Respuestas del maíz que indican que el paclobutrazol induce mayor actividad genética

The aim of the research was to determine the effect of Paclobutrazol (PBZ) in the genetic activity of the maize cultivars Puma, 30P49 and DK2020, through the evaluation of response variables greenness, height of plant, stem diameter, leaf length and width, weight and volume of 1000 grains, protein content and grain yield per hectare. The experimental used was randomized complete blocks design with five replicates in two experiments performed during the 2008-2009 and 2009-2010 agricultural cycles; in the first cycle plots of four row of 40 m of long were used, where 200 kg of N ha-1 were applied; while in the second the length of plots was 5.0 m and fertilized with 250 kg of N ha-1. The doses were 150, 300 and 450 mg of PBZ L-1 of water until exposure of the fourth, sixth and eighth true leaf, respectively. The results indicated that PBZ induced greater genetic activity, since the synthesis of proteins and other components of cells, tissues and organs is a process that depends on the transcription of DNA messages in mRNA, amino acid synthesis, the transport of amino acids by tRNA and the binding of amino acids by the enzyme Peptidyl Transferase, which leads to the translation of messages into structural and active proteins (enzymes), to form more cells and substances that constitute them and consequently , cause more grain yield per hectare.El objetivo de esta investigación fue determinar el efecto que produce el Paclobutrazol (PBZ) en la actividad genética de los cultivares de maíz Puma 1076, 30P49 y DK2020 a través de la evaluación de las variables de respuesta verdor, altura de planta, diámetro del tallo, longitud y ancho de hoja, peso y volumen de 1000 granos, contenido de proteína y rendimiento de grano por hectárea. El diseño experimental fue bloques completos al azar con cinco repeticiones en dos experimentos realizados durante los ciclos agrícolas 2008-2009 y 2009-2010; en el primer ciclo se utilizaron parcelas de cuatro surcos de 40 m de largo, donde se aplicaron 200 kg de N ha-1; mientras que en el segundo experimento la longitud de las parcelas fue de 5,0 m y se fertilizó con 250 kg de N ha-1. Las dosis de PBZ fueron 150, 300 y 450 mg L-1 de agua al exponerse la cuarta, sexta y octava hoja verdadera, respectivamente. Los resultados indicaron que el PBZ indujo mayor actividad genética, ya que la síntesis de proteínas y de otros componentes de células, tejidos y órganos es un proceso que depende de la transcripción de mensajes del ADN en el ARNm, de la síntesis de aminoácidos, del transporte de aminoácidos por el ARNt y de la unión de aminoácidos por la enzima Peptidil Transferasa, lo que conlleva a la traducción de mensajes en proteínas estructurales y activas (enzimas), para formar más células y sustancias que constituyen a éstas y, en consecuencia, ocasionar más rendimiento de grano por hectárea

Sunlight transmitted by colored shade nets on photosynthesis and yield of cucumber

ABSTRACT: Black shading nets are widely used in the protected cultivation of vegetables as a technique for controlling light and temperature, while the colored shading nets, with special optical properties to improve the use of solar radiation, appeared recently in the agricultural plastics market. Light quality transmitted by gray, aluminized, pearl, blue, red and black (control) nets with 30% shade was evaluated, as well as its effects on photosynthetic properties and fruits production of cucumber plants. Treatments (shade nets) were established under a randomized complete block design with four repetitions. The red net transmitted 23.7 and 40.3% more photosynthetic photon flux density (400 to 700nm) and red light (600 to 700nm) and the blue net transmitted 36% more blue light (400 to 500nm) in comparison with the respective transmissions of black net. All nets increased the photosynthetic responses: transpiration, stomatal conductance and CO2 assimilation, observed in plants grown under black net. Leaf greenness (41.6 SPAD units) and foliar area (90dm2) increased 22.8 and 38.9% with the red net, while the dry weight of leaf (52.5g) increased 21.9% with pearl net. Pearl, red, aluminized and blue nets showed to be viable alternatives because the production of fruit increased in 71, 48, 46 and 46%, respectively, in comparison with the conventional black net (52t ha-1)