Thermal imaging to phenotype traditional maize landraces for drought tolerance

Searching and identification of new crops or varieties with higher adaptation or resistance to water stress is one of the strategies to make agriculture profitable and more sustainable. Especially en arid and semi areas with limiting water resources. This study establishes a practical, fast and replicable protocol to select maize genotypes for its capability to respond to water stress. Eight Portuguese maize landraces (LD), traditionally grown in areas with different altitude and subjected to potentially different degrees of water stress (low altitude = potentially lower stress; high altitude = potentially higher stress) was used. Seedlings were subjected to continuous watering (FI) or forced to water withholding (non-irrigated) for a period of 7-8 days followed by re-watering (NI). Leaf temperature was determined every 48 h by thermal imaging and the temperature difference between NI and FI plants (ΔTNI-FI) was calculated. We found that those genotypes that traditionally had been grown at higher altitudes kept more stable leaf temperature values under dry or wet conditions (small ΔTNI-FI) even under severe water stress. These results will help to optimize a screening protocol for maize seedlings and select novel genotypes or LDs better adapted to water stress, especially in regions where irrigation water is scarce.Searching and identification of new crops or varieties with higher adaptation or resistance to water stress is one of the strategies to make agriculture profitable and more sustainable. Especially en arid and semi areas with limiting water resources. This study establishes a practical, fast and replicable protocol to select maize genotypes for its capability to respond to water stress. Eight Portuguese maize landraces (LD), traditionally grown in areas with different altitude and subjected to potentially different degrees of water stress (low altitude = potentially lower stress; high altitude = potentially higher stress) was used. Seedlings were subjected to continuous watering (FI) or forced to water withholding (non-irrigated) for a period of 7-8 days followed by re-watering (NI). Leaf temperature was determined every 48 h by thermal imaging and the temperature difference between NI and FI plants (ΔTNI-FI) was calculated. We found that those genotypes that traditionally had been grown at higher altitudes kept more stable leaf temperature values under dry or wet conditions (small ΔTNI-FI) even under severe water stress. These results will help to optimize a screening protocol for maize seedlings and select novel genotypes or LDs better adapted to water stress, especially in regions where irrigation water is scarce

Descomposición de hojarasca y reciclado del nitrógeno de frutales tropicales y subtropicales en terrazas de cultivo en la costa de Granada (SE España)

El experimento se realizó en la costa de Granada (SE España). Se estudiaron la descomposición de la hojarasca y el reciclado del nitrógeno en cuatro tipos de hojas de frutales de origen subtropical y tropical: mango (Mangifera indica L.), chirimoyo (Annona cherimola Mill.), níspero (Eriobotrya japonica Lindl.) y aguacate (Persea americana Mill.), empleando la técnica de las bolsas. El chirimoyo tuvo las mayores tasas de descomposición de hojarasca, mientras que la de mango fue la más persistente. Las constantes de descomposición (k) para mango, níspero, aguacate y chirimoyo fueron 0,64, 0,84, 0,80 y 1,30 años-1, respectivamente. El nitrógeno en níspero y mango fue inmovilizado durante los primeros meses en un 73 y 21%, respectivamente, siendo liberado más tarde. En contraste con la hojarasca de chirimoyo y aguacate, que no experimentaron periodos de inmovilización. El estudio de la dinámica de liberación de nutrientes en un suelo agrícola y en particular en terrazas de cultivo es muy importante para predecir la disponibilidad y el reciclado de nutrientes para las plantas y en consecuencia, sus implicaciones medioambientales.El experimento se realizó en la costa de Granada (SE España). Se estudiaron la descomposición de la hojarasca y el reciclado del nitrógeno en cuatro tipos de hojas de frutales de origen subtropical y tropical: mango (Mangifera indica L.), chirimoyo (Annona cherimola Mill.), níspero (Eriobotrya japonica Lindl.) y aguacate (Persea americana Mill.), empleando la técnica de las bolsas. El chirimoyo tuvo las mayores tasas de descomposición de hojarasca, mientras que la de mango fue la más persistente. Las constantes de descomposición (k) para mango, níspero, aguacate y chirimoyo fueron 0,64, 0,84, 0,80 y 1,30 años-1, respectivamente. El nitrógeno en níspero y mango fue inmovilizado durante los primeros meses en un 73 y 21%, respectivamente, siendo liberado más tarde. En contraste con la hojarasca de chirimoyo y aguacate, que no experimentaron periodos de inmovilización. El estudio de la dinámica de liberación de nutrientes en un suelo agrícola y en particular en terrazas de cultivo es muy importante para predecir la disponibilidad y el reciclado de nutrientes para las plantas y en consecuencia, sus implicaciones medioambientales. Litter decomposition and nitrogen cycling from subtropical crops grown in orchardterraces in the coast of Granada (SE Spain)AbstractThe experiment was carried out in the Granada coast (SE Spain). It was studied the litterdecomposition and nitrogen recycling in four kinds of fruit leaves of subtropical and tropical: mango(Mangifera indica L.), cherimoya (Annona cherimola Mill), loquat (Eriobotrya japonica Lindl.) Andavocado (Persea americana Mill), using the bag technique. The cherimoya had the highest ratesof litter decomposition, while the mango was the most persistent. Decay constants (k) for mango,loquat, avocado and cherimoya were 0.64, 0.84, 0.80 and 1.30 year-1, respectively. The loquatand mango nitrogen was immobilized during the first months in 73 and 21%, respectively, and thenreleased. In contrast with the cherimoya and avocado leaves which did not experience periodsof immobilization. The study of nutrient dynamics release in an agricultural soil and in particularcultivation terraces is very important to predict the availability and recycling of plant nutrients andhence their environmental implications

Long-term impact of sustained-deficit irrigation on yield and fruit quality in sweet orange cv. Salustiana (SW Spain)

Long-term impact of different sustained-deficit irrigation (SDI) treatments on a 13-year-old orange orchard (Citrus sinensis L. Osbeck, cv. Salustiana) was studied from 2004 to 2008. The experiment consisted of a control irrigation treatment which was applied at 100% of the crop evapotranspiration (ETc) values for the whole season, and three SDIs imposed as a function of different water-stress index (WSI) values, defined as the ratio of the actual volume of water supply to the ETc rate. The values defined by the WSI were 0.75, 0.65, and 0.50. The plant-water status was measured through the midday stem-water potential (ΨStem). Yearly, yield and fruit quality were evaluated at harvest in each treatment, and a global analysis was carried out using the whole dataset. Overall, no significant differences were found in fruit yield between SDIs and control treatments, although significant differences appeared in some of the fruit-quality parameters (total soluble solids and titrable acidity) which also showed significant relationships with integrated stem-water potential (ΨInt) and irrigation water applied. These findings lead us to conclude that SDIs have important and statistically significant effects on fruit quality. Thus, the application of sustained-deficit irrigation (SDI with WSI of 50) provides promising possibilities for optimising citrus irrigation and boosting the water productivity for citrus orchards in a semiarid Mediterranean climate.Long-term impact of different sustained-deficit irrigation (SDI) treatments on a 13-year-old orange orchard (Citrus sinensis L. Osbeck, cv. Salustiana) was studied from 2004 to 2008. The experiment consisted of a control irrigation treatment which was applied at 100% of the crop evapotranspiration (ETc) values for the whole season, and three SDIs imposed as a function of different water-stress index (WSI) values, defined as the ratio of the actual volume of water supply to the ETc rate. The values defined by the WSI were 0.75, 0.65, and 0.50. The plant-water status was measured through the midday stem-water potential (ΨStem). Yearly, yield and fruit quality were evaluated at harvest in each treatment, and a global analysis was carried out using the whole dataset. Overall, no significant differences were found in fruit yield between SDIs and control treatments, although significant differences appeared in some of the fruit-quality parameters (total soluble solids and titrable acidity) which also showed significant relationships with integrated stem-water potential (ΨInt) and irrigation water applied. These findings lead us to conclude that SDIs have important and statistically significant effects on fruit quality. Thus, the application of sustained-deficit irrigation (SDI with WSI of 50) provides promising possibilities for optimising citrus irrigation and boosting the water productivity for citrus orchards in a semiarid Mediterranean climate. Impacto em longo prazo do déficit de irrigação-sustentada na produtividade equalidade dos frutos em laranjeira doce cv. Salustiana (SW Espanha)ResumoO impacto em longo prazo de diferentes tratamentos de irrigação-sustentada (SDI) em um pomarde laranjas de 13 anos de idade (Citrus sinensis L. Osbeck, cv. Salustiana) foi estudado de 2004 a2008. O experimento consistiu de um tratamento de irrigação controle que foi aplicado a 100%da evapotranspiração de cultura (ETc) para toda a temporada e três SDIs impostas em funçãode diferentes valores de estresse hídrico (WSI), definidos como a relação do volume real de águarequerido com relação à taxa de ETc. Os valores definidos pela WSI foram 0,75, 0,65 e 0,50. O statusplanta-água foi medido através do potencial de tronco-água a meio-dia (ΨStem). Anualmente, aprodução e a qualidade dos frutos foram avaliadas no momento da colheita em cada tratamento,e uma análise global foi realizada utilizando o conjunto inteiro de dados. Em geral, não foramencontradas diferenças significativas na produção de frutos entre os SDIs e os tratamentos controle,embora diferenças significativas apareceram em alguns dos parâmetros de qualidade de fruto(sólidos solúveis totais e acidez titulável), que também mostraram relações significativas compotencial tronco-água integrado (ΨInt) e água de irrigação aplicada. Essas observações levam aconcluir que as SDIs têm efeitos importantes e estatisticamente significativos na qualidade dos frutos.Assim, a aplicação do déficit de irrigação-sustentada (SDI com WSI de 50) oferece possibilidadespromissoras para otimizar a irrigação de citros e aumentar a produtividade da água para pomaresde citros em um clima semi-árido Mediterrâneo

Mitigación de la erosión de suelos en plantaciones de almendro por cubiertas vegetales: implicaciones para la agricultura sostenible de montaña (SE España)

The conservation and sustainable management of soil and water resources are some of the biggest challenges in rainfed agricultural systems. During two hydrological years, we have studied the rates of erosion and soil runoff from hillside farming in three types of vegetation: barley (Hordeum vulgare), vetch (Vicia sativa) and thyme (Thymbra capitata), in an extensive planting of almond (Prunus amygdalus). The esperiment was conducted in Lanjaron (Granada, SE Spain) with closed erosion plots of 144 m2 (24 mx 6 m) on a hillside with a slope of 35%. Three meter wide vegetable strips were arranged intermittently and across the slope between rows of almond trees. The recordsof erosion and agricultural runoff were significantly lower in plots covered with thyme, in contrast to those recorded with vetch. The effectiveness of the thyme-covered over the barley and vetch ones in controlling erosion and runoff exceeded 69 and 67%, respectively. Cover crops while cutting and stopping the path of surface runoff retained transported sediments and promote their infiltration into the soil. Besides, the remaining runoff with much less energy can reinfiltrate on the ground before being intercepted by the next swath. We have concluded that the combination of growing woody plant and cover stripes represents an efficient model of adaptation to the traditional systems to improve productivity and sustainability of mountain agriculture in semiarid climate.La conservación y gestión sostenible de los recursos suelo y agua constituyen uno de los mayores retos de los sistemas agrícolas de secano. Durante dos años hidrológicos se han estudiado las tasas de erosión y escorrentía de un suelo de cultivo en ladera con tres tipos de cubierta vegetal: cebada (Hordeum vulgare), veza (Vicia sativa), y tomillo (Thymbra capitata) en una plantación extensiva de almendros (Prunus amygdalus). El ensayo se realizó en Lanjarón (Granada, SE España) con parcelas cerradas de erosión de 144 m2 (24 m x 6 m) en una ladera con pendiente del 35%. Las franjas vegetales de 3 m de ancho se dispusieron de forma intermitente y transversal a la pendiente entre hileras de árboles de almendro. Los registros de erosión y escorrentía agrícolas fueron significativamente inferiores en las parcelas con cubiertas de tomillo, en contraste con las registradas con veza. La efectividad de las cubiertas de tomillo respecto a las de cebada y veza en el control de erosión y escorrentía superaron el 69 y 67%, respectivamente. Las cubiertas vegetales al recortar y frenar la trayectoria de la escorrentía superficial retienen los sedimentos transportados y promueven su infiltración en el suelo. Asimismo, la escorrentía remanente con mucho menos energía puede reinfiltrarse en el suelo antes de ser interceptada por la siguiente franja. Se concluye que la asociación de cultivo leñoso con franjas de cubiertas vegetales representa un modelo eficiente de adaptación a los sistemas tradicionales para la mejora de la productividad y sostenibilidad de la agricultura de montaña de clima semiárido

Bioenergy farming using woody crops. A review

The global energy consumption was 540 EJ in 2010, representing an increase of about 80 % from 1980. Energy demand is predicted to grow more than 50 % by 2025. Fossil fuels will supply about 75 % of the future energy demand in 2030–2050 if there are no significant technological innovations or carbon emission constraints. This will induce in a substantial increase of CO2 atmospheric concentration and, in turn, adverse climatic impacts. A solution to this issue is to replace fossil fuels by renewable fuels such as biomass. For instance cultivated woody biomass shows many advantages such as allowing multiple harvests without having to replant. Poplar, eucalyptus, salix, paulownia and black locust are common examples of woody biomass. Here we review the current situation and future tendency of renewable energy focusing on solid biomass in Europe and Spain. We also discuss the potential production for short-rotation plantations in the bioenergy sector and existing constraints for the implantation in Spain in a sustainable context. Countries with low biomass resources and high targets for renewable electricity may have to depend on imported solid biomass, whereas countries with wide solid biomass resources benefit from international markets. The expansion of short-rotation plantations is much lower than expected in some countries such as Spain

Thermal imaging to phenotype traditional maize landraces for drought tolerance

Searching and identification of new crops or varieties with higher adaptation or resistance to water stress is one of the strategies to make agriculture profitable and more sustainable. Especially en arid and semi areas with limiting water resources. This study establishes a practical, fast and replicable protocol to select maize genotypes for its capability to respond to water stress. Eight Portuguese maize landraces (LD), traditionally grown in areas with different altitude and subjected to potentially different degrees of water stress (low altitude = potentially lower stress; high altitude = potentially higher stress) was used. Seedlings were subjected to continuous watering (FI) or forced to water withholding (non-irrigated) for a period of 7-8 days followed by re-watering (NI). Leaf temperature was determined every 48 h by thermal imaging and the temperature difference between NI and FI plants (ΔTNI-FI) was calculated. We found that those genotypes that traditionally had been grown at higher altitudes kept more stable leaf temperature values under dry or wet conditions (small ΔTNI-FI) even under severe water stress. These results will help to optimize a screening protocol for maize seedlings and select novel genotypes or LDs better adapted to water stress, especially in regions where irrigation water is scarce.Searching and identification of new crops or varieties with higher adaptation or resistance to water stress is one of the strategies to make agriculture profitable and more sustainable. Especially en arid and semi areas with limiting water resources. This study establishes a practical, fast and replicable protocol to select maize genotypes for its capability to respond to water stress. Eight Portuguese maize landraces (LD), traditionally grown in areas with different altitude and subjected to potentially different degrees of water stress (low altitude = potentially lower stress; high altitude = potentially higher stress) was used. Seedlings were subjected to continuous watering (FI) or forced to water withholding (non-irrigated) for a period of 7-8 days followed by re-watering (NI). Leaf temperature was determined every 48 h by thermal imaging and the temperature difference between NI and FI plants (ΔTNI-FI) was calculated. We found that those genotypes that traditionally had been grown at higher altitudes kept more stable leaf temperature values under dry or wet conditions (small ΔTNI-FI) even under severe water stress. These results will help to optimize a screening protocol for maize seedlings and select novel genotypes or LDs better adapted to water stress, especially in regions where irrigation water is scarce

Thermal imaging to phenotype traditional maize landraces for drought tolerance

Searching and identification of new crops or varieties with higher adaptation or resistance to water stress is one of the strategies to make agriculture profitable and more sustainable. Especially en arid and semi areas with limiting water resources. This study establishes a practical, fast and replicable protocol to select maize genotypes for its capability to respond to water stress. Eight Portuguese maize landraces (LD), traditionally grown in areas with different altitude and subjected to potentially different degrees of water stress (low altitude = potentially lower stress; high altitude = potentially higher stress) was used. Seedlings were subjected to continuous watering (FI) or forced to water withholding (non-irrigated) for a period of 7-8 days followed by re-watering (NI). Leaf temperature was determined every 48 h by thermal imaging and the temperature difference between NI and FI plants (ΔTNI-FI) was calculated. We found that those genotypes that traditionally had been grown at higher altitudes kept more stable leaf temperature values under dry or wet conditions (small ΔTNI-FI) even under severe water stress. These results will help to optimize a screening protocol for maize seedlings and select novel genotypes or LDs better adapted to water stress, especially in regions where irrigation water is scarce.Searching and identification of new crops or varieties with higher adaptation or resistance to water stress is one of the strategies to make agriculture profitable and more sustainable. Especially en arid and semi areas with limiting water resources. This study establishes a practical, fast and replicable protocol to select maize genotypes for its capability to respond to water stress. Eight Portuguese maize landraces (LD), traditionally grown in areas with different altitude and subjected to potentially different degrees of water stress (low altitude = potentially lower stress; high altitude = potentially higher stress) was used. Seedlings were subjected to continuous watering (FI) or forced to water withholding (non-irrigated) for a period of 7-8 days followed by re-watering (NI). Leaf temperature was determined every 48 h by thermal imaging and the temperature difference between NI and FI plants (ΔTNI-FI) was calculated. We found that those genotypes that traditionally had been grown at higher altitudes kept more stable leaf temperature values under dry or wet conditions (small ΔTNI-FI) even under severe water stress. These results will help to optimize a screening protocol for maize seedlings and select novel genotypes or LDs better adapted to water stress, especially in regions where irrigation water is scarce

Irrigation of pistachios: strategies to confront water scarcity

Pistachio trees are capable to be profitable under rain-fed conditions. They also have a good response to low amounts of irrigation water, so are a great candidate to be considered for water-scarcity scenarios. The pistachio tree has a singular way of alternate bearing, losing a percentage of its floral buds in the year preceding the harvest year. This percentage of abscission of the fruit buds increases in situations of water stress, making irrigation strategy follow as a 1-year determinant for the next season fruit yield. Despite its high resistance to severe water stress conditions, the pistachio tree has high water requirements. To overcome this issue, regulated deficit irrigation (RDI) was tested as a technique to save water without affecting yield. Coupling the use of plant biosensors to this technique is a research approach that can improve its efficiency. The recourse to these techniques created a greater preference of the resultant product by the consumer