Regulation Effects Of Potash Applied At Different Growth Phases On Sucrose Metabolism Of Tomato In Greenhouse

Regulation effects of potash applied at different phases on tomato growth and sucrose metabolism was studied with Karese (Lycopersicon esculentum Mill) as material in this experiment. There were five treatments in this experiment, (1) applying potash at seedling phase, (2) applying potash at flowering phase, (3) applying potash at fruit enlarging phase, (4) applying 40%, 30% and 30% of total potash at seedling, flowering and fruit enlarging phases respectively (abbreviated to"SFE phases", same as follows), (5) applying no potash (control). The mixture of peat moss and cinder (v/v =1:1) was used as substrate and K2SO4 was used as potash; there were five plants for each treatment and three replications.The main results were as follows:1. Application of potash at flowering phase significantly increased tomato yield and quality. Application of potash at flowering phase obtained the highest yield (2.14kg/plant), which was significantly increased by 23.5% and 38.9% compared with applying potash at fruit enlarging phase and control respectively. Application of Potash at flowering phase obtained the highest content of soluble sugar, organic acid and soluble solid of tomato fruit, and the content of soluble sugar was significantly increased by 40.8% and 44.7% compared with applying potash at fruit enlarging phase and control respectively, organic acid content significantly increased by 28.8% compared with control, and the content of soluble solid was significantly increased by 11.0% compared with applying potash at seedling phase.2. Application of potash at flowering phase significantly improved leaf photosynthesis Application of potash at flowering phase increased chlorophyll a and chlorophyll b content by 19.3% and 45.5% compared with control respectively, and the total chlorophyll content of leaves was significantly increased by 13.9%, 19.9%, 13.9%, and 25.8% compared with applying potash at seedling, fruit enlarging, SFE phases and control respectively. The net photosynthetic rate of tomato leaves was significantly increased by 23.9% compared with control when applying potash at flowering phase.3. Application of potash at flowering phase increased the accumulation of glucose, fructose, sucrose and total soluble sugar in tomato fruit.Application of potash at flowering phase significantly increased glucose content by 73.1%, 93.1% and 85.8% compared with applying potash at fruit enlarging, SFE phases and control respectively at small fruit stage, and glucose content was significantly increased by 69.4% compared with control. Application of potash at flowering phase significantly increased fructose content by 55.6% compared with control at small fruit stage. Applying potash at flowering phase significantly increased sucrose content by 34.3% and 31.3% compared with applying potash at fruit enlarging phase and control at small fruit stage respectively. Total soluble sugar content of fruit was kept highest in all tomato growth stage when potash was applied at flowering phase, and the total soluble sugar content was 16.0%, 29.5% and 19.7% greater than that of control at small fruit stage, green ripe stage and ripe stage respectively. 4. Application of potash at seedling and flowering phases decreased the accumulation of glucose, fructose, sucrose and total soluble sugar in tomato leaf.Application of potash at seedling and flowering phases significantly decreased the content of glucose of tomato leaves by 68.6%, 69.4% and 62.8%, 43.3% at green ripe stage and ripe stage compared with control, respectively; fructose content was significantly decreased by 79.7% and 67.8% compared with control at green ripe stage, respectively; sucrose content was significantly decreased by 37.3% and 33.7% compared with control at ripe stage, respectively; total soluble sugar was significantly decreased by 63.5% and 59.2% compared with control at green ripe stage, respectively.5. Application of potash at flowering phase efficiently regulated activities of sucrose-metabolizing enzymes and increased sugar content of fruit.The activities of AI and NI reached the highest at ripe stage and the activity of AI was significantly increased by 21.7%, 14.5%, 21.1% and 45.4% compared with applying potash at seedling, fruit enlarging, SFE phases and control respectively when potash was applied at flowering phase; SS activity was significantly increased by 32.6% and 30.3% compared with applying potash at fruit enlarging phase and control at small fruit stage, respectively; application of potash at flowering phase had the best regulation effect on SPS activity and the activities were significantly increased by 68.9% and 54.4% at small fruit stage and green ripe stage compared with control, respectively.6. Application of potash at seedling and flowering phases efficiently regulated activities of sucrose-metabolizing enzymes and enhanced the translocation of photosynthate to fruit.The activities of AI in tomato leaves at small fruit stage were significantly decreased by 15.6%, 9.8% and 17.1%, 11.5% compared with control when potash was applied at seedling and flowering phases, respectively; AI activities in tomato leaves at ripe stage were significantly decreased by 38.8% and 42.7% compared with control respectively; SPS activities of leaves were significantly increased by 44.9% and 37.5% compared with applying potash at fruit enlarging phase and control at small fruit stage, respectively.