Macronutrient omission influences morphological parameters, growth, and yield in Arracacia xanthorrhiza Bancroft.

Mineral nutrition in arracacha is a critical production factor that conditions harvest yield. Few studies have been developed in nutrition and physiology, this does not allow to the design of ideal fertilization programs; consequences are increased production costs, soil degradation, and low-quality storage roots. Therefore, this study aimed to characterize the symptoms associated with macronutrient deficiency in arracacha plants and its effect on morphological parameters, the accumulation of fresh and dry biomass, and the distribution of dry matter in the different organs. Under greenhouse conditions, the experiment was conducted in Cajamarca, Tolima, Colombia. A completely randomized design was implemented, with seven treatments and six replicates (6 solutions lacking N, P, K, Ca, Mg, and S and Hoagland complete solution). Forty-two seedlings were transplanted, to which the complete solution was applied for 75 days, increasing the concentrations from 0.25 M to 1 M, and then nutritional deficiencies were induced. Deficiencies caused by macronutrients in arracacha plants exhibited visual symptoms and changes in their morphology. The omission of N, Ca, and S generated the most severe symptoms, drastically affecting plant height, leaf width, number of leaves, and plant mass accumulation. In the case of P, leaves became small and intense green with a violet margin. The Mg and K generated leaves with interveinal and margin chlorosis. Plants with the omission of macronutrients allocated dry mass in the following order: stem, storage roots, propagules, and leaves.

Phenological and physicochemical changes during fruit development in two peach cultivars in the high tropics / Cambios fenológicos y fisicoquímicos durante el desarrollo del fruto en dos cultivares de duraznero en trópico alto

ABSTRACT Several aspects of the development of the peach fruit under tropical conditions are unknown, this information allows agronomic practices to be carried out with technical criteria. Therefore, the objective was to determine the different changes and phenological changes of peach fruit depending on the Growing Degree Days (GDD) in the varieties 'Dorado' and 'Rubidoux', grown in the Colombian high tropics. This study randomly selected 51 trees and 100 flowers per plant that were in full flowering for sampling every 15 days until harvest to determine physical variables such as firmness, color index of the epidermis and pulp, and chemical properties such as soluble solids, titratable acidity, and respiratory rate. From full bloom to harvest, the Dorado and Rubidoux varieties took 1081.8 GDD (153 days) and 1667.1 GDD (205 days) respectively. The firmness increased in the two cultivars during phase 1 of development, then decreased until harvest. The color index of the epidermis and pulp increased during ripening, indicating yellow tones in the two varieties. The soluble solids increased continuously, with final values of 15.9 ± 0.9 and 15.5 ± 0.3 °Brix. The acidity increased during phase 2 and then decreased during ripening. The respiratory rate decreased between phase 1 and 3, with an increase in phase 2, which is related to the lignification of the endocarp in the two cultivars. These results contribute to the understanding of the development of the two peach cultivars under tropical conditions.

RESUMEN Se desconocen varios aspectos del desarrollo del fruto de duraznero en condiciones tropicales, información que permite realizar labores agronómicas con criterio técnico, por tanto, el objetivo fue determinar los diferentes cambios fisicoquímicos y fenológicos del fruto de durazno, en función del tiempo térmico, de las variedades 'Dorado' y 'Rubidoux', cultivados en zonas de trópico alto colombiano. Se seleccionaron al azar 51 árboles y 100 flores/planta, en estado de plena floración. Cada 15 días y hasta la cosecha, se hicieron mediciones de la firmeza, el índice de color de epidermis y pulpa, los sólidos solubles, la acidez titulable y la tasa respiratoria. De plena floración a cosecha, las variedades Dorado y Rubidoux tardaron 1081,8 GDC (153 días) y 1667,1 GDC (205 días), respectivamente. La firmeza presentó un incremento en los dos cultivares durante la fase 1 de desarrollo, luego disminuyó hasta la cosecha. El índice de color de epidermis y pulpa aumentó durante la maduración, con tonalidades amarillas, en las dos variedades. Los sólidos solubles incrementaron de forma continua y en los dos cultivares, con valores finales de 15,9 ± 0,9 y 15,5 ± 0,3 °Brix. La acidez mostró un incremento durante la fase 2 y luego disminuyó durante la maduración. La tasa respiratoria decreció entre la fase 1 y 3, con un incremento en la fase 2, relacionado con la lignificación del endocarpio, en los dos cultivares. Estos resultados contribuyen al entendimiento del desarrollo de los dos cultivares de durazno, bajo condiciones tropicales.

Management alternatives for Carmenta theobromae (Busck, 1910) (Lepidoptera: Sesiidae) and Simplicivalva ampliophilobia (Lepidoptera: Cossidae), limiting pests of guava in Colombia.

The larval stages of Carmenta theobromae Busck (1910) and Simplicivalva ampliophilobia Davis, Gentili-Poole and Mitter (2008) attack the subcortical zone and pith in guava trees, respectively, in the first productive nucleus of fruit trees in Colombia: Hoya del Río Suárez (HRS). The presence of pest insects has been reported in 98% of the farms sampled in HRS (n = 124), with up to 96 and 11 simultaneous larvae per tree, respectively. Although the aspects of the basic biology and life cycle of both pests have been resolved, there are no strategies for managing populations in the field. Therefore, the aim of this study was to evaluate different management alternatives under laboratory and field conditions in HRS. In laboratory conditions, a completely randomized design was used in two separate experiments, each with six treatments: T1: Spinosad (a mixture of Spinosad A and D); T2: S-1,2-di(ethoxycarbonyl) ethyl 0,0-dimethylphosphorodithioate (chemical control); T3: Lecanicillium lecanii; T4: Beauveria bassiana; T5: Mix of B. bassiana and B. brongniartii, and T6: distilled water (control). The number of dead larvae per replicate per treatment was evaluated (DL), with experimental units of five and three larvae, respectively. In the field, to the two best alternatives found for each pest in the laboratory, pruning and keeping the area around the plants free of weeds were added as cultural management, in two separate additional experiments, each with three larvae as experimental unit per treatment. For C. theobromae, the best laboratory alternatives were chemical control (DL: 3.78) and L. lecanii (DL: 2.33), followed without statistical differences by B. bassiana (DL: 1.67). In the field, the virulence of B. bassiana improved (DL: 3), and together with pruning and keeping the area around the plants clear of weeds (DL: 3), they stood out as the best alternatives. For S. ampliophilobia under laboratory conditions, the best alternatives were Spinosad (2.74) and chemical control (DL: 2.66), without significant difference. In the field, there were no statistical differences between the alternatives, except for the control. This statistical parity of cultural practices, and biological and chemical management is an argument in favor of the use of the former to the detriment of the third, especially when the harmful effects of the molecule S-1,2 di (ethoxycarbonyl) ethyl 0, 0-dimethyl phosphorodithioate have been proven in air, water and agricultural soils, in addition to its association with thyroid cancer in humans. This is a strong argument to favor the use of synergies of cultural and biological management methods framed in IPM, as opposed to the use of chemical agents whose harmful effects are strongly documented, and whose use is becoming increasingly prohibited.

Efecto del termofosfato sobre el crecimiento y producción de papa (Solanum tuberosum L.) / Effect of thermophosphate on the growth and production of potatoes (Solanum tuberosum L.)

RESUMEN El cultivo de papa es uno de los más representativos de los Andes colombianos. El cultivo tiene altos costos de producción, entre los cuales, la fertilización representa un 36% del total. Los avances tecnológicos en nutrición vegetal han permitido el desarrollo de nuevos compuestos, que generan una mayor asimilación y disponibilidad de los elementos nutritivos, durante los periodos productivos. Dentro de las diferentes fuentes de fósforo empleadas en Colombia, está como alternativa, el termofosfato o fosfato térmico. Por esto, el objetivo del presente trabajo fue evaluar la aplicación del termofosfato en el cultivo de papa variedad 'Superior', en condiciones de campo, en el municipio de Villa Pinzón, Cundinamarca. Se empleó un diseño completamente al azar, con 4 tratamientos, que correspondieron a diferentes porcentajes de fosfato térmico 100% fosfato diamónico (DAP) (manejo convencional); 80% DAP, 20% fosfato térmico (FT); 40% DAP, 60% FT y 20% DAP, 80% FT, (0, 300, 600 y 900kg ha-1), con tres réplicas, para un total de 12 unidades experimentales. Las variables evaluadas fueron pesos fresco y seco, de parte área y raíz, concentración de fósforo en tejido y rendimiento por calidades y total. Se observó que la aplicación de termofosfato en diferentes concentraciones generó un efecto positivo con diferencias estadísticas (P≤0,05), en todas las variables evaluadas. El tratamiento de 600kg ha-1 de termofosfato, se muestra como una alternativa para el aporte de fósforo dentro de los planes de fertilización, en busca de una mejor respuesta fisiológica y productiva del cultivo de papa.

ABSTRACT Potato cultivation is one of the most representative activities of the Colombian Andes. The crop has high production costs, among which fertilization represents 36% of the total Technological advances in plant nutrition have allowed the development of new compounds that generate greater assimilation and availability of nutritional elements during productive periods. Within the different phosphorus sources available in Colombia, thermophosphate exists as an alternative. For this reason, the objective of this research was to evaluate the application of thermophosphate in the potato crop, Superior 'variety, under field conditions in the municipality of Villa Pinzón-Cundinamarca. A completely randomized design was used with 4 treatments that corresponded to different percentages of thermal phosphate: 100% diammonium phosphate (DAP) (conventional management); 80% DAP, 20% thermal phosphate (TF); 40% DAP, 60% TF and 20% DAP, 80% TF (0, 300, 600 y 900kg ha-1), with three replicas for a total of 12 experimental units. The variables evaluated were fresh and dry weights of areal and root part, phosphorus concentration in tissue and yield by qualities and the total. It was observed that the application of thermophosphate at different concentrations generated a positive effect, statistically different (P≤0.05) in all the variables evaluated. Thermophosphate, at 600kg ha-1 was found to be an alternative for the contribution of phosphorus within the fertilization plans, in search of a better physiological and productive response of the potato crop.

EVALUACIÓN DE UN TERMOFOSFATO EN EL CRECIMIENTO Y PRODUCCIÓN DE FRESA (Fragaria x ananassa Duch.) cv. 'ALBIÓN' / EVALUATION OF THERMOPHOSPHATE IN GROWTH AND PRODUCTION THE STRAWBERRY Fragaria x ananassa Duch.) cv. 'ALBIÓN'

RESUMEN La fresa es una de las frutas más importantes en el mundo, por sus múltiples usos industriales, medicinales y culinarios. En Colombia, la producción se concentra en los departamentos de Cundinamarca, Antioquia, Norte de Santander, Cauca y Boyacá. Su crecimiento y productividad están determinados por una adecuada fertilización en elementos, como nitrógeno (N), potasio (K), calcio (Ca) y fósforo (P), siendo el P un elemento de gran importancia, en diversos procesos fisiológicos, pero con baja disponibilidad para las plantas, en suelos con condiciones de acidez. Por esta razón, el objetivo de la investigación fue evaluar el efecto de una fuente no convencional de fósforo (termofosfato), en el crecimiento y en la producción de plantas de fresa cv. 'Albión', bajo condiciones del municipio de Viracachá, Boyacá. Se utilizó un diseño experimental completamente al azar, con 4 tratamientos, que correspondieron a dosis crecientes de termofosfato (0, 300, 600 y 900kg ha-1), con 4 repeticiones. Se evaluó el contenido de clorofilas totales, peso seco de parte aérea y raíz, número de estructuras reproductivas, producción de frutos, concentración foliar de P, Ca y silicio (Si). Se presentaron diferencias significativas (P≤0,05) en las variables clorofilas totales, peso seco de raíz, producción por calidad, concentración foliar de P y Si; las demás variables no mostraron diferencias estadísticas. Los mejores resultados, se presentaron con los tratamientos de 300 y 600kg ha-1 de termofosfato, convirtiéndolo en una alternativa de suministro en suelos con problemas de acidez y baja disponibilidad de P.

SUMMARY The strawberry is one of the most important fruits in the world for its multiple industrial, medicinal and culinary uses. In Colombia, the production is concentrated in the departments of Cundinamarca, Antioquia, Norte de Santander, Cauca and Boyacá. Its growth and productivity are determined by an adequate fertilization in elements such as nitrogen (N), potassium (K), calcium (Ca) and phosphorus (P), being P an element of great importance in various physiological processes but with low availability for plants in soils with acidic conditions. For this reason, the aim of this study was to evaluate the effect of an unconventional source of phosphorus (thermophosphate), on the growth and production of strawberry plants cv. 'Albión' under conditions of the municipality of Viracachá, Boyacá. A completely randomized experimental design was used, with 4 treatments, which were increasing doses of thermophosphate (0, 300, 600 and 900kg ha-1) with 4 repetitions. The content of total chlorophylls, dry weight of aerial part and root, number of reproductive structures, production and foliar concentration of phosphorus, calcium and silicon were evaluated. There were significant differences (P≤0.05) in the variables total chlorophyll, root dry weight, production by quality, foliar concentration of P, Ca and silicon (Si); the other variables did not show statistical differences. The best results were presented with the treatments of 300 and 600 kg ha-1 of thermophosphate turning it into an alternative supply in soils with acidity problems and low availability of P.