ABSTRACT The use of salt stress attenuators is considered an important tool to minimize the deleterious effects of salts. However, its application to chives (Allium schoenoprasum L.) has not been studied. This study aimed to evaluate the induction of salt stress tolerance in chives plants in relation to growth and enzymatic reactions, when subjected to different salinity levels of the nutrient solution, after acclimation of seeds with hydrogen peroxide (H2O2) for 24 h. The experiment was conducted in a greenhouse, where chives seeds were acclimated by H2O2 at concentrations of 0.0, 0.15, 0.30, 0.45 and 0.60 mmol. After germination, the plants were cultivated in hydroponic system with electrical conductivities of 1.0, 2.0, 3.0, 4.0 and 5.0 dS m-1. Plant height, length and number of leaves, H2O2 content, malondialdehyde and catalase (CAT) activity were evaluated in chives plants. The increase in the salinity of the nutrient solution up to 5 dS m-1 reduced by 5.88%, 17% and 9.63% plant height, leaf length and number of leaves, respectively. It was observed that the acclimation of chives seeds with H2O2 at 0.45 mmol g-1 fresh mass in plants that were cultivated in nutrient solution of 3.73 dS m-1 led to maximum CAT activity, minimizing the deleterious effects of nutrient solution salinity on plant growth.

ABSTRACT Population dynamics of aphids have been studied in sole and intercropping systems. These studies have required the use of more precise analytical tools in order to better understand patterns in quantitative data. Mathematical models are among the most important tools to explain the dynamics of insect populations. This study investigated the population dynamics of aphids Aphis gossypii and Aphis craccivora over time, using mathematical models composed of a set of differential equations as a helpful analytical tool to understand the population dynamics of aphids in arrangements of cotton and cowpea. The treatments were sole cotton, sole cowpea, and three arrangements of cotton intercropped with cowpea (t1, t2 and t3). The plants were infested with two aphid species and were evaluated at 7, 14, 28, 35, 42, and 49 days after the infestations. Mathematical models were used to fit the population dynamics of two aphid species. There were good fits for aphid dynamics by mathematical model over time. The highest population peak of both species A. gossypii and A. craccivora was found in the sole crops, and the lowest population peak was found in crop system t2. These results are important for integrated management programs of aphids in cotton and cowpea.

ABSTRACT The intercropping is an important cultural practice commonly used in pest management. It is based on the principle that increased plant diversity in the agro-ecosystem can lead to reductions of pest populations in the crop. The current study aimed to assess the impact the colored fiber cotton-cowpea intercropped systems on Aphis gossypii and Aphis craccivora and on their predator Cycloneda sanguinea and the losses and the dispersion behavior of these aphids and their predator in these cropping systems. The experiment had a randomized block experimental design with two bioassays and four treatments. The number of apterous and alate aphids (A. gossypii) per cotton plant was 1.46 and 1.73 or 1.97 and 2.19 times highest in the solid cotton system than that found in the cotton-cowpea intercropped systems (S1) and (S2), respectively. On the other hand, the cotton-cowpea intercropped systems (S1 and S2) reduced, respectively, in 43% and 31% the number of apterousA. gossypiiper cotton plant compared to the control. Implementing cotton-cowpea intercropped system in the S1 scheme reduced A. gossypii infestation, favored the multiplication of C. sanguinea, and allowed obtaining heavier open bolls.