为确切查清造成大连市刺槐春季生长异常的原因,对所辖各区、市(县)春季刺槐萌发情况和当地除草剂使用情况进行了调查,并在金州新区七顶山街道海防刺槐纯林中,使用阿特拉津、乙草胺和2,4-D丁酯3种除草剂,以2个质量分数梯度进行交叉处理试验.结果表明:在不使用2,4-D丁酯的地区,其玉米田附近的刺槐春季生长均正常,无小叶和枯黄落叶现象发生.在使用阿特拉津、乙草胺加2,4-D丁酯的地区,邻近刺槐在春季发生小叶、黄叶及落叶,生长势衰弱.从单一药剂施用的受害等级及药物残留量看,施用阿特拉津受害级别最轻,残留量最多,乙草胺和2,4-D丁酯残留很少或不残留,但受害状表现依次较重.在混合除草剂处理中,3种除草剂在混用时均表现出增效作用,2,4-D丁酯具有强烈的挥发性,可导致阿特拉津和乙草胺漂移能力加强.

The aim of this study was to further confirm the influences of two recycling ways of straw mulching and straw deep burial on photosynthesis characteristic,fluorescence characteristic and water use efficiency of maize.In this research,we took spring maize as materials and the ordinary field without straw recycling as control,which were used to study the effects of two straw recycling ways on intercellular CO2 concentration (Ci),transpiration rate (Tr),net photosynthetic rate (Pn),stomatal conductance (Gs),key enzyme activity of photosynthesis,carbon metabolism and water use efficiency of maize leaves.The results revealed that the average Tr,Gs,Pn,qP and Fv/Fm of ear leaves in the way of straw deep burial were significant higher than those in the way of straw mulching after maize blossomed from 0～50 d,and the water use efficiency in the way of straw deep burial was significantly improved.

This article studied the tissue culture of Betula pendula,including inducing callus,buds multiplication and radication of tube seedlings in different culture mediums.The result showed that the highest inducement occurred in culture medium with 1/2MS+6-BA1.00 mg·L-1+NAA0.05 mg· L-1+30 g·L-1saccharose;the highest bud multiplication occurred in culture medium with 1/2MS+6-BA0.20mg·L-1+NAA1.50 mg·L-1+30g·L-1 saccharose,at where the multiplication coefficent was up to 5～8;the highest rooting rate occurred in culture medium with 1/2MS+NAA0.50 mg·L-1+20 g·L-1saccharose culture medium,and the rooting ratio could reach to 100.0%.

Improved techniques is used in tissue culture of Populus alba ×berolinensis,and the results showed that when reproductive materials of the bud were propagated,the production costs was reduced of 50% than conventional techniques;This technique also increased stem tickening of 11.2%,individual fresh weight of 48%;The survival rate of transplanted seedings of 97.8% is higher than the conventional seeding of 81.3%,it is very effective.