Drip irrigation is one of the most efficient method s forapplyingwaterto a crop, capable of deliv- ering water at a rate close to the demand. Many eff orts have been required to estimate the amount of w ater needed by plants. Therefore studying soil water ext raction by plants linked to mathematical modeling f or be- havior prediction, and linked to computational reso urces to allow complex mathematical procedures to b e real- ized in a short space of time, becomes a powerful a nd necessary alternative for the understanding and quantifi- cation of the involved processes. Simulations were performed through a computational model, with the purpose of estimating the crop coefficient (K c ) of watermelon in the region of Mossoró-RN, using a three-dimensional macroscopic root water uptake model, which solves t he sink term of the Richards equation. The simulati ons results were compared with an experiment that estim ated the K c using lysimeter. The results of Kc estimated by the model showed a good agreement with lysimeter re sults in all chosen statistical indexes, indicating that the model can serve as a tool for predicting transpirat ion and evaporation of soil water under certain con ditions, and as a tool to aid the irrigation management.

The Ceara State has a variety of species of non-traditional fruits that are consumed in natura and/or processed by local population, with economic potential for agro-industrial processing, however, still poorly studied. In this context, the aim of this research was to evaluate the genetic variability of puçazeiro ‘Coroa de Frade’, native tree from coastal vegetation of Beberibe, Ceará, Brazil, by physico-chemical and chemical characteristics of their fruits. Fifteen genotypes were evaluated. The traits analyzed were: soluble solids (SS), titrable acidity (TA) (% of citric acid), pH, SS/TA ratio, total sugars, reducing sugars, starch and, total and soluble pectin. The genotypes were characterized as a good alternative to the market of exotic fruits, showing high values of SS (20,40 a 31,00 °Brix) and low mean values of titrable acidity (0,27 a 0,58 % of citric acid), producing SS/TA ratio ranged between 37,5 and 102,43, with emphasis on the genotype '8', which pre- sented SS/TA ratio of 95.05. The genotypes showed fruit netting with high starch (> 1%). The values of total pectin (0.35 to 0.98%) and soluble pectin (0.13 to 0.74%) reinforcing the use of this fruits in the industry, with low cost to manufacture of candy and jellies. The repeatability analysis showed that most of the observed varia- tion among genotypes is associated with the genetic component. Therefore, it can be concluded that the studied genotypes of puçazeiro 'Coroa de Frade' showed wide genetic variability and have fruits indicated even for fresh consumption as well as for processing.

The objective of this work was to study the effects of N and K2O doses applied through fertigation in soil fertility and nutritional status. The experiment was carried out during April, 2002 until March 2004, on Experimental Farm of the Empresa de Pesquisa Agropecuária of the State of Rio Grande do Norte (EMPARN), Brazil. The statistical design was in a completely randomized block with 4 replication, using for composition of treatments Plan Puebla III experimental matrix, treatments being composed of combination of two factors: nitrogen and potassium doses in the form of urea and potassium chloride, respectively. In all 10 treatments, defining the interval for N (256 to 4874 g plant-1 year-1) and K2O (258 to 4872 g plant-1 year-1) were applied through fertigation with microsprinkler irrigation system. The contents of nutrients in the soil presented great variation and tended to decrease with time. The doses of N decreased the pH and contents of Ca and Mg although increased the availability of P in soil and favored its absorption by plant. A negative gradient in concentration of nutrients under fertigation was observed from the soil surface. The K content in leaf 14 were increased with increase in doses of K2O via fertigation presenting high correlation with number of fruits. The application of K in soil increased the contents of Cl and Mg in leaf 14 and decreased the contents of Na, while the application of N in soil increased the contents of Mn in leaves.

Growing cover crops preceding planting common beans and corn may influence the yield of these cash crops. This study aimed to evaluate the biomass production and decomposition of crop residue cover and yield of maize and beans grown on these soils as coverings of plants. The experiment was conducted under field conditions in the 2011/12 harvest in Uberaba. With a randomized block designed in a split - plot scheme, seven cover crops were used : sunn hemp ( Crotalaria spectabilis ), jack bean ( Canavalia ensiformis DC.), mil- let ADR300, ADR500 and ENA2 ( Pennisetum glaucum L.), Sorgo (S orghum bicolor L.) and brachiária ( Urochloa brizantha cv Marandú), and subplots in annual succession crops (maize and bean). The millets ADR300, ADR500 and ENA2 among Poaceae and jack beans between Fabaceae produced more dry biomass (9.8, 8.9, 8.6 and 3.8 t ha - 1 ), respectively; after 150 days of decomposition of plant residues of sunn hemp, jack bean, sorghum, brachiaria, millet ADR500, millet ENA2 and millet ADR300 were in the order of 67.9; 71.7; 53.8; 61.7; 49.9; 45.5 and 46.7%, respectively; the maize yield was higher when the culture was grown on resi- dues of millet ENA2 (7.2 t ha - 1 ) and jack bean (6.8 t ha - 1 ), while the bean was higher when grown on millet ADR300 (1.3 t ha - 1 ) and sunn hemp (1.2 t ha - 1 ).

The postharvest losses index for fruits in Brazil is high. To attend the quality exigencies and minimize those losses, it is initially necessary to detect the problems on the commercialization chain. Because of that, this study aimed to evaluate the postharvest losses in table grapes during the operations carried out in packinghouses of firms located in Petrolina-Pernambuco State/Juazeiro-Bahia State region and during the com- mercialization in Mercado do Produtor de Juazeiro. The study was carried out in three packinghouses and in three sell places of the Mercado do Produtor de Juazeiro. In the packinghouses, it was observed one day of ac- tivity, following the normal procedures. For sampling, the wasted fruits were weighted, characterized according the kind of loss and quantified before doing another weighting for each identified category. In Mercado do Pro- dutor de Juazeiro, the study was carried out in a similar way, including the same evaluations. Because of the rigorous quality criteria, the percentage of losses in table grapes in packinghouses was 3.9%. This percentage was higher than the value observed in Mercado do Produtor de Juazeiro, which was 1.5%. The main cause of postharvest losses in grapes was mechanical injury in both studied conditions.

The rio Doce river basin has great silvicultural potential, areas cultivated with pasture are con- verted to forest plantations. Physical processes in the soil, especially the infiltration water, are very dependent on the type and management of its coverage. The objective of the present study was to evaluate the differences between rates of water infiltration in soils submitted to eucalyptus plantations and pasture and adjust empirical models of infiltration. The experiment was conducted at four sites in the Rio Doce river basin, MG, Brazil, where two were planted with eucalyptus and two with pasture. Five infiltration tests using the concentric rings method were performed in each area. Results show that the soils infiltration rate with eucalyptus plantations were higher than those found in soils from pasture areas, with stable infiltration rates of 78 and 165 mm h-1 in eucalyptus and 47 and 50 mm h-1 in pasture. The model of Horton indicated the highest adjusted confidence index for the four sites analyzed.

The management of wastewater in agricultural crops in order to explore fully their potential of water and nutrients, have proved a viable alternative for irrigated agriculture, especially in semiarid regions. The objective of this work was to study the quality of ornamental sunflower (cv. Sol Noturno) with increasing doses of cattle manure and types of water. The experiment was conducted in a completely randomized block design in factorial scheme (4 x 2), with four replications and five plants per replication, testing two types of water (supply water and treated wastewater) and four doses of cattle manure (5, 10, 15 and 20% in on weight basis) In determining the quality of sunflowers morphological and growth variables were analysed. The manure doses ranging from 15 to 16.7% provided the best morphological and growth characteristics of sunflowers. The nanure dose less than 8.4% provided early onset and opening of buds of the sunflower and the highest number of flower buds was obtained with the manure dose equivalent to 14%. The types of water, as well as the interaction between the factors did not significantly influence the quality of sunflowers (cv. Sol Noturno).

This study was carried out during April to August of year 2009, in field conditions at the horti- culture department Centro de Ciências Agrárias – Universidade Federal da Paraíba, in Areia – PB, aiming to evaluate the effect of nitrogen rates in the presence and absence of bovine manure in the sweet potato yield. The experimental design used was randomized blocks, with four repetitions in factorial scheme 6 x 2, being six nitrogen doses ( 0, 50, 100, 150, 200, 250 kg ha-1 of nitrogen) in the presence and absence of bovine manure. The evaluated variables were commercial roots average weight, commercial roots production plant-1 and com- mercial productivity of roots. The average weight of commercial roots, depending on nitrogen doses in the presence of bovine manure has increased in a linear way in order 0,31 g each kg of nitrogen applied, with maxi- mum weight 233,6 g with 250 kg of nitrogen ha-1. In bovine manure absence it was achieved average weight of 192,1 g. The maximum productivity of commercial roots plant-1 in the presence of bovine manure was 235,42 g, obtained with 243,75 kg ha-1 of nitrogen. In organic fertilizer absence, it was achieved the average of 127,1 g of commercial roots plant-1, depending on nitrogen doses. The dose of 183 kg ha-1 of nitrogen was responsible by maximum productivity of 13,6 t ha-1 of commercial roots, in the presence of bovine manure, while in its absence was achieved medium productivity of 7,9 t ha-1. The cattle manure increased the efficiency of nitrogen production characteristics of sweet potato and set nitrogen use in coverage and cattle manure at planting pro- vides marketable yield of sweet potato than the national average.

Studies related to the absorptions and nutrient partitioning in organs of irrigated beans are scarce and very important for the improvement of different fertilization models. This study aimed to evaluate the growth of irrigated common bean in winter, through biomass production and nutrients uptake to organs and shoots. We used a randomized block design with three replications and seven composed of time periods of plant collection (10, 20, 30, 40, 50, 60 and 70 days after plant emergence) with separation in leaves, stem, flower+pod and grains. After determination of dry matter, the content of N, P, K, Ca, Mg and S absorbed by shoots and components of bean was estimated. Nonlinear sigmoid and gaussian models were fitted to characterize biomassa production and nutrient uptake during bean growth. The absorption of by bean decreasing in the following order, in kg ha-1: 138 K, 112 N, 66 Ca, 16 P, 11 S and 7 Mg, indicating the high absorption of K and N and demand of K replacement by top dressing. During the initial growth stage, leaves were responsible for 80% of macronutrients accumulation in shoots. In the final growth stage, grains exported 90, 75 and 65% of P, N and Mg absorbed, showing its high export rate.

Over the past few years, the increased use of fossil fuels as well as the unsustainable use of land, through the reduction of native forests has increased the greenhouse gas emissions, contributing defini- tively to the rise in temperature on earth. In this scenario, two environmental factors, directly related to the physiology of crop production, are constantly being changed. The first change is the increase in the partial pres- sure of carbon dioxide (CO2), which directly affects photosynthetic efficiency and the associated metabolic processes. The other change is the temperature increase which affects all the physiological and metabolic proc- esses mediated by enzymes, especially photosynthesis and respiration. Therefore, this review aims to discuss the main effects caused by increased CO2 pressure and the temperature rise in the physiology, productivity and post-harvest quality of plants with photosynthetic metabolism C3, C4 and CAM. Based on physiological evi- dence, the increased atmospheric CO2 concentration will benefit net photosynthesis, stomatal conductance and the transpiration of C3 plants, however in hot, dry and saline environments, the C4 and CAM species present an advantage by having low photorespiration. Studies show controversial conclusions about the productivity of C3 and C4 plants, and the quality of their fruits or grains under different CO2 concentrations or high tempera- tures. Thus, there is a need for more testing with C3 and C4 plants, besides of more researches with CAM plants, in view of the low number of experiments carried out in this type of plants.