Orientador: Roberto Testezlaf / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-17T15:07:28Z (GMT). No. of bitstreams: 1 Barreto_CarlosViniciusGarcia_D.pdf: 1170238 bytes, checksum: 3ef00ad2a818db42ea1cce28d13a137b (MD5) Previous issue date: 2011 / Resumo: A produção de mudas de citros no estado de São Paulo se caracteriza pelo emprego de sistemas manuais de irrigação por aspersão com manejo de lamina superestimada, implicando em baixas eficiências de aplicação de água. O emprego da irrigação por capilaridade, ou subirrigação, e uma opção com condições técnicas para maximizar o desenvolvimento de mudas cítricas e aumentar a eficiência do emprego da água. O objetivo do presente trabalho foi desenvolver um sistema de irrigação que utilize os atributos físicos do substrato, permitindo a condução ascendente da água aplicada subsuperficialmente e que atenda adequadamente as necessidades de irrigação da cultura. A pesquisa foi dividida em duas etapas: avaliação das características físicas dos substratos comerciais de casca pinus e fibra coco para determinar aquele que apresenta as melhores características de retenção de umidade e ascensão de água para aplicação na irrigação por capilaridade e analisar o crescimento vegetal de porta-enxertos de limoeiro cravo cultivado em tubete irrigado no equipamento desenvolvido para diferentes posições do nível de saturação no interior do tubete, comparando ao sistema tradicional de irrigação. Nessa etapa, foram avaliados porta-enxertos de limoeiro cravo, aos 30 dias apos a semeadura (30 DAS), cultivados em 3 tratamentos: T1, aplicação de água por capilaridade com nível de saturação a 2/3 da altura do tubete, T2, aplicação de água por capilaridade a 1/3 da altura e T3, aplicação de água por chuveiros, com analises fisiológicas e fotométricas das plantas sob esses tratamentos. Os resultados de avaliação dos substratos demonstraram que os materiais com maior granulometria (grosseiros) não apresentam boa retenção de água, possuindo alta aeração e menor ascensão da água. Constatou-se maior atuação da capilaridade em substratos de menor granulometria (finos), com maior retenção e ascensão de água e com elevação de umidade sob níveis de tensão de água facilmente disponível as plantas. O substrato fino de fibra de coco se mostrou mais adequado por possuir maior capacidade de retenção de água, boa elevação de água por capilaridade e água disponível as plantas em toda sua coluna. A analise da aplicação da irrigação por capilaridade, demonstrou que o tratamento T1 condicionou as plantas a uma menor transpiração sob maior resistência estomática, menor aquecimento das folhas e maior potencial da água na folha na antemanha. O status hídrico-fisiológico das plantas sob T1 resultou em maior assimilação de carbono, expressando maior porte, maior enfolhamento e abreviamento do ciclo em relação as plantas cultivas sob T2 e, principalmente, sob T3. As plantas sob T2 apresentaram resultados próximos a T1, ao passo em que as plantas cultivadas sob T3 apresentaram maior perda de água pelos estômatos, refletindo pior status hídrico e em menor desenvolvimento vegetal. A partir dos resultados obtidos foi possível concluir que o sistema de irrigação por capilaridade demonstrou-se adequado ao cultivo de porta-enxertos de limoeiro cravo, com boa resposta da produção vegetal para o nível de água no tubete nas duas posições do nível de saturação avaliadas, e apresentando possibilidade de reaproveitamento da água de irrigação / Abstract: The nurseries production of Sao Paulo State is characterized by the application of manual sprinkler hose system with over scheduled irrigation depth, resulting in low water application efficiency. The use of capillary irrigation, or subirrigation, is a technical alternative with conditions to maximize the citrus rootstocks growing and to increase the water use efficiency. The objective of present work was to develop an irrigation system that applies the physical attributes of substrates in capillary water rise process from a subsuperficial water source to attend plant water demands. The methodology was divided in two phases: physical evaluation of pine and coconut fiber commercial substrates to determine the most suitable for water holding and water rise capacities for capillary irrigation; and analysis of growing response of Citrus limonia Osbeck rootstocks cultivated in a capillary irrigation equipment for two positions of water saturation level inside of recipients, comparing with the usual irrigation system. In this step, were evaluated rootstocks of Citrus limonia Osbeck at 30 days after sowing (DAS), under three treatments, T1, water application by capillary trays with water level at 2/3 of height from the base of recipients, T2, water level at 1/3 of height, and T3, manually sprinkler hose irrigation, with analysis of physiological and physical parameters of the plants. The results of substrates evaluation confirmed that the materials with greater average particle size distribution (coarse) did not showed good water holding capacity, with high aeration and lower water rise. It was observed good capillary rise in fine textured substrates, with greater water holding and water rise with low water tension profile. The coconut substrate showed more suitable for capillarity application due to the higher water holding capacity, adequate capillary water rise and easily available moisture to the plants in entire substrate column. The analysis of capillary irrigation effects in rootstock growing showed that T1 treatment conditioned the plants to a lower transpiration rate under greater stomata resistance, lower leaf temperature and higher leaf water potential at predawn. The water-physiological relations for T1 resulted in greater carbon assimilation, expressing in bigger plants with more leaves that resulted in crop cycle reduction when compared with T2, and mainly T3 plants. The rootstocks under T2 grew like T1 plants, nevertheless T3 presented more water loss through stomata, reflecting worse water status and lower plant growing. It was possible to conclude from the results, that capillary irrigation is suitable for Citrus limonia Osbeck rootstock growing in nursery production, showing adequate crop response for both saturation levels evaluated and the possibility to be adapted for irrigation water reuse / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola

For millennia, scions have been grafted onto dwarfing apple rootstocks to reduce final tree size. However, it is unclear how scion architecture is first modified by the dwarfing apple rootstock, the time from grafting when this occurs and the endogenous hormonal signalling mechanisms that may cause the initial modifications in growth that then define the future architecture of the scion. In this study, the dwarfing (M.9) rootstock significantly decreased the mean total shoot length and node number of ‘Royal Gala’ apple scions by the end of the first year of growth from grafting when compared with rootstock(s) of greater vigour (MM.106, M.793 and a ‘Royal Gala’ rootstock control). Similarly, the auxin transport inhibitor 1-N-naphthylphthalamic acid (NPA) applied to the stem of vigorous rootstocks significantly decreased mean total shoot length and node number of the scion, and the architectural changes imposed were generally similar to those imposed by M.9. For example, both treatments decreased the mean length and node number of the primary shoot, reduced the formation of secondary axes on the primary shoot and caused a greater proportion of primary and secondary shoots (if present) to terminate growth early. Decreased formation of secondary axes imposed by both treatments was reversed by applying the cytokinin benzylaminopurine (BAP) repeatedly to the scion, whilst applications of gibberellins (GA4+7) reduced the proportion of primary and secondary shoots that terminated growth early, therefore increasing the final mean length and node number of these shoot types. Both M.9 and NPA also significantly decreased the final mean dry mass and length of the root system. Given these general similarities, it is proposed that the basipetal IAA signal is of central importance in rootstock-induced scion dwarfing, and that a shoot/root/shoot signalling mechanism may exist whereby the stem tissue of the M.9 rootstock decreases the basipetal transport of IAA to the root during summer, thereby decreasing root growth and the amount of rootproduced cytokinin and gibberellin transported to scion. Reduced amounts of cytokinin transported to the scion may decrease branching, whilst reduced amounts of gibberellins may decrease the duration for which a large proportion of primary and secondary shoots grow. Analysis of endogenous hormones for newly grafted composite ‘Royal Gala’ apple trees on rootstocks of different vigour provided some additional support for these ideas. It is recommended that future studies elucidate what unique properties of the M.9 bark act to restrict IAA transport, whilst it is concluded that gene(s) regulating rootstock-induced scion dwarfing are likely to control processes within the rootstock that modify the metabolism of IAA, its basipetal transport and the subsequent synthesis of root-produced vigour-inducing hormones including cytokinins and gibberellins.