野燕麦繁殖和抗逆特性及其对小麦的他感效应研究

作为一种分布广泛的农田恶性杂草,野燕麦具有很强的环境胁迫适应能力,并且在种间竞争中常处于优势地位。本试验对野燕麦种群的繁殖与扩散特性、种子与幼苗抗逆特性及其根系分泌物对小麦的异株克生作用进行了研究,以期为找寻治理野燕麦的有效措施提供参考。结果表明:(1)野燕麦具有很强的种子繁殖与扩散能力,开花结实比小麦早,种子产量大、地下储量多、扩散距离远;(2)野燕麦种子对温度的适应范围较广,在室温与变温条件下均可以正常萌发,而冷冻后置于室温环境是其萌发最佳条件,总发芽率可达93.33%;(3)野燕麦种子对盐胁迫具有一定的适应性,在浓度低于1.8%的NaCl溶液中均可正常萌发;(4)野燕麦幼苗对盐胁迫和干旱胁迫具有较强的适应性,随着NaCl浓度和PEG浓度的升高,野燕麦幼苗叶片的脯氨酸含量显著增加(P0.01),过氧化氢酶活性呈现先增加后下降的趋势;(5)野燕麦根系水浸提液对小麦幼苗株高、干重、根长及根系活力均有极显著影响(P0.01),证明野燕麦根系分泌物对小麦幼苗生长具有异株克生作用。以上结果表明,野燕麦的竞争优势主要体现在强大的繁殖扩散能力、较强的抗逆性以及异株克生效应,相关研究可为大田野燕麦防除提供一定理论参考。

Reproductive and stress resistance characteristics of wild oat and its allelopathic effects on common wheat

As a widespread malignant weed in farmlands, wild oat has strong survival ability and can adopt multiple strategies to cope with various and changing environmental stresses. This high adaptive ability always makes wild oat to occupy a dominant place in the interspecific competition. In this study, the reproductive and dispersal characteristics of the population, stress resistance of seeds and seedlings, and allelopathic effects (root exudates) on common wheat seedlings of wild oat were investigated. The study aimed to understand the survival strategies of wild oat and find effective methods of controlling natural spread of this plant species. The main results of the study were as follows:1) Wild oat had a strong sexual reproduction and population dispersal ability in farmland ecosystems. This included earlier flowering and higher grain-setting than common wheat, high seed yield, huge seed bank, far seed dispersal distance, etc. 2) The germination of wild oat seed occurred within a wide temperature range and could germinate normally under room or varying temperature conditions. Room temperature was the optimum condition for wild oat seed germination after freezing treatment, which was highly benefited the plant by breaking seed dormancy and increasing total germination rate to up to 93.33%. 3) Wild oat seed had some adaptable responses to the salt stress, but germinated normally when NaCl concentration was below 1.80%. 4) Wild oat seedling was also adapted very well to both salt and drought stresses. Proline accumulation in seedling leaf of wild oat increased significantly (P<0.01) with gradual increase in NaCl or PEG concentration. However, catalase activity of wild oat seedling leaf increased at the start of NaCl or PEG stress and then declined as NaCl or PEG concentration increased. 5) Root aqueous extract of wild oat negatively affected the plant height, plant dry weight, root length and root vitality of wheat, which was significant at P<0.01 level. This demonstrated that the root of wild oat had a strong allelopathic effect on the growth of common wheat seedling. The above results suggested that the competitive advantage of wild oat was reflected in several ways- strong sexual reproduction and seed dispersal ability, high resistance to salt and drought adversities, and significant allelopathic effect on adjacent plants. Related in depth studies were required to provide firm theoretical basis for controlling wild oat dispersal in farmlands, especially in wheat fields.