This study aimed to evaluate the emergence, growth, biomass accumulation and tolerance of peanut genotypes under salt stress. The experiment was conducted in a protected environment (greenhouse), evaluating six peanut genotypes (Tatuí, L7151, Caiapó, IAC8112, IAC881 and Havana), which were subjected to two levels of irrigation water salinity (0.5 [control] and 3.5 dS m-1), arranged in a 6 x 2 factorial scheme, in a randomized block design, with five repetitions, with two plants per plot. Plants were cultivated for 30 days after sowing in lysimeters with capacity for 0.5 dm3, filled with a mixture of non-saline, non-sodic soil and commercial substrate in 1:1 proportion on volume basis. During this period, plants were evaluated for emergence, growth, biomass accumulation, tolerance to salinity and dissimilarity. The genotypes Tatuí and L7151 are the most sensitive to salt stress in the emergence stage. Irrigation with high-salinity water reduced the growth and biomass accumulation of the peanut genotypes, and Caiapó and IAC8112 were the least affected. The classification of salinity tolerance had the following sequence: Caiapó > IAC8112 > Havana > Tatuí > IAC881 > L7151.
A agricultura orgânica está cada vez mais crescente e, neste modelo agrícola o uso de biofertilizantes tem se tornado uma alternativa viável economicamente e ambiental, substituindo assim, o uso de fertilizantes minerais. O objetivo do trabalho foi avaliar o crescimento inicial do meloeiro (Cucumis melo L.) cv. Gold Mine submetido a diferentes doses de biofertilizantes em cultivo orgânico. Os tratamentos foram obtidos a partir da diluição do biofertilizante I e biofertilizante II em água, sendo que a primeira diluição foi obtida através do volume de 2,5 L de biofertilizante e 2,5 L de água, totalizando 5 L da solução. A partir desta solução, os biofertilizantes foram diluídos em diferentes proporções: proporção de 5% (300 mL do bio + 2,7 L de água); 10% (600 mL do bio + 2,4 L de água); 15% (900 mL do bio + 2,1 L de água); 20% (1200 mL do bio + 1,8 L de água); 25% (1500 mL do bio + 1,5 L de água); que foram aplicados via solo semanalmente. As variáveis avaliadas foram: diâmetro do caule, comprimento do ramo, número de folhas, clorofila (a e b) e área foliar. Para os resultados obtidos verificaram que a cultura do meloeiro apresentou resposta positiva ao uso do biofertilizante II em todas as variáveis analisadas, recomendando a dosagem de 15% do produto.
The large variation in the response of sunflower to nitrogen fertilization indicates the need for studies to better adjust the optimum levels of this nutrient for production conditions. Our objectives were to analyze the agronomic yield of sunflower cultivars as a function of nitrogen fertilization; indicate the cultivar with high nitrogen use efficiency; and measure the adequate N dose for sunflower through nutritional efficiency. The completely randomized block design with split plots was used to conduct the experiments. The treatments included five nitrogen rates being allocated in the plots and the four sunflower cultivars. To estimate the nutrient use efficiency in the sunflower, we measured agronomic efficiency (AE), physiological efficiency (PE), agrophysiological efficiency (APE), apparent recovery efficiency (ARE), and utilization efficiency (UE). The results indicate that all cultivars had a reduction in AE due to the increase in N doses in the first crop. For PE, the highest values were observed for Altis 99 during the 2016 harvest. In that same harvest, Altis 99 had the highest APE. The dose of 30 kg ha−1 provided greater ARE for all cultivars in both crops, with greater emphasis on BRS 122 and Altis 99. The cultivation of cultivars Altis 99 and Multissol at a dose of 30 kg ha−1 in is recommended semiarid regions.
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