Analyses On Variations Of American Black Walnut

American Black Walnut (Juglans nigra ,ABW) belongs to Juglandaceae, Juglans. Because of its stiff timber, close structure, graceful pattern, beautiful color and luster as well as its delicious and nutritious fruitage, American Black Walnut has already become one of the highest economic worthy plant. But many of black walnut seeds grow slowly and unhealthy, and their shapes are not beautiful. So, ABW needs to be improved urgently. In this research, studies have been taken on Eastern Black Walnut of three years. In order to find quickly growing, good quality or spinney that suit to plant in our country as well as make a academic base to choose and early appraise breeding material, we have investigated morphologic characters, growth dynamics, photosynthesis efficiency and DNA marker of its variations. The main results are as follows:(1) The main morphologic characters of variations of Eastern Black Walnut have been surveyed. The results indicate that Eastern Black Walnut have engendered differentiations respectively in tresses, leaves, buds and etc.. Variations can be separated primarily into three types: Type Ⅰ are those seedlings grow quickly while their leaves are small; Type Ⅱ are those seedlings grow quickly and their leaves are large; Type Ⅲ are those seedlings grow slowly. Eastern Black Walnut is prescribed Type Ⅳ.(2) Studies on growth dynamics of height and diameter of four types black walnut shows, the diameter of TypeⅠand Type Ⅱ are 189.9% and 212.7% that of Type Ⅳ. The diameter of Type Ⅲ is 64.8% that of Type Ⅳ.(3) Photosynthesis characteristics of four types black walnut have been studied with isolated leaves. The results were as follows: The AQY, CE and Pn of the type ⅡandⅠare higher which means their capabilities of photosynthesis and CO2 fixations are the strongest. While the AQY, CE and Pn of the type Ⅲ are the smallest, that means the capabilities of photosynthesis and CO2 fixation of type Ⅲ black walnut are the lowest. In the whole seasons, the Pmax of the typeⅠand Ⅱ are higher and the Pmax of the type Ⅲ is the lowest.(4) Black walnut DNA extraction and RAPD amplification conditionshave been established and optimized. The DNA that extracted from the leaves of black walnut by the simplified way using CTAB is high quality and yield. Then the stability of RAPD amplification can be guaranteed. The amplification procedure which is appropriate to black walnut is as follows: 94℃, 2 min; 94℃,30 sec; 36℃, 40 sec; 72 ℃,1 min; 45 cycles; 72℃,5 min. The optimized amplification conditions are as follows: 2.5 mmol.l-1 dNTP 1μl, 2.0 mmol.l-1 Mg2+ 2μl, Taq enzyme 1.0U, 10pmol primer 1μl. Under this condition, the stable results can be achieved. (5) The result of RAPD clustering showed that three types variations of black walnut are genotype variation. TypeⅠandⅡare fast growing types while type Ⅲ is a slow growing one . They all can be used as breeding resources of black walnut.(6) 100 random sequence decmer-primers were used to screen bulked samples for marker linked to the fast or short growth. The primers S10600 and S8560 produced two polymorphic bands that linkaged with fast growth character. The primer S15520 produced a polymorphic band that linkaged with short growth character. The result can be used to select walnut breeding material and do early prarising...