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The artificial water application through irrigation systems can provide uneven applications, causing excess or deficit in part of the cultivating area. The companies that supply irrigation equipment have been investing in the development of products that optimize the efficiency of application, and consequently the cost of production. The objective of this study was to evaluate the influence of the structural modification of the 3D diffusion arm on the performance and uniformity of a Netafim ™ D-Net ™ 9575 sprinkler. The structural modification made by the company was to allocate bulkheads (teeth) in the diffusion arm, in order to optimize water distribution. In Lavras, state of Minas Gerais, Brazil the experiment was performed, assays with teeth (WT) and no teeth (NT), at three pressures (200, 300 and 400 kPa), with three repetitions. The evaluation of the sprinkler performance was based on the determination of the radial profile of each combination, Christiansen uniformity coefficient (CUC), application intensity, and sprinkler flow. The results indicated that the average application intensities (Ia) of each pressure with the teeth (WT) and without the teeth (NT) of the diffuser are coherent compared to the values indicated in the catalog. The Ia values for all NT tests and for some WT pressures are slightly above that recommended by the Netafim ™ catalog. Overall the diffuser arm WT reduces the range of the water jet. The CUC uniformity coefficient with 300 kPa working pressure for the WT and NT tests achieved the best results according to the objective.

Conditions of water deficit can cause morphological changes in plants which consequently affect physiological processes and interfere with plant metabolism. As grafting is a standard process used for citrus trees, these changes depend on the rootstock used and its interaction with the scion; this interaction will determine which plant has the best performance. This study involved assessment of changes in DNA and chlorophyll A and B content in Navelate orange seedlings grafted onto five different rootstocks (Indian and San Diego citrandarin, Swingle citrumelo, Santa Cruz Rangpur lime and Sunki mandarin) under conditions of water deficit. The seedlings from the respective combinations were approximately 12 months-old when they were transferred to 5 L polyethylene bags filled with substrate, comprising standard soil and sand at a 3:1 ratio. Plants were maintained in a greenhouse for three months. After this period, the experiment was set up using a randomized block design with a 5x2x5 factorial scheme based on the following: five rootstocks with and without irrigation, and time-points at 25, 29, 32, 35 and 38 d after stopping irrigation. At each of these time-points, chlorophyll content was assessed by direct reading in cloroLOG CFL1030 equipment and also the DNA content was determined using flow cytometry. The results suggest that severe water deficit can cause morphological changes in DNA content and in chlorophyll concentration, and that the changes are most marked with Sand Diego and Swingle rootstocks. Index terms: flow cytometry, chlorophyll content. Respostas morfológicas da laranjeira Navelate enxertada em diferentes porta-enxertos e sob déficit hídrico RESUMOAs condições de déficit hídrico podem causar alterações morfológicas em plantas que consequentemente afetam os processos fisiológicos e interferem em seu metabolismo. Essas mudanças dependem do porta-enxerto usado e sua relação com a copa uma vez que a enxertia é um processo padrão usado na formação das plantas cítricas. Este estudo teve como objetivo identificar o melhor desempenho da interação de diferentes porta-enxertos com a copa Navelate em condições de estresse hídrico; mediante avaliação do conteúdo de DNA e clorofila A e B. Foram estudados os portaenxertos citrandarin Indio e San Diego, citrumelo Swingle, limão Cravo Santa Cruz e tangerina Sunki

The aim of this paper was to analyze the behavior of non-parametric statistical distributions on the prediction of probable monthly and total annual rainfall as well as to determine the monthly and annual probable rainfall with different levels of probability for Divinópolis, Minas Gerais State, Brazil. The analysis consisted in adjusting the theoretical probability distribution to a data series of 66 years of monthly and annual rainfall. The data were obtained from the Hidroweb service, controlled by the National Water Agency (ANA, in Portuguese). The frequency distributions of Gumbel for Maximus, Fréchet and Gamma were adjusted to the observed series, where the adherence of these models to the data were tested by the Kolmogorov-Smirnov and Chi-Squared test, both with 5% of probability. The model that best represented, in most cases, the frequency distributions of the series of total monthly precipitation was Gumbel for Maximus, while the Fréchet model had the worst result, not fitting to the data of the historical series for both tests performed in the study. The probable monthly maximum precipitation for Divinópolis is 527 mm, associated with a probability of 5% and for January, while the lowest one is 0.0042 mm, with probability of 95% in July.

Increased anthropic activity in the environment leads to degradation and increased waste generation that includes tires, which can be used for the manufacture of porous pipes by extrusion for irrigation or aeration. There are no defined methodologies for the hydraulic characterization of porous pipes; in addition, their performance is questionable because the permeability of the wall in contact with water seems to decrease with time. Thus, this study aimed to perform the hydraulic characterization of porous pipes. Experiments were performed to assess the variation in permeability over time, the head loss, the friction factor, and the roughness. Statistical tests were performed to investigate possible significant differences between treatments. The results showed that the permeability varies over time and tends to decrease with each application of water. After a certain period, the permeability tends to become constant, and a stable flux can be determined, being the lowest average permeability and flux values found 0.591 × 10−15 m² 0.109 m³·m−2·s−1. There is variability in the permeability between pipe samples from the same batch as well as variability within the same sample, as indicated by the fact that some samples are similar to each other while others differ when performing a pairwise multiple comparison.