Biomass production and potential water stress increase with planting density in four highly productive clonal Eucalyptus genotypes§

The choice of planting density and tree genotype are basic decisions when establishing a forest stand. Understanding the interaction between planting density and genotype, and their relationship with biomass production and potential water stress, is crucial as forest managers are faced with a changing climate. However, few studies have investigated this relationship, especially in areas with highly productive forests. This study aimed to determine the interaction between biomass production and leaf water potential, as a surrogate of potential water stress, in different clonal Eucalyptus genotypes across a range of planting densities. Four clones (two clones of E. urophylla × E. grandis, one clone of E. urophylla, and one clone of E. grandis × E. camaldulensis) and four planting densities (ranging from 591 to 2 949 trees ha^?1) were evaluated in an experimental stand in south-eastern Brazil. Biomass production was estimated 2.5 years after planting and predawn (ψ_pd) and midday (ψ_md) leaf water potential were measured 2 and 2.5 years after planting, in February (wet season) and August (dry season) in 2014. For all clones, total stand stemwood biomass production increased and leaf water potential decreased with planting density, and their interaction was significant. Thus, wood biomass at tighter spacings was higher but exhibited lower leaf water potentials, resulting in a trade-off between productivity and potential water stress. These are preliminary findings and still need to be supported by more experimental evidence and repetitions. However, in light of the increased frequency of extreme climate events, silvicultural practices that are tailored to the potential productivity of each region and that result in low potential water stress should be considered.     

Osmoregulators in <Emphasis Type="Italic">Hymenaea courbaril</Emphasis> and <Emphasis Type="Italic">Hymenaea stigonocarpa</Emphasis> under water stress and rehydration

The objective of this work was to evaluate the effect of different water deficiency and rehydration levels on the concentrations of osmoregulators in two plant species (Hymenaea courbaril and H. Stigonocarpa) in the Amazon. We adopted a 2 × 5 × 5 factorial system, referring to 2 species (H. courbaril and H. stigonocarpa) and 5 stages of hydration and rehydration. The five hydration and rehydration stages were established in: (1) Control treatment E0; (2) Plants with 13 days of stress after incubation—E13; (3) Plants with 26 days of stress E26; (4) The plants that were established after 26 days after incubation and rehydrated for two days (RD2); (5) rehydrated for two days (RD4). The plants that were established after 26 days after incubation and rehydrated for four days. The experiment totaled fifty young plants with five replicates. Biochemical measurements were performed at the beginning of the experiment (E0) at 13 (E13) and 26 (E26) days after the water stress, in which the plants were rehydrated, repeating the analyses after two (RD2) and four (RD4) days. Both species increased the sucrose concentration by 18%, with a decrease of 52% in starch content. The RD4 time presented the highest mean starch concentration (0.19 mmol g^?1 of the residue for H. courbaril and 0.27 mmol g^?1 of residue for H. stigonocarpa). Increased proline concentrations were recorded for controls until RD2 for both species. For glycine betaine, the highest increases in treatments E26 and RD2 were observed for the H. courbaril species. Our rehydration period was not sufficient for total recovery of pre-stress concentrations of all studied solutes.     

Genetic evaluation of the probability of pregnancy at 14 months for Nellore heifers

To estimate the heritability for the probability that yearling heifers would become pregnant, we analyzed the records of 11,487 Nellore animals that participated in breeding seasons at three farms in the Brazilian states of S?o Paulo and Mato Grosso do Sul. All heifers were exposed to a bull at the age of about 14 mo. The probability of pregnancy was analyzed as a categorical trait, with a value of 1 (success) assigned to heifers that were diagnosed pregnant by rectal palpation about 60 d after the end of the breeding season of 90 d and a value of 0 (failure) assigned to those that were not pregnant at that time. The estimate of heritability, obtained by Method R, was 0.57 with standard error of 0.01. The EPD was predicted using a maximum a posteriori threshold method and was expressed as deviations from 50% probability. The range in EPD was -24.50 to 24.55%, with a mean of 0.78% and a SD of 7.46%. We conclude that EPD for probability of pregnancy can be used to select heifers with a higher probability of being fertile. However, it is mainly recommended for the selection of bulls for the production of precocious daughters because the accuracy of prediction is higher for bulls, depending on their number of daughters.     

Brassinosteroid analogue effects on the yield of yellow passion fruit plants (Passiflora edulis f. flavicarpa)

The effects of successive brassinosteroid analogue (BR) applications (0.1 mg l⁻¹ of brassinosteroid analogue BB-16) were evaluated on commercial yellow passion fruit (Passiflora edulis f. flavicarpa) orchards in the first year of production. The treatments applied were: control, BR-1 (1 BR application shortly after the first flowers appeared), BR-2, BR-3, BR-4 and BR-5 (BR application in two, three, four and five consecutive weeks after the appearance of the first flowers, respectively). The fruits were collected for seven consecutive weeks (105 fruits treatment⁻¹) and fruit mass, length and diameter, soluble solid contents; pulp mass and peel thickness were evaluated in the laboratory. Multivariate analysis was performed in order to determine whether there were differences among the treatments taking into account all the measurements made. BR-3 was the most promising treatment because it produced the highest number of fruits plant⁻¹ (81.5) compared to the control (53.5) and the soluble solid content was 1 °Brix greater than the control. The BR-3 treatment resulted in a 65% increase in the estimated yield of the passion fruit plants, corresponding to 20 t ha⁻¹ compared to the control yield of 12 t ha⁻¹. The results showed that BB-16 sprayed during a period of reproductive development can increase the number of fruits per plant.     

Aerobic Training, But Not Creatine, Modifies Longissimus Dorsi Muscle Composition

The goal of this study was to investigate by means of an ultrasound examination the composition of the longissimus dorsi muscle in 12 purebred Arabian horses submitted to aerobic training for 90 days, with and without creatine supplementation. Creatine supplementation was carried out by daily administration of 75 g creatine monohydrate mixed into the ration during 90 days of training. Physical conditioning was conducted on a high-performance treadmill, and training intensity was stipulated by calculating the velocity at which blood lactate reaches 4 mmol/l, determined monthly for each animal. The individual intensity of physical force was established at 80% of velocity that resulted in a blood lactate level of 4 mmol/l. The cross-sectional area and the thickness of the layer of fat of the longissimus dorsi muscle were measured for each group at the end of 8 months of inactivity and after 30, 60, and 90 days of training without (control groups) or with creatine supplementation (experimental groups). The results showed that aerobic training combined with or without creatine supplementation caused significant longissimus dorsi hypertrophy and reduction in the thickness of the fat layer. No beneficial effect from prolonged creatine supplementation on the body composition of horses was detected.     

Study of stayability in Nellore cows using a threshold model

The objectives of the current study were to assess the feasibility of using stayability traits to improve fertility of Nellore cows and to examine the genetic relationship among the stayabilities at different ages. Stayability was defined as whether a cow calved every year up to the age of 5 (Stay5), 6 (Stay6), or 7 (Stay7) yr of age or more, given that she was provided the opportunity to breed. Data were analyzed based on a maximum a posteriori probit threshold model to predict breeding values on the liability scale, whereas the Gibbs sampler was used to estimate variance components. The EBV were obtained using all animals included in the pedigree or bulls with at least 10 daughters with stayability observations, and average genetic trends were obtained in the liability and transformed to the probability scale. Additional analyses were performed to study the genetic relationship among stayability traits, which were compared by contrasting results in terms of EBV and the average genetic superiority as a function of the selected proportion of sires. Heritability estimates and SD were 0.25 +/- 0.02, 0.22 +/- 0.03, and 0.28 +/- 0.03 for Stay5, Stay6, and Stay7, respectively. Average genetic trends, by year, were 0.51, 0.34, and 0.38% for Stay5, Stay6, and Stay7, respectively. Estimates of EBV SD, in the probability scale, for all animals included in the pedigree and for bulls with at least 10 daughters with stayability observations were 7.98 and 12.95, 6.93 and 11.38, and 8.24 and 14.30% for Stay5, Stay6, and Stay7, respectively. A reduction in the average genetic superiorities in Stay7 would be expected if the selection were based on Stay5 or Stay6. Nonetheless, the reduction in EPD, depending on selection intensity, is on average 0.74 and 1.55%, respectively. Regressions of the sires' EBV for Stay5 and Stay6 on the sires' EBV for Stay7 confirmed these results. The heritability and genetic trend estimates for all stayability traits indicate that it is possible to improve fertility with selection based on a threshold analysis of stayability. The SD of EBV for stayability traits show that there is adequate genetic variability among animals to justify inclusion of stayability as a selection criterion. The potential linear relationship among stayability traits indicates that selection for improved female traits would be more effective by having predictions on the Stay5 trait.     

Biophysical parameters of coffee crop estimated by UAV RGB images

Precision Agriculture - The advance of digital agriculture combined with computational tools and Unmanned Aerial Vehicles (UAVs) has enabled the collection of data for reliably extracting...     

Effects of soil moisture, organic matter and grass mulching on the carpogenic germination of sclerotia and infection of bean by Sclerotinia sclerotiorum

Microplot experiments were carried out during the autumn and winter of 1995 to determine the effects of soil moisture and levels of organic matter on the carpogenic germination of Sclerotinia sclerotiorum and subsequent infection of Phaseolus vulgaris . Soil moisture treatments were established by irrigation to field capacity: (a) when soil had dried to − 25 KPa, (b) when soil had dried to − 54 KPa, and (c) eight days after the soil had dried to − 54 KPa. Three levels of organic matter were established by mixing compost and yellow-red latosol in the following proportions (by volume): (a) 0% compost and 100% soil, (b) 50% compost and 50% soil, and (c) 100% compost and 0% soil. More apothecia and diseased plants were observed in the plots with higher moisture levels. Drier treatments resulted in a reduction in number (in the winter experiment) or elimination (in the autumn experiment) of apothecia. Other experiments were designed to examine the effect of grass mulching and organic matter levels on the carpogenic germination of S. sclerotiorum . In one experiment, grass mulching was compared with no mulching, and in another, the effects of different depths of mulch on the soil surface (0, 1.5, 3, 6 and 9 cm) were examined. Fewer apothecia were formed in mulched soil and the effect was most pronounced with 6 and 9 cm of mulch. The highest level of mulch (9 cm) impaired the vigour and yield of bean plants. In these experiments, carpogenic germination was increased by high soil organic matter content. Control of soil moisture and grass mulching may reduce the production of apothecia of S. sclerotiorum even in soils rich in organic matter.     

Elemental characterization of commercial mate tea leaves (Ilex paraguariensis A. St.-Hil.) before and after hot water infusion using ion beam techniques

Ilex paraguariensis A. St.-Hil. is used to prepare a traditional tealike beverage widely appreciated in Argentina, Paraguay, Uruguay, and southern Brazil. In these countries, the tea is popularly known as mate or chimarr?o. The aim of this work is to characterize the elemental composition of commercial Ilex paraguariensis and determine the portion of each element present in the leaves that is eluted in the water during the infusion process and consequently ingested by the drinker. Using the particle-induced X-ray emission technique, we verified the presence of Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, and Rb at different concentrations, which accounts for about 3.4% of the total mass. The results show a loss of about 90% of K and Cl, 50% of Mg and P, and 20% of Mn, Fe, Cu, Zn, and Rb by the leaves after the infusion. The volume of water used in the infusion affects only the concentration of elements such as Cl, P, K, and Mg until the first 600 mL of water, where a steep decrease in the concentration of these elements was observed in brewed leaves. Furthermore, higher water temperatures (typical temperatures used in infusions, between 80 and 100 degrees C) favor the extraction of K and Cl into the infusion, while the concentration of other elements remains practically constant as a function of temperature.     

Rapid determination of hydrogen peroxide using peroxidase immobilized on Amberlite IRA-743 and minerals in honey

Hydrogen peroxide and trace metals (K+, Ca2+, Na+, Mg2+, Mn2+, and Li+) were determined in 14 samples of Brazilian commercial honeys. The method for the determination of H2O2 is based on selective oxidation of H2O2 using an on-line tubular reactor containing peroxidase immobilized on Amberlite IRA-743 resin. Reactors presented high stability for at least 2 weeks under intense use. The results show a simple, accurate, selective, and readily applied method to the determination of H2O2 in honey. The trace metals were determined by capillary zone electrophoresis. Mean contents of 656, 69.1, 71.8, 36.0, 21.4, and 1.70 mg/kg were found, respectively, for K+, Ca2+, Na+, Mg2+, Mn2+, and Li+ in the analyzed honeys. The cations were identified by comparison of the relative migration times of their peaks with the Ba2+ migration time used as reference. The electrophoretic analysis was simple and rapid and did not require any other preparation of sample than dilution and filtration.