Studies On Nutrition Control During Flowering Period For Preventing "Premature Senility" Of Paulownia In Drought And Saline Area

Tianjin economic and technical development area (TEDA) is a developed area that was built on salinized mud flat where few plants can grow healthily. Paulownia tomentosa (Paulownia tomenlosa (Thunb.) Steud.), for its strong resistance, is one of the most trees in TEDA.Trees were planted though exchanging soil to reduce salt. The root is localized in a cavity(4*1m) outside which the soil still is salinized. In recent years, some old Paulownia tomentosas suffer from the problem of "premature senility".To solve the problem of "premature Senility", the nutrition consuming dynamics in flower period and the effect of pruning(inflorescences were pruned compared with control) and N (i.e.250g carbamide and 500g carbamide were used compared with control) to Paulownia tomentosa were studied in this paper.Lots of nutrition was consumed in the flower period. During the whole flower period, above 639.22g total sugar (WSC+starch)and 256.87g crude protein were consumed per 10 years old Paulownia tomentosa.The nutrition condition was improved remarkably by pruning that saved the nutrition wasted by flowers. Leaf and branch were accelerated. The net photosynthesis rate(Pn) and transpiration rate were boosted. The N content and Water-soluble carbohydrates(WSC) in leaf were increased significantlyAfter fertilizing, the Pn and transpiration rate were improved greatly. The N content and WSC in leaf were increased significantly too.The result showed that flowering needs consume lots of nutrition. Pruning can save nutrition consuming and maintain the well-being of Paulownia tomentosa. N can inproved the nutrition condition and promote the growth of Paulownia tomentosa. Therefore pruning and fertilizing can alleviate the problem of "premature Senility".