This work was aimed at testing the involvement of ethylene in the maturation of grain and senescence of the foliar structures of the wheat inflorescence . Whole wheat ears emitted ethylene to the atmosphere . From pre-anthesis, ethylene emission progressively increased from 0.76 nl g -1 FW h -1 to a peak 1 .53 nl g -1 FW h -1 at the hard dough stage of the grains, to fall to a minimum of 0 .10 nl g -1 FW h -1 at the dormant seed stage . Ethephon increased the ethylene release, hastened the process of grain maturation and senescence of the ears . Aminoethoxyvinylglycine and silver thiosulfate produced the opposite effects . It is concluded that ethylene plays a role in grain maturation and in the senescence of the green bracts of the inflorescence .Abbreviations : Ag+ = silver ion ; AVG = aminoethoxyvinylglycine ; SAM = S-adenosylmethionine ; STS = silver thiosulfate ; TGW = thousand grain weight 107
Treatment of flag leaves and ears of wheat plants with MJ (jasmonic acid methylester) (10 −5 and 10 −4 M) did not increase ethylene production, but it did accelerate senescence as indicated by the loss of chlorophyll. MJ also caused the closure of stomata, and consequently the rates of transpiration and photosynthesis decreased. Early maturity shortened the grain filling period, so the thousand grain weight was lower. Although ethylene elicited the same physiologic effects, the syndrome of senescence by MJ is independent of the former. We conclude that senescence and death in wheat are far from being elucidated; however, MJ and ethylene seem to participate in the phenomenon.
About ten years ago nurseries began to test several novel apricot stocks developed either to reduce plant vigour and boost early as well as high cropping or as a more suitable replacement for Myrabolan (Prunus cerasifera) and Apricot seedling in water-logged or chlorotic soils. These stocks were the Italian bred selections of Prunus domestica Penta and Tetra, the P. cerasifera Adara and the Prunus insititia Adesoto® 101, both Spanish-bred seedlings, and Plumina®, a Prunus bessey × P. cerasifera hybrid developed in France. Performance testing was carried out under a national project. The trials were set up in 2001 in plots of pilot orchards at Imola in Bologna Province, Ancona, Caserta, Palermo and Cagliari, their soil profiles differing notably from each other. They were tested against Apricot seedling and Myrabolan 29C controls grafted to cv. San Castrese. The experimental layout was split-plot with 15 replicates per plant and the trees were trained to delayed vase. Performance results after the first seven years indicate the viability of Penta and Tetra and, contrary to expectations, that Adesoto® 101 is incompatible with apricot and Adara is too weak in heavy soils.
Background and aims: Baccharis notosergila is an aggressive weed inhabiting the Salado river basin, Buenos Aires province, Argentina. The aims of this work were: to analyze the morpho-anatomy and histochemistry of aerial vegetative organs in order to understand the adaptation strategies that ensure its survival, as well as to expand knowledge on traits determining resistance to the control methods applied. M&M: The material collected was prepared and examined with conventional techniques of microscopy. Histochemical tests to identify starch, resins, polyphenols, and lipophilic substances were performed. Results: The major features found were small and deciduous leaves; uniseriate epidermis with massive and striate cuticle; stomata at level or slightly above the other epidermal cells and glandular trichomes secreting oily substances; stomata on both surfaces and isobilateral mesophyll. Tannins, starch and lipophilic substances were identified in leaves and stems; polyphenols, resins and lipids in ducts, and calcium oxalate crystals in leaves, stems and capitate trichomes. Conclusions: The aerial vegetative organs features of B. notosergila explain its tolerance to the unfavorable conditions of the Salado river basin area, as well as its high competitive ability over others species of the natural prairie. The reduced and deciduous leaves, the epidermal traits, and chemical substances found constitute a physical and chemical barrier reducing dehydration as well as the penetration of the herbicides applied for its control. Botanical knowledge of B. notosergila is the basis for the design and development of new and appropriate management methods for this species.
With the aim of evaluating the distribution of assimilates in tomato (Lycopersicon esculentum Mill), a trial under greenhouse was carried out with plants in hydroponic solution. The treatments were: H 1 ; H 2 and H 3: Controls with the first, second and third leaf (among the first and the second truss) supplied with glucose [ C 14 (U) ] respectively H 4: Pruning of the third leaf between trusses and the second leaf supplied. The pruning was done 25 days after the anthesis of the first cluster, the leaves were supplied in all treatments. 24 hours later, the plants were fractionated in root, shoot, basal leaves, expanded leaves, non expanded leaves, 1 st , 2 nd and 3 rd trusses and apex. The plant material remained in stove up to constant weight. The samples were digested with OHNa 9N, homogenized, and scintillating solution Bray + cab-o-sil at 5% was added. The activity of the samples were measured in a Beckman LS 100 C liquid scintillation counter. The pruning of the third leaf modified the pattern distribution of assimilates in the plant. The group of clusters were the most important sinks in all treatments, reaching the highest value in H 4 (70%). The stem was an important sink in all treatments. The highest contribution to it (30%) was done by the second leaf (H 2 ). The removal of the third leaf increased the amount of assimilates entering the fruits and decreased the amount of glucose entering the stem.
24 de abril de 2015 I Agradecimientos Agradezco a la Universidad Nacional de La Plata y en especial a la Facultad de Ciencias Agrarias y Forestales por haberme brindado la formación y el soporte económico para la realización de este trabajo. Al Instituto de Fisiología Vegetal (INFIVE-CONICET) donde pude llevar a cabo los ensayos experimentales que forman parte de este trabajo. A la Facultad de Ciencias Naturales y Museo, institución que me otorgó el título de grado y cuyos pasillos continué transitando todos estos años para recibir el aporte y ayuda desinteresada de investigadores y amigos que me brindaron sus conocimientos y ayuda de forma permanente. Deseo agradecer a las siguientes personas que han sido un baluarte importante durante todo el transcurso de este trabajo: -A mi director, Ing. Agr. José Beltrano, por sus aportes constantes de conocimientos, sugerencias e ideas que enriquecían las charlas y debates, agradeciendo muy profundamente su acompañamiento durante toda esta etapa. -A mi codirector, Ing. Agr. Horacio Acciaresi, quien me brindó sus conocimientos y ayuda durante el desarrollo de este trabajo. -A los Ing. Agr. Omar Pagani del INTA Banderas (Santiago del Estero) y Pablo Beluccini del INTA Marcos Juárez (Córdoba) por el envío del material vegetal con el cual se llevó a cabo este trabajo. -A la Dra. Marta Ronco, por su ayuda y compañía incondicional y desinteresada. -A las Dras. María Luján Luna, Gabriela Giúdice y Mariana Grossi por compartir sus conocimientos y experiencias en morfología vegetal y por brindarme su amistad. -A mis compañeros de las cátedras de Fisiología Vegetal y Morfología Vegetal de la Facultad de Ciencias Agrarias, que me han brindado su compañerismo a diario. -A Luciana Saldúa, quien me ha acompañado y brindado su apoyo durante toda esta etapa. II -A mis compañeros de trabajo del INFIVE, quienes me brindaron su compañerismo a diario, especialmente aportar los datos climáticos de las localidades evaluadas en este trabajo.A los señores evaluadores, quienes han aportado sus conocimientos y enriquecido los contenidos de la tesis.-A mi familia, especialmente mi hija Julia y mis padres, que han sido el ejemplo y estímulo más importante para encarar la vida con optimismo a pesar de las dificultades. III
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