the fruits of ‘Fuji’ apples, and bitter pit incidence was assessed in a study conducted in a commercial orchard in south-central Chile for three seasons. Two treatments (control without shade cloth and 30% shade cloth cover) were evaluated with five replicates in a split plot design. Averaged results for the three seasons showed that shade cloth increased Mg, Mn, and Zn concentrations in leaves by 0.02%, 40 mg kg-1, and 5.5 mg kg-1, respectively, and decreased K, Mg, and S concentrations in fruits by 12, 0.35, and 0.38 mg 100 g-1 fresh fruit, respectively. Bitter pit incidence was not affected by shade cloth (values between 0.3% and 6.6%), but seasonal conditions did affect this abiotic disorder. In conclusion, the use of shade cloth in apples did not affect bitter pit incidence, but it caused some changes in leaf and fruit nutritional concentration.

ABSTRACT The rice (Oryza sativa L.) crop is very important worldwide for its contribution to human nutrition. Rice grain yield depends on several agronomic management factors that must also be adjusted to the cropping system such as permanent inundation (anaerobic conditions) or direct seeding (aerobic and anaerobic conditions) mainly in response to the application of nutrients such as N. In Chile, the cropping system with direct seeding has limited agronomic and scientific development. The objective was to determine the effect of increasing N (0, 40, 80, 120, and 160 kg ha-1), P (0, 30, 60, and 120 kg P2O5 ha-1), and K (0, 30, 60, and 120 kg K2O ha-1) rates on grain yield and N agronomic efficiency (NAE) (kg grain produced per kg N applied) in two paddy rice soils for two consecutive seasons. Grain yield had a positive response to increasing N rates in the two evaluated soils (grain yield increased from 6.7 to 8.9 Mg ha-1 in the Vertisol and from 7.4 to 11.0 Mg ha-1 in the Alfisol) and a low response to P rates in the Vertisol. The Alfisol showed no response to increasing P rates, and both soils had no response to K application. The N rates that obtained the highest rice grain yield were 120 and 160 kg ha-1 for Alfisol and Vertisol, respectively. The P rate that obtained the highest rice yield in the Vertisol was 30 kg ha-1 P2O5. In addition, NAE values associated to those N rates were 74 and 61, respectively. In conclusion, direct seeding in rice cropping had a response to high rates of applied N, low response to P, and no response to K.

ABSTRACT Organic food production has increased the demand for organic supplies in agriculture. Organic fertilizers are known to have an effect on crop and soil properties, but this effect has been little studied. This research evaluated the effect of seven nitrogen fertilizers allowed for use in organic production and one conventional fertilization treatment adjusted to a similar dose of total nitrogen (N), on chemical properties of two soils of contrasting physicochemical properties (sandy loam Mollisol and silty loam Andisol) incubated under aerobic conditions and controlled 6 times over 112 d. Treatments were: Compost (CO), Fertil (F), Purely Grow (PG), Purely Lysine (PL), Blood meal (BM), Lupine meal (LM), Sodium nitrate (SN), conventional fertilization (CF), and a control without fertilization (CT). The experiment was conducted in a split-plot design for each soil. The results showed that the fertilizers affected soil pH, salinity (electrical conductivity, EC), and the concentrations of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S). In general, the highest values of pH, available P, and exchangeable K, Ca and Mg were obtained using CO in both soils, whereas PL reported the lowest values for most parameters evaluated. The evolution of each parameter over time showed interactions with the fertilization treatment, with a steady decrease in pH and an increase in EC in both soils. Differences in the average values of chemical properties during incubation with respect to their initial values were related to the physicochemical and organic characteristics of each soil.

Abstract The use of wood residues to produce energy and steam in the pulp and paper industry generates ash waste and sewage sludge that contain nutrients for plants as a potential fertilizer. The objective of this study was to evaluate the possible toxic effects of pelletized waste from the pulp and paper industry using bioindicators. Two controlled experiments were conducted with radish seeds and perennial ryegrass seeds: an experiment to determine the germination index and root growth in soil extracts incubated with pelletized waste, and a pot experiment with ryegrass seeds sown in an amended Alfisol with pelletized wastes in which aerial and root biomass production was determined. The results indicate that the Alfisol amended with pelletized waste did not exhibit any acute or sub-acute toxic effects in radish germination. None of the evaluated pellets showed evidence of deterioration in root elongation, including at a 40 Mg ha-1 dose. The highest root growth was with pellet 2, with ash and sludge at the 40 Mg ha-1 dose, which was higher than that in the control treatment (p<0.05). Seed germination was between 93.9% and 100%. The highest ryegrass aerial biomass occurred with pellets 1 and 2 (p<0.05). Pelletized waste from the paper industry exhibited neither mild nor acute effects of toxicity in both radish seed germination and aerial and root biomass production of ryegrass sown in degraded soil.

Resumen El uso de residuos de madera para producir energía y vapor en industrias de pulpa y papel genera residuos de cenizas y lodos de depuradora que contienen nutrientes para las plantas con potencial fertilizante. El objetivo fue evaluar posibles efectos tóxicos de residuos peletizados de industrias de pulpa y papel mediante bioindicadores. Se realizaron dos experimentos controlados con semillas de rabanitos y ballica perenne; uno determinó el índice de germinación y crecimiento de radículas en extractos de suelo incubados con residuos peletizados. El segundo fue con semillas de ballica perenne sembradas en un Alfisol enmendado con residuos peletizados, determinando producción de biomasa aérea y raíces. Los resultados indican que el Alfisol enmendado con residuos no presenta efectos tóxicos en germinación de rabanitos, incluso con 40 Mg ha-1 no se evidencian deterioros en germinación o elongación de radículas para ningún tipo de pellets. El mayor crecimiento de radícula se obtuvo para pellet 2 con 40 Mg ha-1, siendo mayor al control (p<0.05). La germinación de semillas estuvo entre 93.9% y 100%. La mayor biomasa aérea de ballica se obtuvo con los pellets 1 y 2 (p<0.05). Los residuos peletizados de la industria del papel no presentan efectos de toxicidad leve ni aguda, tanto en la germinación de semilla de rabanito como en la producción de biomasa aérea y de raíces de ballica sembradas en un suelo degradado.

ABSTRACT Blueberry production under netting has increased in recent years to mitigate the adverse effects of climate change. The objective of the present study was to evaluate the effect of different radiation intensities on rabbit-eye blueberry (Vaccinium virgatum Aiton) ‘Ochlockonee’ photosynthetic efficiency and productive parameters. Four treatments were established: T1 (control), T2, T3, and T4 at 0%, 30%, 60%, and 90% radiation decrease (RD), respectively, with black shedding netting. The following were recorded for each treatment: environmental conditions, photosystem II (PSII) maximum quantum yield (Fv/Fm), photosystem II effective quantum yield , leaf stomatal conductance (gs), quality parameters, and fruit yield. Results showed an increase of 4.6 ºC in mean minimum temperatures for the different netting treatments, which promote development and fruit set, as well as prevent damage at temperatures near 0 ºC. The RD treatments increased between 175% and 325% (P < 0.05) compared to the control. It can be concluded that netting decreased soil temperature between 1 and 3 ºC and increased minimum temperatures between 1 and 6 ºC, which promoted plant development and decreased frost damage during flowering and fruit development. Current direct radiation levels over 1000 µmol m-2 s-1 in V. virgatum inhibited productivity in T1. Netting decreased the degree of photoinhibition and increased photosystem II photochemical efficiency throughout the day, and T4 and T3 exhibited the highest efficiency.

Anthropogenic soil contamination with heavy metals has received much attention in recent years, especially cadmium (Cd), which is a very toxic element for human health and is exposure is mainly through contaminated food. Maize (Zea mays L.) is one of the most important cereals in the human diet that is characterized as species whose cultivars differ in Cd accumulation. Therefore, identifying and selecting low Cd-accumulating genetic material will contribute to reducing its ingestion. Among the agricultural crops that are important for Cd in the human diet is maize. Cadmium contents in three maize cultivars were grown under different environments conditions in Chile where soils were enriched with increasing Cd rates, were evaluated. Grain yield, Cd concentration in different plant tissues, and soil post-harvest, were evaluated. Results showed that grain yield was not affected by soil Cd; however, plant tissues generally exhibited differences in Cd concentration associated with the environment, La Serena showed the highest grain Cd accumulation (30 µg kg-1; P < 0.05). In addition, among cultivars, Pioneer showed the highest grain Cd concentration (19.5 µg kg-1; P < 0.05).. Grain Cd concentration of the three maize cultivars were within the range cited in the bibliography as not toxic.

Abstract Controlled deficit irrigation (CDI) is a management strategy where water is applied according to the crop phenological stages. As a result, different irrigation management conditions can produce significant changes in production, fruit quality and the reduction in the applied total water volume. The objective of this research was to evaluate the effect of CDI on the production and quality of kiwi (Actinidia deliciosa) Hayward, in Chile. During the production cycles from 2009 to 2012 four water restriction periods were applied: 1) from 10 d to 30 d before flowering, 2) when fruits reached 60 % of their final weight, 3) when fruits reached more than 70 % of the final weight, and 4) when fruits reached more than 80 % of their final weight. The results of each restriction period were compared with a control treatment which had a 100 % evapotranspiration replacement. The experimental design was completely randomized in blocks with four replicates per treatment. The experimental unit was of three rows of seven plants each. Treatment means were compared by the Tukey test (p≤0.05). Throughout the study, soil moisture, water status of the plant, applied water volume, fruit development and uniformity were measured. The main results were the decrease of water volume and its associated costs of pumping between 24 and 60 % compared to the control treatment; the applied CDI showed significant differences (p≤0.05) on the size in the evaluated years. With CDI there was good uniformity in 24.2 % of the fruits without effects on productivity (p>0.05).

Resumen El riego deficitario controlado (RDC) es una estrategia de manejo donde se aplica agua según las etapas fenológicas del cultivo. Como consecuencia, condiciones diferentes del manejo del riego pueden producir cambios importantes en la producción, calidad de la fruta y una disminución del volumen de agua utilizado. El objetivo de esta investigación fue evaluar el efecto de RDC en la producción y calidad del kiwi (Actinidia deliciosa) Hayward, en Chile. Durante los ciclos de producción de 2009 al 2012 se aplicaron cuatro periodos de restricción hídrica: 1) desde 30 d y hasta 10 d antes de la floración, 2) cuando el fruto alcanzó más de 60 % del peso final, 3) cuando el fruto alcanzó más de 70 % del peso final y 4) cuando el fruto alcanzó más de 80 % del peso final. Los resultados de cada período de restricción fueron comparados con un tratamiento testigo con 100 % de reposición de la evapotranspiración. El diseño experimental fue de bloques completamente al azar con cuatro repeticiones por tratamiento y la unidad experimental fue de tres hileras de siete plantas cada una. Las medias de tratamientos se compararon con la prueba de Tukey (p≤0.05). Durante todo el estudio se midió humedad del suelo, estado hídrico de la planta, volúmenes de agua aplicados, desarrollo y uniformidad del fruto. Los resultados principales fueron: disminución del volumen de agua y costos asociados al bombeo entre 24 y 60 %, respecto al tratamiento testigo; el RDC aplicado mostró diferencias significativas (p≤0.05) en calibre para los distintos años de estudio. Con RDC hubo una buena uniformidad en 24.2 % de los frutos sin efectos en la productividad (p>0.05).

ABSTRACT Pulp and paper mill waste, such as biomass fly ash and sewage sludge, is commonly disposed of in landfills. This waste can be valuable as nutrients and C sources for degraded soils. Ash and sludge samples were chemically characterized before ash/sludge pellets were experimentally manufactured for use as soil amendment. An incubation experiment was carried out with controlled moisture and temperature; nutrient input and N mineralization were evaluated at 0, 15, 30, 45, and 60 d intervals using three pellet types with different proportions of ash, sludge, and gypsum (as a binder) and applied at four doses equivalent to 0, 10, 20, and 40 Mg ha-1. Results indicated that the Alfisol that was amended with pelletized residues increased P Olsen and exchangeable K and Ca contents, as well as soil pH (p < 0.05) in direct response to the applied doses. Organic matter decreased during incubation at all the doses and pellet types (p < 0.05); however, N mineralization did not show a clear pattern during incubation. Nitrogen mineralization potential (N0) was different depending on pellet types and application rates; Pellet 2 (10% sludge) exhibited the highest N0 values, while Pellet 3 (20% sludge) had lower N0 than the control. Pulp and paper mill waste can be used to amend degraded soils by creating sustainable use through pelletizing because it facilitates transport and can evenly distribute sludge and ash on soils in a single application.

The use of fertilizers based on calcium (Ca) generates changes in the soil chemical properties, affecting acidity, sum of bases (BS), and Ca and magnesium (Mg) concentrations in the medium to long term. However, there is no information available about short-term changes. A study was conducted to determinate the most readily available Ca source and the best impact on the chemical properties of two different types of soils from south-central Chile, texture class loamy (Haplaquept) and clay (Duraqualf), respectively. The study was conducted under controlled conditions, using different Ca sources (Ibisoil, Nitrate, Clorhide, Sulphate, and Carbonate of Ca). The soils were fertilized with 100 mg kg-1 of Ca and incubated for 16 days at 25°C and 80% of available water. Results indicate differences in some chemical properties that depend on the soil. The highest pH value was obtained with the use of carbonate alone in the loam soil, while no differences were found in the clay soil. Similarly, no significant differences were observed in terms of Ca and K concentrations due to the fertilization treatments in any of the soils, but all of them increased Ca concentration compared with the control treatment. The highest Ca/BS ratio was obtained with Ibisoil. The lowest electric conductivity (EC) was obtained with Ibisoil and Ca Carbonate in both soils, while the highest sodium concentration and EC values were obtained with Ca Clorhide. The fertilizer with the highest increase in the Ca/BS ratio and the lowest EC was Ibisoil.

El uso de fertilizantes cálcicos genera cambios en las propiedades químicas del suelo, que a mediano y largo plazo afectan principalmente la acidez, suma de bases (SB), y concentraciones de calcio (Ca) y magnesio (Mg). Sin embargo, no hay información sobre cambios en el corto plazo, por lo cual se realizó un estudio en condiciones controladas con dos suelos de la zona centro-sur de Chile, clases texturales franca (Haplaquept) y arcillosa (Duraqualf), respectivamente, empleando diferentes fuentes de cálcio (Ibisoil, Nitrato, Cloruro, Sulfato, y Carbonato de Ca), con el objetivo de determinar la fuente cálcica de disponibilidad más rápida y mejor impacto sobre las propiedades químicas. Todos los suelos fueron fertilizados con una dosis de 100 mg kg-1 de Ca e incubados por 16 días a 25°C y 80% de humedad aprovechable. Los resultados indicaron diferencias en algunas propiedades químicas dependientes del tipo de suelo. El mayor pH se logró con el uso de Carbonato de Ca sólo en el suelo franco, sin detectar diferencias en el suelo arcilloso. En ambos suelos la concentración de Ca y potasio no fue afectada por los tratamientos de fertilización, pero todos presentaron aumento de Ca en relación al testigo. La mayor relación de Ca/SB se logró con Ibisoil, la menor conductividad eléctrica (CE) en ambos suelos se logró con Ibisoil y Carbonato de Ca, y la mayor concentración de sodio y CE se obtuvo con Cloruro de Ca. Finalmente, el fertilizante con rápido incremento en la relación Ca/SB y menor CE fue Ibisoil.

Organic farming does not allow using certain inputs, such as N, which differ in nutrient release rates and dynamics. To evaluate the effect of different organic fertilizers on the vegetative, nutritional, and productive parameters of blueberries (Vaccinium corymbosum L.), a pot experiment was conducted in three consecutive seasons in a sandy soil of south-central Chile using ’Corona’, ’Legacy’ and ’Liberty’. The following fertilizers were evaluated: compost (CM), Purely Grow (PG), Purely Lysine (PL), Fertil (F), blood meal (BM), lupine meal (LM), along with a control treatment without fertilization (C) and two conventional treatments with urea (CF) and sodium nitrate (S). Results indicate that vegetative growth and leaf N concentration prior to senescence were different among cultivars in the three evaluated seasons. The highest leaf N concentration was recorded in ’Corona’ followed by ’Legacy’ and ’Liberty’ while levels tended to increase in the seasons. Quick-release N sources had greater effects on these parameters but with differences among cultivars. Fruit yield and weight were higher in ’Corona’ followed by ’Legacy’ and ’Liberty’. Fruit yield was generally higher when using LM and F and showed no effect on fruit weight. Leaf chlorophyll content was higher in ’Corona’ followed by ’Legacy’ and ’Liberty’, which increased when using CF, LM, BM, and PG. Finally, the organic fertilizer and blueberry cultivar that obtained the highest values for most of the evaluated parameters were LM and Corona, respectively.

The phytoextraction process implies the use of plants to promote the elimination of metal contaminants in the soil. In fact, metal-accumulating plants are planted or transplanted in metal-contaminated soil and cultivated in accordance with established agricultural practices. The objective of the present study was to evaluate the productivity and Cd phytoextraction capacity of white lupine (Lupinus albus L.) and narrow-leafed lupine (Lupinus angustifolius L.), as well as the effect on residual Cd concentration in the soil. Both species of lupines were grown at three CdCl2 rates (0, 1, and 2 mg kg-1), under three agroclimatic conditions in Chile in 2013. In the arid zone (Pan de Azúcar, 73 mm precipitation), narrow-leafed lupine production was significantly (P < 0.05) higher than white lupine (4.55 vs. 3.26 Mg DM ha-1, respectively). In locations with higher precipitation (Santa Rosa, 670 mm; Carillanca, 880 mm), narrow-leafed lupine DM production was slightly higher than in Pan de Azúcar, but white lupine was approximately three times higher. Total plant Cd concentrations in white and narrow-leafed lupine increased as Cd rates increased in the three environments, but they were much higher in narrow-leafed lupine than white lupine; 150%, 58%, and 344% higher in Pan de Azúcar, Santa Rosa, and Carillanca, respectively. Cadmium uptake (g Cd ha-1) and apparent recovery were also higher (P < 0.05) in narrow-leafed lupine in two environments (Pan de Azúcar and Carillanca). These results suggest that narrow-leafed lupine present higher potential as phytoremediation species than white lupine.

An important N source for rice (Oryza sativa L.) is mineralization of the organic forms of N present in the soil. The correct N determination will help to optimize the amount of fertilizer used. Our objective was to calculate an index that relates crop N uptake from previous N fertilization and N mineralized in rice paddy soils. To do so, we used two rice paddy soils, Alfisol and Vertisol, in Chile under different anaerobic incubation times and temperatures. We determined both soil mineralization and residual effect of fertilization in the previous season under field and laboratory conditions in an Alfisol and a Vertisol managed with a rice monocrop. Anaerobic incubations were carried out at 20 and 40 °C; and at five different times (0, 7, 14, 21, and 28 d). Our results indicate that residual fertilization affects N mineralization, which increases in both paddy soils when compared with the control without N. In the Alfisol it fluctuates between 6.1 and 13.3 mg N-NH4+ kg-1, whereas in the Vertisol ranged between 18.4 and 28.0 mg N-NH4+ kg-1. Crop N uptake as a residual effect of applied N ranged between 29.3 and 33.9 kg N ha-1 in the Alfisol and 28.3 and 45.8 kg N ha-1 in the Vertisol. Thus, N mineralization is mainly affected by incubation time, temperature, and N fertilization rate of the previous crop season; it can be represented by quadratic models with high determination values, R² = 0.73** and R² = 0.78**, for Alfisol and Vertisol, respectively. Moreover, we found that the best incubation time and temperature were 7 d at 20 °C and 21 d at 40 °C, for the Altisol and Vertisol, respectively. In addition, there are potential savings in the next rice crop season from 0.86 to 0.43 kg N applied for each 1 mg N kg-1 mineralized in the Alfisol and Vertisol, respectively. We conclude that crop N uptake was related to mineralized N and that the equation here developed that relates them is a good predictor to optimize fertilizer use in rice paddy fields.