Submitted by LEANE CASTRO DE SOUZA null (leane_castro@hotmail.com.br) on 2017-04-02T14:54:55Z No. of bitstreams: 1 Leane_Castro_de_Souza.pdf: 1339773 bytes, checksum: 5be718ef938179ca41f5889b98eaa019 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2017-04-07T14:45:15Z (GMT) No. of bitstreams: 1 souza_lc_me_jabo.pdf: 1339773 bytes, checksum: 5be718ef938179ca41f5889b98eaa019 (MD5) / Made available in DSpace on 2017-04-07T14:45:15Z (GMT). No. of bitstreams: 1 souza_lc_me_jabo.pdf: 1339773 bytes, checksum: 5be718ef938179ca41f5889b98eaa019 (MD5) Previous issue date: 2017-03-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O trator assim como qualquer maquina, necessita de alguns ajustes para que ele possa realizar determinadas operações com qualidade e eficiência. Objetivou-se avaliar as consequências que a relação massa/potencia da maquina e as pressões internas dos pneus causa no solo, observando a deformação que o pneu causou ao solo, a largura do recalque, a profundidade do recalque, a resistência mecanica do solo a penetração (RMSP) e o avanço dinâmico em superfície de solo mobilizado. O experimento foi montado em blocos casualizados no esquema fatorial 4 x 4, com 16 tratamentos e quatro repetições. As combinações dos tratamentos foram quatro relações massa/potência no trator (53; 50,5; 47 e 44 kg cv-¹) e quatro pressões de inflação dos pneus traseiros (32, 28, 24 e 20 psi). Os dados foram submetidos a análise de variância e ao teste de regressão linear. A relação massa/potência e a pressão interna do pneu não afetaram a deformação que o pneu causou ao solo e a largura do rastro do mesmo, mas influenciaram a resistência mecânica do solo à penetração, o avanço dinâmico e a profundidade do rastro do pneu. A relação massa/potência e a pressão interna do pneu traseiro afetam diretamente a resistência a penetração, na camada de 11 a 20 cm, e a profundidade do recalque. A pressão nos pneus traseiros afetou o avanço dentro das massa/potência 53, 47 e 44 kg cv-1. / The tractor, like any machine, needs some adjustments so that it can perform certain operations with quality and efficiency. The objective of this study was to evaluate the effects of the mass / power ratio of the machine and the internal pressures of the tires on the ground, observing the deformation that the tire caused to the ground, the width of the repression, the depth of the repression, Penetration (RMSP) and the dynamic advance on mobilized soil surface. The experiment was assembled in randomized blocks in the 4 x 4 factorial scheme, with 16 treatments and four replications. The treatment combinations were four mass / power ratios in the tractor (53; 50.5, 47 and 44 kg cv-¹) and four inflation pressures of the rear tires (32, 28, 24 and 20 psi). Data were submitted to analysis of variance and linear regression. The mass / power ratio and the internal pressure of the tire did not affect the deformation caused by the tire to the ground and the track width of the tire, but influenced the mechanical resistance of the tire to penetration, dynamic advancement and tire tread depth. The mass / power ratio and the internal pressure of the rear tire directly affect the penetration resistance in the 11 to 20 cm layer and the depth of the rebound. The pressure on the rear tires affected the advance within the mass / power 53, 47 and 44 kg cv-1.

L’arboriculture en milieu méditerranéen nécessite un apport d’eau via l’irrigation important, notamment pendant la période estivale. Pour améliorer l’efficience d’utilisation de l’eau, il convient de mieux connaître les besoins en eau de l’arbre et les zones d’exploration et d’exploitation des racines. La croissance des racines varie dans le temps et dans l’espace en lien avec des facteurs endogènes, en particulier la disponibilité en assimilats carbonés, et des facteurs exogènes comme les propriétés du sol. Ces facteurs sont modulés par les pratiques culturales, et en particulier l’irrigation, le compactage du sol et l’éclaircissage, qui affectent la croissance racinaire, et d’une manière générale le fonctionnement global de l’arbre. La dynamique de croissance des racines est ponctuée par deux périodes de croissance intense. La première période de croissance intense se situe tôt dans la saison, en avril-mai, pendant la phase de durcissement du noyau des fruits. En début de saison la demande en carbone à l’échelle de l’arbre est importante (forte croissance des feuilles, fruits, rameaux, racines) et nécessite la mobilisation intense des réserves carbonées présentent sous forme d’amidon. La charge en fruits affecte la croissance des racines et des fruits, et la restriction hydrique affecte surtout la croissance de la partie aérienne. La deuxième période de croissance racinaire intense intervient après la récolte en juillet-août, quand les feuilles et les rameaux ont finis leur croissance. La compétition est moins forte et l’amidon s’accumule, surtout chez les arbres sous restriction hydrique. L’accumulation d’amidon résulte d’une plus grande sensibilité de la croissance au déficit hydrique que la photosynthèse. Pendant les périodes de croissances racinaires intenses, le diamètre apical et la longueur de leur zone apicale non ramifiée des racines sont augmentés, ainsi que les teneurs en sucres solubles dans les pointes racinaires. Les paramètres architecturaux racinaires et les teneurs en sucres solubles dans les pointes racinaires sont de bons indicateurs de la dynamique de croissance racinaire. La répartition des racines au verger est très variable et dépend des propriétés du sol. Les racines des arbres bien alimentés en eau ont colonisé surtout les volumes de sol sous le rang des arbres (proches des goutteurs) jusqu’à 1 m de profondeur. Au contraire les racines des arbres sous-alimentés en eau ont colonisé surtout les 50 cm en profondeur sous le rang et vers l’inter-rang. Les racines se sont réparties dans les zones les moins contraignantes pour leur croissance, qui sont plus restreintes quand l’irrigation est restrictive. En conditions non contraignantes, de par une faible densité de sol ou une forte teneur en eau, la vitesse de croissance, et notamment des grosses racines, est forte. Par contre, les fines racines ont une vitesse de pénétration des sols contraignants plus rapide. La contrainte mécanique entraîne aussi une baisse de la hiérarchisation des systèmes racinaires, les racines latérales seront davantage ramifiées / Fruit tree production in Mediterranean climate needs water supply via irrigation, particularly during summer. To improve water use efficiency, it is necessary to better understand the water need of tree and to localize soil volumes colonized by roots. Root growth varies in time and space following endogenous factors, like carbohydrate availability, and exogenous factors like soil properties. These factors are affected by cultural practices and particularly by irrigation, soil compaction and thinning. Root growth dynamics is marked by two intensive root growth periods. The first period of intensive root growth occurs early in the season, in April-May, during the phase of stone hardening of fruit. Early in the season, carbohydrates demand at tree scale is high (leaves, fruits, shoots, roots are growing) and leads to an intense mobilization of starch reserve. Crop load affects root and fruit growth, and the deficit irrigation affects principally the aerial growth. The second period of intensive root growth occurs after the fruit harvest in July-August, when leaves and shoot stopped their growth. Competition for carbohydrates is reduced and starch contents rise, particularly in trees submitted to deficit irrigation. Starch accumulation traduces a higher sensibility of growth than photosynthesis under deficit irrigation. During intensive root growth periods, apical diameter and the length of apical unbranched zone are increased, and water soluble carbohydrates contents in root tips too. Root architectural parameters and water soluble carbohydrates contents are good indicators of root growth dynamics. Root distribution in orchard is variable and depends of soil properties. Roots of wellirrigated trees colonized especially soil volumes in the row (under drippers) until 1 m in depth. On the opposite, root of trees submitted to deficit irrigation colonized the first 50 cm in depth, both in the row and the inter-row. Root colonized soil volumes where soil mechanical resistance was the lowest, and these soil volumes are more reduced in deficit irrigation. Low soil mechanical resistance, with low bulk density and high water content, allows a higher root elongation and particularly for thick roots. On the opposite, fine roots have a higher elongation in strength soil than thick roots. The soil mechanical resistance leads to reduce the root system hierarchy; lateral roots were more branched