Effect of Ethephon Application on Fruit Quality at Harvest and Post-harvest Storage of Japanese Plum (Prunus salicina) cv. Fortune

Abstract The objective of this work was to evaluate different concentrations of ethephon on Fortune plum ripening, also observing the effect of ethephon concentration on the fruit parameters of yield, soluble solids (SS), titratable acidity (TA), SS/TA ratio, firmness, wooliness, diameter, length, and average fruit mass at harvest and post-harvest. The experimental design was completely randomized with five treatments and four replications, each experimental unit consisting of four plants. The ethephon concentrations of zero, 100, 200, 300, and 400 mg∙L-1 were applied on the plums 20 days before the estimated harvest time. The results indicated that ethephon application induced a higher fruit yield in earlier harvest time, but with no effect on overall yield. Relative to the quality characteristics, the application of ethephon induced a reduction of fruit firmness, soluble solids content, and titratable acidity. Fruit length was not affected. The parameters of soluble solids, titratable acidity, and firmness presented a negative significant correlation with the ethephon dose. Relative to post-storage evaluation, the ethephon application induced a higher SS/TA ratio, and lower wooliness, titratable acidity, and soluble solids content. The parameters of soluble solids and titratable acidity presented a significant negative correlation, whereas the SS/TA ratio was positively correlated with the ethephon dose.

Insecticidal Activity of Lavandula dentata L. Essential Oil on Anticarsia gemmatalis (Hübner, 1818)

Abstract Anticarsia gemmatalis, commonly known as soybean caterpillar, causes important economic losses in soybean crops. Synthetic pesticides are the standard practice to control this insect. However, the indiscriminate use of these substances has increased the resistance of this pest. Thus, it is necessary to search for different control alternatives that are also more environmentally friendly. The objective of this work was to evaluate the chemical composition of Lavandula dentata L. essential oil (EO) and its activity on A. gemmatalis. The major compounds of essential oil were 1,8-cineole (31.5 wt.%), camphor (16.6 wt.%), and fenchone (15.9 wt.%). Bioassays were performed with third-instar caterpillars. EO concentrations of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0% v/v were diluted in Tween-80® 0.5% v/v and incorporated into the artificial diet given to caterpillars. Water, Tween-80® 0.5% v/v, and novaluron 0.075% w/v were added as negative and positive controls. For the aversion tests, soybean leaf discs were immersed in solutions with 0.4, 0.6, 0.8, and 1.0% v/v of EO, plus a negative control (water), and offered to caterpillars. In the bioassay, 100% mortality was observed from the concentration 0.6% v/v of the essential oil of L. dentata in 24 h; without statistical difference from 0.4 and 0.5% v/v. There was no important change in mortality between 24 and 72 h. In the aversion test, all EO treatments caused deterrence of caterpillars when compared to control, but without difference between EO concentrations. It was observed that L. dentata EO can be used as an alternative in the control of A. gemmatalis.

Bioactivity of Schinus molle L. and Schinus terebinthifolia Raddi. Essential Oils on Anticarsia gemmatalis (Hübner 1818)

Abstract Anticarsia gemmatalis is one of the main pests of the soybean crop, being controlled mainly with agrochemicals. The environmental and health risks, as well as the development of resistance by the pests, has led to the search for alternative control measures, aiming to use more eco-friendly procedures. The objective of this research was to evaluate the chemical composition and the bioactivity of Schinus molle and Schinus terebinthifolia essential oils (EOs) on A. gemmatalis. The major compound in both EOs was α-pinene (60.04 wt.% for S. molle and 38.49 wt.% for S. terebinthifolia). Bioassays were carried out with third instar larvae, with five replicates and each replicate with ten larvae, totaling 50 larvae per treatment. The oils were incorporated in the artificial diet (0.1, 0.5, 1.0, 1.5, and 2.0% v/v). The controls were: water, Tween-80® 0.5% v/v, and novaluron 0.075% v/v. According to the Probit method, the S. terebinthifolia EO presented a LC50 of 1.74% v/v (1.58-1.97% v/v); it was not possible to determine the LC50 for the S. molle EO. The mortality percentage after 24 and 48 h was 52% and 30% at 2.0% v/v for S. terebinthifolia and S. molle oil, respectively. After 72 h, the mortality rate for S. molle EO have not changed; for S. terebinthifolia EO it increased to 70%; the larvae treated with the chemical control (synthetic insecticide) had a mortality of 100%.

Effect of Chitosan Addition in Whey-based Biodegradable Films

Abstract Whey, a by-product of dairy industry, is a feedstock widely employed in the production of biodegradable films. However, these films present some limitations when considering the performance of synthetic polymers, especially biological transformation by decomposition. This work aimed to evaluate the effects of chitosan addition to whey-based films to improve films physical-chemical properties and resistance to microbial degradation. The results showed that there was an interaction effect between the chitosan concentration and the storage time for the physical-chemical properties of elongation at break and opacity. There was statistical difference among the formulations; however, for the moisture content and film thickness, there was no interaction effect between the formulation and the storage time. The films with 1.5 and 3.0 wt.% chitosan presented a yellowish hue, characteristic of the polysaccharide; this could also be detected by SEM analysis. The films presented an excellent biodegradability, being decomposed in about 8 days. Considering all chitosan contents tested had similar performances, the chitosan content of 0.15 wt.% was the one with the better cost-benefit relation.

Poejo (Cunila galioides Benth. ) Production in Five Agroecological Regions of Rio Grande do Sul

Abstract The objective of this study was to evaluate the biomass and essential oil production of nine populations of poejo (Cunila galioides) cultivated in five agroecological regions of the state of Rio Grande do Sul, under different edaphoclimatic conditions. The experiments were performed in field conditions in Erechim, Caxias do Sul, Pelotas, São Francisco de Paula, and Santa Vitoria do Palmar. The experimental design was completely randomized, with nine populations, eight plants per plot and four repetitions. The following were evaluated: biomass production and essential oil chemical composition and yield. The data underwent ANOVA, followed by Tukey's multiple range test. The adaptability and stability of the populations in the different environments were also evaluated by regression analysis. The results showed great differences between the populations and cultivation sites, with genotype vs. environment interaction. Most populations presented the best biomass production results at Erechim. Pelotas and Santa Vitória do Palmar were the worst locations for poejo production, mainly due to a water deficit occurred during the experiment. The Santa Lucia population presented broad stability and the greatest adaptability to the environments for biomass and essential oil production, but its average production was not satisfactory. The André da Rocha population presented the highest average production of essential oil, and was favored in favorable environments. Regarding essential oil chemical composition, the populations kept stable contents of the major compounds at all locations, with a few variations. In some populations, a higher concentration of sesquiterpenes was observed, which can be attributed to environmental stress.