The Effect Of Water Adversity On Onion And The Preventable Effect Of Pesticide At The Different Nitrogen Levels

In the recent years, the cultivated area of onion (Allium cepa L.) becomes larger and larger. The quantity of export continually increases. However, the circumstance (water and disease) greatly affect the growth of onion, leading to the nutrition and yield of onion decreased. In view of chemical-free production, this paper was carried out, one side, to study the effect of water adversity and nitrogen on physiology, yield and quality of onion, the other side, to study the effect of pesticide and nitrogen on physiology, yield and quality of onion. The aim of this paper is to alleviate the water adversity and purple plot disease (Alternaria porri) on the hurt of onion, and the theory basis for establishing high quality, security technique is provided. The results are as follow:1 The water adversity restrains the growth and development of onion plant, the Nh can alleviate the restrained function. As water adversity time goes on, root fresh weight ,leaf fresh weight and so on ,the difference between the treatment and the water adversity treatment becomes bigger and bigger. At the same nitrogen level, the difference between the treatment ck and the water adversity treatment reaches the ultimate prominence level, as follow: ck>drought, ck>waterlog. At the same water condition, the difference among each nitrogen treatment shows the prominence level, as follow: Nh>Nm >N1. The development of bulb shows the growth trend of slow-quick-slow and the growth curve of "S".Azoxystrobin and N1 can speed the growth and development of onion plant. Root fresh weight ,leaf fresh weight and so on , N1 is as follow: Azoxystrobin > Oxadixyl+Mancozeb > Metataxyl+Mancozeb > Chlorothalonil > Polyoxins >ck, N2 is as follow: Azoxystrobin > Oxadixyl+Mancozeb> Metataxyl+Mancozeb> Chlorothalonil> Polyoxins >ck,N3 is as follow: ck> Azoxystrobin > Oxadixyl+Mancozeb > Metataxyl+Mancozeb > Chlorothalonil > Polyoxins.The difference between the treatment ck and the Azoxystrobin and (Oxadixyl+Mancozeb ) of Nl,the (Oxadixyl+Mancozeb) of N3 treatment respectably shows the ultimate prominence level, the difference between the treatment ck and (Oxadixyl+Mancozeb ) treatment shows the prominence level, the onion growth of Azoxystrobin treatment are the most quick.2 The water adversity reduces root activity and Chlorophyll content, destroys the structure and the function of cell membrane system, and increases the accumulation of saturated adjustment and soluble protein content. As water adversity time goes on, Chlorophyll content ascends ,and then descends, as follow: ck>drought>waterlog, Nh and Nm>Nl; the conductance of ck treatment is under the one of drought and waterlog treatment, the hurt rate of water and Nl treatment is the highest, the Nh reduces the hurt rate of water adversity; the water adversity treatment increases MDA content, the unsaturated fatty acid is befallen in the cell membrane, the structure and function of cell membrane system is...