ABSTRACT With the limited availability of water in semi-arid regions, it is necessary that irrigation is accurate and there is high water use efficiency. This study aimed to evaluate the regulated deficit irrigation (RDI) and partial rootzone drying (PRD) in yield, water use efficiency and gas exchange of ‘Tommy Atkins’ mango tree in semi-arid conditions. The experimental design was a randomized block with seven treatments for RDI under micro sprinkler and five treatments for the PRD under drip. Treatments were applied in phases PI - early blooming to early fruit expansion, PII - early expansion to early physiologic ripening and in phase III - physiologic ripening of fruits, with application of the RDI of 100, 75 and 50 % of ETc in different combinations of phases and application of PRD 100, 80, 60 and 40 % of ETc in three phases with the partial rootzone druing at 15 days. Photosynthesis, carboxylation efficiency and quantum efficiency of photosynthesis are lower in PRD 40% ETc at 8 a.m. compared to full irrigation and PRD 80 % of ETc. Phases of expansion and fruit ripening are more appropriate for application of RDI with 50 % and 75% of ETc without loss to the crop yield of ‘Tommy Atkins’ mango tree and greater water use efficiency. The strategy of partial rootzone drying, PRD, every 15 days with 40 % of ETc, provides greater WUE.

ABSTRACT The objective of this study was to evaluate the nutrient contents in ‘Tommy Atkins’ mango leaves at the flowering and fruiting stages under different strategies to reduce irrigation levels during flower induction. Five irrigation level reduction strategies, based on crop evapotranspiration (ETc) were used in the plots: T1 (0% ETc), T2 (25% ETc), T3 (50% ETc), T4 (75% ETc) and T5 (100% ETc); two production cycles in the split-plots; and in two development stages, flowering and harvest, in the split-split plots. The content of N, P, K, Ca, Mg, and S, as well as B, Cu, Fe, Mn, Zn, and Na was determined and leaf chlorophyll index was measured during the second cycle. The content of P, K, Mg, and Cu in the ‘Tommy Atkins’ mango trees leaves varied according to phases and cycles, regardless of the strategies to reduce irrigation levels in floral induction. The contents of N, Ca, B, Fe, Mn, and Na varied with stages and with the production cycles, in an independent manner. Foliar N contents were above the sufficiency range at the different development stages and cycles evaluated. The indices of a, b, and total chlorophyll varied independent of reading time. The nutrient contents with lower mobility in the plant, Ca, B, Fe and Mn increase in ‘Tommy Atkins’ mango trees leaves from flowering to fruiting, with the return of irrigation at 100% crop evapotranspiration, while the levels of N, P, K and Mg, nutrients with high mobility in plant decrease.

RESUMO Objetivou-se avaliar estratégias de redução de lâminas de irrigação para manejo adequado da indução floral e produção da mangueira 'Tommy Atkins', na região do semiárido baiano. Cinco tratamentos com redução de lâminas de irrigação, baseadas na evapotranspiração de cultura (ETc), foram aplicados em duas fases de desenvolvimento, FI - floração e FII - frutificação: T1, 0% da ETc na FI e 100% na FII; T2, 25% da ETc na FI e 100% na FII; T3, 50% da ETc na FI e 100% na FII; T4, 75% da ETc na FI e 100% na FII; e T5, 100% da ETc em FI e FII, dispostos num delineamento experimental em blocos casualizados, com seis repetições. As taxas de fotossíntese e de transpiração de mangueira 'Tommy Atkins', nas fases FI e FII, são maiores às 8 que às 14 horas, independentemente das estratégias utilizadas. Essas estratégias conduzem a menores valores de fotossíntese, transpiração e de potencial hídrico foliar da mangueira 'Tommy Atkins' na fase de florescimento. As características produtivas não foram influenciadas pelas estratégias de redução de lâminas de irrigação no processo de indução floral da mangueira 'Tommy Atkins', apenas pelos ciclos avaliados. Estratégias com 0% da ETc na FI e 100% na FII ou 25% da ETc na FI e 100% na FII são adequadas ao processo de indução floral da mangueira 'Tommy Atkins'.

ABSTRACT This study aimed to evaluate reduction strategies of irrigation for proper management of floral induction and production of 'Tommy Atkins' mangoes, in the semiarid region of the Bahia state, Brazil. Five treatments with reduced irrigation levels based on crop evapotranspiration (ETc) were applied in two development stages, FI - flowering and FII – fruiting. Water depths were T1 - 0% of ETc in FI and 100% in FII; T2 - 25% of ETc in FI and 100% in FII; T3 - 50% of ETc in FI and 100% in FII; T4 - 75% of ETc in FI and 100% in FII; and T5 - 100% of ETc in FI and FII. The treatments were arranged in a randomized complete block design with six replications. Photosynthesis and transpiration rates in phases FI and FII were larger at 8 am than at 2 pm, regardless of the strategies used. These strategies lead to smaller values of photosynthesis, transpiration and leaf water potential within flowering stage. Productive characteristics were not affected by irrigation level reduction for flower induction process, only for the cycles evaluated. Strategies with 0% of ETc in FI and 100% in FII or 25% of ETc in FI and 100% in FII are appropriate to flower induction in 'Tommy Atkins' mango.