Ryegrass (Lolium multiflorum Lam.) is the main winter weed of crops in Southern Brazil. High competitiveness, adaptability, widespread resistance to herbicides and seed dormancy make the plant a permanent problem. Herbicides, as well as plant growth regulators, can be used as a management option for ryegrass seed production, however there is no consensus among authors at which stage of the plant the application is most effective. Thus, this study aimed to evaluate the production and physiological quality of ryegrass seeds in response to the application of herbicides and plant growth regulators in three stages of plant development (inflorescence emergence, flowering and fruit development). Each treatment consisted of applying two different doses of each of the active ingredients: ammonium glufosinate, clethodim, glyphosate, iodosulfuron-methyl, paraquat and 2,4-D (herbicides); ethephon and trinexapac-ethyl (plant growth regulators), still an untreated control, totaling 17 treatments for each stage of development. The experimental design used was randomized blocks, with three replications. The variables evaluated were: seed production (kg ha⁻¹), thousand seed weight (g), viability (%), germination (%), first germination count (%), dormant seeds (%) and dead seeds (%). The ryegrass seed production reduced 100% with clethodim, glyphosate, ammonium glufosinate or paraquat applied in the inflorescence emergence or flowering stages. In the fruit development stage, all treatments (herbicides and plant growth regulators) caused deleterious effects on seed production, the greatest effect occurred with paraquat (95%). Paraquat, ammonium glufosinate and clethodim affected the physiological quality of the seeds when applied in fruit development stage. This research demonstrated that the application of herbicides in the ryegrass reproductive stage decreases its seedbank replenishment (natural re-sowing), with the potential to harm its progeny.

Helicoverpa armigera is a pest insect with a large dispersal range, a high degree of polyphagy in the larval stage, and of difficult control. The pest's ability to survive due to the availability of food and persist in grain production systems present in several Brazilian regions allows it to infest a wide range of crops, including soybeans and invasive plants during the off-season. There is general knowledge that the larva prefers to feed on plant reproductive organs, but it is unknown if this is true for soybeans, a crop to which it is adapting following its recent recognition as a pest. Basic knowledge of herbivore feeding behavior is necessary to support control within the integrated pest management philosophy. The purpose of this study was to examine the preference behavior of H. armigera larvae in their first, fourth, and sixth instars for vegetative and reproductive organs of soybean plants. It is concluded that the larvae, regardless of instar, feed on all available vegetative and reproductive organs, but they have preferences based on their current developmental stage.

The use of dual-purpose wheat emerges as an agricultural strategy to maximize soil use, mainly for forage and grain production, aiming to enhance natural resources in the autumn and winter seasons in Rio Grande do Sul. The objective of this work was to evaluate the effect of nitrogen rates on the production of pre-dried and wheat grains cv. BRS Pastoreio. The study consisted of eight treatments resulting from the factorial arrangement of four nitrogen (N) doses x two managements allocated in a randomized block design. The N rates were 70, 100, 130 and 160 kg/ha and the management consisted of: (1) only grain yield and (2) forage harvest for pre-dried silage and sprouting for grain production. The grain yield of the sprouting of plants harvested as pre-dried was drastically reduced. Nitrogen fertilization did not affect the yield components of dual-purpose wheat in the two managements studied. There was an effect of nitrogen doses on forage production in management 2. Regardless of the nitrogen dose, the CP content of pre-dried sprouting grains was higher than the exclusive management for grains.