Influência de diferentes sistemas de microaspersão na distribuição de água no solo e nas respostas morfofisiológicas do Citrus latifolia Tanaka sobre o porta-enxerto Citrus limonia Osbeck

• Autor(a) principal: Simões, Welson Lima
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/620
• topic: Lima ácida Tahiti; Irrigação; Fisiologia; Citrus latifolia Tanaka; Irrigation; Physiology; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE AGUA E SOLO

Irrigation has been a decisive factor in maximizing the production of acid lime 'Tahiti' (Citrus latifolia Tanaka), mainly in the driest areas, inasmuch as the occurrence of water deficit affects plant growth and development. In fruit orchard under microsprinkler irrigation system, the characteristics of water emitters and their location influence water distribution and availability, altering water absorption by the roots. Therefore, this work aimed to evaluate the influence of different arrangements of microsprinklers in the soil water distribution and morphophysiological parameters of Citrus latifolia Tanaka on door-graft Citrus limonia Osbeck. We evaluated water extraction by plants, root system distribution, daily sap flow, foliate transpiration and temperature, stomatal conductance and leaf water potential during flowering and fructification, besides productivity and fruit quality. The experiment was carried out at the EPAMIG experimental farm in Mocambinho, Jaíba in northern Minas Gerais. The crop used in the tests was acid lime 'Tahiti' (Citrus latifolia Tanaka), grafted on four-year old "clove" lemon (Citrus limonia Osbeck), 5 x 7 m spaced and daily submitted to irrigation by microsprinkler. The soil was classified as Quartzogenic neosoil and the experimental design was arranged in randomized blocks with three treatments and six replicates. Three microsprinkler arrangements were evaluated: T1 - one emitter per plant, located among plants along the plant row, with discharge of 35 L h-1; T2 - one emitter per two plants, located among plants along plant row, with discharge of 70 L h-1; and T3 - one emitter per plant, located 0,3 m near the plant, with discharge of 35 L h-1. In the field, two vertical trenches were made close to the plant, one useful plant for each treatment, 60 days before the beginning of the field evaluations. The trenches were opened longitudinally and traverselly to the plant line, starting from the plant up to a distance of 2.5 m and from the soil surface up to 1.0 m depth and, with subsequent installation of TDR probes 0.10 m long. Moisture readings were made by TDR100, during 3 days in uncovered soil and 3 days in covered soil after irrigation, with readings performed at 10-minute intervals to evaluate the distribution of available water in the soil and the amount of water extracted by the roots between irrigation cycles. During flowering and fructification, daily sap flow using heat balance technique, and transpiration, stomatal conductance, water potential and leaf temperatures were measured. The soil samples containing the roots were collected after harvest, to a depth of 1 m and distance of 2.5 m from the plant, evaluated for length and diameter profile in the soil. Productivity and fruit quality were also evaluated. For all treatments, up to the depth of 0.625 m, over 5% of the water extraction was performed by the roots. T2 presented a more homogeneous water distribution pattern than the other treatments, providing larger amount of water available in the soil, mainly in the traverse profile. T2 and T3 presented greater water extraction rate than T1. Acid lime 'Tahiti' productivity was significantly different between T2 (19,506 kg ha-1) and T1 (13,545 kg ha-1). However, there was no significant difference between T3 (16.683 kg ha-1) and the other treatments. T3 and T2 fruits presented higher acid ascorbic contents than those in T1. The roots with d ≤ 0.2 cm diameter represented more than 90% of the total. About 80% of the finer roots were found in the 0-0.625 m soil depth and up to a distance of 2 m from the tree trunk, in all treatments. T2 also presented higher sap flow, transpiration, water potential, stomatal conductance and lower leaf temperature than the other treatments. Therefore, T2 plants were considered better morphophysiologically developed than the T3 and T1 plants , probably due to the better water distribution and availability in that treatment.