Research On Characteristics Of Walnut In Germination And Growth

Walnut (Juglansregia L.) is a deciduous tree and an important forest tree species which belongs to the genus Juglans L. It has strong resistance and can growth in most part of China. At present, the walnut cultivation area of China is the first, while the export is only the second of the world. The breeding of improved varieties of walnut and the management technology of quality seedlings is an important factor to restrict the development of walnut industry. In this experiment, three kinds of container seedlings of walnut (Xiangling walnuts of Xinjiang, Shanxi walnuts and Jizhaomian walnut of Shandong) were planted. The physiological and biochemical indexes during XiangLing walnut seed germination were measured. And then we studied and compared the annual change regularity of three kinds of walnut seedlings including growth, biomass, mineral nutrition and photosynthetic characteristics. In the end, we discussed the different growth characteristic and evaluted the quality of walnut container seedlings comprehensiving variety of factors, aiming at providing some theoretical support for the genetic improvement of walnut and cultivation of stock for propagation (grafting, tissue culture, ect) and basis for the management of walnut breeding. The main results are as following:1. Walnut seeds arrived at the saturation of water absorpution after 5 days, germinatrd after 7-8 days, and emerged after sowing for 10 days approximately. All seeds emergenced completely after 45 days. Different varieties of walnut seeds had different qualities, and the germination characteristics were also differences. Germination rate: Xiangling > Jizhaomian > Shanxi walnut. Germination index: Xiangling > Jizhaomian > Shanxi walnut. Emergence: Xiangling > Jizhaomian > Shanxi walnut.2. During the germination process of Xiangling walnut, at the beginning major carbohydrates were consumed, and the fats and storage proteins played a major role in later germination. Close to period of radicle breaking the seed coat, soluble sugar and soluble protein content decreased rapidly. With the protease and lipase being mobilized, a large number of fat were consumed, fatty acid content increased and soluble sugar and soluble protein content began to rise. In this process, the lipase activity were negatively correlated with the fat content and positively correlated with the fatty acids.3. The height and basal diameter of walnut container seedings growthed fast twice a year. Height growthed a large at the first stage: Jizhaomian > Xiangling > Shanxi walnut. Basal diameter growthed a large at the second stage: Xiangling > Jizhaomian > Shanxi walnut. At the stage of growthing exuberantly, the aboveground biomass accumulated fast. Annual total biomass accumulation: Xiangling > Jizhaomian > Shanxi walnut. The phenomenon that the aboveground biomass was more than the underground one was all occurrenced in three kinds of walnut.4. The mineral element content of walnut container seedings at the beginning of growth: N> K> Ca> P> Mg. The content changed throughout the year, the content of N, P, K decreased on the total, Ca and Mg increased, but at last the content of Mg had a little descent. The changes of different elements were different. N, P and Mg in Xiangling walnut had a high content, and K and Ca in Jizhaomian walnut had a high content.5 Walnut is a kind of C3 plant. The diurnal change of photosynthesis rate had double peaks with a clear midday depression. The double peaks occurred at 11:00 am and 3:00 pm, and the first peak was higher than the second one. The net photosynthetic rate was negatively correlated with the internal CO2 concentration, and positively correlated with the stomatal conductance, leaf temperature, transpiration rate and photosynthetic active radiation. A comparison of photosynthetic rate between three kinds of walnut in the same period showed: Xiangling > Jizhaomian > Shanxi walnut.