Schroeder B K, Humann J L, du Toit L J
Washington State University, Pullman 99164.
Washington State University Mount Vernon NWREC, Mount Vernon 98273.
Plant Dis. 2012 Oct;96(10):1548-1555. doi: 10.1094/PDIS-02-12-0117-RE.
The influence of postharvest curing temperature and duration on development of slippery skin (caused by Burkholderia gladioli pv. alliicola) and sour skin (caused by B. cepacia) in onion (Allium cepa) bulbs during storage was evaluated by inoculating bulbs of the storage cultivars 'Redwing' and 'Vaquero' with each of the pathogens after harvest, curing the bulbs at 25, 30, 35, or 40°C for 2 or 14 days, and storing the bulbs at 5°C for 1, 2, or 3 months. Noninoculated bulbs and bulbs injected with sterile water served as control treatments. The onion bulbs were from drip-irrigated, commercial onion crops grown in the semiarid Columbia Basin of central Washington in 2009 and 2010. Each bulb was cut through the point of inoculation from the neck to the basal plate to assess severity of bulb rot (percentage of cut bulb surface area with bacterial rot symptoms) after 1, 2, or 3 months of storage. Bulb rot severity in the 2009-10 and 2010-11 trials was negligible for noninoculated bulbs (mean of 4.0 and 4.5%, respectively) and bulbs injected with water (6.2 and 10.1%, respectively) compared with bulbs inoculated with B. cepacia (34.6 and 39.8%, respectively) and B. gladioli pv. alliicola (20.7 and 27.4%, respectively). Bulbs inoculated with B. cepacia developed significantly more severe rot than those inoculated with B. gladioli pv. alliicola, even though a 10-fold greater inoculum concentration was used for B. gladioli pv. alliicola, demonstrating the more aggressive nature of B. cepacia compared with B. gladioli pv. alliicola. Severity of bulb decay caused by B. cepacia or B. gladioli pv. alliicola was affected significantly (P < 0.05) by season (trial), cultivar, curing temperature, curing duration, and storage duration, with significant interactions among these factors. In both trials and for both pathogens, bulb rot was significantly more severe the greater the curing temperature and the severity of bulb rot was significantly greater when bulbs were cured for 14 versus 2 days prior to cold storage. Overall, the severity of bulb rot was greater with a longer duration of storage after curing. This increase in bulb rot severity, which resulted from an increase in curing temperature and duration, was significantly greater for Vaquero than Redwing and significantly greater for bulbs inoculated with B. cepacia than B. gladioli pv. alliicola. The results suggest that postharvest curing at temperatures <35°C for a limited duration can significantly reduce the severity of sour skin or slippery skin in storage.
通过在收获后用每种病原菌接种贮藏品种‘红翼’和‘牛仔’的洋葱鳞茎，在25、30、35或40℃下将鳞茎进行2天或14天的愈伤处理，然后在5℃下贮藏1、2或3个月，评估了采后愈伤温度和持续时间对洋葱（Allium cepa）鳞茎在贮藏期间滑皮病（由唐菖蒲伯克霍尔德氏菌洋葱致病变种引起）和酸腐病（由洋葱伯克霍尔德氏菌引起）发生的影响。未接种的鳞茎和注射无菌水的鳞茎作为对照处理。洋葱鳞茎来自2009年和2010年在华盛顿州中部半干旱的哥伦比亚盆地通过滴灌种植的商业洋葱作物。贮藏1、2或3个月后，将每个鳞茎从颈部到基部盘沿着接种点切开，以评估鳞茎腐烂的严重程度（有细菌腐烂症状的切开鳞茎表面积百分比）。在2009 - 10年和2010 - 11年的试验中，与接种洋葱伯克霍尔德氏菌（分别为34.6%和39.8%）以及唐菖蒲伯克霍尔德氏菌洋葱致病变种（分别为20.7%和27.4%）的鳞茎相比，未接种的鳞茎（分别平均为4.0%和4.5%）和注射水的鳞茎（分别为6.2%和10.1%）的鳞茎腐烂程度可忽略不计。接种洋葱伯克霍尔德氏菌的鳞茎比接种唐菖蒲伯克霍尔德氏菌洋葱致病变种的鳞茎腐烂严重得多，尽管唐菖蒲伯克霍尔德氏菌洋葱致病变种使用的接种浓度高10倍，这表明洋葱伯克霍尔德氏菌比唐菖蒲伯克霍尔德氏菌洋葱致病变种更具侵染性。由洋葱伯克霍尔德氏菌或唐菖蒲伯克霍尔德氏菌洋葱致病变种引起的鳞茎腐烂严重程度受季节（试验）、品种、愈伤温度、愈伤持续时间和贮藏持续时间的显著影响（P < 0.05），这些因素之间存在显著的交互作用。在两个试验中以及对于两种病原菌，愈伤温度越高，鳞茎腐烂越严重；与冷藏前愈伤2天相比，鳞茎在愈伤14天后冷藏时，鳞茎腐烂严重程度显著更高。总体而言，愈伤后贮藏时间越长，鳞茎腐烂严重程度越高。这种因愈伤温度和持续时间增加而导致的鳞茎腐烂严重程度增加，对于‘牛仔’品种比‘红翼’品种显著更高，对于接种洋葱伯克霍尔德氏菌的鳞茎比接种唐菖蒲伯克霍尔德氏菌洋葱致病变种的鳞茎显著更高。结果表明，在低于35℃的温度下进行有限时间的采后愈伤处理可以显著降低贮藏期间酸腐病或滑皮病的严重程度。
