琼脂共培法测定小麦化感潜力的微生物污染及其对策

Microbial contamination in agar bioassay to evaluate wheat allelopathy and its countermeasure

小麦常规消毒后的琼脂培养过程难免会经常发生微生物污染,并影响琼脂共培法测定小麦化感潜力的准确性。为寻求一个恰当的对策,本研究对9个化感潜力不同的小麦品种采用琼脂迟播共培法培养,莴苣迟小麦3天播种,共培到第2、4、6、8、10、12、14天时分别测定小麦对莴苣的根长抑制率。结果表明,小麦成熟籽粒在培养过程发生微生物污染的程度与抑制率测定值的偏差呈显著正相关,小麦的污染程度随共培养天数的延长而加重。另一方面,小麦品种的化感潜力测定值在共培早期变动较大,直到共培12天后才有相对稳定的表现。兼顾缩短小麦培养时间可减少微生物污染对测定结果的影响,以及小麦化感潜力稳定表达所需的时间,优化的小麦化感潜力测定时间是受体植物比小麦迟播3天后再与小麦共培12天。

It is inevitable that microbial contamination occurred when wheat seeds were cultured in agar though the normal disinfection procedure had been conducted. The contamination affected the accuracy of allelopathic potential tested by relay seeding technique in agar bioassay. To search a countermeasure, nine wheat varieties with different allelopathic potential were cultured in agar. The root length inhibition rate （IR） of lettuce was measured after coculture with wheat for 2, 4, 6, 8, 10, 12 and 14 days respectively. Microbial contamination resulted in the deviations of the allelopathic potential values. There was a significant positive correlation between the contamination degree and IR deviation. The contamination degree increased with the increase of co-culture days. In order to avoid the influence of contamination, it is necessary to shorten the co-culture period. However, Ig values fluctuated greatly at the beginning periods until day 12. Considering the balance of stable expression of the allelopathic potential and reduction of the contamination impact, 3 days of seeding delay and 12 days of co-cultured period for lettuce are suitable for evaluating wheat root allelopathic potential.