Nitrogen fertilization affects yield and fruit quality in pear

Abstract

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 respectively.