| Wheat(Triticum aestivum Linn.) isone of the most important crops in theworld, it is also the second most common crop in China. However, wheat yellow mosaic virus(WYMV) has been occurringin local regions and extending rapidlyin China. Its symptoms in the field areleaf etiolated, green faded, plant dwarfed,and tillers decreased. MYMV affectswheat yield and quality seriously. Since the virus exists in the spores of Polymyxa graminis, while the spore’ wall is thickness that showed strong resistance to stress, so it is difficult to use chemical method to prevent and control. Wheat aphids, e.g. the Sitobion avenae(Fabricius), arethe economically important pests in China and in many other countries. Aphids can not only damage plant directlyby feeding on phloembut also transmit virus of plant diseases as efficient vectors. The traditional control method is chemical control, but it has more and more negative effects on environment, ecologicalbalance and human health. Therefore,new strategies and tactics should be exploredto control WYMV and wheat aphids in the future.Plant activator could trigger effective and broad-spectrum resistance in plants. The objective of this study is to shed light on the resistance induced by oligosaccharins·plant activator protein against wheat yellow mosaic virus(WYMV) and wheat aphids, which provides basis for the research and developmental program of activator proteins. In this paper, with or without activator spray on wheat plants infected with WYMV both in field and in laboratory, the disease index, chlorophyll content, height of wheat plant, thousand grain weight, the seeds per era and the yields were measured and calculated. This paper analyzed the population dynamics of wheat aphids and their natural enemies, and made a comparison of wheat yields after the activator(6% concentration) spray on wheat crops both in 2014 and in 2015,which providing theoretical basis for the functional evaluation of the activator in wheat fields. The results are as follows:1. Effect of Induced Resistance to WYMV,The laboratory experiments showed that after 30 days of the activator spray, the chlorophyll content increased dramatically(P<0.05), the disease index decreased as the result of the control efficiency reached up to 63.32%. The field experiment showed that the control efficiency was 46.67% after 2 weeks spray. However, the chlorophyll content and the height of wheat plants showed no significant differences. Although the seed numbers per ear significantly increased, no difference was observed on thousand grain weight. As a result, the yields were significantly increased.2. Effect of Induced Resistance to wheat aphidsAfter two times spray(2014: P< 0.05; 2015: P< 0.05), the numbers of coccinellids(Harmonia axyridis and Propylaea japonica)(2014: P< 0.05; 2015: P< 0.05) and the mummified aphid(2014: P< 0.05) were significantly higher than those of control during the grain filling period after three times spray. The corrected biological control indexes(BCI) were24.97 ± 0.72 and 13.42 ± 3.79 during wheat grain filling stage and the yields increased by 7.74% and 16.51% compared with the control both in 2014 and in 2015 respectively.Oligosaccharins·plant activator protein could induce wheat plant resistance to WYMV. It was showed that the activator could relieve WYMV damage and reduce yield loses in wheat fields. The increasing number of aphids in wheat flowering and early grain filling periods could control by the abundance increasing of natural enemies. Moreover, the activator protein might regulate the plant photosynthesis, or induce the expression of defense and stress-resistance gene to promote wheat growth and then increase yields. |
