Caracterización fisiológica, productiva y de calidad en arroz negro (Oryza sativa spp. japonica) bajo condiciones hídricas contrastantes
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Date
2025
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Universidad de Concepción
Abstract
El arroz (Oryza sativa L.) es uno de los cultivos más importantes a nivel mundial y se considera un alimento básico para gran parte de la población. En Chile, su producción se concentra principalmente en las regiones del Maule y Ñuble, donde las condiciones ambientales resultan más favorables. No obstante, el cultivo enfrenta diversas limitaciones, como bajas temperaturas, disponibilidad limitada de agua y suelos de baja fertilidad, lo que limita las opciones de manejo y de rotación para la industria arrocera.
El arroz se cultiva tradicionalmente en condiciones de inundación, lo que requiere un elevado volumen de agua para mantener la sostenibilidad y la productividad del cultivo. En los últimos años, los efectos del cambio climático se han intensificado, evidenciándose principalmente en la disminución de la frecuencia y la cantidad de las precipitaciones, lo que ha provocado una creciente escasez hídrica que afecta directamente la producción arrocera. Frente a este escenario, resulta fundamental desarrollar nuevos cultivares capaces de tolerar el déficit hídrico y de utilizar el agua de manera más eficiente, sin comprometer la calidad del grano.
El arroz blanco es el más producido y consumido a nivel mundial; sin embargo, dentro de la especie Oryza sativa existen otros tipos de arroz, denominados pigmentados, que presentan tonalidades que van desde el rojo hasta el púrpura oscuro, siendo este último conocido como arroz negro. Originario de Asia, el arroz negro se distingue por su alta concentración de antocianinas en el pericarpio, responsables de su coloración característica. Estudios comparativos entre arroces pigmentados y no pigmentados han evidenciado una mayor tolerancia de los primeros al déficit hídrico.
El Programa de Mejoramiento Genético de Arroz (PMGA) del Instituto de Investigaciones Agropecuarias (INIA) de Chile ha concentrado sus esfuerzos en la evaluación de genotipos para determinar su rendimiento en condiciones de cambio climático y en el desarrollo de cultivares adaptados a ambientes variables. Sin embargo, los genotipos de arroz negro solo han sido caracterizados en condiciones de inundación, por lo que aún se desconoce su desempeño frente al estrés hídrico en términos de rasgos agronómicos, productivos y de calidad. En este contexto, el presente estudio evaluó las características agronómicas, fisiológicas, de calidad industrial, nutricional y funcional en líneas avanzadas de arroz negro desarrolladas por el PMGA, cultivadas bajo regímenes hídricos contrastantes.
Mediante ensayos multiambiente realizados durante tres temporadas, se evaluaron 19 genotipos de arroz negro y un cultivar de arroz blanco (Zafiro-INIA) utilizado como referencia, bajo dos condiciones de manejo hídrico: inundación tradicional (IND) y riego sin inundación (NI). Se estimaron componentes de varianza, valores genotípicos, heredabilidad e interacción genotipo × ambiente para los distintos rasgos evaluados. El tratamiento NI redujo significativamente la floración, la calidad del grano y el rendimiento. En promedio, los genotipos de arroz negro mostraron un 31 % menos de rendimiento que el cultivar blanco y obtuvieron 2,4 veces más producción bajo condiciones de inundación que bajo riego sin inundación. Se observaron fuertes correlaciones genéticas entre el rendimiento de grano y características como los días a antesis, el peso del grano, así como la blancura y la translucidez del grano, todas ellas con alta heredabilidad en sentido amplio (H² > 0,9). La mayoría de los rasgos evaluados presentaron una heredabilidad elevada (H² > 0,7), lo que indica una alta
estabilidad genética. El rendimiento de grano se correlacionó negativamente con el porcentaje de esterilidad de la panícula (r = −0,84) y presentó una heredabilidad de 0,76. A pesar de este alto valor de heredabilidad, las condiciones de cultivo tuvieron un efecto significativo en el rendimiento.
Se seleccionaron dos líneas avanzadas de arroz negro (Quila 279101 y Quila 292008), que, junto con el cultivar Zafiro-INIA, fueron evaluadas en dos localidades bajo ambas condiciones hídricas (IND y NI). A los genotipos se les evaluaron diversos rasgos de calidad, incluidos parámetros industriales, nutricionales y funcionales, con énfasis en la composición fenólica y la actividad antioxidante. Los genotipos de arroz negro presentaron altos niveles de contenido fenólico total (TPC), con un promedio de 74,8 mg GAE 100 g⁻¹, y una capacidad antioxidante significativamente superior a la del cultivar de arroz blanco, atribuida principalmente al elevado contenido de cianidina-3- O-glucósido en los granos pigmentados. El perfil fenólico varió entre el grano integral y el grano pulido, mientras que la composición mineral dependió de la localidad y del régimen de riego. Se observó una alta correlación entre el color del grano, el TPC y la actividad antioxidante. La calidad del grano estuvo influida por el ambiente, tanto en sus características industriales como en sus propiedades nutricionales, y se detectaron diferencias significativas entre el grano integral y el pulido.
Adicionalmente, se caracterizaron funcionalmente los granos de arroz en términos de digestibilidad, capacidad antioxidante y citotoxicidad. En los granos cocidos de arroz negro se observó una mayor liberación de grupos amino durante todas las fases del proceso de digestión. Entre los péptidos identificados, destacó RA05_ORYSJ por su perfil funcional. No se detectó citotoxicidad del arroz negro en células intestinales Caco-2 ni en células neuronales SH-SY5Y bajo condiciones de estrés oxidativo inducido. Los genotipos de arroz negro redujeron significativamente (>50%) la producción de especies reactivas de oxígeno. Asimismo, el arroz negro disminuyó la actividad de la β-galactosidasa en más de un 65%, lo que sugiere un posible efecto protector frente a la senescencia celular.
Estos resultados destacan la importancia de establecer criterios y herramientas de selección basados en la caracterización integral del arroz negro, que permitan orientar el mejoramiento genético hacia la obtención de cultivares resilientes frente a la variabilidad climática, con alto rendimiento y elevado valor nutracéutico, contribuyendo a diversificar y agregar valor al sector arrocero en Chile, mediante la producción de granos con potencial para el desarrollo de alimentos funcionales.
Rice is traditionally cultivated under flooded conditions, which requires a high volume of water to maintain crop sustainability and productivity. In recent years, the effects of climate change have intensified, primarily manifested in reduced rainfall frequency and amount, leading to increasing water scarcity that directly impacts rice production. Under these circumstances, it is essential to develop new cultivars that tolerate water deficit and use water more efficiently, without compromising grain quality. White rice is the most produced and consumed type worldwide; however, within the Oryza sativa species, there are other types of rice, known as pigmented rice, which range in color from red to dark purple, the latter commonly referred to as black rice. Native to Asia, black rice is distinguished by its high anthocyanin content in the pericarp, which gives it its characteristic color. Comparative studies between pigmented and non-pigmented rice have shown that pigmented varieties exhibit greater tolerance to water deficit. The Rice Breeding Program (RBP) of the Institute of Agricultural Research (INIA) in Chile has focused on evaluating genotypes to assess their performance under climate change conditions and on developing cultivars adapted to variable environments. However, black rice genotypes have been characterized only under flooded conditions, and their performance under water stress remains unknown for agronomic, productive, and quality traits. In this context, the present study evaluated agronomic, physiological, industrial, and nutritional quality, as well as functional characteristics of advanced black rice lines developed by the RBP, cultivated under contrasting water regimes. Through multi-environment trials conducted over three seasons, 19 black rice genotypes and a white rice cultivar (Zafiro-INIA) were evaluated under two water management conditions: traditional flooding (IND) and non-flooded irrigation (NI). Variance components, genotypic values, heritability, and genotype × environment interactions were estimated for the evaluated traits. The NI treatment significantly reduced flowering, grain quality, and yield. On average, black rice genotypes produced 31% less than the white rice cultivar and yielded 2.4 times more under flooded conditions than under NI. Strong genetic correlations were observed between grain yield and traits such as days to anthesis, grain weight, chalkiness, and translucency, all of which showed high broad-sense heritability (H² > 0.9). Most evaluated traits exhibited high heritability (H² > 0.7), indicating strong genetic stability. Grain yield correlated negatively with panicle sterility percentage (r = −0.84) and had a heritability of 0.76. Despite the high heritability, growing conditions had a significant impact on yield. Two advanced black rice lines (Quila 279101 and Quila 292008) and the cultivar Zafiro-INIA were assessed at two locations under both water regimes (IND and NI). The genotypes were evaluated for various quality traits, including industrial, nutritional, and functional traits, with a focus on phenolic composition and antioxidant activity. Black rice genotypes exhibited a high total phenolic content (TPC), averaging 74.8 mg GAE/100 g⁻1, and significantly higher antioxidant capacity than the white rice cultivar, primarily due to their elevated cyanidin-3-O-glucoside content. The phenolic profile varied between whole and polished grains, whereas the mineral composition depended on location and irrigation regime. High correlations were observed between grain color, TPC, and antioxidant activity. Grain quality was influenced by the environment, affecting both industrial and nutritional characteristics, and significant differences were observed between whole and polished grains. Additionally, the functional properties of rice grains were characterized by evaluating protein digestibility, antioxidant capacity, and cytotoxicity. Cooked black rice grains showed higher release of amino groups throughout all digestion phases. Among the identified peptides, RA05_ORYSJ stood out for its functional profile. No cytotoxicity was detected in black rice using Caco-2 intestinal cells or SH-SY5Y neuronal cells under induced oxidative stress. Black rice genotypes significantly (>50%) reduced reactive oxygen species production. Moreover, black rice decreased β-galactosidase activity by more than 65%, suggesting a potential protective effect against cellular senescence. These results highlight the importance of establishing selection criteria and tools based on the comprehensive characterization of black rice, enabling the breeding of resilient cultivars with high yield and high nutraceutical value, thereby contributing to the diversification, and added value of the rice sector in Chile through the production of grains with potential for functional food development.
Rice is traditionally cultivated under flooded conditions, which requires a high volume of water to maintain crop sustainability and productivity. In recent years, the effects of climate change have intensified, primarily manifested in reduced rainfall frequency and amount, leading to increasing water scarcity that directly impacts rice production. Under these circumstances, it is essential to develop new cultivars that tolerate water deficit and use water more efficiently, without compromising grain quality. White rice is the most produced and consumed type worldwide; however, within the Oryza sativa species, there are other types of rice, known as pigmented rice, which range in color from red to dark purple, the latter commonly referred to as black rice. Native to Asia, black rice is distinguished by its high anthocyanin content in the pericarp, which gives it its characteristic color. Comparative studies between pigmented and non-pigmented rice have shown that pigmented varieties exhibit greater tolerance to water deficit. The Rice Breeding Program (RBP) of the Institute of Agricultural Research (INIA) in Chile has focused on evaluating genotypes to assess their performance under climate change conditions and on developing cultivars adapted to variable environments. However, black rice genotypes have been characterized only under flooded conditions, and their performance under water stress remains unknown for agronomic, productive, and quality traits. In this context, the present study evaluated agronomic, physiological, industrial, and nutritional quality, as well as functional characteristics of advanced black rice lines developed by the RBP, cultivated under contrasting water regimes. Through multi-environment trials conducted over three seasons, 19 black rice genotypes and a white rice cultivar (Zafiro-INIA) were evaluated under two water management conditions: traditional flooding (IND) and non-flooded irrigation (NI). Variance components, genotypic values, heritability, and genotype × environment interactions were estimated for the evaluated traits. The NI treatment significantly reduced flowering, grain quality, and yield. On average, black rice genotypes produced 31% less than the white rice cultivar and yielded 2.4 times more under flooded conditions than under NI. Strong genetic correlations were observed between grain yield and traits such as days to anthesis, grain weight, chalkiness, and translucency, all of which showed high broad-sense heritability (H² > 0.9). Most evaluated traits exhibited high heritability (H² > 0.7), indicating strong genetic stability. Grain yield correlated negatively with panicle sterility percentage (r = −0.84) and had a heritability of 0.76. Despite the high heritability, growing conditions had a significant impact on yield. Two advanced black rice lines (Quila 279101 and Quila 292008) and the cultivar Zafiro-INIA were assessed at two locations under both water regimes (IND and NI). The genotypes were evaluated for various quality traits, including industrial, nutritional, and functional traits, with a focus on phenolic composition and antioxidant activity. Black rice genotypes exhibited a high total phenolic content (TPC), averaging 74.8 mg GAE/100 g⁻1, and significantly higher antioxidant capacity than the white rice cultivar, primarily due to their elevated cyanidin-3-O-glucoside content. The phenolic profile varied between whole and polished grains, whereas the mineral composition depended on location and irrigation regime. High correlations were observed between grain color, TPC, and antioxidant activity. Grain quality was influenced by the environment, affecting both industrial and nutritional characteristics, and significant differences were observed between whole and polished grains. Additionally, the functional properties of rice grains were characterized by evaluating protein digestibility, antioxidant capacity, and cytotoxicity. Cooked black rice grains showed higher release of amino groups throughout all digestion phases. Among the identified peptides, RA05_ORYSJ stood out for its functional profile. No cytotoxicity was detected in black rice using Caco-2 intestinal cells or SH-SY5Y neuronal cells under induced oxidative stress. Black rice genotypes significantly (>50%) reduced reactive oxygen species production. Moreover, black rice decreased β-galactosidase activity by more than 65%, suggesting a potential protective effect against cellular senescence. These results highlight the importance of establishing selection criteria and tools based on the comprehensive characterization of black rice, enabling the breeding of resilient cultivars with high yield and high nutraceutical value, thereby contributing to the diversification, and added value of the rice sector in Chile through the production of grains with potential for functional food development.
Description
Tesis presentada para optar al grado de Doctora en Ciencias de la Agronomía
Keywords
Mejoramiento vegetal, Riego - Eficiencia, Arroz