The objective of this study was to identify and determine the spatial distribution of the physiological quality of soybean seeds in a field of 39 hectares with production through precision farming techniques. Soil sampling and harvest seeds, georeferenced points for determining soil fertility, seed quality and range of spatial dependence were performed. The results were submitted to analysis of descriptive statistics, Pearson correlation, and geostatistics. The data presented coefficient of variation of 1,63% for emergency, 1,74% for germination, 1,63% for viability, 2,59% for accelerated aging and 4,28% vigor evaluated by the tetrazolium test. Soil pH was negatively correlated with germination, emergence, and viability. The grid point per hectare and a georeferenced grid sampling, spacing of 100 meters between points, was efficient in assessing the spatial variability. Physiological quality is not uniform, particularly in nexion of vigor, providing better diagnosis through interpolation maps. Precision agriculture allows one to determine the spatial distribution of seed physiological quality in a production area of soybean seeds, facilitating decision-making, in what refers to the areas to be harvested.

The maintenance of a plant water status is essential for keeping of its development in environments with limited water availability. Different species have different mechanisms that provide greater ability to survive under drought conditions. The objective of this study was to evaluate physiological parameters changes of the isohydric species Beaucarnea recurvate Lem. under irrigation suspension. The study involved experiments with slow dehydration (SD) performed by withholding water followed by plants rehydration, and with rapid dehydration (RD), where individual leaves were detached and placed to dehydrate in the laboratory bench. The results showed that although of the soil water content (% H2O) reach critical values (12%) in the first days of the irrigation suspension, the plants showed maintenance of the relative water content (≅80%) over the 54-day SD period, when the net photosynthesis (PN) reached null values. Throughout SD, it was observed that the PN, stomatal conductance (gs), instantaneous carboxylation efficiency, the electrons transport rate, the potential quantum efficiency of PSII and chlorophyll content were reduced. In RD, experiment was observed a high correlation between PN and gs . The results suggest that the reduction in photosynthesis was initially caused by a stomatal adjustment that culminated in an imbalance between photochemical energy production and its consumption by biochemical apparatus of photosynthesis. However, after rehydration, all gas exchange parameters were recovered, indicating that the isohydric behavior of this species contributed to the plants did not suffer extensive damage during a prolonged period of irrigation suspension.

Watermelon is a cucurbit, grown in almost all regions of the world, and it is enjoyed by most of the population. In Rio Grande do Norte the cultivation of watermelon has been increasing, because of the good climatic conditions in the region that provides adequate light and temperature throughout the year. In this con-text, the present study aimed at evaluating the yield and quality of watermelon cultivars in different planting dates in Mossoró-RN. The experiment was conducted in the garden didactic Department of Plant Sciences, Federal Rural University of the Semi-Arid in the period between June and December 2010. The experimental design was a randomized complete block in a split plot design with four 3 x 3 repetitions. The plots consisted of three cultivars of watermelon (Crimson Sweet, Olympia and Denver) and subplots were planting (June, Au-gust and October). It is concluded that the yield and fruit quality were influenced by planting dates. The water-melon sowing in August resulted in higher average fruit weight and commercial productivity, and the fruits of lower acidity and better palatability were collected in the June planting.

The modeling for agriculture is a mathematical tool that allows us to weigh the effects of factors, environmental or management on crop productivity. Therefore, the aim of this study was to evaluate the efficiency of mathematical models, in the estimation of the productivity of maize over the need for nitrogen fertilization. Estimates of nitrogen fertilization were performed to obtain the potential productivity and depleted grain yield and silage corn genotypes. The Model 1 was based on estimates obtained in the literature and Model 2 on estimates generated by the proposed alternative model, calibrated with data observed in the experiment. To evaluate the performance of the models we used statistical indicators, such as Pearson correlation coefficient, Willmott agreement index, the performance index of Camargo, percentage deviation and medium square error. Recommendations of nitrogen generated by the models for the potential productivity and depleted much grain as silage were higher compared with the recommendations of the culture ways. The AG30A91 genotype had a higher leaf area index, reflecting higher estimates of potential productivity and depleted grain and silage. The model 2 can be used to estimate the yield of grain and silage and the need for simulation of nitrogen for grain production, however, requires adjustments to estimate nitrogen needs for the production of silage. Both models are efficient in simulating the crop cycle.

In fruit pulp industrialization often use thermal processes to (heating and/or cooling) that may cause changes in its viscosity, which causes the study of the influence of temperature on the rheological behavior of this type of product is of great importance. Data of the apparent viscosity of fruit pulp are used in equipment design and process optimization. The research objective was to evaluate the influence of temperature on the apparent viscosity of the Myrtle pulp. The rheological analysis was conducted on a Brookfield viscometer model DV - II +Pro. The apparent viscosity curves as a function of strain rate were described by rheological models Sisko, Power Law, and Falguera - Ibarz. The full Myrtle pulp was classified as non - Newtonian fluid and shear thinning. The behavior of this fluid can be well described by models Sisko, Law of Power and Falguera - Ibarz, especially the Sisko model. The effect of temperature on the apparent viscosity was described by Arrhenius equation with activation energy presenting high values at low shear rate.

Calotropis procera (Aiton) W.T. Aiton - Apocynaceae (silk-flower) is an important species for several usages: ornamental, forage, timber, textile and medicine, that justify its study. We investigated the physiological behavior and the vigor of seeds under different storage conditions. There were performed month-ly evaluations of germination, seedling emergence, speed of emergence, seedling length and weight of seedling dry matter, during 180 days. Experimental design was completely randomized with a 6x5x3x2 factorial, using combinations of six storage periods (30, 60, 90, 120, 150 e 180 days), five moisture contents (30, 24, 18, 12 e 7%), three package types (paper bags, plastic bags and PET bottles) and two environmental conditions (chamber: 16 °C a 18 °C and laboratory: 27 °C a 30 °C, both environments with 50±5%) with four replications of 50 seeds. Data were analyzed using analysis of variance using F (p≤ 0.05) test to treatments and Tukey test for averages comparison, with polynomial regression analysis considering the storage periods. There were con-cluded that silk flower seeds presented orthodox physiological behavior; the vigor decreased when stored for 180 days; silk flower seeds with 7% moisture content are preserved efficiently in paper bags and controlled environment for 90 days.

This work aimed to evaluate the growth and yield of banana cv. "Nanicão", in intercropping with live coverage crops in the semi - arid region. The experiment was analysed as a randomized complete block with four replications. The experiment used a split - plot design, and some variables were sub - subdivided over time. In the plots, factor "A", made of three management strategies of soil cover - the leguminous, calopo and tropi- cal kudzu, and bare soil (hoed soil); Factor "B", on the sub - plots, banana plants in three morphophysiological ages (different cycles and sizes) and factor "C", dates of collections in the sub - plots. The cultivation of banana cv. Nanicão in soil under live coverage with calopo and tropical kudzu in the semi - arid region promotes an increase in the number of fruits, fruit weight and bunches.

The study evaluated potato tuber yield and quality, using cultivar Atlantic, as a function of organomineral fertilizer doses applied in the planting furrow. The experiments were done in Cristalina, Goiás, in winter and summer cultive. The experimental design was randomized blocks, with six doses in the winter experiment and seven doses in the summer one, both with four replications. The doses were fixed according to the recommendation for mineral fertilizer. The doses evaluated were 2800 kg ha - 1 of formulation 3 - 32 - 6, 1629.10, 2443.60, 4072.70 and 4887.30 kg ha - 1 of organomineral fertilizer, corresponding to 40, 60, 80, 100 and 120% of the mineral fertilizer dose. A treatment with no fertilizer (control) was included in the summer experiment . Fertilizers were applied in the planting furrow. Side dressing fertilization was done 30 DAP, in winter crop, with 300 kg ha - 1 of formulation 20 - 00 - 20. Tubers were harvested, classified, weighed and yield (kg ha - 1 ) was determined at the end of the experiment. Results of winter crop were greater than those of sum- mer, for yield and tuber classification. Organomineral fertilizer, in the dose 4072.70 kg ha - 1 , representing 100% of the mineral one, increased the yield of tubers Class Special. Winter crop presented good results for soluble solids contents.

The aim of this study was to evaluate the kinetics of ruminal fermentation dry matter and car-bohydrates of two varieties of sugar cane ensiled with different additives using a semiautomatic technique in vitro gas production. We used a completely randomized design with a factorial 2 x 5, two varieties of cane sug-ar (RB 86 7515 and IAC 86 2480) and five additives (urea, NaOH, CaO, corn and L. buchneri) and without additive treatments, with the opening of the silos being made at 60 days after ensiling. Pressure readings were performed on days 0; 2; 4; 6; 8; 10; 12; 15; 19; 24; 30; 36; 48; 72 and 96 h. The pressure caused by organic matter was recorded in a pressure transducer universal and for adjusting the parameters kinetic model was used bicompartmental. The technique of in vitro gas production satisfactorily estimated the volume of gases from silage and sugarcane raw. The higher gas volume fraction of fiber was not in IAC 86 2480, with the additive NaOH. In the fiber fraction only difference between varieties with the additive urea, and the IAC 86 2480 that had the highest volume. The cane silage IAC 86 2480, showed the best values for most of the evaluated kinetic parameters. The best results for the parameters of degradability were in silages with NaOH and CaO.

Aiming at evaluating the postharvest shelf life of banana Prata Catarina coated with cassava starch or PVC films, were harvested bunches of bananas in the physiological maturity stage. The fruits were packed in boxes and transported to the Food Chemistry Lab of the Federal Institute of Ceará, Campus of Limoeiro do Norte for 10 days at room temperature (27.5 °C and RH 62.5%). The design used was a complete-ly randomized one in 3 x 5 factorial scheme, which the first factor was treatment (control, cassava starch 3% and PVC film,) and the second period of storage (0, 4, 6, 8 and 10 days) with four replications of four fruits per plots (clusters). The use of PVC film and cassava starch 3%, influenced the physical and physicochemical char-acteristics evaluated, except for firmness and soluble solids of the „Prata Catarina‟ banana stored under ambient conditions. The use of PVC film was effective in maintaining the external appearance and reduced weight loss. However, the application of cassava starch 3%, was not effective in reducing weight loss, maintained the fruits with good appearance till the end of storage. The „Prata Catarina‟ bananas control had a shelf life of 8 days, while the bananas coated with cassava starch and PVC had a shelf life of 10 days stored at ambi-ent conditions.