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Fisiologia y Nutricion Vegetal

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  • 1. FISIOLOGIA Y NUTRICION VEGETAL Hugo Soplin V. Ph.D. Marzo 2013
  • 2. 6 CO2 + 6 H20 + Energia lumínica + clorofila=> C6H1206 + 6 02 C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + Energy Reducción Oxidación oxidación Reducc. FOTOSINTESIS RESPIRACION
  • 3. SON PLANTAS C-3 FOTORESPIRAN RESPONDEN AL ENRIQUECIMIENTO ATMOSFERICO CON CO2 Y AL ABONAMIENTO ORGANICO
  • 4. FISIOLOGIA VEGETAL - LUIS ROSSI 17 CLOROPLASTOS: MEMBRANA DEL TILACOIDE COMPOSICION QUIMICA : • -CLOROFILAS:10%. Son complejos de porfirinas-Mg. • Tipos: a,b,c y d. • Formadas por un núcleo porfirínico tetrapirrólico con un átomo de Mg en el centro; presentan una cadena hidrocarbonada de fitol embebida en la membrana del tilacoide. Mg
  • 5. FISIOLOGIA VEGETAL - LUIS ROSSI 18 CLOROPLASTOS: MEMBRANA DEL TILACOIDE COMPOSICION QUIMICA : • - CAROTENOIDES: 2%. • Pueden ser de color amarillo o anaranjado. • Tipos: Los carotenos y las xantófilas. • El más abundante es el ß-caroteno • Función: • colector de la energía luminosa, y • protegen a la clorofila contra la fotooxidación por el O2.
  • 6. FISIOLOGIA VEGETAL - LUIS ROSSI 22 FASES DE LA FOTOSINTESIS • Comprende 2 fases: • La fase luminosa que se lleva a cabo a nivel de las membranas de los tilacoides y • La fase oscura que se lleva a cabo a nivel del estroma.
  • 7. FISIOLOGIA VEGETAL - LUIS ROSSI 24 PS II PS I H2O 2e- 2e- 2e- 1/2 O2 2H+ NADP+ NADPH + H+ PQ ferredoxina 2e- 2e- 2hv 2hv ADP + Pi ATP Cit b - f PC FOTOFOSFORILACION NO CICLICA FOTOFOSRORILACION CICLICA FASE LUMINOSA- ESQUEMA Z
  • 8. FISIOLOGIA VEGETAL - LUIS ROSSI 35 PLANTAS C4 CELULAS DEL MESOFILO CELULAS DE VAINA VASCULAR CO2 C1 + C3 C4 C4 C3+C1 C3 +Productos CICLO DE CALVIN AMP + Ppi ATP H A Z V A S C U L A R
  • 9. FISIOLOGIA VEGETAL - LUIS ROSSI 39 FOTORESPIRACION • Proceso que se da en las plantas debido a la característica de la RUBISCO de funcionar en una forma diferente a como lo hace durante la Fotosíntesis de acuerdo a la [ ] de CO2 que se presenta en el medio, lo que provoca una pérdida del carbono en la forma de CO2, durante los períodos de luz.
  • 10. 1. Fotosintesis neta = Fotosíntesis bruta – Respiración (AHORRO) = INGRESO - GASTO 2. Fotosíntesis neta = Fotosíntesis bruta - (Respiración + Fotorespiración) ¿Que tipo de planta responde mucho mejor al a) Aumento en la concentración de CO2 atmosférico b) Abonamiento orgánico Las plantas C4 ¿ Fotorespiran? Igualdad Tipo de planta ¿ C3 o C4 ? 1 ¿? 2 ¿?
  • 11. Figura 1. Destinos posibles de la Chl excitada. Cuando la Chl absorbe luz se excita desde su estado de reposo a su estado singlete excitado, 1Chl*. De allí tiene varios modos de regresar de nuevo al estado de reposo. Puede regresar emitiendo luz que se observa como fluorescencia (1). La energía de excitación puede usarse como combustible para las reacciones fotosintéticas(2),o puede desexcitarse disipando calor. Estos dos últimos mecanismos reducen la cantidad de fluorescencia de la clorofila. Por eso se hace referencia a ellos como qP y DNF de la fluorescencia de la clorofila. Finalmente, vía cruzamiento intersistemas1Chl*, produce3Chl* (4), que a su vez es capaz de producir 1O2*, una especie de oxígeno muy reactivo.
  • 12. Los estados de activación de oxígeno. La primera reacción de reducción es superóxido Las reducciones subsiguientes forman peróxido de hidrógeno, radical hidroxilo y agua.
  • 13. ¿QUÉ ES UN RADICAL LIBRE? Radical libre es aquella especie química capaz de existir independientemente y que posee uno o más electrones desapareados. Este electrón desapareado confiere al radical libre cierto grado de inestabilidad. para alcanzar la estabilidad, el radical libre puede perder este electrón, en cuyo caso se comporta como agente oxidante. Activación del oxígeno Puede ocurrir por dos mecanismos diferentes La absorción de energía suficiente para invertir el giro de uno de los electrones desapareados La forma birradical de oxígeno está en un estado fundamental triplete debido a que los electrones tienen espines paralelos Si el oxígeno triplete absorbe la energía suficiente para invertir el giro de uno de sus electrones desapareados, se forma el estado de singlete, tienen espines opuestos
  • 14. SITIOS DE PRODUCCIÓN DE OXÍGENO ACTIVO CLOROPLASTOS MITOCONDRIAS RETICULO ENDOPLASMICO Microcuerpos Las membranas plasmáticas PARED CELULAR
  • 15. Oxígeno activado y agentes que generan radicales libres de oxígeno, tales como las radiaciones ionizantes, inducir lesiones en el ADN que numerosas deleciones, mutaciones causan y otros efectos genéticos letales. El daño oxidativo al ADN
  • 16. Overall picture of the regulation of photon capture and the protection and repair of photodamage. Protection against photodamage is a multilevel process. The first line of defense is suppression of damage by quenching of excess excitation as heat. If this defense is not sufficient and toxic photoproducts form, a variety of scavenging systems eliminate the reactive photoproducts. If this second line of defense also fails, the photoproducts can damage the D1 protein of photosystem II. This damage leads to photoinhibition. The D1 protein is then excised from the PSII reaction center and degraded. A newly synthesized D1 is reinserted into the PSII reaction center to form a functional unit. (After Asada 1999.)
  • 17. MECANISMOS DE DEFENSA No enzimáticas:  Ácido ascórbico  Glutatión  Tocoferol (Vitamina E)  Carotenoides Enzimáticas:  Superóxido dismutasa  Catalasa  Ascorbato peroxidasa MANTIENEN EL (ROS) EN NIVELES NO PERJUDICIALES
  • 18. ANTIOXIDANTES Es una sustancia capaz de neutralizar la acción de un radical libre. Muchos alimentos vegetales los contienen en gran cantidad. Son las mismas sustancias que les protegen de ser fácilmente oxidados por la acción del aire y el sol.
  • 19. ANTIOXIDANTE NEUTRALIZANDO RADICALES LIBRES
  • 20. MICRONUTRIENTE FUNCION Boron A primary function of boron is related to cell wall formation, so boron- deficient plants may be stunted. Sugar transport in plants, flower retention and pollen formation and germination also are affected by boron. Seed and grain production are reduced with low boron supply. Boron-deficiency symptoms first appear at the growing points. This results in a stunted appearance (rosetting), barren ears due to poor pollination, hollow stems and fruit (hollow heart) and brittle, discolored leaves and loss of fruiting bodies. Boron deficiencies are found mainly in acid, sandy soils in regions of high rainfall, and those with low soil organic matter. Borate ions are mobile in soil and can be leached from the root zone. Boron deficiencies are more pronounced during drought periods when root activity is restricted.
  • 21. Copper Copper is necessary for carbohydrate and nitrogen metabolism and, inadequate copper results in stunting of plants. Copper also is required for lignin synthesis which is needed for cell wall strength and prevention of wilting. Deficiency symptoms of copper are dieback of stems and twigs, yellowing of leaves, stunted growth and pale green leaves that wither easily. Copper deficiencies are mainly reported on sandy soils which are low in organic matter. Copper uptake decreases as soil pH increases. Increased phosphorus and iron availability in soils decreases copper uptake by plants.
  • 22. Iron Iron is involved in the production of chlorophyll, and iron chlorosis is easily recognized on iron-sensitive crops growing on calcareous soils. Iron also is a component of many enzymes associated with energy transfer, nitrogen reduction and fixation, and lignin formation. Iron is associated with sulfur in plants to form compounds that catalyze other reactions. Iron deficiencies are mainly manifested by yellow leaves due to low levels of chlorophyll. Leaf yellowing first appears on the younger upper leaves in interveinal tissues. Severe iron deficiencies cause leaves to turn completely yellow or almost white, and then brown as leaves die. Iron deficiencies are found mainly on high pH soils, although some acid, sandy soils low in organic matter also may be iron-deficient. Cool, wet weather enhances iron deficiencies, especially on soils with marginal levels of available iron. Poorly aerated or compacted soils also reduce iron uptake by plants. Uptake of iron decreases with increased soil pH, and is adversely affected by high levels of available phosphorus, manganese and zinc in soils.
  • 23. Manganese Manganese is necessary in photosynthesis, nitrogen metabolism and to form other compounds required for plant metabolism. Interveinal chlorosis is a characteristic manganese-deficiency symptom. In very severe manganese cases, brown necrotic spots appear on leaves, resulting in premature leaf drop. Delayed maturity is another deficiency symptom in some species. White/gray spots on leaves of some cereal crops is a sign of manganese deficienc. Manganese deficiencies mainly occur on organic soils, high-pH soils, sandy soils low in organic matter, and on over-limed soils. Soil manganese may be less available in dry, well-aerated soils, but can become more available under wet soil conditions when manganese is reduced to the plant-available form. Conversely, manganese toxicity can result in some acidic, high-manganese soils. Uptake of manganese decreases with increased soil pH and is adversely affected by high levels of available iron in soils.
  • 24. Molybdenu m Molybdenum is involved in enzyme systems relating to nitrogen fixation by bacteria growing symbiotically with legumes. Nitrogen metabolism, protein synthesis and sulfur metabolism are also affected by molybdenum. Molybdenum has a significant effect on pollen formation, so fruit and grain formation are affected in molybdenum-deficient plants. Because molybdenum requirements are so low, most plant species do not exhibit molybdenum-deficiency symptoms. These deficiency symptoms in legumes are mainly exhibited as nitrogen-deficiency symptoms because of the primary role of molybdenum in nitrogen fixation. Unlike the other micronutrients, molybdenum-deficiency symptoms are not confined mainly to the youngest leaves because molybdenum is mobile in plants. The characteristic molybdenum deficiency symptom in some vegetable crops is irregular leaf blade formation known as whiptail, but interveinal mottling and marginal chlorosis of older leaves also have been observed. Molybdenum deficiencies are found mainly on acid, sandy soils in humid regions. Molybdenum uptake by plants increases with increased soil pH, which is opposite that of the other micronutrients. Molybdenum deficiencies in legumes may be corrected by liming acid soils rather than by molybdenum applications. However, seed treatment with molybdenum sources may be more economical than liming in some areas.
  • 25. Zinc Zinc is an essential component of various enzyme systems for energy production, protein synthesis, and growth regulation. Zinc deficient plants also exhibit delayed maturity. Zinc is not mobile in plants so zinc- deficiency symptoms occur mainly in new growth. Poor mobility in plants suggests the need for a constant supply of available zinc for optimum growth. The most visible zinc deficiency symptoms are short internodes and a decrease in leaf size. Delayed maturity also is a symptom of zinc- deficient plants. Zinc deficiencies are mainly found on sandy soils low in organic matter and on organic soils. Zinc deficiencies occur more often during cold, wet spring weather and are related to reduced root growth and activity as well as lower microbial activity decreases zinc release from soil organic matter. Zinc uptake by plants decreases with increased soil pH. Uptake of zinc also is adversely affected by high levels of available phosphorus and iron in soils.
  • 26. Chloride Because chloride is a mobile anion in plants, most of its functions relate to salt effects (stomatal opening) and electrical charge balance in physiological functions in plants. Chloride also indirectly affects plant growth by stomatal regulation of water loss. Wilting and restricted, highly branched root systems are the main chloride-deficiency symptoms, which are found mainly in cereal crops. Most soils contain sufficient levels of chloride for adequate plant nutrition. However, reported chloride deficiencies have been reported on sandy soils in high rainfall areas or those derived from low-chloride parent materials. There are few areas of chloride-deficient so this micronutrient generally is not considered in fertilizer programs. In addition, chloride is applied to soils with KCl, the dominant potassium fertilizer. The role of chloride in decreasing the incidence of various diseases in small grains is perhaps more important than its nutritional role from a practical viewpoint.
  • 27. CLAVE PARA EL DIAGNOSTICO VISUAL DE DESÓRDENES DE NUTRIENTES. La “Clave para el diagnostico visual de desórdenes nutricionales” que se muestra a continuación es una herramienta útil que puede ayudar a diagnosticar problemas nutricionales específicos en cultivos. La clave le pregunta primero escoger si los síntomas visuales observados estaban en las hojas superiores o en las inferiores. Debajo de estas dos primeras selecciones se encuentran cuatro recuadros con descripciones de diferentes síntomas visuales que pueden aparecer en plantas de apariencia no saludable. Si encuentra un recuadro que concuerda con el problema que observa en sus plantas, mire al recuadro debajo de el para identificar el nutriente o grupo de nutrientes que pueden causar esos síntomas cuando ellas son deficientes. La fila inferior de recuadros, que no están presentes para tres de los síntomas visuales, enumera los nutrientes que pueden causar síntomas similares cuando ellos están presentes en cantidades excesivas o tóxicas.
  • 28. Precautions in identifying nutrient stress symptoms include the following: 1. Many symptoms appear similar. For instance, N and S deficiency symptoms can be very alike, depending upon plant growth stage and severity of deficiencies. 2. Multiple deficiencies and/or toxicities can occur at the same time. More than one deficiency or toxicity can produce symptoms, or possibly an abundance of one nutrient can induce the deficiency of another (e.g. excessive P causing Zn deficiency). 3. Crop species, and even some cultivars of the same species, differ in their ability to adapt to nutrient deficiencies and toxicities. For example, corn is typically more sensitive to a Zn deficiency than barley and will show Zn deficiency more clearly
  • 29. 4. Pseudo (false) deficiency symptoms (visual symptoms appearing similar to nutrient deficiency symptoms). Potential factors causing pseudo deficiency include, but are not limited to, disease, drought, excess water, genetic abnormalities, herbicide and pesticide residues, insects, and soil compaction. 5. Hidden hunger. Plants may be nutrient deficient without showing visual clues. 6. Field symptoms appear different than ‘ideal’ symptoms. Many of the plants shown in this module as photographs were grown under controlled nutrient conditions, and deficiency/toxicity symptoms observed in the field may or may not appear as they do here. Experience and knowledge of field history are excellent aids in determining causes for nutrient stress.
  • 30. Chlorophyll meters are faster than tissue testing for N. Samples can be taken often and repeated if results are questionable. The meters are used to measure leaf greenness, which is positively related to leaf chlorophyll content. Research indicates a close correlation between leaf chlorophyll content and leaf N content because much of the leaf N is contained in the chlorophyll.
  • 31. La absorción de nutrientes durante las primeras Nueve semanas de establecida la plantación es muy baja, luego se incrementa , encontrándose que los valores máximos de absorción ocurren en las semanas 18, 23 y 28, etapas que coinciden con las etapas de mayor producción de frutos. El período de mayor absorción se encuentra entre las semanas 9 y 26 y las épocas de aplicación de fertilizantes que venían siendo utilizadas en Costa Rica no reflejaban los picos altos de requerimientos de nutrientes. Basándose en los datos obtenidos en el estudio de absorción de nutrientes a través del tiempo se determinó que, en términos prácticos, la fertilización de la fresa puede distribuirse en 3 etapas importantes del cultivo. Durante las primeras 12 semanas se debe agregar el 20% del fertilizante requerido, en el período comprendido entre las semanas 12 y 18 se debe aplicar 40% y entre las se-manas 20 y 24 se debe aplicar el restante 40%.
  • 32. La existencia de plantas en las que hasta e l de la 50% del peso seco de la savia del xilema es mineral, es el origen de los metodos modemos de "fitoextraccion". Estos c onsisten en la reclamacion de suelos contaminados mediante el cultivo de estas especies "hiperacumuladoras« y el procesamiento posterior del material vegetal cosechado. Estas especies capaces de extraer cantidades importantes de Se (alfalfa), Mn (Macadamia neurophylla), Al (Te), Cu (Ipomoeaa alpina) y Ni (Psychotria caerorulescens) entre otras, han sido identificadas.
  • 33. GRACIAS POR VUESTRA PACIENCIA