The Research Of Adaptability Of Energy Plant Sweet Sorghum Under Excess Pb, Zn And Cu Stress

Bioenergy is a new kind of energy as a clean and substitute for conventional energy. But planting bioenergy will occupy lots of farmland.It is not according with the national condition of china having too many people and less land to developing bioenergy with farmland.In the long run,it is an effective solution of using edge soil for energy plant to solve the bioenergy material problem.There are many pollution soil with heavy metal in our country.Because the toxicity of heavy metal to biology,the pollution soil is not suit for planting crop entering to the food chain.If developing energy plant in these soil,it not noly resolve the problem of bioenergy material,but also has the phytoremediation effection to enviroment.Sweet sorghum containing much sugar is an important material for forming fuel ethanol.But how much is the actual energy value and potential of it? Sweet sorghum has the ability to resist drought,flood and saline-alkaline,but how about the tolerance to heavy metal? Which one is more suitable for planting in heavy metal pollution soil comparing to corn that is another material of fule ethanol? They are all questions needed to resolve.In this experiment,we chose three sweet sorghum variety called Zaoshu No.1,Nengsi No.1 and Dalishi and compared their adaptability in Nanjing,the ability to accumulating sugar and the potential energy.Then solution culture experiment was carried out to study the growth,the change of chlorophyll content the root activity,the content of malondialdehyde and the heavy metal content under the different zinc,copper and lead levels in corn(Yudan No.8) and sweet sorghum seedling(Zaoshu No.1).The main results were as follows:1 The growth period of Zaoshu No.1 and Dalishi was the shortest and longest respectively.The shoot length,total fresh and dry weight,stem diameter and weight,stem node of Dalishi was more than the other varieties.The biology characteristic of Zaoshu No.1 was better than Nengsi No.1.The sucrose and soluble sugar content in stem of Zaoshu No.1 and Nengsi No.1 was significantly higher than that of Dalishi.The carbon and calorific value per unit of Zaoshu No.1 and Nengsi No.1 was slightly higher.But there was no significant difference among three varieties.The analysis of total suger and calorific value in plant showed that Zaoshu No.1 had the highest total sucrose and sugar and Dalishi had the highest total carbon and calorific value in plant.The energy conversion efficiency of sucrose in stem was highest in Zaoshu No.1.2.The shoot and root length and dry weight of sweet sorghum and corn were significantly influenced negatively by Pb,Zn,Cu.The EC50 of physiological index was lower under Cu supply.The chlorophyll content and the root activity reduced and MDA increased gradually with the increase of the levels of heavy metal.It was more than corn of the change range of growth and physiology index of sweet sorghum under Pb,Zn stress, and it apperenced the opposite effect under Cu.The tolerance of corn was higher than sweet sorghum under stress of Pb and Zn,while sweet sorghum had the higher tolerance than corn for Cu.The content of the heavy metal in plant increased with the increase of the levels of heavy metal,and the content in root was higher than shoot.Corn could accumulate more Cu and few Pb and Zn than sweet sorghum.