Abstract:

Rice allelopathy is considered as a complex phenomenon of chemical ecology, and temperature plays an important role in regulating allelopathic potential. Former studies have demonstrated that the wild rice (Oryza longistaminata) has high allelopathic potential.Therefore,understanding the allelopathic responses to temperature of wild rice and its descendants is very important to finally exploit and utilize allelopathic genes of wild germplasm resources.The root exudates of different allelopathic potential rice accessions(OL, RD23, F1, RL159, RL169 and RL219)were respectively collected by the resin of AG 50W-X8,followed by the evaluation of their allelopathic potential to barnyardgrass.The results demonstrated: 1) Allelopathic response to temperature,leaf ages and temperature×leaf age were significantly different among different allelopathic potential rice accessions. The allelopathy was significantly affected by temperature, leaf age and temperature×leaf age of OL, F1, RL159 and RL169, but low allelopathic rice accessions of RD23 and RL219 followed an opposite trend. 2) Regardless of leaf ages,the root exudates have weakest inhibitory ability to the growth of barnyardgrass at low temperature(15℃). The effects of allelopathic rice accessions OL, F1, RL159 and RL169 were greater than low allelopathic ones at low temperature(15℃) condition. 3) High temperature was conducive to the allelopathic enhancement of allelopathic rice, but the allelopathy was not always enhanced with increasing temperature. The allelopathy was strengthened with increasing temperature of allelopathic rice accessions OL, F1, RL159 and RL169 when they were at the 6-leaf stage and 8-leaf stage, but at the 2-leaf stage and 4-leaf stage, the allelopathy was enhanced first and then decreased with increasing temperature, and the allelopathy was strongest at 25℃. 4)Allelopathic responses to leaf ages were significantly different among different allelopathic potential rice. The allelopathy is the highest at the 2-leaf stage for allelopathic rice accessions OL, F1, RL159 and RL169 except for 15℃, then the allelopathy weakened with the increasing rice leaf ages.This finding suggests that allelopathic enhancement by temperature conditions at different leaf ages were worthwhile in future for the understanding of allelopathic responses to associated weeds.

Key words: wild rice (Oryza longistaminata), root exudates, temperature, leaf age, allelopathy

摘要：

掌握温度对长雄野生稻(Oryza longistaminata)及其后代化感作用的影响, 对开发利用野生种质资源的化感抗草基因具有重要意义。采用直接树脂吸收法收集不同叶龄长雄野生稻及其后代在各温度条件下的根系分泌物,并以稗草作为受体,测定其化感作用。结果表明:1)温度、叶龄和温度×叶龄对水稻化感作用的影响与其自身化感潜力正相关,且对强化感和中化感潜力水稻(OL、F₁、RL159 和RL169)的化感作用影响极显著,而对弱化感水稻(RD23和RL219)的化感作用影响不显著。2)供试条件下长雄野生稻及其后代根系分泌物对稗草的化感作用均为抑制作用,其中,低温不利于水稻化感潜力的发挥。15℃时, 强和中化感潜力水稻在不同叶龄对稗草的苗高、根长和生物量的抑制作用最弱,化感综合效应指数也显著大于同等叶龄的高温处理。3)高温有利于水稻化感潜力的发挥,但并非总是随温度的升高而增强。在6叶期和8叶期,水稻材料OL、F₁、RL159和RL169随温度的升高化感作用逐渐增强,但在2叶期和4叶期则表现为先增强后减弱,在25℃时对稗草化感作用最强。4)在15℃时,强和中等化感潜力水稻在2叶期化感作用最弱,而在其他温度条件下,其化感作用随叶龄的增加表现为先减弱后增强,在2叶期化感作用最强。研究结果显示,温度对不同叶龄的水稻化感作用具有调控作用,幼苗阶段高温有利于强和中化感潜力水稻化感作用的发挥。

关键词: 长雄野生稻, 根系, 分泌物, 温度, 叶龄, 化感作用