Variation in pathogenicity among the three subspecies of Phytophthora alni on detached leaves,twigs and branches of Alnus glutinosa

Pathogenicity tests were carried out on leaves, twigs and branches of Alnus glutinosa using several isolates of Phytophthora alni ssp. alni, P. alni ssp. multiformis and P. alni ssp. uniformis in vitro. Healthy fresh leaves were collected from disease‐free areas and inoculated with mycelium on agar discs or by dipping in zoospore suspensions. In addition, twigs and branches were collected from both disease‐free and disease‐affected areas, inoculated with mycelium on agar discs and incubated at four temperatures (15, 20, 25, 30°C). All subspecies tested were pathogenic but with varied level of virulence. In inoculation tests on foliage, wounding was a key factor in causing infections: lesions on inoculated wounded leaves were larger than on non‐wounded leaves. In the twig and branch inoculation tests, no differences in virulence were observed among the P. alni subspecies in terms of sampling locations, but lesions differed in size according to incubation temperature, with the largest lesions occurring on tissues incubated at 25°C. The work is the first to report foliar necrosis caused by P. alni on A. glutinosa. P. alni ssp. uniformis was the least virulent of the subspecies in branch inoculations. These findings demonstrate that various tissues of A. glutinosa could act as sources of pathogen inoculum and may disseminate alder Phytophthora in natural ecosystems.     

Chemical Composition of Green Tea (<Emphasis Type="Italic">Camellia sinensis</Emphasis>) Infusions Commercialized in Portugal

To evaluate the potential benefits and risks associated with tea consumption it is important to identify the constituents of this beverage. Levels of some minerals, caffeine and catechins in green tea samples commercialized in Portugal were evaluated. Potassium is the metal present in larger amount (92–151 mg/l). The content of sodium, calcium, fluoride, aluminium, manganese and iron were 35–69, 1.9–3.5, 0.80–2.0, 1.0–2.2, 0.52–1.9, 0.020–0.128 mg/l, respectively. Chromium and selenium were not detected. The resulting data showed considerable variability in catechins content. The levels of epigallocatechin gallate (EGCG) ranged from 117 to 442 mg/l, epicatechin 3-gallate (EGC) from 203 to 471 mg/l, epigallocatechin (ECG) from 16.9 to 150 mg/l, epicatechin (EC) from 25 to 81 mg/l and catechin (C) from 9.03 to 115 mg/l. Caffeine contents in the green tea infusions studied were between 141–338 mg/l. Green tea infusions provide significant amounts of catechins and could be an important source of some minerals.     

Predictive models of drought tolerance indices based on physiological,morphological and biochemical markers for the selection of cotton (Gossypium hirsutum L.) varieties

The use of tolerant crop varieties is a strategy that mitigates the water deficit effect in a sustainable way. The generation of these varieties is more efficient when variables associated with this tolerance have been identified, since they can facilitate the breeding processes. This study aimed to establish the relationships between water deficit tolerance of four cotton varieties (Nevada-123, Oasis-129, Guatapuri, and Festivalle) and morphological variables (monopodial branches, boll weight, root/shoot ratio, and leaf and root dry matter), physiological variables (relative water content, net photosynthesis, stomatal conductance, electron transport rate, photochemical quenching, photochemical efficiency of PSII, chlorophyll a/b ratio (Chl a/b), C¹²/C¹³ isotope ratio, and electrolyte leakage), and biochemical variables (contents of sugars, proline, carotenoids, and malondialdehyde). Furthermore, calibrated predictive models of the drought tolerance indices were developed based on the key variables identified. For this purpose, a pot experiment was established where plants were subjected to a moderate or severe water deficit during the blooming stage for 12 days. The stress tolerance index (STI) and mean productivity (MP) were calculated. For the evaluated variables, the differences between well-watered and water deficit plants (Δ) were calculated and ANOVA, partial least squares, Pearson's correlation, and multiple linear regression analyzes were performed. A model was generated that explained 95% of the STI and was composed of Δmalondialdehyde, Δproline, and Δboll weight. For MP, the model was comprised of Δstomatal conductance, Δroot/shoot ratio, and ΔChl a/b, and explained 89% of the MP. The analysis of the assessed variables allowed the identification of key variables and the development of calibrated predictive models that can be used in screening to obtain cotton varieties with different levels of water deficit tolerance.     

Variable-rate seeding in soybean according to soil attributes related to grain yield

Precision Agriculture - Defining the ideal soybean stand is essential for obtaining maximum grain yield. As a hypothesis of the work, it was questioned whether it is possible to vary seeding...     

Yield map generation of perennial crops for fresh consumption

Yield mapping technologies can help to increase the quantity and quality of agricultural production. Current systems only focus on the quantification of the harvest, but the quality has equal or greater importance in some perennial crops and impacts directly on the financial profitability. Therefore, a system was developed to quantify and relate the quality obtained in the classification line with the plants of the orchard and for decision-making. The system is comprised of hardware, which obtains the location of the harvester bag during harvesting and unloading at the unloading site, and software that processes the collected data. The cloud of real-time data contributed from the different collectors (bins) allows the construction of yield maps, considering the multi-stage harvesting system. Further, the system enables the creation of a detailed map of the plants and fruits harvested. As the harvest focuses on quality, it takes place in stages, depending on the ripening of the fruits. In addition to the yield maps, the system allows identification of the efficiency of each worker undertaking the harvest by the number of performed discharges and by the time spent. The system was developed in partnership with the Federal Technological University of Paraná and Embrapa Uva & Vinho and was tested in apple orchards in southern Brazil. Although the system was evaluated with only data from apple cultivation, monitoring the quality and quantifying other orchard fruits can positively impact the fruit sector.

     

Effects of suspended solids in the survival and haematological parameters of pacu juveniles (Piaractus mesopotamicus) in a biofloc technology culture system

This study determined the effects of total suspended solids (TSS) on pacu (Piaractus mesopotamicus) culture in a biofloc technology (BFT) system by performing two experiments. Experiment 1 evaluated the LC50-96 h of pacu at seven TSS levels (0, 1500, 3000, 4000, 5000, 6000 and 7000 mg L^?1). Experiment 2 evaluated haematological variables (glucose, pH, haematocrit, haemoglobin, erythrocytes and haematimetric indices) in juveniles exposed to five different sublethal TSS concentrations (0, 250, 500, 750 and 1000 mg L^?1) for 5 days. Treatments below 5000 mg L^?1 did not cause mortality, and the LC50-96 h of TSS was estimated at 5477 mg L^?1. The TSS concentrations that caused mortality in pacu juveniles were extremely high and rarely maintained in culture systems. Exposure to high TSS concentrations (mainly 750 and 1000 mg L^?1) increased blood glucose, pH, heamatocrit, erythrocytes, haemoglobin values and haematimetric indices on the first day. On the fifth day, most of the evaluated parameters stabilized at different TSS concentrations. In conclusion, pacu exposed to high TSS concentrations for short periods may undergo physiological changes, and TSS concentrations below 250 mg L^?1 are recommended for its culture in a BFT system.     

Influence of diet and feeding strategy on the performance of nitrifying trickling filter,oxygen consumption and ammonia excretion of gilthead sea bream (Sparus aurata) raised in recirculating aquaculture systems

Gilthead sea bream (Sparus aurata) was raised in six individual recirculating aquaculture systems (RAS) whose biofilters’ performance was analyzed. Fish were fed with three different diets (a control diet, a fishmeal-based diet (FM), and a plant meal-based diet (VM)) and with three different feeding strategies (manual feeding to apparent satiation, automatic feeding with restricted ration, and auto-demand feeding). For every combination of diet and feeding strategy, the mean oxygen consumption, ammonia excretion, and ammonia removal rate were determined. Fish fed with the VM diet consumed the most oxygen (20.06?±?1.80 gO₂ consumed kg^?1 day^?1). There were significant differences in ammonia excretion depending on the protein content and protein efficiency of the diet, as well as depending on feeding strategy, which in turn affected ammonia removal rates. Fish fed by auto-demand feeders led to the highest mean ammonia removal rate (0.10 gN-TAN removed m^?2 biofiltration area day^?1), while not leading to peaks of high ammonia concentration in water, which preserve fish welfare and growth.