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Escola Superior de Agricultura Luiz de Queiroz (2004)

Distribuição radicular e consumo de água de goiabeira (Psidium guajava L.) irrigada por microaspersão em Petrolina - PE.

Ferreira, Marcelo de Novaes Lima

Titre : Distribuição radicular e consumo de água de goiabeira (Psidium guajava L.) irrigada por microaspersão em Petrolina - PE.

Root distribuition and water consumption of microsprinkler irrigated guava (Psidium guajava L.) in Petrolina-PE.

Auteur : Ferreira, Marcelo de Novaes Lima

Université de soutenance : Escola Superior de Agricultura Luiz de Queiroz

Grade : Doutorado 2004

Résumé
A field experiment was carried out to estimate the crop water consumption in a guava cv. Paluma orchard, with two and half year-old plants in a 6 x 5 grid spacing irrigated by microsprinkler, at the Brazilian Agricultural Research Corporation – Agricultural Research Center of the Semi-Arid Tropic in Petrolina, Pernambuco State, Northeastern Brazil, based on the soil water balance method and the root distribuition pattern in the soil profile (digital image analysis). The soil water content was measured by two methods, the time domain reflectometry (TDR) and the neutron scattering (neutron probe). It was assumed that both soil water measuring methods provide similar values and, consequently, similar estimations of crop evapotranspiration would be obtained. The reference evapotranspiration (ETo) was measured by the class A evaporation pan and by the Penman-Monteith-FAO method. The crop coefficient (Kc) was obtained by the ETc/ETo ratio taking in account the method used to estimate the reference water consumption. Around 80% of total roots were found in the 0.94 m soil depth and until the 1,23 m distance from the trunk, although roots were observed until 1.2 m depth and 2.4 m distance from the plant row. Most of the roots sampled by the monolith method in the 0.2-0.6 m distance from the trunk presented a diameter (d) ≤ 2 mm (92,1%), while 4.8, 2.7 and 0.4% of roots were within the 2 < d ≤ 5 mm, 5 < d ≤ 10 mm, and d > 10 mm intervals. Soil water monitoring and application of fertilizer and manure should be performed at a 0.6 m distance from the trunk and until 0.6 m depth. Total crop water consumption was 691.38 mm and 679.17 mm in a 200 days growing season, using the TDR and neutron probe equipments, which leaded to an average daily water consumption of 3.70 mm and 3.63 mm, respectively. Using the ETc from soil water content measured by TDR, average Kc values were 0.71 and 0.79 with ETo from pan and Penman-Monteith-FAO methods, while using the ETc from neutron probe data, average values were 0.70 and 0.78, respectively. A range from 0.58 to 1.03 was observed in all source of data combinations throughout the phenologic phases. The soil water content measured by TDR and neutron presented close values. Consequently, it was obtained close values of soil water storage changing, which is accounted in the soil water balance method.

Mots clés : consumo hídrico - evapotranspiração - goiaba - irrigação por microaspersão - sistema radicular - evapotranspiration - microsplinkler irrigation - root system - water consumption

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Page publiée le 7 mars 2006, mise à jour le 5 juillet 2017