Abstract

The utilization of organic fertilizers is of growing interest to improve soil quality and increase environmental sustainability. There is, however, limited information on the use of organic fertilizers for sweet onion production. The objective of this study was to evaluate the effects of chemical, mixed, and organic fertilizers on plant growth, bulb yield and quality, and mineral nutrients of sweet onion. The study was conducted at the Horticulture Farm, Tifton Campus, University of Georgia, in the winters of 2013, 2014 and 2017. The experimental design was a randomized complete block with three fertilizer treatments and four replications. Fertilizer treatments consisted on the application of Chemical (100% N), Mixed [chemical (50% N) + organic (50% N)] and Organic (100% N) fertilizers. In all treatments, the crop received a total of 150 kg·ha⁻¹ N. Plants in the Organic treatment showed augmented root growth and decreased leaf nitrogen compared to the Chemical and Mixed treatments. There were no differences in mean seasonal shoot and bulb dry weights and root-to-shoot ratio among treatments. Fertilizer treatments also had no impact on marketable and total bulb yields, bulb concentrations of macro and micronutrients, bulb disorders and diseases, and bulb chemical composition. Shoot and root growth increased with increasing air temperature, which explains the reduced plant growth during the winter. In conclusion, sweet onion grown with organic fertilizer alone or mixed (50% organic N + 50% inorganic N) produced plants and bulb yields and quality comparable to those grown with chemical fertilizer.

摘要

有机肥的利用在改善土壤质量和提高环境可持续性方面越来越受到关注。然而，关于在甜洋葱生产中使用有机肥料的信息有限。本研究的目的是评估化学肥料、混合肥料和有机肥料对甜洋葱的植物生长、鳞茎产量和质量以及矿质营养素的影响。该研究于 2013 年、2014 年和 2017 年冬季在佐治亚大学蒂夫顿校区园艺农场进行。实验设计为随机完整区组，包含三种肥料处理和四次重复。肥料处理包括施用化学（100% N）、混合[化学（50% N）+有机（50% N）]和有机（100% N）肥料。在所有处理中，作物总共接受了 150 kg·ha^-1 N。与化学处理和混合处理相比，有机处理中的植物表现出根系生长增强和叶氮减少。处理之间的平均季节性枝条和球茎干重以及根茎比没有差异。肥料处理也没有影响可销售的和总的球茎产量、球茎常量和微量营养素的浓度、球茎疾病和疾病以及球茎化学成分。芽和根的生长随着气温的升高而增加，这解释了冬季植物生长减少的原因。总之，单独或混合使用有机肥料（50% 有机 N + 50% 无机 N）种植的甜洋葱生产的植物和鳞茎产量和质量与使用化肥种植的洋葱相当。