Effects Of Grafting On The Growth Of Watermelon Seedlings Under Different Nitrogen,Phosphorus And Potassium Supplies

Watermelon is a high-fertilizer crop,but the problems caused by excessive application of chemical fertilizers are becoming more and more serious.In order to provide a reference for scientific fertilization in the production of grafted watermelon,this study uses pumpkin type rootstock variety 'Strong No.7' as the rootstock,small fruit type watermelon variety 'Nabite' as the scion,through the experiment of different supply of nitrogen,phosphorus and potassium in the hydroponic state of the grafted seedlings and the self-rooted seedlings of watermelon,to investigate its biological properties,and to detect the nitrogen,phosphorus and potassium contents of the aboveground and the underground.The effects of grafting under different nitrogen,phosphorus and potassium supply on watermelon seedling growth and nitrogen,phosphorus and potassium absorption and distribution were analyzed.The main results obtained are as follows:1.Under different nitrogen supply,the grafted seedlings are more resistant to high nitrogen or low nitrogen stress than the self-rooted seedlings;The growth of the underground parts of the self-rooted seedlings is inhibited by the low nitrogen supply;The nitrogen and potassium contents of the self-rooted seedlings are generally higher than the grafted seedlings;Grafting improves nitrogen,phosphorus and potassium absorption,and the increase in the absorption of grafted seedlings compared to self-rooted seedlings is greater under high nitrogen supply than under low nitrogen supply.The nitrogen absorption can be increased by 139.1%,the phosphorus absorption can be increased by 274.6%,and the potassium absorption can be increased by 160.2%.2.Under different phosphorus supply,the aboveground is relatively less affected by phosphorus generally;Grafted seedlings are more resistant to high phosphorus or low phosphorus stress than the self-rooted seedlings;The nitrogen and potassium contents of the self-rooted seedlings are generally higher than the grafted seedlings;For the absorption of nitrogen,phosphorus and potassium,the grafted seedlings are generally higher than the self-rooted seedlings.Under conventional supply,the increase in the absorption of grafted seedlings compared to self-rooted seedlings is greater than that under high phosphorus and low phosphorus supply.The nitrogen absorption can be increased by 95.1%,the phosphorus absorption can be increased by 177.2%,and the potassium absorption can be increased by 121.7%.3.Under different potassium supply,within a certain range(K+50 to K-25),the more potassium supply,the stronger the root system;The nitrogen content of the self-rooted seedlings is generally higher than the grafted seedlings;Grafting improves nitrogen,phosphorus and potassium absorption,and the increase of phosphorus and potassium absorption of grafted seedlings compared to the self-rooted seedlings is higher than that of nitrogen.The nitrogen absorption can be increased by 41.8%,the phosphorus absorption can be increased by 115.3%,and the potassium absorption can be increased by 123.7%;Grafting can improve the ability of watermelon plants to withstand low potassium stress.4.Under the lower supply of nitrogen,phosphorus and potassium,the nitrogen,phosphorus and potassium contents of grafted seedlings were generally lower than that of self-rooted seedlings,but the biomass and nitrogen,phosphorus and potassium absorption are higher than that of self-rooted seedlings.Grafting can improve watermelon seedling nitrogen,phosphorus and potassium excess and starvation stress tolerance;The absorption of phosphorus in watermelon seedlings is more susceptible to the environment influences than nitrogen and potassium,and the demand for nitrogen,phosphorus and potassium is: potassium is the highest,nitrogen is the second,phosphorus is the lowest;Grafted seedlings had the largest increase in phosphorus absorption compared to self-rooted seedlings;The contents of nitrogen and potassium in the aboveground are generally higher than that in the underground,phosphorus is opposite.Grafting reduces the crown-root ratio of watermelon seedlings,and promotes the proportion of underground biomass and the absorption of nitrogen,phosphorus and potassium.The grafted seedlings are more able to adapt to changes in nitrogen,phosphorus and potassium supply than self-rooted seedlings,and have lower soil fertility requirements during production.The application of technology can further increase the cultivation area of watermelon.