O objetivo deste trabalho foi avaliar a influência da aclimatação, da intensidade de geada e da disponibilidade hídrica sobre os danos causados pela geada em trigo. Os experimentos foram conduzidos em telados, com trigo cultivado em vasos. A aclimatação e a incidência de geada foram simuladas em câmaras de crescimento. Os fatores abióticos avaliados foram: regimes de aclimatação (com e sem); gradiente de temperatura (2, -2, -4 e -7°C); e variação de disponibilidade hídrica no solo, antes da geada (9, 6, 3 e 1 dia sem irrigação). Todos os fatores foram avaliados no afilhamento, alongamento e espigamento das cultivares: BR-18 Terena, mais tolerante à geada; e BRS 194, menos tolerante. As variáveis avaliadas foram: grau de queima de folhas, sete dias após a geada; massa de matéria seca total; e massa de grãos. A aclimatação do trigo, antes da geada, diminuiu os danos provocados antes do espigamento, e resultou em menor queima de folhas e maior rendimento de grãos. A temperatura de -7°C, no espigamento, resultou em falha na produção de grãos de ambas as cultivares; e os prejuízos com geada foram menores nas plantas com nove dias sem irrigação. As condições anteriores à ocorrência de geada têm influência sobre os danos provocados por ela.

The estimated corn grain yield is dependent on plant density and should be monitored from the beginning of its development, especially between the phenological stages V3 and V10, since these stages are more responsive to management strategies. This study aimed to evaluate the efficiency of two methods [normalized difference vegetation index (NDVI) and plant occupation index (POI)] to estimate the density of corn plants, in order to identify the plant population in different phenological stages and corn grain yield. Two field experiments were conducted in two crop seasons and treatments consisted of four plant densities (4, 6, 8 and 10 plants m-2). The NDVI measurements of the vegetative canopy were performed in the growth stages V4, V5, V6, V7, V8 and V9 (2014) and V3, V5, V6, V8, V9, V10 and V13 (2015/2016). For the POI, the measurements were performed in the stages V5, V6, V8 and V9, in both crop seasons. The different plant densities were efficient in generating variability in the NDVI and POI values throughout the corn crop development cycle, and both tools were efficient in identifying density variations. It was observed that these tools should be used between the V4 and V9 growth stages.

The aim of this study is to assess the impact of various row spacings on the morphology, components of grain yield, and overall grain yield of soybean. The experiments were conducted over two planting seasons (2014/2015 and 2015/2016) using two planting dates (November and December) and two cultivars, FPS Urano RR and BMX Tornado RR. The row spacings tested were: 45 cm (wide row), 45 × 45 cm (cross row), 22.5 × 45 cm (twin row), and 22.5 cm (narrow row). Measurements included leaf area index and sunlight interception at R2 stage, as well as grain yield components and overall grain yield. Narrow rows, in addition to achieving canopy closure, also demonstrated enhanced sunlight interception at the R2 stage. However, the positive effect of increased sunlight interception on grain yield was only significant for the December planting date, with no notable difference observed for the November planting date. These findings imply that while narrow rows may offer advantages, particularly in later planting dates, their implementation should be carefully considered and may not consistently lead to increased grain yield, reinforcing the continued preference for conventional row spacing.

The present work aims to evaluate the possibility of anticipating the wheat harvest by the application of non-selective herbicides in the pre-harvest conditions, thereby providing productive and economic viability. In total, 13 treatments were executed, which includes the spraying of different herbicide combinations (glufosinate-ammonium, glyphosate, and paraquat) in the phenological stages (Z-83, Z-85, Z-87, Z-92), and treatments without application of herbicides. Further, the treatment step was followed by providing different harvest conditions such as (i) glufosinate-ammonium: 9.5 and 8.8 days, (ii) glyphosate: 11.2 and 10.9 days, and (iii) paraquat: 7.9 and 8.5, where the first numerical value corresponds to number of days for the year 2016 followed by 2017. A mean reduction in seed yield of 4.6 % (BRS Parrudo) and 25.4 % (TBIO Sinuelo) was observed upon application of herbicides in the first two phenological stages. Additionally, an economic loss reaching up to R$ 2512 ha-1, was demonstrated. Therefore, the application of the non-selective herbicides glufosinate-ammonium and paraquat in the pre-harvest results in wheat phytointoxication, however, promoting harvest anticipation in 4.8 and 5.3 days, respectively.