Preliminary Study Of Rooting Characteristics And Nitrogen Nutrition Based On Different Ramie Species

Ramie(Boehmeria nivea L.), belonging to Urticaceae Boehmeria, is a perennial-perennial herb. It is an important fiber crop. Compared with other nutrient elements, nitrogen has the most significant effect on growth, yield and quality formation of ramie. Nitrogen diagnosis of plant, achieved through symptom observation and chemical diagnosis, is a method to determine the nitrogen level in plants. It assists to determine whether or not the plant needs additional nitrogen fertilizer so as to apply Nitrogen fertilizer accurately. Nitrogen nutrition diagnosis has been studied adequately at home and abroad, and the relevant technology is mature. However this technology is mainly applied on major crops and fruit trees. The study of nitrogen nutrition of ramie is important to ramie production. It also bears much significance to the establishment of the nitrogen nutrition detection system of ramie and to the establishment of the index database of ramie.The main results we obtained are as follows:1In the study of shoot cutting propagation, we got the number of roots and survival rate of30varieties of ramie. Of all these ramie varieties, ChuanzhuNo.1, huazhuNo.4,98S-063, guizhoutongzikongganma,037-047, weiyuanqingma, dianjiangbaima, wangcangwujiaoma, wuma, chuanhuangma,100-088, ziguidouerma and xingwenxiaohuangpi have good quality and higher survival rate (>90%) and reproduction rooting rate (can reach100%in5days).2The change regulation of the physiological and biochemical indexes of ramie are different under different nitrogen treatments. In the treatment of nitrogen concentration from0mmol/L to20mmol/L, dry weight, peroxidase activity, soluble protein content, soluble sugar content, nitrogen content and photosynthetic rate first increased then decreased. The dry weight, peroxidase activity and photosynthetic rate reach maximum under the treatment of8mmol/L. The leaf soluble protein content and the leaf nitrogen content reach maximum under the treatment of12mmol/L. Leaf nitrate nitrogen content and root nitrogen content increased with the increasing of nitrogen concentration from0to20mmol/L. The nitrogen content of leaf is more than that of root and stem. The phosphate and potassium contents of root is more than those of stem and leaf The plant dry weight, leaf soluble protein content, leaf peroxidase activity and photosynthetic nitrogen use efficiency under the treatment of0mmol/L is63%,60%,49%,50%,60%respectively of those of the treatment of8mmol/L. This study suggests that the ramie grows best under the treatment of8mmol/L based on the results and the consideration of reducing the cost.3The ramie seedlings under the treatment of0%N are short with little and small leaves, leaf yellowing, long and thin roots (50%longer than those under the treatment of100%N.) The ramie seedlings under the treatment of20%N grew higher than those under the treatment of0%N, but are accompanied with Leaf Chlorosis. The ramie seedlings under the treatment of100%N grew best with many green leaves and thick roots. The soluble protein content reduced considerably when the nitrogen concentration went down. The soluble protein content under the treatment of0%N is60%of that under the treatment of100%N. The soluble sugar content under the treatment of0%N is much less than that of the treatment of20%N and100%N. The maximum soluble sugar content (100%N) is1.7times of the minimum (0%N). The net photosynthetic rate, stomatal conductance, Intercellular CO2concentration and transpiration rate dropped when the nitrogen concentration was lowered.