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.

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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.

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Background and aims: Baccharis notosergila is presented as a productivity-reducing weed in the fields of the Salado river basin, Buenos Aires, Argentina. The aims of this work were: to describe the structure of the underground system, the origin of sprouts, locate the secretory structures and storage substance to understand the adaptation strategies of this species as well as its ability to withstand chemical and mechanical control. M&M: The collected material was examined with conventional optical microscopy techniques. Histochemical tests to identify secondary metabolites were performed, and crystals were analyzed by a scanning electron microscope. Results: The subterranean system found was a xylopodium which has high shoot bud-forming potential. Storage substance was found to be inulin. Test for starch was negative. Resins and lipids (oil drops) were identified in ducts of roots; tannins and crystals of calcium oxalate were also found in the xylopodium and roots. Conclusions: The presence of these characteristics on the underground systems could explain the frequency of this species in the floristic from Salado river basin in which alternate periods of 2 high humidity and drought. The belowground bud bank would be important to B. notosergila survival in this area with extreme climatic factors, and its resistance to mechanical and chemical control. Understanding the anatomical features of these plants is one of the steps to appropriate management of this species in the Salado river basin.

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.