Nitrogen fertilization affects yield and fruit quality in pear

Mineralized nitrogen (N) from organic matter and decomposing residues in most soils are not always taken into account. Little is known about the correct N application dose for pear trees to promote yield and fruit quality, without increase the risk of N loss into the environment. The study aimed to evaluate the effect of N doses application on N soil content, tree yield and fruit quality. The treatments consisted of the application of 0, 40, 80, 120 and 160 kg N ha(-1) year(-1), whereas urea was applied on the soil surface in September and February for 5 seasons (2011/12 to 2015/16). Leaves were collected, prepared and submitted to nutrient analysis. Fruit weight, number and yield were evaluated. Soil samples were collected at 0-0.20 m for 3 seasons (2013/2014 to 2015/2016), prepared and submitted to NH4+-N and NO3-N analysis, and then mineral N content was calculated. Peel color, ethylene production, and respiration rate were analyzed in the 2015/2016 crop season after 90 days inside the controlled atmosphere storage chamber. The fruits were kept at ambient conditions for 7 days and evaluated again for peel color, ethylene production and respiration rate, as well as destructive parameters such as titratable acidity, soluble solids and pulp firmness. The doses of N application affect the fruit number and yield, but did not affect leaf nutrient concentration. The highest N levels in the soil were observed in the 2014/2015 and 2015/2016 crops. The most economical doses were 122.0, 66.4, 22.5 and 96.0 kg N ha(-1) in the crops of 2011/2012, 2012/2013, 2013/2014 and 2015/2016 respectivel

Controle de Sitophilus zeamais Mots. através de diferentes concentrações de CO2 e O2 Control of Sitophilus zeamais Mots with different concentrations of CO2 and O2

Instalou-se um experimento com objetivo de avaliar o efeito de diferentes concentrações dos gases: CO2 e O2 balanceado com N, no controle de Sitophilus zeamais. Utilizou-se parcelas subdivididas no tempo com parcela principal distribuída segundo o delineamento inteiramente casualizado com quatro repetições. A unidade experimental constou de um vidro com volume de cinco litros, onde estavam acondicionados 0,15 kg de milho desinfestado e 200 insetos adultos não sexados. Foram avaliadas oito concentrações de gases (tratamentos): 0,03% de CO2 e 21% de O2 (testemunha), 10% de CO2 e 16% de O2, 15% CO2 e 16% O2, 20% CO2 e 16% O2, 0% CO2 e 5% O2, 0% CO2 e 1% O2, 75% CO2 e 5% O2, e 12% CO2 e 8% O2. Os resultados demonstraram que 20% de CO2 controla totalmente os insetos em cinco dias. Tratamento com 15% de CO2 associado com 5% de O2, controla a totalidade dos insetos após dez dias. Concentração de 1% O2, sem adição de CO2, também controla 100% da população de Sitophilus zeamais. após 15 dias.<br>This experiment was carried out aiming to evaluate the effect of different CO2 and 0(2) concentrations on the contral of Sitophilus zeamais. The experimental design was a split-plot in time, with the main plot distribucted in a completly randomized design, with four replications. The plot was consisted of a 5-liter glass chamber, in which 0.15 kg of desinfected maize with 200 unsexed adults insects. Eight gas concentrations were avaluated: 0.03% of CO2 and 21% of O2 (control), 10% of CO2 and 16% of O2, 15% of CO2 and 16% of O2, 20% of CO2 and 16% of O2, 0% of CO2 and 5% of O2, 0% of CO2 and 1% of O2, 15% of CO2 and 5% of O2 and 12% of CO2 and 8% of O2. Results demonstrated that 20% of CO2 controlled the insects in five days. Treatment with 15% of CO2 and 5% of 0(2) controlled 100% of insects in 10 days and 0% of CO2 and 1% of O2 controlled in 15 days